[advances in food research] advances in food research volume 5 volume 5 || composition of wines. i....

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Composition of Wines. I. Organic Constituents BY MAYNARD A. AMERINE Department of Viticulture and Enology, College of Agriculture, University of California CONTENTS Page I. Introduction.. ............ .................................... 354 11. General Methods OP Analysis.. ...................................... 356 1. Ethyl Alcohol. ... ......... ......... 7. Other Fixed Acids.. .......................................... 407 8. Volatile Acidity (Acetic Acid). ................................ 407 9. Other Volatile Acids.. ........................................ 412 ......... 413 VI. Carbohydrates .................................................... 418 419 6 ................ 423 3. Sucrose ...................................................... 424 ......... ........ 353 Composition of Wines. I. Organic Constituents BY MAYNARD A. AMERINE Department of Viticulture and Enology, College of Agriculture, University of California CONTENTS I. Introduction.. . . . . . . , , 111. Alcohols and Related Compounds. . 1. Ethyl Alcohol.. . . . . . . . . . . . . . 2. Methyl Alcohol. . . . 3. Higher Alcohols.. . 5. 2,3-Butylene Glycol, Acetylmethylcarbinol, and Diacetyl IV. Aldehydes and Related Compounds.. . . 1. Acetaldehyde.. , , . . . . . . . . . . . . . . . 2. Acetal .... . . . . . . . . . . . . 3. Acetone and Benzaldehy 4. Hydroxymethylfurfural 5. Acrolein 11. General Metho s . . . . . . . 4. Glycerol .............. V. Acids.. . . . . .... . . 1. Titratable Acidity. . . 2. Tartaric Acid.. 3. Malio Acid. . . . . 4. Citric Acid., . . . 5. Succinic Acid. . . 6. Lactic Acid.. . . . . . . . 7. Other Fixed Acids.. . . . ... 8. Volatile Acidity (Acetic Acid). . . 9. Other Volatile Acids. . . . . . . . . . . . 10. pH.. .. . . . . . . . . . . . . . . . . . . . . . . . 1. Hexoses.. . . . . . . . . . . . . . . . . . . . . . . 2. Pentoses and Related Compounds VI. Carbohydrates.. . . . _ .......... 6. Extract ..... . . . . . . . . 1. Tannins.. . . . . . . . . 2. Color-Red Wines. 3. White Wines.. . . . . Page 354 356 358 359 366 368 372 377 382 382 385 385 385 386 386 390 391 395 397 402 403 407 407 412 413 418 419 423 424 . 424 , 426 428 430 I 435 436 441 447 353

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Page 1: [Advances in Food Research] Advances in Food Research Volume 5 Volume 5 || Composition of Wines. I. Organic Constituents

Composition of Wines. I. Organic Constituents

BY MAYNARD A. AMERINE

Department of Viticulture and Enology, College of Agriculture, University of California

CONTENTS Page

I . Introduction.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354 11. General Methods OP Analysis.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356

1. Ethyl Alcohol. . . .

. . . . . . . . .

. . . . . . . . .

7. Other Fixed Acids.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407 8. Volatile Acidity (Acetic Acid). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407 9. Other Volatile Acids.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412

. . . . . . . . . 413 VI. Carbohydrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418

419 6 . . . . . . . . . . . . . . . . 423

3. Sucrose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424

. . . . . . . . . . . . . . . . . 353

Composition of Wines. I. Organic Constituents

BY MAYNARD A. AMERINE

Department of Viticulture and Enology, College of Agriculture, University of California

CONTENTS

I. Introduction.. . . . . . . , ,

111. Alcohols and Related Compounds. . 1. Ethyl Alcohol.. . . . . . . . . . . . . . 2. Methyl Alcohol. . . . 3. Higher Alcohols.. .

5. 2,3-Butylene Glycol, Acetylmethylcarbinol, and Diacetyl IV. Aldehydes and Related Compounds.. . .

1. Acetaldehyde.. , , . . . . . . . . . . . . . . . 2. Acetal . . . . . . . . . . . . . . . . 3. Acetone and Benzaldehy 4. Hydroxymethylfurfural 5. Acrolein

11. General Metho s . . . . . . .

4. Glycerol . . . . . . . . . . . . . .

V. Acids.. . . . . .... . . 1. Titratable Acidity. . . 2. Tartaric Acid.. 3. Malio Acid. . . . . 4. Citric Acid., . . . 5. Succinic Acid. . . 6. Lactic Acid.. . . . . . . . 7. Other Fixed Acids.. . . . . . . 8. Volatile Acidity (Acetic Acid). . . 9. Other Volatile Acids. . . . . . . . . . . .

10. p H . . . . . . . . . . . . . . . . . . . . . . . . . . .

1. Hexoses.. . . . . . . . . . . . . . . . . . . . . . . 2. Pentoses and Related Compounds

VI. Carbohydrates.. . . . _ . . . . . . . . . .

6. Extract . . . . . . . . . . . . .

1. Tannins.. . . . . . . . . 2. Color-Red Wines. 3. White Wines.. . . . .

Page 354 356 358 359 366 368 372 377 382 382 385 385 385 386 386 390 391 395 397 402 403 407 407 412 413 418 419 423 424

. 424 , 426

428 430

I 435 436 441 447

353

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354 MAYNARD A . AMERINE

Page IX. Nitrogenous Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 448

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 448 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 448

449 4. In Clouding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451 5. Amounts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452

X. Enzymes, Vitamins, and Aromatic Constituents.. . . . . . . . . . . . . . . . . . . . . . 454 1. Vitamins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 456 2. Aromatic Constituents . . . . . . . . . . . . . . . . . . . . . . . 461

XI. Summary. . . . . . . . . . . . . . . . . . . . . 464 Acknowledgments . . . . . . . . . . . . . 466

3. In Fermentation and Aging.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

References.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 466

I. INTRODUCTION

Whereas Pasteur, Berthelot, and other chemists of the last century studied wine' from a biochemical point of view, the emphasis in enology since 1900 has been primarily on determining the percentage of the various constituents normally present in the wines of a given region or type, on studies to detect sophistication, or on the influence of processes on the composition of wines. More recently, however, enologists have again studied wine from the biochemical point of view. The nature, source, and fate of the constituents of wine have thus been investigated and the results interpreted biochemically.

The present review is limited to the organic components of wines and to publications in the period 1930 to 1953. Both phases of enology will be reviewed, but it is obvious that the more significant studies have been those of a physical-chemical nature. The organic components of wines are discussed in broad general groups-acids, carbohydrates, alcohols, etc. For each component, information on the methods of determination is given first, followed by a review of work on the occurrence or significance of the compound.

During this period many text books and reviews have been pub- lished. Among these are Seifert (1938), Garoglio (1941-1942), Vogt (1945), Ventre (1946-1947), Cruess (1947), Genevois and RibBreau- Gayon (1947), Ribdreau-Gayon (1947), Sannino (1948), Amerine and

1 In this review wine is the fermented beverage of the fruit of one of the several species of Vitis. Other terms which may be unfamiliar include: table wine, a wine of 14% or less of alcohol; dessert wine, a wine of over 14% alcohol; must, unfermented grape juice with or without the skins; free-run, the juice which drains from the crushed grapes without pressing; fortified wine, a wine to which alcohol distilled from wine (fortifying brandy) has been added during or after fermentation; racking, the transfer of wine (less its sediment) from one container to another; fining, the use of organic or inorganic materials to assist clarification; and lees, the sediment which is deposited after fermentation.

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COMPOSITION OF WINES 355

Joslyn (1951), Benvegnin et al. (1951)) Frolov-Bagreev and Agabal’gnG (1951). Amerine (1951) included an annotated list of 171 of the most important books now available. The problems of reviewing the enological literature have been studied by Amerine and Wheeler (1951) and Kiel- hofer (1952), both of whom noted the more important reference sources. Reviews of work on the chemistry of wine from about 1920 to 1937 were given by Reichard in Bleyer (1938) and Hewitt (1939). A review of the period 1927 to 1936 was given by Kielhofer (1937). Practical wine- making advances are particularly well-covered. A selected list of recent publications on fermentation physiology, wine-handling, and wine chemistry have been reviewed by Hennig (1951-1953). German, Russian, and American articles were included, with lesser attention to French, Spanish, and Italian work.

Reviews of the process of alcoholic fermentation have been made by Joslyn (1940a, 1949), Cruess (1950), Genevois (1949b, 1950), Meyerhof (1952), and Antoniani (1951a, b). Many of the mutual chemical inter- relationships of microorganisms and musts and wines are reviewed by Schanderl (1950). Although only a limited amount of chemical data is included, Schmitthenner (1937) has reviewed 50 years of the micro- biological aspects of enology.

Germany. The technical enological problems of the Moselle region were summarized by Petri (1932). Use of ultraviolet light, production of low-alcohol and normal sparkling wines, and differentiation of wines made from normal and sugared musts were considered the primary problems. Kramer (1942) summarized the latest problems in winery practice as removal of arsenic, influence of yeast strains, malo-lactic fermentation, aging of wines, wine diseases, and wine analysis. A brief review of the status of German viticulture and enology on the eve of World War I1 was made by Husfeld et al. (1939). Among the most important of these from the chemical point of view were reports on the danger of using pure aluminum in wineries; recovery of oil, oenin, tartaric acid, and other products from the pomace; and methods of analysis. Further advances in German enology were reported by Eckert (1950). Among the subjects discussed were the errors of the chlorbenzaldehyde procedure for sorbite, the use of citric acid, and the earthy taste resulting from bentonite. An excellent account of the analytical procedures used in Germany was given by Reichard in Bleyer (1938).

Hungary. An excellent summary of the enological work being pursued in Hungary was given by Dicenty et al. (1935), including a discussion of such fundamental problems as methods of determining the organic acids as benzoic esters, detection of concentrate in wines, studies on the use of potassium ferrocyanide for removal of iron and copper, changes in alcohol

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356 MAYNARD A. AMERINE

in wines under various conditions of humidity, and studies on the fructoselglucose ratio. So65 et al. (1948) also reviewed Hungarian re- search on the aromatic principles in grapes and with strains of yeasts and molds and their influence on the process of fermentation.

Other Countries. A review of the applied aspects of viticulture and enological research in France was made by SBmichon (1948). An informal review of selected research in enology (mainly American) was presented by Cruess (1942). Numerous articles on various phases of the biochemistry of wine appear in the publication of the Institut Biokhimii of the Akad- emifa Nauk (1947-1950) of Russia. Sherry, brandy, and sparkling wines are favored subjects for study. K a t a r ’ h (1951) reviewed the enological work of the Magarach Institute: the malo-lactic fermentation, production of sherry, use of bentonite, and studies on the redox potential.

11. GENERAL METHODS OF ANALYSIS

Reviews of methods of analysis of wines have been published by Anonymous (1933, 1934, 1937), Fabre (1936), Dujardin et al. (1938), Azevedo (1942), Garoglio (1941-1942), Campllonch-Romeu (1945), RibBreau-Gayon and Peynaud (1947a), Florentin (1948), Sudario (1949) , Association of Official Agricultural Chemists (1950), Hennig (1950) , Joslyn (1950), Jaulmes (1951), and Amerine (1952). The books by RibBreau-Gayon and Peynaud and Jaulmes are probably the best discus- sions of the analysis of wines now available. They include original research and comments on procedure. General studies and criticisms of the methods of analysis of wines have been presented by Malvezin (1931), von der Heide (1934), Marcilla (1934) , Anonymous (1935) , RibBreau- Gayon and Peynaud (1946a), Valaer (1947) , Garino-Canina (1948, 1950), Godet (1949), and RibBreau-Gayon (1949).

A special congress on wine analysis was held in Rome in 1935. Reports concerning this congress and comments on the results are given by Filaudeau (1933) , Benvegnin (1934), Anonymous (1935) , and Marcille (1937). Godet (1949) noted that too many empirical procedures and methods of expressing the results were used. He recommended milli- equivalents per liter. The primary problems in this usage arise in the analyses where mixtures of substances are determined : total acidity, extract, etc. He recommended that all methods should be clearly defined as to objective, principles, apparatus, analytical steps, method of expres- sion, and sources of error. The 6th International Congress of Viticulture and Enology in 1950 also studied the general problem of analysis of wine. The results were summarized by Garino-Canina (1950) and Anonymous (1952). These reports are valuable in indicating the differences in pro- cedures and definitions among various countries and the general dissatis-

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COMPOSITION OF WINES 357

faction with the lack of preciseness in certain methods: extract, alkalinity of the ash, tannin, etc. The methods followed in the National Department of Public Health in Brazil were reviewed by Bicalho (1933) and those used in Venezuela by Noguero (1942). The Italian (and some other) pro- cedures for preventing the sophistication of wines and for protecting named types of wines were reviewed by Garino-Canina (1951b). He noted the variation in regulations between various countries and the need for more attention to control of antiseptics.

Reviews of less general interest were given in many reports. Comments on methods of wine analysis were made by Marcille (1933) with respect to indicators, standard solutions, and volatile and total acid determina- tions. fjumuleanu and Ghimicescu (1935) reviewed their micro pro- cedures. Comparative results of various methods for alcohol, extract, and total acidity were given by Joslyn and Marsh (1935). A brief summary of the methods of wine analysis in use in California was given by McCharles and Pitman (1936). Various analytical methods were discussed by Bremond (1937~) and Lagneau (1945). Special procedures for deter- mining the less common fermentation by-products were given in Neish (1950). SBmichon and Flanzy (1932a) proposed dichromate oxidation of various acids. HeyrovskJi el al. (1933) applied his polarographic procedure to the determination of fructose and malic acid in wines. Various im- provements in the electrochemical methods for wine analysis were reported by Mestre and Garcia (1947). They used barium hydroxide titration for determination of ash and sulfates, silver nitrate for chlorides, and lanthanum nitrate for strong and weak acids. The procedures used in their studies on sherry wines were detailed by Bobadilla and Navarro (1949). The detection of grape wine in blackberry wine was studied by spectrophotometric means by Beyer (1945). Various analytical uses of the photoelectric colorimeter in wineries were outlined by Barini-Banchi (1949). Jaulmes (1950) described an elaborate steam-distillation appa- ratus suitable for the determination of ammonia, alcohol, volatile acidity, and other constituents in wines.

Chromatography. Ramos and Oliveira (1949) made chromatograms of port wines. A native clay and aluminum oxide were used. The presence of elderberry wine in ports could be detected. Use of chromatography as a means of detecting sophistication was also proposed by Valaer (1949).

Hozumi and Sat6 (1950) used paper-partition chromatography to demonstrate d-maltose as one of the sugars present in a Japanese white wine. Sulser (1951) described a procedure to detect tartaric acid, sorbitol, fructose, glucose, and glycerol in wines and these, citric acid, and hy- droxymethylfurfural in vinegars. Marsh and Kean (1951) also applied the technique to detect grape in berry wine. Identification of foreign

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358 MAYNARD A. AMERINE

colors which may occur in wines was successfully accomplished by paper chromatography by Ruf (195213). The general advantages of the pro- cedure were summarized by Ruf (1952a). Data on the behavior of various fruits including white and red grapes in a chromatography column of aluminum oxide were given by Jakovliv (1952).

Statistical Analysis. Application of statistical methods to analytical data on wines has not been common. Oliveira (1941), however, made a detailed statistical study of the analyses of various constituents in 600 white and 1071 red port wines. The frequency curves are somewhat asymmetric, particularly for the volatile acidity; this is, perhaps, to be expected in dessert wines-where a small constant amount is formed during fermentation and where the quantity present increases slowly during aging. The averages were:

Type of No. of port samples

Volatile acidity (% acetic) Red 1068 White 400

Total acidity (% tartaric) Red 1070 White 600

Alcohol (% by vol.) Red 1068 White 600

Range of 98% Mean of samples 0.066 0.035-0.126 0.058 0.30 -0.099 0.41 0.30 -0.55 0.37 0.28 -0.50

- 19.4 19.3 -

Hickinbotham and Ryan (1948) made a useful application of analyses of variance to data obtained on the factors influencing the formation of glycerol during fermentation. Heitz et al. (1951) also applied several interesting statistical procedures to data obtained in connection with the influence of aeration and various constituents of the wine on the changes taking place during baking of sherry. Bohringer (1943) used statistical procedures in determining the probable error of refractometer readings.

111. ALCOHOLS AND RELATED COMPOUNDS

The organoleptic and physiological properties of alcoholic beverages are largely conditioned by the ethyl alcohol they contain. Wines are classified, taxed, and bought and sold according to alcohol content. Therefore, great attention has been given to its accurate and rapid determination. Less attention is paid to methyl alcohol as a component of beverage wines, but its toxicity has led to many reports on its presence in brandies and in the wines from which they were distilled. Higher alcohols are apparently of some importance in the odor of some wines, and of course they play an important role in brandies. Glycerol, 2,3- butylene glycol, and acetylmethylcarbinol are related products of lesser importance. Mixtures of methyl, ethyl, isopropyl, n-butyl, and isoamyl alcohols can be resolved by partition chromatography according to Neish (1951), and 2,3-butylene glycol does not interfere. Antoniani

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(1951b) has reviewed the theories for the production of glycerol, acetyl- methylcarbinol, 2,a-butylene glycol, higher alcohols, succinic, citric, formic, acetic, and lactic acids, methyl alcohol, and isobutylene glycol. Need of more work on higher alcohols, citric acid, isobutylene glycol, and formic acid, particularly, was noted.

1. Ethyl Alcohol

Wines may contain from 8% to 24% alcohol2 depending on the sugar content of the grapes, the amount added during or after fermentation, if any, and the losses that occur during fermentation or aging. A number of general studies on accurate alcohol determination have been made, among them Fabre and BrBmond (1935), Joslyn et al. (1937), and Mica1 (1949). Fairly complete discussions will also be found in RibBreau-Gayon and Peynaud (1947a) , Joslyn (1950) , Jaulmes (1951) , and Amerine (1952).

Methods-Ebulliometric. Enology has made more use of ebulliometry than any other industry. A dozen different instruments are in use throughout the world for the rapid determination of the per cent alcohol. An historical review of ebulliometry in enology and data on the proper construction of ebullioscope scales from water :alcohol boiling point data were given by De Astis (1933). He constructed an ebullioscope on the basis of these studies. Unfortunately wine is more than a water-alcohol mixture, and the boiling point is influenced by the other constituents. The amount of change in the boiling point depends on the concentration of electrolytes and nonelectrolytes, the tendency of the liquid to separate into two phases, and the volume occupied by the dissolved materials. Most of the studies have been directed toward reducing these errors. Joslyn et al. (1937), RibBreau-Gayon and Peynaud (1947a), and Jaulmes (1951) have discussed the historical and theoretical aspects of the determination. On the basis of collaborative analyses, Joslyn et al. (1937) concluded that results accurate to f0.2% may be expected. Prior to using the ebullioscope Korotkevich (1949) distilled 25 ml. into a 50-ml. volumetric flask. Correction factors to apply to the usual empirical ebullioscope scale were given. His results also agreed with the pycnometer to f0 .2%. Errors in the ebulliometric determination of alcohol in wines of -0.2% to f1 .5% were found by Lherme (1933), who discouraged their use in white wines and did not find that a table of correction based on sugar content was acceptable. His results sug- gest that studies based on an analysis of variance might prove valuable in determining the influence of the various factors on the apparent boiling point. Bertin (1933) reported that below 1% sugar there was little influence of the sugar on the boiling point.

Jaulmes (1951) has emphasized that many ebullioscope scales are incorrectly constructed as to the relation between boiling point and per cent alcohol. He considers De Astis’ (1933) data the best for correcting such scales. De Astis (1941) has also given useful information on the relation of barometric pressure and boiling point. Not only is this important in the construction of ebullioscope scales, but abrupt changes in barometric pressure occasionally occur and cause errors. Balestrazzi (1952) presented a simple method for correcting the ebullioscope reading for changes due to barometric pressure.

Various Italian ebullioscopes were tested by Cusmano (1949). In the sweeter, more alcoholic wines the De Astis ebullioscope gave better results than the Malligand. An * The alcohol content of wines is customarily expressed as per cent by volume.

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example of the variation between ebullioscopes is SBmichon and Flanzy's (1934) report of 0.05% to 0.4% difference in alcohol with three instruments. The Dujardin- Salleron ebullioscope has been discussed by Churchward and Johns (1940) and Church- ward (1953), who found that the thermometers supplied with the 1901 model of Dujardin-Salleron Ebulliometer (official in France since 1907) did not agree-errors in excess of 0.1" were not uncommon. They also found that for precise work the slide- rule disc was unsatisfactory owing to irregularities in the graduations. They published a set of tables for use with the Dujardin-Salleron ebullioscope in which the British Proof Spirit value is given for each ebulliometer degree-the depression of boiling point measured in "C. This system has been officially adopted by the Australian Excise Authorities. The ebulliometer reading on dry wines gives a direct indication of spirit content. For sweet wine the reading was corrected by the following formula: True P.S. = Apparent P.S.(l - "B6. X 0.015).

Some errors of the method and of the instruments in the ebulliometric determina- tion of alcohol were pointed out by Niehaus (1934). Dilution of sweet wines was recommended. A table for correction of ebulliometric determinations of sweet wines was given by Churchward and Johns (1940). As Amerine (1952) has indicated: "The presence of sugars in dessert wines is a complicating factor in the determination of per cent alcohol based on the boiling point. According to Raoult's law dissolved sub- stances, such as sugars, raise the boiling point. However, this increase in the boiling point of sweet wines is usbally somewhat less than that which would be indicated by the per cent alcohol. This lower boiling point of sugar-alcohol solutions is usually explained by considering that sugar is insoluble in alcohol and that the sugar thus occupies a part of the volume that would otherwise contain the water-alcohol mixture. The per cent alcohol determined by the ebullioscope is thus generally slightly higher than that determined by distillation procedures. The presence of aldehydes and esters likewise is a complicating factor, they lower the boiling point and thus indicate too high a percentage of alcohol. In an attempt to avoid the error due to sugars it is com- mon practice to dilute sweet wines two or three times. Whether this avoids the error or not is doubtful as the result must be multiplied by the appropriate factor which likewise multiplies the relative error."

Bertin (1933), for example, showed that addition of increasing amounts of sugar (and water to maintain a constant volume) gave an increasing per cent alcohol by the ebullioscope. He corrected the ebullioscope reading by multiplying the per cent sugar by 0.05 and subtracting the value obtained. Emiliani (1938) calculated a correction equal to 1.001A + 0.0262 - O.OOSAZ, where A is the per cent alcohol determined and Z the per cent sugar in the wine. Procopio (1939) calculated a correction of M z - (MzZ o*62), where M1 is the per cent alcohol found with the Malligand

1 on --- ebullioscope and 0.62 is a factor which represents the volume occupied by 1 g. of sugar. Paronetto (1950) has reviewed the various proposals (Bertin, 1933; Emiliani, 1938; Procopio, 1939) as well as his own which have been made for correcting the alcohol determination by the ebullioscope according to the amount of sugar present. The deviation from the true value by the various formulas (in per cent alcohol) were:

-0.21 -0.11 0.00 +0.01 +0.11 +0.21 Outside to to to to to to Outside

Procedure -0.31 -0.31 -0.20 -0.10 +O.lO +0.20 +0.30 +0.31 Total Bertin 6 2 5 11 12 7 9 20 72 Emiliani 1 1 6 19 29 11 3 2 72 Paronetto - 5 5 27 11 2 - 2 52 Procopio 5 1 6 23 18 16 2 1 72

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Venezia (1949) criticized Procopio’s formula based on analysis of 54 wines, and Procopio (1950~) replied that the anomalous results are inconsequential. Analysis of 86 sweet wines of his own showed the ebullioscope value corrected by Procopio’s formula to vary from -0.38 to +0.42, but 71 of the values were within f O . l . He gives further data in a later publication (1950d), using density and a table for calcu- lating the correction.

Further difficulties in determining the alcohol content of sweet wines using the ebullioscope were found by Tartaglia (1950). He also noted that the esters lowered the boiling point, and some of the difference between ebulliometric and distillation procedures could be traced to this. He doubted if a correction formula could be used. Jaulmes (1951) reported very variable results on the same wines according to the instrument used.

A slightly different type of ebullioscope was described by Fantoni (1949). In this a lower flask, containing water, is first heated and the boiling point determined. Then two-thirds of the wine in an upper flask are distilled into the lower flask, the volume is brought to the same as that of the wine, and the boiling point is again determined. Empirical tables were given for calculating the alcohol content. This procedure is probably better than determining the boiling point directly, but it takes more time.

Double ebullioscopes are on sale in this country, and Errichelli (1952) reported a new one in Italy. The advantage of these is that the boiling points of the water and the wine are determined at the same time.

Methods-Hydrometric. The limitations of the hydrometer for determining the alcohol content were indicated by Luckow (1935). He discussed the problems of making to volume, clean dry hydrometers, time required for equilibrium, free floating of the hydrometer, clean cylinders, and other frequently neglected factors influencing accuracy. The method for the exact determination of alcohol by distillation as used in Peru was reviewed by Pozzi-Escot (1949). No new points are involved, though he stresses careful distillation to prevent losses of alcohol (adequate condenser capacity, dilution of sample, delivery tube in water in the receiver, etc.). Jaulmes (1951) gave a complete theoretical discussion on the separation of alcohol from wine.

A spiral still, with three spirals in series, vertical axis, and eccentric movement, was proposed by Piazza and Rouzaut (1939) for the distillation of alcohol from wines. Results higher by 0.1% to 0.2% compared to those with the ebullioscope were ob- tained. Using the apparatus Rouzaut (1939) was able to obtain all of the alcohol in 7 minutes. Hanak (1932) proposed an all-glass apparatus which Colombier and Clair (1936) have adopted for the distillation of wines. The latter investigators claim results from 0.1% to 0.2% higher than with the usual apparatus.

Marcel and Bastisse (1942) recommended neutralization of the wine prior to distillation. They suggested use of calcium hydroxide instead of potassium carbonate for neutralization of the wine before distillation in order to remove foam-producing materials.

Wines high in sulfur dioxide should be treated for its removal before distillation. Got (1947) showed that wines of 15% to 18% alcohol and 200 to 400 p.p.m. of sulfur dioxide yielded results 0.2% to 0.5% low. Use of concentrated alkali in a bubble cap in the condenser prevents sulfurous acid from distilling over and gives a better distil- late for the determination of alcohol, according to Rocques (1950).

Zheltkevich (1951) suggested manufacture of smaller alcohol hydrometers in order to reduce the volume of distillate required. The necessity of checking the scale of each hydrometer was emphasized by Luckow (1931). Errors in alcohol hydrometers of 0.4% were found by SBmichon and Flanzy (1934). Joslyn et al. (1937) on the basis of collaborative analyses reported that results accurate to +0.1% should be obtained

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with alcohol hydrometers. Jaulmes (1951) noted differences in "certified" French hydrometers of -0.23 to +0.06 of the true value. Later (1953) he found errors of about f. 0.15 between French alcohol hydrometers. These, however, are not graduated as closely as American alcohol hydrometers. However, he notes that there are errors due to surface tension and inherent in the tables of temperature correction. He, there- fore, calculated a new table. The corrections at 10% and 20% alcohol in his table and in the United States table are as follows:

Temperature, 10 % 20 % "C. Jaulmes U. S. Jaulmes U. S.

20 (68°F.) 0.80 0.71 1.41 1.33 25 (77" F.) 1.75 1.65 2.87 2.81

There thus appears to be an error of about 0.1 % in the American tables. Jaulmes and Marignan (1953) have calculated the corrections to be applied when a hydrometer calibrated a t 15" C. (59" F.) is used a t 20" C. (68" F.).

Methods-Pymmetric. Details for the accurate use of the pycnometer were out- lined by Twight (1951). He stressed the necessity of an accurate calibration of the pycnometer and control of temperature. Rankine (1952) obtained results to +0.05% when proper attention was given to temperature control. He recommended use of a water bath set slightly above room temperature and pycnometers calibrated to the same temperature. Botelho (1939) preferred the pycnometer for the determination of alcohol.

Gomes (1941) has made a thorough study of the factors affecting the distillation of alcohol from port wines. Among these were: volume distilled, per cent of amyl alcohol, ethyl acetate, acetic acid, or acetaldehyde present, amount of rectification, and distillation a t reduced pressure. Using the pycnometer he obtained slightly lower results with a high acetic acid percentage and slightly higher results when amyl alcohol, ethyl acetate, or acetaldehyde were present.

Bordas and Touplain (1930) have defined the fundamental terms used in alco- holometry and recommended the use of the apparent density in commerce rather than the absolute density. Bordas and Roelens (1930) also prepared some useful tables on the temperature corrections a t below-zero temperatures. The influence of acetic acid on the determination of the specific gravity of the alcoholic distillate has been calcu-

1OOOd - 0.42a where is lated by Errichelli (1950). The true specific gravity equals looo - 0.3981a,

the density as measured and a is grams of acetic acid per liter. This assumes that 42% of the acetic acid is found in the distillate, which is only an average value. He calculates that the volatile acidity must exceed 0.146% to have an influence on the density of the alcoholic distillate in wines of 16% to 18% alcohol, over 0.150% in wines of 13% to 15% alcohol, and over 0.155% in wines of 10% to 12% alcohol. To simplify the calculation Errichelli gives a table of 0.42a and 1000-0.3981a for values of a from 0.130 to 0.50. Palieri (1950) has criticized these values as being too high and calculates

approximately that IOOOz + HAc - - 5 = 10000, where z is the corrected

density of the alcoholic distillate, HAc the weight of the acetic acid in grams per liter in the distillate, and D the density of the distillate in the presence of the volatile acidity.

Methods-Refractometric. A rapid method for determination of alcohol in wines by refractive index was developed by Newton and Munro (1933). Use of their formula for the immersion refractometer determination of alcohol was found inapplicable to

HAc 1.4

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COMPOSITION OF WINES 363

Argentinian wines by Pr6lat and Mendivelzda (1934), probably because the formula assumes that the extract is only sucrose. Use of the immersion refractometer was also recommended by Sampietro and Invernizzi (1940). Tables and procedures for the cor- rections due to acidity were given. The practicability and accuracy of the refracto- metric method for determining alcohol and extract of wines was demonstrated by Jilke (1950, 1951), who obtained very close agreement between the refractometer and hydrometer values for twenty-three Rhine wines. Use of a direct-reading immersion refractometer was proposed by Fischl (1942). Formulas for various ranges of alcohol and sugar were devised and an error of 0.5% indicated.

The theory of the use of the refractometer as applied to alcohol determination in wine was reviewed by Bohringer (1951a). He obtained good correlation between the refractive index of the wine and that calculated from the refractive indices of the alcohol and the extract. He then showed how to calculate the alcohol content of dry table wines when the refractive index and extract content or the refractive index and specific gravity of the wine are known. Formulas and tables are given to facilitate the calculations. Either dipping or sugar refractometers can be used for the determination of alcohol and extract in wines, according to Vetscher (1947). Equations for both are given.

Methods-Chemical. Fabre and Br6mond (1935) compared pycnometric, hydro- metric, ebulliometric, and chemical methods for determination of alcohol and for the most accurate results preferred the chemical over the pycnometric. The former is hased on oxidation of the alcohol with dichromate. Prior to chemical determination of alcohol in sweet wines and vermouth, Paronetto (1938) used a double distillation, the second one with alkali. A special adaptation of the chemical method for the determina- tion of alcohol was proposed by Schulek and R6zsa (1939), in which the distilled alcohol was purified by adsorption on charcoal.

Fessler (1941) gave a practical procedure for the dichromate method. Later modi- fications of the Fessler procedure were outlined by Zimmermann (1949). Dubrowskaja (1946) diluted the wine 1 to 60 and used only 8 ml. of the diluted wine plus-5 or 6 ml. of water. This is made slightly alkaline, and 8 ml. are then distilled into 10 ml. of stand- ardized potassium dichromate (plus 5 ml. of concentrated sulfuric acid). Then 10 to 15 ml. of 20% potassium iodide are added; after 5 minutes 200 to 250 ml. of water are added; and the iodine released is titrated with thiosulfate to a starch end point. A modification of the chemical oxidation procedure to eliminate calculations was de- veloped by Barini-Banchi (1948).

Ferrari (1949) studied the Hoppler method for the chemical determination of alcohol. This is based on oxidation with dichromate in the presence of sulfuric acid, adding iodide, and titrating the iodine with thiosulfate. He studied temperature, time of reaction, order of adding the solutions, volume, and concentration of alcohol and the reagent. Results comparable to those of the pycnometer method were obtained. Cordebard (1939) and Jaulmes (1951) reported better results using a nitric acid- dichromate mixture.

A microchemical procedure was devised by Prange (1941). Only 1 ml. is required and the dichromate-oxidation procedure was employed. If the wine was made alkaline prior to distilling, high results were obtained. A similar micro procedure was used by Tomaghelli (1942). An error of only 0.1% was claimed. A colorimetric modification of the dichromate oxidation method was developed by Williams and Reese (1950). They used dilute solutions and measured the violet color of the residual dichromate ion with s-diphenylcarbazide at 540 m l . Chromic ion does not interfere, and Beer’s law is followed. Other alcohols interfere but no more so than in other similar pro-

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cedures. The economy of time and material and the precision of the results are the main advantages of the chemical method.

Other Methods. Remy (1932) calculated the alcohol content from the formula 73 - W/n , where W is the absolute surface tension of the wine and n the ratio of the absolute surface tensions of water and alcohol less 0.2. The error was said to be f0.13 g. per 100 ml.

Another physical method is that of Etienne (1950, 1952) and Etienne and Breyer (1951). This is based on the principle of extracting the alcohol with an immiscible solvent and reading the per cent alcohol from the position of the meniscus. They used 70 ml. of pentasol (synthetic amyl alcohol), 28 ml. of toluene, and 1.8 ml. of 10% hydrochloric acid in a specially calibrated tube. The determination requires about 5 minutes, and an accuracy of f0.5% from 5% to 22% alcohol is claimed. Wines which tend to emulsify should be pretreated with charcoal. Etienne (1952) has reported on a collaborative study of about 100 determinations with his tube. In 43% of the cases the values fell within rt0.15% of those determined by the pycnometer, 60% of the values were within f0.3, and 94% fell within f0.5. To reduce error he found that the temperature should be controlled a t 25.5" C. (78" F.); in any case, the test should be conducted between 21.1" and 29.4" C. (70" and 85" F.)

Ettinger (1947) used a capillary tube, sealed a t one end, containing a drop of wine to determine the alcohol content of wine. The tubes were slowly heated in a water- sulfuric acid bath and the temperature of the bath noted when the wine rose in the capillary. The per cent alcohol is determined from special tables. Reid and Truelove (1952) have developed a colorimetric procedure using ceric ammonium nitrate. This appears useful for small amounts of alcohol and may find winery applications for analyses of still slops, pomace washes, etc.

Alcohol Yield. Ever since Pasteur's studies the alcohol yield in fer- mentation has interested enologists as well as law enforcement agencies. Use of sugar by yeasts, losses of alcohol by entrainment, and difficulties in density determination make the calculation difficult. Furthermore, a little alcohol may result from hydrolysis of glucosides. Savary (1940) suggested that the Pasteur balance needed to be revised in certain cases because he obtained higher than predicted yields. Perard (1939, 1940) reaffirmed his belief in the Pasteur balance. Rustia (1949) determined the alcohol yield during fermentation. Using a factor of 0.6 to convert un- fermented sugar to alcohol (by volume), he then calculated the theo- retical yield at various stages of the fermentation. He found an increase in the ratio alcoho1:sugar up to 10% sugar fermented and a decrease thereafter. The over-all efficiency varied from 0.52 to 0.58 compared t o Pasteur's 0.611 and the theoretical of 0.64. Calculation of the original sugar content of the must based on the alcohol content of the finished wines was studied by Benz (1931). He used a factor of 0.45 for the sugar- to-alcohol conversion (by weight). Niehaus (1937), however, obtained yields of 0.476 and 0.477. He reported that only very small amounts of alcohol were lost by evaporation during fermentation even from open fermenters. The fermentations were conducted on musts with and with- out the skins.

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COMPOSITION OF WINES 365

The alcohol yield from a given amount of sugar is of great interest to winery operators. Although it should be obvious that there can be no constant factor of sugar-to-alcohol (because of variation in environ- mental conditions and microflora), many enologists continue to search for one. Bassler and Trauth (1934), for example, found the alcohol yield (by volume) to vary from 57.0% to 61.8% (average 58.7%) of the actual sugar content. They found that at the higher sugar contents there was an apparently greater yield of alcohol per degree of sugar fermented. Muth (1934) obtained similar results. The disagreement on the exact relation between the sugar content of the must and the resulting alcohol content of the wine was reviewed by Trauth and Bassler (1936). They did not find the nonsugar content to vary with maturity, and the alcohol yield was remarkably constant. However, the yield was larger than predicted from the sugar constant of the must (which earlier workers reported as 45% based on a sugar-to-alcohol conversion) and amounted to 46.4% to 47.1% (by weight). Various formulas for predicting the yield from density only were investigated. The yield of alcohol (in per cent by volume of the sugar content) for different types of musts, based on the actual sugar content of the musts, according to Miconi (1952a) is given by the factor: white, 0.60; pink (1 to 2 days on skins), 0.58; red (de- stemmed, 4 to 6 days on the skins), 0.56; red (not destemmed, 4 to 6 days on skins), 0.54. The relation of alcohol yield to the specific gravity of the must as measured by several formulas was studied by Balavoine (1939). No very definite conclusions were reached as to the preferred procedure. The problem is that the Oechsle and other hydrometers measure not sugar but total soluble solids.

In contrast to other investigators Stradelli (1951) calculates that the amount of alcohol lost by entrainment by carbon dioxide is very small. Direct evaporation from a hot cap and losses during transfer are more important. Bolcato et al. (1941) reported losses by entrainment of 0.7% to 0.8% of the alcohol produced, the loss varying with the height of the must in the fermenter. Flanzy and Boudet (1949) found a loss of about 0.1 % alcohol for a fermentation temperature of about 30" C. (86" F.) and a negligible loss a t 5" C. (41" F.). The type of fermentation is the other variable to be considered.

Vogt (1934) showed that musts of low acid and medium-to-high sugar contents produce more alcohol than would be anticipated from the specific gravity, and conversely that high-acid low-sugar musts yield less. The relationship is not exact, since the alcohol is related to the sugar content and not to the specific gravity of the must. Fischler (1937) also indicated that unexpectedly high alcohol yields are obtained in very warm years, such as 1921 and 1929, probably owing to some of the high-sugar

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shriveled berries not being crushed sufficiently to provide their propor- tional share of the sample. The low-sugar and very high nonsugar solids of the 1936 Moselle musts were found by Kielhofer and Gunther (1937) to yield from 55.6% to 62.63% alcohol (by volume), average 59.75%. In very cold (low-sugar) seasons Seiler (1938) has shown that the alcohol yield, based on total soluble solids, is notably low-owing, no doubt, to the greater percentage of acids in the total soluble solids content. In very warm (high-sugar) years Fischler (1938) has again demonstrated the opposite result. Rather large deviations in the alcohol yield from year to year were noted by Seiler (1936a) in Moselle wines, but no special corrections for sugaring were found necessary in 26 years experience.

Another factor is the strain of yeast employed. On the same must Beckwith (1935) obtained 12.2% to 12.8% alcohol, using eight yeasts. The lower values, however, were wines with residual sugar. Ventre (1936) reported stable strains of Saccharomyces ellipsoideus which had different alcohol-producing properties.

2. Methyl Alcohol

Methods. The difficulty of determining methyl alcohol in the presence of ethyl alcohol was stressed by Ionescu and Popesco (1930). They investigated various pro- cedures and recommended reactions with salts of mercury either on the pure alcohols or on products of their oxidation. A review of the methods of determining methyl alcohol in wines was given by SBmichon and Flanzy (1931b). Their oxidation pro- cedure to formaldehyde and its determination in the distillate yielded almost quan- titative results. Flanzy (1934a, b ; 1935a, b) reviewed the previous methods and made a detailed study of the determination. His micro-method is lengthy and is essentially a research procedure. Von Fellenberg (1937) employed the Denigbs reaction. A detailed colorimetric procedure for-amounts of methyl alcohol as small as 0.01 % to 0.02 % was described. Ant-Wuorinen and Kotonen (1935-1937) made a careful study of the factors influencing the accuracy of the colorimetric determination. Cerutti and Vedani (1951) described a modification of Ant-Wuorinen’s procedure. A simple qualitative colorimetric procedure for detecting amounts of 0.5% or more of methyl alcohol in wines was presented by Brune (1948). Bertrand and Silberstein (1948) studied the DenigAs reaction and suggested several improvements including use of a photoelectric colorimeter. Mariani (1950) also studied the colorimetric procedure. Exact details for the preparation of the reagents and timing of the procedure are given.

Although the reports of Guymon (1951) and St. Mokranjac and Radmic (1951) were primarily directed toward spirits, their results are applicable to the determination of methyl alcohol in wines. They investigated the factors influencing the development of color with Schiff’s reagent using the Denigbs procedure. As little as 1 mg. of methyl alcohol in 100 ml. of 0.95% ethyl alcohol could be determined. Hall et al. (1962) used the DenigAs reaction but used chromotropic acid for the development of the color.

A micro-method was proposed by Leon061 (1946). The methyl alcohol is first con- centrated by fractional distillation and then carefully oxidized with a dichromate-

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COMPOSITION OF WINES 367

sulfuric acid mixture, and the carbon dioxide produced is purified and measured. Results accurate to 2% with 2 mg. of methyl alcohol were reported. By careful control of oxidation conditions, Zeglin (1952) reported a procedure sensitive to 0.02%. Akiya and Sasao (1951) neutralized and distilled the wine, oxidized the diluted distillate with permanganate, and determined the color with chromotropic acid.

Hunkk’s (1938) procedure for oxidation of methyl alcohol to formaldehyde by bromine in the presence of sugar is capable of detecting only 5% of the alcohol. A colorimetric procedure for methyl alcohol in vinegar was developed by Piccoli (1933). Jauker (1937) tested various procedures and used a semiquantitative method said to be sensitive to 0.0001%.

The volume of sodium hydroxide required to produce cloudiness in 80% ethyl alcohol is proportional to the methyl alcohol content and can be used for its deter- mination, according to Charles (1938). Since only two alcohols may be present at once, the procedure does not appear to be of interest in alcoholic beverages. A micro- method based on formation of methyl p-bromobensoate mas described by Goldbach and Opperschaum (1950).

Source. The general conclusion is that methyl alcohol is not produced in alcoholic fermentation. Cerutti (1951), for example, found no methyl alcohol after fermenting an artificial must. He also showed that glycine is not a source of methyl alcohol, which is a theoretical possibility accord- ing to Antoniani (1951b). Bertrand and Silberstein (1949-1952, 1950- 1952) have shown that methyl alcohol does not result from the alcoholic fermentation of sugars but that it is probably derived from the hydrolysis of the naturally occurring pectins of the grape skins. Peynaud (1952), using Bertrand and Silberstein’s (1950-1952) data on white and red wines, calculated that 0.023%, to 0.066% pectin would have to be hydrolyzed in white musts and 0.082% to 0.112% in reds to account for the methyl alcohol. Kilbuck et al. (1949) and Hall et aE. (1952) reported that use of pectolytic enzymes increased the methyl alcohol content. The latter found the increase greatest when added to the pomace. This does not agree with Flanzy’s (1934b) concept that methyl alcohol is one of the minor products of alcoholic fermentation. Jauker (1937) found little or no difference in the amounts of methyl alcohol formed in various substrates using pure cultures or wild yeasts. Flanzy (1951) fermented all his wines on the skins, and he questions whether wines fermented out of contact with the skins would contain much methyl alcohol.

Amounts. Bertrand and Silberstein (1949-1952) considered Flanzy’s (1935a, b) values only approximately correct because of the procedure used. Their range and averages, however, were approximately the same as Flanzy’s. Jauker (1937) found only 0.5 t o 10 mg. per liter in four wines and none in three others. Data on the methyl alcohol content of other alcoholic beverages were also given. Col$escu et al. (1941) reported as much as 0.3 g. of methyl alcohol per 100 ml. in wines of hybrid vines.

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Data on the methyl alcohol content of various wines are given in Table I.

TABLE I Methyl Alcohol Content of Various Wines

(Grams per liter) No. of Mini- Maxi- Aver-

Region Type of wine Source of data samples mum mum age France Table Bertrand and Silberstein 21 0.038 0.188 0.103

France Vitis vinijera Flanzy (1951) 121 0.050 0.282 0.089 France Hybrids Flanzy (1951) 15 0.066 0.200 0.136 France White table Bertrand and Silberstein 9 0.041 0.114 0.071

France Red table Bertrand and Silberstein 7 0.062 0.200 0.146

Greece Vitis vinijera Flanzy (1951) 4 0.177 0.185 0.181 Italy White table Cerutti (1951) 17 0.000 0.182 0.040 Italy Red table Cerutti (1951) 43 0.000 0.635 0.103 U. S. White Hall et al. (1952) 10 0.004 0.018 0.016 U. S. Red Hall et al. (1952) 7 0.014 0.026 0.021

(1949-1952)

(1949-1952)

(1949-1952)

3. Higher Alcohols

The alcohols above ethyl in the series are generally spoken of as higher alcohols. An extensive literature on their presence in brandy has developed because of their importance to the organoleptic character of brandy. Much less information is available for wines. The chief higher alcohols found are isoamyl (3-methyl-l-butanol), active amyl (( -)-2- methyl-1-butanol), n-propyl (1-propanol), isobutyl (2-methyl-1-propa- nol), n-butyl (1-butanol), and ( - ) sec-butyl (2-butanol). Others doubtless occur and will be identified as better methods for their separation are developed. Buscar6ns (1941) fractionated (under vacuum) a fusel oil from wine pomace and identified amyl, propyl, isobutyl, butyl, and isopropyl (2-propanol)alcohols as esters and higher alcohols up to decyl. No higher secondary alcohols were found. The residue consisted of esters, fatty acids, furfural, cylic bases, and hydrocarbons. Only acids with an even number of carbon atoms were demonstrated. The unsaturated acids oleic and linoleic were present in small amounts, presumably from the seeds. Ethyl esters were more important in amount than amyl esters. There was 3% furfural, 5.5% fatty acids (free and esterified), 30.9% ltlcohols (free and esterified), and 1.6% hydrocarbons (terpene). Dupont and Dulou (1935) demonstrated sec-butyl alcohol in a technical propyl alcohol that had been produced from fusel oil.

The presence of isopropyl alcohol in wines has been the subject of some controversy. Bodendorf (1930), for example, demonstrated iso- propyl alcohol in brandy, but his procedure was rather insensitive.

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Flaney and Banos (1938) also isolated isopropyl alcohol from the fusel oil of a wine. They calculated that wines contain a t least 6.6 mg. per liter. Metra et al. (1938), however, were unable to detect this alcohol in samples from wines or from the heads using a colorimetric procedure reputedly sensitive to 0.01 % of this alcohol. They concluded that isopropyl alcohol may be present only in traces, if at all. I n the fraction of the heads boiling at 27.8" to 30" C. (82" to 86' F.) only sec-butyl alcohol was found in a wine distillate by Durodie and Roelens (1942) ; and isopropyl alcohol was not detected.

More recently Webb et al. (1952) reported no isopropyl alcohol in a wine fusel oil sample. They did find 4.1% n-propyl, 1.9% n-butyl, 4.9% (-)-sec-butyl, 18.3 % isobutyl, 9.6 % (-)-2-methyl-l-butanol, 54% isoamyl, trace of n-amyl, 1.5% n-hexyl, 5.6% esters, and traces of acetic and butyric acids and acetal. The esters included 0.19% ethyl caproate, 0.60% ethyl caprylate, 0.52% isoamyl caprylate, 1.32% ethyl caprate, 0.38 % isobutyl caprate, 0.58 % ethyl laurate, 0.25 % ethyl palmitate, a trace of butyrate ester, 0.06 % myristate ester. Probably present were methyl salicylate, isoamyl caprate, active amyl caproate, isoamyl caproate, active amyl caprylate, isobutyl caprylate, active amyl caprate, active amyl laurate, and isoamyl laurate.

Methods. The higher alcohols are usually determined by a colorimetric procedure based on a condensation reaction with an aromatic hydroxy aldehyde such as p-di- methylaminobenzaldehyde, vanillin, or salicylaldehyde-the Komarowsky reaction. Von Fellenberg (1929) studied the details of time and color intensity by this pro- cedure, using three different mixtures of higher alcohols. Siirgi (1932) revised the method to a micro-procedure and gave exact details for its execution. Trost (1935) also studied the reaction and gave information on it. In this country the Penniman el al. (1937) modification is used. A slightly different variation was used by Guymon and Heitz (1952) and Osborn and Mott (1952). A spectrophotometric modification of the Komarowsky-Fellenberg procedure was proposed by Federico and Cioffi (1947). Salicyaldehyde is used for development of the color. Guymon and Heitz (1952) sug- gested that differences in procedure may have accounted for the somewhat high values reported by Cioffi (1948). A systematic study of the influence of concentration, per cent alcohol and sulfuric acid, temperature, time, etc., of the Komarowsky reaction was made by Gierer and Hoffman-Ostenhof (1951) and a micro-procedure developed; with this they obtained results to &2% with concentrations of 0.2 to 2 mg. per 100 ml. using only 0.5 to 1 ml. A similar study was made by Rosenthaler and Vegezzi (1953).

Moreno (1934) and Clavera and Moreno (1936) showed that methyl alcohol inter- feres in the determination of higher alcohols by the procedure of Rose (which depends on the increase in volume of chloroform with higher alcohols under specified condi- tions). They obtained a curve for correcting for this error. Bonaterra (1949) developed a procedure based on the color developed by higher alcohols in alcoholic furfural- sulfuric acid mixtures.

A procedure to determine isopropyl alcohol in alcoholic beverages is given by Alessandrini (1933). It is based on Noetzel's procedure of oxidation to acetone and the reaction of acetone with hydroxylamine hydrochloride.

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Formation. The mechanism of the formation of higher alcohols has been studied by Zalesskaya (1938), Cioffi (1949), and Castor and Guymon (1952). Zalesskaya (1938) also reported that higher alcohol formation coincided with the beginning of the main fermentation and that the amount produced increased as the amount of fermented sugar or the less the initial number of yeast cells present. Cioffi studied the influence of various fermentation inhibitors on amino acid utilization during fer- mentation. He found less higher alcohols were produced in the presence of sodium arsenite (either on an absolute basis or relative to ethyl alcohol production). Sodium sulfite reduced the production relative to ethyl alcohol production in comparison with hydrogen cyanide, but the amounts produced were about the same, and the quantity of the amino acids deaminated was greater; Castor and Guymon showed that the formation of higher alcohols paralleled ethyl alcohol formation. Contrary to expectation, amino acid disappearance preceded higher alcohol appear- ance. They explained this by suggesting that the enzyme systems of the latter stages of the conversion of sugar to ethyl alcohol and of amino acids to higher alcohols are identical. Their finding that more higher alcohols were formed than could be accounted for by amino acid disap- pearance was accredited to formation at the expense of the yeast% own proteins. Luers (1948) found higher alcohol formation in beer to occur during the later stages of fermentation and to be independent of amount of yeast. An increase in fermentation temperature resulted in an increase in amount of higher alcohols produced. In potato and molasses fermenta- tions, Kilp and Deplanque (1934) found higher alcohol formation to occur generally before ethyl alcohol production.

Genevois (1952) suggested two mechanisms for conversion of amino acids to higher alcohols: an “endogenous” metabolism of yeast protein, in which for each kilogram of sugar fermented 2 to 4 g. of amino acids were utilized, and an “exogenous” metabolism on the amino acids of the media, in which 10 to 12 g. of amino acid were utilized per kilogram of sugar fermented.

Yamada (1932) found higher alcohol production to depend on the presence of amino acids. However, in the presence of glutamic acid, asparagine, or ammonium phosphate or sulfate only traces of higher alcohols were produced. Addition of nitrogenous materials during fer- mentation reduces the deamination of amino acids ‘and also the pro- duction of higher alcohols, according to Antoniani (1951s). Antoniani and Cioffi (1949) found the higher alcohol content of a Saccharomyces ellipsoideus fermentation of grape juice to be as follows when glycine was added:

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COMPOSITION O F WINES 37 1

Amino N, Ammonia N, Higher mg./lOO ml. mg./100 ml. alcohols,

Alcohol Before After Before After mg./100 ml. Control-200 ml. 7 . 8 8 . 6 2 . 8 0 .14 0.00 0.052 +170 mg. glycine 7 . 8 22.2 3 . 4 0 .14 0.00 0.217 +250 mg. glycine 7 . 8 30.0 9 . 1 0.14 0.00 0.242 +420 mg. glucine 7 . 7 42.1 23.5 0.14 0.00 0.251 +670 mg. glycine 7 . 7 62.4 46.5 0 . 1 4 0.00 0.315

Gobis (1950) also showed that addition of 50 mg. of ammonium sulfate decreased the higher alcohol from 0.060 ml. for 100 ml. to 0.025 ml. Castor (1950) reported 30% less higher alcohols when ammonium phosphate was added, and Vogt (1952) reported a 50% reduction when the chloride and asparagine were added.

Amounts. Casale (1934) reported 0.85 and 0.73 g. per liter of higher alcohols in two wines fermented a t a starting temperature of 0" to 3" C. (32" to 37.4" F.). Mestre and Mestre (1939), however, reported 0.86 and 0.95 g. per liter of higher alcohols in musts fermented a t room tempera- ture, and 1.00 and 1.00 when fermented a t 4" to 12" C. (39.2" to 53.6" F.). In seventy California dessert wines Filipello (1951) reported 0.125 to 0.685 g. per liter.

Other data on higher alcohol content of wines have been summarized by Guymon and Heitz (1952), who add extensive analysis of California wines (see Table 11). They reported lower results than Cioffi (1948)

TABLE I1 Higher Alcohol Content of Various Types of Wines

(Grams per liter)

Region wine Source of data samples mum mum age

California White table Guymon and Heita (1952) 120 0.162 0.366 0.250 California Red table Guymon and Heitr (1952) 130 0.140 0.147 0.287 California Dessert Guymon and Heita (1952) 117 0.156 0 .90 0.374 Italy White table Cioffi (1948) 12 0.44 1.37 0 .87 Italy Red table Cioffi (1948) 22 0 . 1 4 1.72 0.77

(Italian wines) and less in white table wines than red-also contrary to his findings. Their results are similar to those of Pettigiani (1943) (Argen- tinian wines). In California dessert wines, very variable results were obtained by Guymon and Heitz, probably because of the varying amounts of higher alcohols in the fortifying brandies employed.

Type of No. of Mini- Maxi- Aver-

Argentina Unknown Pettigiani (1943) 24 0.15 0 .30 -

Filipello (1951) found a high degree of negative correlation,

T = -0.480

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372 MAYNARD A. AMERINE

between the amount of the higher alcohol present in the wine and the organoleptic score of the wine. Pool and Heitz (1950) also reported that high-fuse1 brandies produced poor dessert wines. Genevois (1952) and Guymon and Heitz (1952) suggested that higher alcohols may play a role in the odor of wines. The latter reported a red table wine with an obvious higher alcohol odor which was confirmed by analysis.

4. Glycerol

While glycerol usually constitutes from 0.5% to 1.5% of wines, it is seldom determined, particularly in sweet wines, because the procedures for its determination are long and tedious and often inaccurate. However, next to alcohol, it is the major product of fermentation present in wines. It has a measurable influence on taste, and it is sometimes used in the enological ratios to detect sophistication. Whereas it figures in most of the schemes depicting the several stages of fermentation, its exact genesis has not been evaluated, according to Antoniani (1951a).

Methods. Peynaud (1947b) has reviewed the primary problems of glycerol deter- mination in wine: separation from sugars, 2,3-butylene glycol, and other oxidizable organic materials, and prevention of loss by heating and clarification or during extrac- tion. Pritzker and Jungkunz (1930a, b) apparently were the f i s t to point out that 2,3-butylene glycol might interfere in the glycerol determination but that, as the determination is normally conducted, no correction is necessary. The standard United States procedure (Association of Official Agricultural Chemists, 1950) removes the sugars by treatment with a freshly prepared, carbonate-free calcium hydroxide solu- tion. Although this is fairly satkfactory for table wines, it is seldom so for dessert wines. Pritzker and Jungkuna (1930a, b) demonstrated that when the official German evaporation procedure is used (for table wines) practically pure glycerol, uncon- taminated with 2,3-butylene glycol, is found. Espil's (1936) lead subacetate-lime- copper procedure involves a voluminous precipitate from which it is difficult to extract glycerol. The FerrbMichel (1938) method removed 2,3-butylene glycol as an inter- fering substance but is long and tedious. Fleury and Fatome's (1935) and Fatome's (1935) alkali or alkali-plus-lead-acetate clarification may not remove all interfering substance. Peynaud (194713) objected to this procedure, used by Amerine and Dietrich (1943), as leading to the production of methylglyoxal from sugars. However, this would apply only to sweet wines and only when the sugar-alkali mixture is heated excessively. Vasconcellos (1946) used lead subacetate in an ammoniacal solution for removal of acids and sugars. Satisfactory results were also obtained by Thaler and Roos (1950) using a basic clarification. They attributed the variable results obtained in most methods to the volatility of glycerol in aqueous solutions and recommended that glycerol solutions should not be boiled. They modified the Fleury and Fatome (1935) procedure so as to avoid mannite interference by using a methanol/acetone (1/8) mixture rather than ether/alcohol (1/3). Barium hydroxide was used for removal of acids and sugars. The 2,a-butylene glycol was not removed. Whereas most pro- cedures proposed for the determination of glycerol depend on purification by alkali treatment, Sfimichon and Flanzy (1930a) proposed distilling the glycerol. They and von Fellenberg (1931) entrained the glycerol with steam a t 115" C. (237" F.). Chroma-

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COMPOSITION OF WINES 373

tography separation is also practical. Purified ether or isopropyl acetate were recom- mended by Jacquin and Tavernier (1952) for extraction.

A certain polemic has developed over the question of the possible loss of glycerol during evaporation. Von Fellenberg (1931), for example, found none, but it may be significant that the standard United States procedure cautions against local over- heating during evaporation. Further data were given by Jaulmes (1951), who reported a very low volatility.

Once the glycerol is separated, various methods have been used for determining it. The Association of Official Agricultural Chemists (1950) procedure requires weighing the extracted glycerol before and after ashing and subtracting the ash; or for oxidation with dichromate. When dichromate oxidation is employed, an aliquot should be tested for sugars, except in the case of the S6michon and Flanay (1930a) and von Fellen- berg (1931) procedures, where the glycerol is separated by steam. Oxidation with dichromate was also employed by Ferr6 and Michel (1938), Pavolv-Grishin (1940), and Korotkevich and Arbuzova (1949). Determination of glycerol in wines by periodic acid oxidation is now common. The basic reaction is that of Malaprade: CH20HCHOHCHZOH + 2HIO4 -+ 2HCOH + HCOOH + 2HIOs. Various meth- ods of determining the extent of the reaction have been devised-Fatome (1935), Fleury and Fatome (1935), Amerine and Dietrich (1943), Vasconcellos (1946), Peynaud (1948b), and Thaler and Roos (1950). Peynaud (1948b) made a notable improvement in removing 2,3-butylene glycol, which causes a 4% to 7% error. Lambert and Neish (1950) used the periodic oxidation, the excess iodate or periodate being reduced with sodium arsenite, and the formaldehyde colorirnetrically deter- mined with chromotropic acid.

A number of colorimetric procedures have been devised. Bertram and Rutgers (1938) used the fixing of cupric ion by glycerol as the basis of their procedure. The color produced by methylglyoxal with morphine and its derivatives was used by Legkov (1931). The glycerol was oxidized to dioxyacetone and then converted to methylglyoxal. Greater sensitivity and accuracy compared to the usual procedure was claimed. A similar micro-procedure was proposed by Prado (1934)-the bromine oxidation was used to prepare dioxyacetone and colored derivatives were then pre- pared. As an alternative he also converted the dioxyacetone to formaldehyde with sulfuric acid. Compared to the usual weighing procedures high values were obtained. A micro-colorimetric procedure was developed by Ghimicescu (1935f). The glycerol was oxidized by bromine and the product determined colorimetrically by pyro- catechine. He obtained good recovery of glycerol added to a white wine. A colorimetric procedure in sugar-free wines was developed by Diemair et al. (1940), and a semi- quantitative procedure was developed by Cunha (1939)4ecolorizing the wine, treating with bromine, resorcinol, and sulfuric acid, and matching the color produced with that of similarly treated standard glycerol solutions.

In Dessert Wines. Pritaker (1940a), considering the problem of accurate glycerol determination in sweet wines, recommended determining the amount of reducing sugar in the glycerol extract and subtraction of the amount found. Using calcium oxide and magnesium carbonate for clarification, he found from 2 to 11 mg. of sugar in the extract with 47 to 141 mg. of glycerol. Von Fellenberg’s (1943) micro-method avoids the coprecipitation of the alkaline-treated sugars and glycerol by use of large amounts of acetone. He distills to separate 2,3-butylene glycol. The possibility of methyl- glyoxal production in the hot methanol-barium hydroxide-sugar mixture should be considered. Recovery from sweet wines was 95% to 106%. Hog1 (1952) proposed separating the glycevol from the sugars in dessert wines by paper chromatography. The solvent was a miiture of ethyl alcohol, butyl alcohol, and water in the proportions

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374 MAYNARD A. AMERINE

1.1/4.0/1.9. Silver nitrate was used for developing the chromatogram. The wine was first run through an anion exchanger to remove acids. The method can be made quan- titative to about fO.O1 g. per 100 ml. by the use of standard glycerol solutions. He recommended the method as a means of distinguishing fortified musts from dessert wines which had been fortified after some fermentation. Hydroxymethylfurfural, various types of sugars, and sorbite can be similarly determined. For a colorimetric method in connection with the determination of lactic acid, see p. 404.

Source. Hickinbotham and Ryan (1948) believed glycerol imparts smoothness to wines and in particular ameliorates the burning taste of alcohol. They review previous work on the factors influencing the pro- duction of glycerol in wines. They found less in laboratory-prepared wines than in larger trials and questioned whether the low carbon dioxide pressure in small fermenters may not have an effect. Analysis of variance of their data showed more glycerol in fermentations a t 13" and 22" C. and less a t 28" and 36" C. (82.4 and 96.8" F.). They believe that high tem- perature of fermentation is one reason Australian wines have less glycerol than European. Brockmann and Stier (1948) also found less a t higher temperatures and suggested as a cause lower phosphatase activity, which would reduce hydrolysis of glycerol-1-phosphate. However, Uchimoto (1951) found the glycerol content increased as the fermentation tem- perature was increased from 12.8' to 32.2" C. (55" to 90" F.). This might be associated with the greater number of yeast cells present a t the higher temperatures of fermentation. Amerine and Webb (1943) showed that the per cent glycerol in California dessert wines was lower than what would be expected, even taking dilution and the shorter period of fer- mentation into account.

Hickinbotham and Ryan (1948) found a significant difference in the ability of different yeasts to produce glycerol. Some musts and seasons led to significantly higher yields than others. Using eight yeasts, Beck- with (1935) obtained 0.54 to 0.71 g. of glycerol per 100 ml. in duplicate fermentations. Anibal (1935) found glycerol formation to be faster a t the start of the fermentation. The ratio of succinic acid to glycerol also

100 X g. glycerol/l decreased during fermentation. He used the ratio

g. alcohol,l. * to determine addition of alcohol or water. When this ratio falls'below 6, sophistication may be suspected. In connection with their calculations of the balance of fermentation products in Bordeaux red and white wines, Genevois et al. (1949a) have shown that the high glycerol content of certain sweet wines resulted from its production by Botrytis cinerea growing on the grapes. In some cases the glycerol produced by fermenta- tion was less than that found in the grapes. Ferr6 and Michel(l938) using their relatively foolproof procedure found 0.60 to 1.1 g. per 100 ml. of glycerol in sound Burgundy wines, and 1.04% to 1.51% in wines made

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COMPOSITION O F WINES 375

from moldy grapes. The glycerol, as per cent of alcohol, varied from 6.5 to 9.6 in the sound grapes, and from 10.1 to 12.5 in moldy grapes. These results substantiate earlier investigations. Schumakov (1930) studied the influence of sulfur dioxide on the production of glycerol. Daily additions of 21 to 63 mg. of sulfur dioxide per liter increased production by 0.42% to 0.61 %. To increase glycerol production he recommended daily addition of sulfur dioxide in amounts just short of that needed to stop fermenta- tion. This would also increase the “fixed” sulfur dioxide content by fixing acetaldehyde as it is produced by fermentation. Venezia and Gentilini (1941) studied the possibility of using poor-quality grapes for the produc- tion of glycerol by sulfite fermentation. They obtained yields of as much as 7.8% using 10% yeast at 15” C. (59” F.) with very high sodium sulfite and a pH of 9.1. As much as 35% of the sugar fermented was converted to glycerol. Addition of a “2” factor (from boiled yeast) stimulated glycerol production according to Venezia (1939-1940) , but the effect decreased as the sulfite content increased. Changes in glycerol due to bacterial action are discussed by Osterwalder (1952).

Amounts. A summary of the glycerol content of a variety of types of wines is given in Table 111. Whereas there is much variation between averages, there is also a wide range within the types-owing no doubt to the varying amounts of glycerol in moldy grapes, to diperences resulting from fermentation practices, to varying amounts of sugar, and of course to dilution owing to fortification or watering.

Alcohol/Glycerol Ratio. This ratio has been thought to be of diagnostic value, a low ratio indicating higher quality. The data of Table IV indicate that this has limited validity. Von Fellenberg (1943) found normal alcohol/glycerol ratios for wines prepared from raisins-9/20. In fer- mented apple and pear juice Jacquin and Tavernier (1952) found less glycerol formed than in grape fermentations-ratios varying from 10 to 18.7. In order to calculate the ratio of fortified wines on the basis of the glycerol and alcohol produced by fermentation Amerine and Webb (1943)

(100 - A ) F * 1375 - 13.754 - 55E 100 - A - 0.55E ’ proposed the formula __ 1 where F =

A is the per cent alcohol, E the extract of the fortified wine. G, the glycerol corrected for dilution by fortification, is defined as equal to G(1OC) - F )

1 where G is the glycerol in grams per 100 ml., F* is in grams (1UO - A ) per 100 ml., and F in milliliters per 100 ml. Using this formula and assuming an initial soluble solids content of 25” Balling, they found slightly below normal ratios for California dessert wines. Post-Repeal California wines seemed to have more uniform and normal alcohol/ glycerol ratios than pre-Prohibition wines.

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376 MAYNARD A. AMERINE

Region

Algeria

Argentina Argentina Australia

California California Czechoslovakia France

France

France France France Germany

Germany Germany Germany Germany

Germany

Germany

Germany Germany Hungary Italy

Italy

Italy

(Mascara)

Italy

Italy (Sicily)

Italy (Falerno)

TABLE I11 Glycerol Content of Table and Dessert Wines

(Grams per 100 ml.)

Type of wine

Table

Table Table Table

Wh. table Red table Table Table

Table

Table Table* Sparkling Table

Table Wh. table Table Wh. table

Table

(unsugared)

(sugared)

(unsugared) Table

Table Sparkling Wh. table Table

Wh. table

Tablet

Table

Swt. table

Table

No. of Mini- Source of data samples mum Table wine

Bertin (1931) 25 0.67

Prado (1934) Anibal (1935) Hickinbotham and

Ryan (1948) Amerine (1947) Amerine (1947) Kopal (1938) Ferr6 and Michel

Genevois et al.

Peynaud (1950a) Peynaud (1950b) Hennig (1952) Heiduschka and

Pyriki (1930) Alfa (1932) Remy (1932) Alfa (1933) Heide and Zeissett

(1935) Mader (1936)

(1938)

(1948b)

Mader (1936)

Hennig (1952) Hennig (1952) Torley (1942) Sallusto (1936-

Dalmasso and

Sallusto and

1937)

Dell’Olio (1937)

Sculco (1937- 1938)

Sallusto (1938- 1939b)

Sallusto and Di- Natale (1938- 1939)

1939a) Sallusto (1938-

46 39 12

79 60

650 25

31

6 6

14 29

47 10 46 24

11

8

11 43 10 77

143

26

32

30

16

0.37 0.61 0.47

0.63 0.46 0.51 0.57

0.70

0.72 0.79 0.58 0.42

0.43 0.51 0.45 0.49

0.76

Maxi- mum

1.57

1.33 1.05 0.86

1.68 1.43 1.39 1.51

1.04

0.85 2.60 0.95 0.85

1.40 0.87 0.92 1.38

1.42

0.68 1.13

0.56 1.08 0.40 1.10 0.47 1.10 0.64 1.20

0.41 1.00

0.61 1.66

0.62 0.88

0.57 1.57

0.75 1.53

Aver- age

1.07

0.87 0.77 0.63

0.96 1.06 0.83 1.00

0.86

0.80 1.65 0.81 0.59

0.65 0.68 0.72 0.90

1.01

0.89

0.73 0.70 0.74 0.86

0.67

1.30

0.79

1.14

1.03

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COMPOSITION OF WINES

TABLE I11 (Continued)

377

Region Italy Italy Portugal

Portugal

Roumania

Switzerland Tunisia

California France Italy Portugal

Portugal

Portugal

Spain Spain

Spain

Type of wine Table Pink table Table

Table

Table

Table Table

Dessert Dessert Dessert Red port

White port

Port

Dessert Fino

Oloroso

No. of Mini- Maxi- Aver- Source of data samples mum mum age

Lucchetti (1941) Cosmo (1950) Correia and

Ribeiro (1942) Vasconcellos

(1946) Vumuleanu and

Ghimicescu (1936)

Berner (1952) Sallusto (1938-

Dessert wines Amerine (1947) Peynaud (1950b) Pritzker (1940a) Ramos and Reis

(1945) Ramos and Reis

(1945) Vasconcellos

(1946) Pritzker (1940) Bobadilla and

Bobadilla and

1939a)

Navarro (1952)

Navarro (1952)

12 0.44 0.86 0.66 22 0.52 1.24 0.74

114 0.30 1.00 0.70

8 0.73 0.90 0.84

33 0.28 1.28 0.74

25 0.41 0.97 0.65 25 0.92 1.28 1.10

124 0.34 1.671 0.75 8 0.54 0.71 0.58 5 0.36t 0.71 0.54

38 0.11 0.86 0.40

19 0.19 0.48 0.32

17 0.33 0.81 0.54

6 0.24 0.71 0.49 15 0.379 1.023 0.663

10 0.640 1.266 0.743

* Sweet. High glycerol owing to "botrytiaed" grapes. t Average per cent alcohol 16.3: reducing sugar 1.1. $ A mistell. which is aupposed to be a fortified must.

6. 2,d-Butylene Glycol, Acetylmethylcarbinol, and Diacetyl

Another constant product of alcoholic fermentation is 2,3-butylene glycol. Usually this is determined along with glycerol, though it is par- tially lost in the usual evaporative procedures. It can, however, be separated by fractional distillation. Its oxidation product, acetylmethyl- carbinol, is of lesser importance. The oxidation product of the latter, diacetyl, is present in even smaller amounts or is absent. Although 2,3-butylene glycol appears to have little organoleptic importance, the other compounds may play a minor role. Diacetyl, for example, can be detected organoleptically at only 2 to 4 mg. per liter.

Methods. Kniphorst and Kruisheer (1937) made an extensive study-of the deter- mination of 2,3-butylene glycol, acetylmethylcarbinol, and diacetyl in wines. Their procedure, the Legmoigne reaction, is based on oxidation of the two to diacetyl- CHsCHOHCHOHCH3 -+ CHaCOCHOHCHs + CH8COCOCH8.-and its determi-

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378 MAYNARD A. AMERINE

TABLE IV Alcohol/Glycerol Ratios (by Weight) of Table Wines

Region

(Mascara) Algeria

Argentina Argentina Australia

Australia

California

California

Croatia

Type of wines Table

Table Table Table (wh)

Table (red)

Wh table

Red table

Table Czechoslovakia Table France Table

France Table Germany Wh. table

Germany Table

Germany Table

Germany Table Italy Table

(sugared)

(unsugared)

Italy Table

Italy Pink table Italy (Falerno) Table

Italy (Sicily) Swt. Table

Portugal Table

Roumania Table

Tunisia Table

No. of Mini- Source of data samples mum

Bertin (1931) 25 8.0

Prado (1934) Anibal (1935) Hickinbotham and

Ryan (1948) Hickinbotham and

Ryan (1948) Amerine and Webb

(1943) Amerine and Webb

(1943) Pereti6 (1950) Kopal (1938) F e d and Michel

Peynaud (194813) Heiduschka and

Pyriki (1930) Mader (1936)

(1938)

46 3 . 7 39 10.7

6 11.0

6 13.0

68 5 . 6

56 5 . 0

25 4.6 650 7 . 7 25 8 . 7

48 15.4 29 9 . 0

11 8 . 4

Mader (1936) 8 7.9

Hennig (1952) Sallusto (1936-

Sallusto and Sculco

Cosmo (1950) Sallusto (1938-

1939b) Sallusto and Di

Natale (1938- 1939)

Vasconcellos (1946)

_Sumuleanu and Ghimicescu (1936)

Sallusto (1938- 1939a)

1937)

(1937-1938)

11 8.3 77 6 . 5

26 7 .8

22 8 .9 16 7 . 7

30 9 . 3

8 10.0

33 9 . 3

25 8.1

Maxi- mum 16.4

14.0 16.7 15.6

21.7

12.9

11.1

12.4 16.4 15.4

10.2 16.7

12.2

11.2

15.9 10.0

17.5

17.7 15.1

14 .3

11.9

27.8

12.7

Aver- age 11.7

8.7 12.5 14.2

15.6

10.2

9 . 3

8 .9 11.1 10.8

12.2 12.5

10.0

9 . 4

11.4 8 . 1

9 .7

14.0 10 .7

11.1

10.8

13 .3

10.4

nation as nickel dimethylglyoxime. A similar method was used by Pritzker and Jungkunz (1930a, b) and Garino-Canina (1933). The disadvantage is that the oxida- tion is not complete, and a correction factor must be used. The advantage is the large weight factor of the precipitate. Matignon et al. (1934) obtained a yield of only 75.6%. This was a colorimetric procedure, as was that of Moureu and Dod6 (1934). Kniphorst

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COMPOSITION OF WINES 379

and Kruisheer (1937) increased this to 93%. The Lemoigne reaction was also used successfully by Diemair and Kleber (1941) to determine 2,3-butylene glycol and acetylmethylcarbinol. They used a special distillation flask to prevent losses and determined the nickel dimethylglyoxime colorimetrically.

Von Fellenberg (1932a) used chromic acid oxidation, but Kniphorst and Kruisheer (1937) criticized this procedure as yielding high results when only small amounts were present. Perdigon (1941) developed a semi-micro periodic acid procedure similar to Brockmann and Werkman’s (1933) but applied specifically to wines. Peynaud (1947b) criticizes Perdigon’s procedure as being inapplicable because more glycerol than 2,3-butylene glycol is present.

Peynaud (1947a) and Ribbreau-Gayon and Peynaud (1947a) separated the 2,3- butylene glycol from most of the glycerol by steam distillation. The acetaldehyde was removed by refluxing under a Vigreux column. The actual determination was madc by periodic acid oxidation in which 2,3-butylene glycol yields acetaldehyde and glycerol produces formaldehyde. Formaldehyde was fixed by adding asparagine and the acetaldehyde then distilled.

Source. The production of acetylmethylcarbinol during fermentation was studied by Antoniani (19514. Actively fermenting yeasts produced only 2,3-butylene glycol. Moderately fermenting yeasts produced both 2,3-hutylene glycol and acetylmethylcarbinol, whereas weakly fermenting yeasts produced only acetylmethylcarbinol. Antoniani and Gugnoni (1941) reported that Pseudosaccharomyces apiculatus and P . magnus produced only acetylmethylcarbinol and normal wine yeasts only 2,3- butylene glycol. In mixed cultures they found the latter, as the normal wine yeasts predominate. However, when both types were present and the samples were stored in air acetylmethylcarbinol was produced. The question of which yeasts produce 2,3-butylene glycol and which acetyl- methylcarbinol is a complicated one. Peynaud and Lafon (1951b, 1952) have shown that a wide variety of yeasts produce both, but Antoniani considers that some yeasts produce exclusively one and some exclusively the other. Their differences are aired in a polemic (Antoniani, 1953).

The differences may be due to the fact that the analyses were made immediately after the main phase of the fermentation in one case and about 3 weeks later in the other. More data on the conditions in the fermenter, oxidation-reduction potential, etc., the amounts present a t various stages of the fermentation and data on the microflora are needed.

The formation of 2,3-butylene glycol and acetylmethylcarbinol during fermentation was studied by Diemair and Kleber (1941). They found variable amounts of 2,3-butylene glycol in wines, depending somewhat on fermentation conditions. Using a Jerez strain of yeast, they obtained no more 2,3-butylene glycol than with a regular strain of Saccharomyces. This seems to indicate that 2,3-butylene glycol is not produced by an oxidative mechanism. I n the same fermentations, acetylmethylcarbinol was produced in only one case, and in general they conclude that i t is not

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380 MAYNARD A. AMERINE

produced from 2,3-butylene glycol. In acetic fermentations they found a simultaneous increase in acetylmethylcarbinol and a decrease in citric acid but little change in 2,3-butylene glycol-another indication that the production of the former is not from the latter. On the other hand, Kobakhidze (1950) studied the formation of acetylmethylcarbinol during acetification, which may or may not be the same as that of wines. He concluded that 2,3-butylene glycol and not citric acid is the source of acetylmethylcarbinol in the acetic acid fermentation.

Peynaud and Lafon (1951b) reported 2 to 20 mg. per liter of acetyl- methylcarbinol in wines and considered it a product of fermentation. Diacetyl was found in all red wines (2 to 3 mg. per liter), but it was not present in some white wines. I n brandy distilled from wine, Peynaud and Lafon (1951a, b) found 2,3-butylene glycol and acetylmethylcarbinol and traces of diacetyl. They found these not to be related to the quality of the brandy, except possibly diacetyl in some cases, but concluded that they might prove useful in differentiating various brandies. For example, the armagnacs contained about eight times as much 2,3-butylene glycol as did the cognacs. In contrast to cognac the pomace brandies of Burgundy did not contain diacetyl.

In Italian wines Romano (1951) found varying amounts of 2,3- butylene glycol (Table V) but no relation between the amounts of this substance and the contents of alcohol, sugar, total or volatile acidity, or organoleptic quality was noted. Garino-Canina (1933) reviewed the previous work on the presence of 2,3-butylene glycol and acetylmethyl- carbinol in wines and the methods for their determination. He showed that grape juice fermented in the presence of acetaldehyde produced acetylmethylcarbinol. He also reported less in fortified wines and in wines of low alcohol content. Usually 0.2% to 0.66% of 2,3-butylene glycol was found, and the amount reported was proportional to the per cent alcohol. Kniphorst and Kruisheer (1937) also found no acetylmethylcarbinol or diacetyl in twenty-one assorted European wines. The absence of the former was probably due to analytical problems. They pointed out how useful the data on 2,3-butylene glycol was in determining sophistication in wines. Table wines of normal alcohol content and low 2,3-butylene glycol content have been fortified. Dessert wines with no 2,3-butylene glycol have been fortified before fermentation. Rib6reau-Gayon and Peynaud (1947b) observed no relationship between the quantity of 2,3-butylene glycol and that of glycerol. The influence of 2,3-butylene glycol on the organoleptic character of the wine was shown to be small, as it has similar properties to the glycerol, which is present in 10 to 20 times greater amounts. Gobis and Farfaletti-Casali (1952) did not find any direct relationship between the acetylmethylcarbinol content and the

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COMPOSITION O F WINES 38 1

age of the wine, although one might expect more in older wines with their higher oxidation-reduction potential. Differences in the amount of oxygen reaching the wines during aging might account for the lack of correlation. According to Gvaladze and Rodopulo (1946) acetylmethylcarbinol is formed in wines at the expense of 2,3-butylene glycol when Acetobacter aceti begins to grow. Garino-Canina (1933) also showed the presence of large amounts of acetylmethylcarbinol in wine vinegar. In apple wines

TABLE V 2,BButylene Glycol in Various Types of Wines

Region France

France France France Germany

Germany

Italy Italy

Italy

Misc.

Misc.

Misc. Spain

Switzerland

Type of wine

Table

Red table Swt. table Dessert Wh. table*

Wh. tablet

Table White

Red table

Table

Dessert

Table Montilla

Table

(Grams per liter) No. of Mini- Maxi- Aver-

Ribbreau-Gayon and 12 0.328 1.350 0.699

Peynaud (1950a) 6 0 .62 0.78 0.70 Peynaud (1950a) 6 0 .44 1.11 0 .86 Peynaud (1950b) 8 0 .45 1.05 0.65 Diemair and Kleber 25 0.062 0.596 0.220

Diemair and Kleber 35 0.094 0.973 0.365

Romano (1951) 14 0.080 0.980 0.320 Gobis and Farfaletti- 13 0.256 0.810 0.414

Gobis and Farfaletti- 51 0.259 0.986 0.489

Kniphorst and Kruisheer 9 0.379 0.983 0.575

Kniphorst and Kruisheer 9 0.065 0.302 0.260

Krauze (1933) 34 0.73 1.57 1.15 Casares and Gonealee 51 0.269 1.397 0.696

Berner (1952) 22 0.197 0.509 0.311

Source of data samples mum mum age

Peynaud (1947b)

(1941)

(1941)

Casali (1952)

Casali (1952)

(1937)

(1937)

(1953)

* Laboratory fermentations. t Commercial fermentations.

Guittonneau et al. (1941a, b) found Aerobacter aerogenes and A . cloacae to be primarily responsible for the high acetylmethylcarbinol and 2,3- butylene glycol contents.

Amounts Reported. Genevois et al. (1948a) reported 5 to 10 millimoles of 2,3-butylene glycol in commercial fermentations but only 3 to 6 milli- moles in laboratory fermentations. The ratio of 2,3-butylene glycol to glycerol normally varied from 4 to 9, though under different fermentation conditions it was 7 to 12. The presence of 2,3-butylene glycol in amounts up to 0.06% was demonstrated by Pritzker and Jungkunz (1930a, b). Using the Pritzker-Jungkunz (1930a) technique Garino-Canina (1933)

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reported 0.12 to 0.41 g. per liter of 2,3-butylene glycol in Italian wines- and the amount was generally proportional to the alcohol content. Balavoine (1943) reported 0.045 to 0.225 g. per liter (average 0.137) of 2,3-butylene glycol in 6 M4lagas but the best had 0.224; he proposed a minimum value of 0.200. Ramos and Reis (1945) in fifty-seven red and white ports found from none to 0.031% 2,3-butylene glycol, with more in the reds than in the whites. There was a fair correlation between high sugar and low 2,3-butylene glycol, which was to be expected.

Ribbreau-Gayon and Peynaud (194713) reported diacetyl in amounts of 0 to 6 mg. per liter in Algerian wines and 0 to 1 in Bordeaux wines. In

TABLE VI Acetylmethylcarbinol in Various Types of Wines

(Milligrams per liter) Type of No. of Mini-

Region wine Source of data samples mum France Table RibBreau-Gayon and 12 2.0

Peynaud (194713) France Wh. table Peynaud (1950a) 6 4.5 France Red table Peynaud (1950a) 6 6.0 Italy Wh. table Gobis and Farfaletti-Casali 13 3 . O

Italy Red table Gobis and Farfaletti-Casali 51 3.0 (1952)

(1952) Switzerland Table Berner (1952) 12 0.0

Maxi- Aver- mum age 20.0 7.0

12.0 7.0 18.0 11.0 14.3 7 . 0

28.0 6.6

29.3 13.1

the former it could therefore be a factor in the aroma. The amounts of 2,3-butylene glycol reported in other studies are given in Table V, and of acetylmethylcarbinol in Table VI. The amounts of the former reported by Rib6reau-Gayon and Peynaud are appreciably higher than in other studies, but their results for acetylmethylcarbinol fall in line with the others reported.

IV. ALDEHYDES AND RELATED COMPOUNDS

Although acetaldehyde is the primary aldehyde present in wines, there are reports of hydroxymethylfurfural, furfural, and higher alde- hydes. Acetal and acetone are also found in some wines.

1. Acetaldehyde

Acetaldehyde is a normal by-product of alcoholic fermentation, but it may increase during aging owing to oxidation of ethyl alcohol or to the activity of film yeasts. It is easily fixed by sulfur dioxide, so that much of that present is “bound.”

Methods. The total absence of aldehyde from some wines reported by Nelson and Wheeler (1939) was probably due to analytical errors. The primary methods employed

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COMPOSITION OF WINES 383

are the colorimetric procedure with Schiff’s reagent and the distillation procedures in which the aldehyde distilled is received in sulfite or hydroxylamine solution. Teixeria JGnior (1940) showed that low results were obtained if the distillate from the alcohol determination was employed. Charles (1930) used a distillation procedure and titrated with alkali after adding hydroxylamine hydrochloride or used Schiff’s reagent. Com- parable results were obtained. Tarantola (1934) made a study of factors influencing the development of color with Schiff’s reagent, using a Pulfrich photometer and a Lange photoelectric colorimeter. He pointed out that the procedure must be followed exactly in order t o obtain satisfactory results. He did not use carbon dioxide during distillation.

The procedure of Jaulmes and Espezel (1935) is now widely used. It depends on fixing the aldehyde in a buffered sulfite solution, titrating the excess sulfite in acid solution, hydrolyzing the aldehyde-bisulfite complex under alkaline conditions, and then titrating the bisulfite released-which is equivalent to the aldehyde present. Joslyn and Comar (1938) studied this and other procedures. They noted that less than 100% of the aldehyde present is recovered. This procedure can be improved by con- trolling the p H when hydrolyzing the aldehyde-bisulfite complex, e.g., with a less alkaline solution such as bicarbonate. To improve the sensitivity of Jaulmes’s pro- cedure Roche (1948) recommended a more dilute iodine solution and a standard color to determine the end point. He proposed a dilute mixture of basic fuchsin and indigo carmine for this.

A comparison of procedures for the determination of acetaldehyde was made by Iribarne, (1941). The colorimetric Schiff, the bisulfite procedure, and the hydroxylamine method were compared. I n general, the bisulfite procedure gave a better and more regular recovery, but on 49 wines it showed only 101 mg. per liter of aldehyde, and the hydroxylamine, 104.

A polarographic procedure for determining the acetaldehyde content of port wines was developed by Almeida (1950). His results (Table VII) are generally lower than those obtained earlier in port wines by Teixeira Jdnior (1940) using the Jaulmes and Espezel procedure. A summary of the methods for determination of aldehydes was given by Mestre and Campllonch (1942).

While much of the aldehyde present in wines is bound to bisulfite, etc., some is free. Villforth (1940) outlined a procedure for its determination which has also been used by Koch and Bretthauer (1950-1951). It is based on treating ice-cold wine with calcium carbonate and calcium hydroxide, decarbonating with ice-cold barium chloride, and filtering. The filtrate is distilled with calcium carbonate and the alde- hyde determined by the usual procedures. Probably more than the free aldehyde is determined.

Formation. The experiments of Mestre and Campllonch (1942) sup- port the view that acetaldehyde is an intermediary in the process of alcoholic fermentation. In some cases they report high volatile acidity arising from oxidation of aldehydes, even in the absence of bacteria. Uchimoto (1951) found a positive correlation between temperature of fermentation and amount of acetaldehyde formed. Many investigators have demonstrated a rapid rise in the aldehyde content of wines under a film yeast. Ter-Karapetian (1952) has studied the formation of acetalde- hyde in 16% alcohol wines. Aldehyde formation occurred only when the wine was aerated and yeast cells were present. Fornachon (1953) has

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shown that alcoholic suspensions of Saccharomyces beticus accumulate acetaldehyde when shaken in air. Added acetaldehyde is consumed under anaerobic conditions but in nonalcoholic suspensions under either anaerobic or aerobic conditions. The alcohol/aldehyde equilibrium under aerobic conditions varies with the concentration of alcohol, temperature, and the composition of the substrate. (See p. 464 for the relation of acet- aldehyde to the other by-products of alcoholic fermentation.)

Amounts. The presence of acetaldehyde is usually objectionable in red wines. Charles (1930) finds it possible to recognize acetaldehyde in amounts not exceeding 0.1 g. per liter and considers the wine unmarket-

TABLE VII Aldehyde Content of Various Wines

(Milligrams per liter) Type of No. of Mini-

Region wines Source of data samples mum Argentina Table Iribarne (1941) 49 9 California White table Amerine and Joslyn (1951) 480 9 California Red table Amerine and Joslyn (1951) 170 5 California Dessert Joslyn and Amerine (1941) 142 15 France Dessert Peynaud (1950b) 8 62* France Red table Peynaud (1950a) 6 22 France White table Peynaud (1950a) 6 44 France Sparkling Hennig (1952) 13 10

Portugal Port Almeida (1950) 30 20 Portugal Port Teixeira Jtnior (1940) 135 15 Spain Sherry Bobadilla and Navarro 25 90

* Total includes that bound to polyphenols.

Germany Sparkling Hennig (1952) 40 3

(1952)

Maxi- mum

310 92

491 217 264 *

53 84 47

100 90

166 500

Aver- age 101 54 46 87

128* 36 68 20 50 38 95

218

able a t 0.5 g. per liter. Although there is usually a simultaneous decrease in acetaldehyde, color, and tannin contents of red wines during aging, Joslyn and Comar (1941) found that this varied from wine to wine. Furthermore, the higher the initial acetaldehyde content, the more rapid its disappearance during storage. As expected, they found that sulfur dioxide reduced the rate of disappearance of aldehyde. It is of practical interest to note that addition of tartaric acid decreased the rate of acet- aldehyde formation. This aspect of these experiments might be further investigated. Teixeira J6nior (1940) found that in high-quality ports there was slightly greater variation in acetaldehyde and volatile acidity than in poor-quality ports, and the wines of higher quality had a some- what higher acetaldehyde content. The amounts in several types of wines are given in Table VII.

I n untreated German fruit dessert wines Koch and Bretthauer (1950- 1951) reported 22.2, 24.9, 76.7, and 99.3 mg. per liter of free aldehyde. A

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COMPOSITION OF WINES 385

vermouth contained 129.9 and a white table wine, 31.3. Peynaud (1950b) calculated that 0 to about 60% of the total aldehyde in eight French dessert wines was free.

2. Acetal

Little quantitative information is available on the acetal content of wines. RibEreau-Gayon and Peynaud (1947~) gave a procedure based on the fact that acetal distills without decomposition at a pH of 9. The distillate, which also contains the acetaldehyde, is brought to volume, and aliquots are distilled a t pH 9 and 1 to give the acetaldehyde and acetalde- hyde plus acetal contents, respectively. Out of twelve wines they found no acetal in eight, traces in three, and 3 mg. per liter in a port. In brandy the content is much higher, 24 to 118 mg. per liter. Joslyn and Comar (1941) reported 6 and 8 mg. per liter of acetal in two red California wines. Sisakhi et al. (1950a) reported 35 mg. per liter of acetal during fermenta- tion but only 2.7 mg. at the time of the first racking. During growth of a sherry film this rose to 35.4 mg. in six months. They consider the ratio of acetal to acetaldehyde to be an important factor in the quality of sherry- a lower ratio indicating poor quality. This appears to be a fruitful field for further investigation. Sapondzhian and Gevorkian (1953) found that the larger the amount of acetal and the lower the per cent alcohol, the more acid and the longer periods of distillation required to obtain complete recovery. A more specific procedure for acetal is greatly to be desired.

3. Acetone and Benzaldehyde Chelle et al. (1936) developed a colorimetric procedure for the deter-

mination of acetone in wine distillates. They were able to secure good checks with this procedure, even in the presence of considerable amounts of higher alcohols. Acetone was reported in wines to which commercial ethyl alcohoI had been added. No benzaldehyde was found in grapes by Mathers and Schoeneman (1952), but cherries contain significant amounts. During fermentation benzyl alcohol, benzyl, and benzoin are produced from benzaldehyde. A polarigraphic procedure for its determi- nation was developed.

4. Hydroxymethylfurfural Methods. Von Fellenberg (1935) reported on three methods for the determinatiou

of hydroxymethylfurfuratl. He preferred precipitation by phloroglucin and oxidation of the precipitate by dichromate. Kruisheer et al. (1935) criticized the phloroglucin oxidation procedure as giving high results and weighed the precipitate directly. Cunha (1947) developed a semiquantitative colorimetric phloroglucin method. He distin- guished wines with 0, traces, below 60 mg. per liter, and above 60 mg. per 1.

Botelho (1938) and Amerine (1948) used Fiehe’s reagent for a qualitative test. I n Fiehe’s reaction resorcinol in concentrated hydrochloric acid reacts with the hydroxy- rnethylfurfural previously ether-extracted from wine. The amount of red precipitate

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is roughly proportional to the color. Levulinic acid does not interfere. Michel (194813) recommended use of very clean equipment and freshly distilled (over dichromate) and washed ether.

Maaskant (1936) suggested p-nitrophenylhydrazine for its qualitative or quantita- tive determination. Amerine (1948) also used this for preparing the derivative. A somewhat different procedure for identifying hydroxymethylfurfural in sweet wines was developed by Huntenburg (1936). He criticized the phloroglucin procedure as lacking specificity. His rather lengthy procedure is based on heating in acid solution to convert the hydroxymethylfurfural to levulinic acid. This then forms a derivative with l-phenyl-3-methyl-6-oxo-1,4,5,6, tetrahydropyridazine. It is less useful for quantitative studies, as only a 40% yield waa obtained.

Amounts. Kruisheer et al. (1935) first recognized that hydroxymethyl- furfural in wines would not occur in wines which had not been heated or which had not been prepared by heating or by addition of caramel. Genuine ports, for example, had only 0 to 24 mg. per liter.

Botelho (1938) confirmed these results, finding none in 28 genuine port wines of the vintage of 1888 to 1933. Prosstosserdov and Taranova (1949) used phloroglucin for detecting hydroxymethylfurfural in 16 of 24 port-type wines and in 6 of 8 madeira-type wines produced in Russia- indicating rather general heating of these wines during preparation. Amerine (1948) found the same true of 154 California dessert wines-all except 44 contained hydroxymethylfurfural using Feihe's test. Using the phloroglucin procedure 32 to 305 mg. per liter (average 161) were found in 6 California sherry-type wines. Only traces or no hydroxymethyl- furfural occurred in experimental dessert wines that had not been heated. Kniphorst and Kruisheer (1937) found hydroxymethylfurfural in 2 Hungarian Tokay wines, which they therefore believed to have been prepared with concentrate. Spanish wines of Mtilaga and Tarragona were also high in hydroxymethylfurfural, indicating heating or the use of con- centrate. Using this rather specific procedure, Huntenburg (1936) found 5 to 1149 mg. per liter in 7 dessert wines. The largest was in a "dark" Mtilaga to which presumably reduced must had been added. Michel (194813) reported that commercial pasteurization of grape juice for 30 minutes a t 75" C. (167" F.) did not result in formation of hydroxymethyl- furfural, but that use of concentrators and desulfiters did lead to its formation.

6. Acrolein A procedure for the quantitative determination of a c r k i n in musts

and spirits was developed by Wilharm and Holz (1951). It occurs rarely, and then apparently as a by-product by bacterial attack on glycerol.

V. ACIDS The organic acids of wines play an important role in their flavor,

color, and keeping quality. Three are derived from the grape: tartaric,

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malic, and citric; others are produced during alcoholic fermentation : formic, acetic, lactic, and succinic; and some may be formed by bacterial action: acetic, lactic, butyric, and possibly other acids. Markley et aZ. (1938) identified linoleic, oleic, palmitic, stearic, and higher saturated fatty acids of the series CZO to C32 in the saponified bloom of Concord (Vitis Zabrusca) grapes, and oleanolic acid was identified in the ether extract. The enologist is primarily interested in the total titratable acidity, the pH, and the volatile acidity.

In the grape, of course, the total titratable acidity is almost entirely composed of fixed or nonvolatile acids. The relative and total amounts of the two important acids, tartaric and malic, vary greatly from variety to variety, from region to region, or from season to season (for the same variety), and according to the amount of crop, vine diseases, etc. In the wine the fixed exceed the volatile acids five to twenty times. However, the volatile acids are important from the regulatory point of view. See also Ribdreau-Gayon (19384.

General methods for analyzing the organic acids of wine were studied by Gadzhiev (1940) and Torley (1942). Gadzhiev (1940) separated the tartrates (as the acid tartrate) and lactic, malic, and succinic acids by their differential solubilities and varying percentages of alcohol-not an altogether happy solution. A review of the difficulties of determining the organic acids and a comparison of the various methods was given by Saburov et al. (1938). Konek and Wettstein (1934) used benzoyl chloride to separate lactic, malic, and tartaric acids from acetic and succinic acids. At 150’ C. (302” F.) the former are benzoylated and treatment with hot water precipitates the former as insoluble benzoyl malic and dibenzoyl tartaric acids. The acetic acid is distilled in the usual way and the succinic acid determined as iron succinate. The oxyacid precipitate is treated with potassium hydroxide and when reacidified, the benzoic acid precipitates. The tartrate was determined as insoluble potassium bi- tartrate. Deviations of 8% to 10% for malic and 7% to 9% for succinic with known mixtures of the four acids were reported. Paper chromatography was used by Rodopulo (1952a) to identify tartaric, malic, citric, and oxalic acids in musts. In wines succinic and fumaric acids were also reported. He believed formation of fumaric acid to occur by oxidation of succinic acid when wines were stored for a long period under aerobic conditions in contact with a yeast deposit. Mathers (1951) noted that ammonium vanadate was useful in paper chromatography studies on the acids of wines-tartaric acid turning red, citric and malic, yellow, and oxalic, blue. An electrical conductivity method was used by Lakkopoulos (1939) for the determination of citric, malic, and tartaric acids. The procedure (being long) appears to offer little of interest-the values for citric were high (up to 35%), and the tartaric/malic ratio must be 3.7 or greater.

A review of the acids in wines was made by Genevois (1951). Pey- naud’s (1947~) thesis on the organic acids of grapes and wines is also important. Peynaud has developed a number of new methods or has modified older procedures for determining the various organic acids present in musts and wines. These are also summarized by Genevois et al. (1938b), Peynaud (1946), Rib6reau-Gayon and Peynaud (19474, and

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Genevois (1949a). Peynaud has determined the amount of organic acids present in musts and wines and made a balance to show that all the acidic elements were accounted for. The average balance in forty-seven Bor- deaux red wines (average pH 3.40) was given by Peynaud (1947~) as follows (in milliequivalents) :

A. Cations Titratable acidity Alkalinity of the ash Ammonia

Sum of cations B. Anions

Tartaric acid Malic acid Citric acid Acetic acid Succinic acid Lactic acid Acid esters Phosphoric acid Sulfurous acid

Sum of anions

75.00 23.50

1.20

99.70 ___

26.9 2 . 8 1.4

17.4 15.5 25.5 3 . 1 4.5 0 . 8

97.9 __

Similar data for other regions of France have been reported by Peynaud ( 1950a, b).

Two methods of calculating the acid balance were given by Peynaud (1947~). The first procedure is to determine all of the organic and inor- ganic anions such as tartrates, malates, chlorides, and sulfates. This should equal the summation of the cations and titratable acidity (potassium, sodium, ammonia, etc.). The second procedure involves only a balance of the organic acids. The alkalinity of the ash, ammonia, and titratable acidity should just balance the organic anions, the acid esters, one func- tion of the phosphate, two functions of the free sulfur dioxide, and one- half of the bound. An example of this type of calculation has already been given. Bremond ( 1937a, b, 1937c, 1938a) made a complete balance of the acid constituents of three Algerian wines and Marcilla (1934) for a young Montilla wine.

It is also possible to make a balance of the acids only in musts using

for the and pH = pKz -k acid salt salt acid salt

acid the equations pH = pK1 + acids. From the amount of free acid and acid salt present the titratable acidity may be calculated. This should, of course, equal that actually determined. This method has also been used by Amerine and Winkler (1943). An application of the methods of calculating the percentage of the

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COMPOSITION O F WINES 389

organic acids present as free acid and as acid salts and salts was made by Pato (1932). Using this data the pH may be approximately calculated. Pato then calculates t,he necessary amount of acid to add to various musts in order to secure a satisfactory pH. The corrections reported are somewhat greater than those used in practice but are less than those recommended by some earlier enologists. Pato (1935) recommended simultaneous use of tartaric to combine with the potassium translocated to the fruit after the fruit was ripe and enough malic to replace that which had been respired following full maturity. Finally, he recommended a preliminary experiment on a sample of the must to determine the exact amount to add. Kondareff (1940) made a complete analysis of the acids in two Bulgarian wines and made a balance of them. The correction of the must acidity for Elparkling wines was discussed by Ferr6 (1943). He noted also (1945) that the wines made from the last juice coming from the press were more subject to a malo-lactic fermentation than was the free-run. For the correction of the wine acidity prior to the bottle fermentation he recommended lactic acid. No experimental results are available.

During ripening of the grapes three factors operate to decrease the acidity: dilution owing to an increase in the size of the fruit, continuous translocation of bases into the fruit, and respiration. Peynaud (1947~) showed that tartaric as well as malic acid decreased during ripening. Genevois and Gatet (1940) have also studied the changes in the acids during maturation. They note that the problem of methodology is impor- tant. Peynaud used water to extract the acids from the pomace, while they used the pressed juice and added 50% alcohol. However, they found the usual regular decrease in tartaric and malic acids as the grapes ripened.

The difference in the organic acid content of different varieties is quite clear from the work of Peynaud (1947~) and Amerine and Winkler (1943). Peynaud classified grape varieties into high-acid varieties, if they were high in malic acid, and low-acid varieties, if they were low in malic acid. Because of the variable influence of climatic conditions on the acidity Peynaud believes the Balling degree/acid ratio is of limited value in determining the harvest date for Bordeaux conditions. Amerine and Winkler (1941), however, found it a useful means of distinguishing varieties under the more uniform climatic conditions of California.

Peynaud (1939-1940) has also studied the changes in organic acids during fermentation. Acetic, citric, lactic, arid succinic acids are formed, whereas malic and tartaric acids decrease: malic appears to undergo a genuine fermentation and tartaric is precipitated as the bitartrate. Rib6reau-Gayon and Peynaud (1938a, b) have summarized the evidence in favor of permitting acid-reducing bacteria to reduce the total acidity

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in the production of fine table wines, particularly reds. They therefore indicated that both pasteurization and addition of sulfur dioxide might be injurious to the development of some wines and beneficial to others. I n contrast to wines, a malic acid fermentation does not occur in fer- mented pears, according to Jacquin and Tavernier (1951-1952), but is common in fermented cider. However, a notable decrease in malic acid takes place during the alcoholic fermentation.

1. Titratable Acidi ty

Methods. Usually a simple titration is employed. The primary problem is in select- ing an indicator for red wines. Use of neutral litmus as an outside indicator is illogical, because it is difficult to standardize and because it changes color a t a p H of 7, whereas the theoretical end point is about 8.2. If red wines are diluted and the indicator added after the color of the natural red pigments has changed to grey or green, then phenol- phthalein may be employed. However, phenolphthalein was reported to give too high results in the total acidity titration of red wines by JimBnez (1937). Phenol red was recommended but not litmus. Jaulmes and Slisewica (1943) showed the theoretical and actual differences in determining total acidity that may result from use of different indicators. Melcher (1947) proposed using bromothymol blue. Bromocresol purple was recommended by Miconi (1948).

A simple procedure for the rapid determination of the total acidity in wines and fruit juices was patented by Holabach (1936). He prepared alkaline pieces of filter paper corresponding to 0.05% to 0.01 % acid, which he added to the solution. Bromo- cresol was used as an indicator, and from the number of pieces of alkaline paper added the acidity was calculated. A simple blue patented German indicator, useful for all except the medium-to-dark red wines, was employed by Larsen (1951). Indicators, such as acridine and umbelliferone, which are fluorescent in ultraviolet light for the end point in the acidity determination, were proposed by Volmar and Clavera (1931). One advantage of these was that they can be used in red wines.

Acetic acid is quantitatively produced from sodium acetate in the presence of fixed acids and acid salts. This was used by Fontanelli (1941) for determining the total acidity. The results were higher than those obtained by titration. The distillation was accelerated by saturating the solution with sodium chloride.

An iodometric procedure, based on the reaction IOs- + 51- + 6Hf 3 3 1 2 + 3H20 was proposed by Vihles (1939). Slightly high results were obtained, and the reaction took 24 hours. The main advantage claimed was the end point. Because of the diffi- culty in detecting the color change at the end point, SBmichon and Flanzy proposed (1930b, 1932d) a method based on the amount of carbon dioxide released when wine is placed on calcium carbonate. The procedure is empirical and not suited to routine analysis, as Ferr6 (1931) indicated. He preferred titration to a pH of 7, although this is not the true end point for the titration of a weak acid with a strong base. An adapta- tion of the old gasimetric procedure of Bernard (see Jaulmes, 1951) for determining the total acidity was reported by Voskoboinikov and Negenzev (1930), who recommended the procedure for dark-colored hybrids. But, although speedy, this procedure offers nothing useful.

Gunts (1950) proposed using an ion exchanger. The diluted wine was slowly run through Amberlite IR lOOH to remove hydrogen ion. The hydrogen ion was then washed off the column with water and titrated. If the wine is run through both an

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COMPOSITION OF WINES 391

anion and cation exchanger, only nonionized materials such as glycerol, sugars, and coloring material appear in the final solution. To selectively remove acetate he recom- mended fist saturating the column with tartrate, malate, succinate, and lactate anions. The necessity of heating wines to remove carbon dioxide before titrating for the total acidity was emphasized by Flygare (1949).

The ability of Botrytis cinerea to reduce the total acidity is well known. For a review of the literature see Schanderl(l950). Ventre (1936) reported permanent differences in the acid-producing properties of several strains of wine yeasts.

Deacidification of wines by various materials was reviewed by Genevois (1934b). Sodium carbonate gave a disagreeable taste. Ammo- nium bicarbonate, potassium carbonate, or potassium tartrate can be used, but their effect varies markedly with the composition of the wine treated. Calcium carbonate has a regular action, but carbon dioxide is evolved and the precipitate is voluminous. Magnesium salts give an un- pleasant taste.

The total acidities of a large number of Argentinian wines were reported by Ruspini (1936). Reports on the empirical relationships between the total acidity and the sugar content of the grapes have been given by Amerine and Winkler (1941) and Korotkevich (1948). The former classified the varieties of grapes into three groups on the basis of their sugar/acid ratios. The latter showed that the ratio also varied with the region and season and classified grape varieties into eight groups.

2. Tartaric Acid Potassium Acid Tartrate Procedure. lmprovements in this procedure for deter-

mining tartaric acid were given by Seiler (1932, 1943b). At least 0.5 mg. of potassium acetate must be added for every milligram of free tartaric acid present. Methyl alcohol may be substituted for ethyl. A similar modification of the standard German pro- cedure was made by von der Heide and Hennig (1934) and Steuart (1934) by varying the amount of potassium acetate added according t o the total titratable acidity. Podkletnov (1951) and Amerine (1952) also used this method. A modification of the procedure was presented by Berg and Schmechel (1932). No correction factor for the solubility of the acid tartrate was used, yet rather accurate values were reported, particularly with the lower percentages of tartrate. Dubaqui6 (1932) reviewed the methods for tartaric acid and potassium but gave a minimum of analytical data.

Hartmann and Hillig (1930) found the potassium acid tartrate procedure unsatis- factory because when alcohol is added pectins and other colloidal materials are pre- cipitated and occlude other acids. To avoid this they recommend adding alcohol first to remove the pectins and to precipitate the acids in the filtrate with lead acetate. The precipitate is then dissolved and treated with hydrogen sulfide to remove the lead. Recovery of 97% to 100.2% of the tartaric acid from mixtures with malic and citric acid was reported. The procedure of Beis (1934) for the determination of tartrates and tartaric acid is based on the relative insolubility of the tartrates in alcohol. Titration before and after removal of the tartrates was used to obtain the tartrates by difference. Other procedures appear to be more suitable.

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392 MAYNARD A. AMERINE

Racemute Procedure. Precipitation as calcium racemate, usually called the Kling procedure, has been frequently employed, but the cost and availability of levotartaric acid or its salts have discouraged investigators. S6michon and Flanzy (1933a) used calcium sulfate in place of calcium acetate to prevent coprecipitation of lev0 calcium tartrate and recommended other changes in Kling's procedure. Their results showed the racemate method to give the best recovery. Peynaud (1936b) also employed the racemate procedure but used a double precipitation, increased the time allowed for the first precipitation, and made other changes to improve the method. Kling (1936) has supported his original procedure.

The method of determining the precipitated calcium racemate has also been a subject of debate. Some have ashed the precipitate to the carbonate; others have oxidized it with permanganate. Hartmann and Hillig (1930) reported that the tem- perature for the permanganate oxidation should be a t least 80" C. (176" F.). Pato (1944) gave an excellent review of the various procedures and the criticisms of each, preferring the racemate method. A correction curve was given for determining the equivalence of permanganate and tartaric acid. He also studied methods of avoiding coprecipitation of lev0 calcium tartrate and proposed a modified racemate procedure. A micro-method using periodic acid to oxidize the racemate was developed by Poux (1949) and Poux and Ournac (1949). Compared to the macro-procedure it showed an error of about +4%. Peynaud's modification of the Kling procedure was applied to port wines by Guimar&es (1950). Sugars did not interfere, the temperature of oxidation must not exceed 70" to 75" C. (158" to 167" F.), and errors of only 0.5% to 2.6% were obtained. Peynaud (1951a), noticing the difficulty and expense of securing levo- tartaric acid, recommends using an aqueous extract of Bauhinia reticulata D. C., which is rich in the lev0 acid.

Other Methods. Various procedures for determining tartrates were tested by FAbregues and Mestre (1948). They preferred a conductometric method for tartrates in lees, based on diluting with ammonium hydroxide to the point of minimum con- ductivity, adding a known amount of tartaric acid, and repeating the dilution. For wines they favored the racemate procedure.

Apparently the first to use the red color developed by tartaric acid and sodium metavanadate in dilute acetic acid for the determination of tartrates in wines was Ghimicescu (193513, c). However, he separated the tartrates by precipitation as the acid tartrate. This method was also employed by workers a t the Western Regional Research Laboratory (1943), by Iljin (1943), and by Bergman and Magoon (1945). Because there is an inflection in the titration curve a t pH 4.05, the pH2 for tartaric acid, Canals and Vergnes (1940) suggested this as a means of quickly estimating the tartaric acid content of wines.

Sophistication of berry wines with grape wines is a frequent problem of law enforce- ment agencies in this country. A sensitive test for tartaric acid is necessary, since most authorities agree that little or no tartaric acid occurs in berries. Marsh and Kean (1951) recommended chromatographic methods. In a genuine berry wine they found no tartaric acid; by the Association of Official Agricultural Chemists (1950) procedure they found it in three. The colorimetric procedure of Mathers (1949) is also applicable but subject to interference. It gave, for example, a positive test on one of the samples in which paper chromatography showed no tartaric acid. In Brazil the problem is apparently the opposite-sophistication of grape wines with fruit wines. Buhrer (1950) has developed an empirical test bases on the voIume of precipitate obtained when mercuric oxide solution is added to hot wine-the precipitate being greater with grape wine. Further tests based on presence of citric acid are not applicable, as this acid is frequently added to grape wines.

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COMPOSITION OF WINES 393

Mathers et al. (1951) have developed a polarographic procedure for determining srnall amounts of tartaric acid. They precipitated the tartaric acid with bismuth and complexed the tartrate with antimony. The polarographic waves were best in a p H range of 3 to 4. Although recovery was only about 90%, this is satisfactory at low roncentrations compared to other methods. Tartrates were not found in genuine loganberry, gooseberry, currant, blackberry, peach, chrrry, apple, or elderberry wines.

Changes during Ripening or Aging. The tartrate content of ripening Australian grapes was studied by Swaby (1943). He found the usual decrease during maturation. He also reported appreciable amounts in the skins and seeds. Amerine and Winkler (1943) showed that malic acid decreases relatively more rapidly than tartaric during ripening but that the varieties differ markedly and characteristically from each other in the total and relative amounts of each present at maturity. In the studies of Babadilla and Navarro (1949) the tartrate in Spanish grapes decreased during ripening, increased when the grapes were drying in the sun, decreased during fermentation, and underwent little change during aging under the "flor."

Cambitzi (1947) found optically inactive racemic calcium tartrate in old wine deposits. Since wine normally contains only dextrotartaric acid, he interpreted this as indicating autoracemization. The calcium salt of racemic tartaric acid is only about one-eighth as soluble as the salt of the dextro acid. Storage at room temperature favored the racemization, and hence the precipitation. A review of the solubility of potassium and calcium tartrates in wine and musts and the factors influencing their solubility was given by Genevois (193413). Malic acid increases the solu- bility of potassium tartrate and acid tartrate. The decreased solubility of calcium tartrate as the pH is raised is undoubtedly of importance in wine aging, where the pH generally increases. Tables giving the solubility of potassium acid tartrate at temperatures at 5" to 25" C. (41" to 77" F.), a t alcohol percentages of 0 to 25, and at various pH values with tartaric, citric, malic, succinic, lactic, and acetic acids were reported by Ivanov (1947). Marsh and Joslyn (1935) have studied the factors influencing the deposition of potassium acid tartrate from wines. The process is slow, even a t low temperatures, but is much more rapid at -3.9" C. (25" F.) than at other temperatures-as much tartrate was removed at -3.9" C. (25" F.) in about 2 days as at 25" C. (77" F.) in 225 days. Mursaeva and Brailovskai; (1952) have shown that the deposition of tartrates is a com- plicated process depending on many factors. They studied the removal of tartrates by cooling to between 2" to -30" C. (35.6" to -2220" F.). The more rapid deposition of tartrates took place at -5" C. (22" F.). At this temperature the frozen phase is principally water with a minimum of dissolved material.

A decrease in tart,aric acid owing to bacterial action occasionally

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394 MAYNARD A. AMERINE

occurs and was discussed by Osterwalder (1952). Sallusto (1935) studied the rather variable ratio of potassium acid tartrate to per cent alcohol; the average is 1/48.

Genevois (1951) considered the aging of wines as partially a problem of the aging of a solution of tartaric acid. He envisages a system in which ferrous ion plays a part and tartaric acid yields dihydroxymaleic acid,

Region Alsace

France

Germany

Germany Germany Hungary Italy Portugal Portugal Spain

Spain

Spain

Switzerland

(Nante)

TABLE VIII Tartrate Content of Various Wines (Grams per 100 ml. as tartaric acid)

Type of No. of Mini- wine Source of data samples mum

Wh. table Lobstein and Schmidt 19 0.09 (1931)

Wh. table Wh. table

Wh. table Wh. table Wh. table Table Table Red table Fino

Oloroso

Montilla

Table

Huriez (1948) Heiduschka and Pyriki

(1930) Hennig (1952) Seiler (1944) Torley (1942) Violante (1950) Correia and SBrgio (1943) Correia and Vilas (1943) Bobadilla and Navarro

Bobadilla and Navarro

Casares and Gonzales

Berner (1952)

(1952)

(1952)

(1953)

11 29

19 128 10 40

113 27 15

10

51

25

0.15 0.08

0.14 0.12 0.066 0.17 0.07 0.16 0.084

0.118

0.066

0.087

Maxi- mum 0.36

0.37 0.33

0.37 0.45 0.278 0 .29 0.47 0.32 0.221

0.214

0.195

0.289

Aver- age

0.22

0 .28 0.17

0.20 0.26 0.129 0.21 0.19 0 .19 0.144

0.144

0.100

0.231

whose ketonic form, oxytartaric, by oxidation-reduction produces dioxytartaric acid-which, in turn, by decarboxylation, gives carboxy glyoxal (oxypyruvic acid). This, in turn, by hydration yields tartronic (hydroxymalonic) acid, which finally by decarboxylation results in glyoxal. These reactions are summarized as follows:

COOHCHOHCHOHCOOH+ COOHCOH=COHCOOH+ COOHCHOHCOCOOH+COOHCOCOCOOH+COOHCOCHO+

COOHCHOHCOOH+CHOCHO.

Gatet and Genevois (1941) reported 10 to 20 mg. per liter of dihydroxy- maleic acid in wines containing 3 to 7 mg. per liter of iron, and 60 to 100 mg. in wine containing 20 to 40 mg. of iron. They explained its formation on the basis of oxidation of tartaric acid by ferric salts. Apparently dioxytartaric acid accumulates first and is converted to carboxy glyoxal acid by the action of ferric salts. Rodopulo (1951) has also studied the

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COMPOSITION OF WINES 395

changes in tartaric acid. He found that prolonged action of iron on the acid resulted in an iron-tartrate complex salt. This catalyzes the oxidation of tartaric acid. Prolonged storage led to formation of the complex. During racking it particularly catalyzed the oxidation of tartaric acid. The products of the oxidation were glyoxyalic acid and finally oxalic acid. During bottle storage, however, diketosuccinic and dihydroxymaleic acids were formed. Dihydroxymaleic acid also accelerated the oxidation of tartaric acid in the presence of iron salts. The dihydroxymaleic, diketosuccinic, glyoxylic, and oxalic acids are genetically related, as is glyoxal, which is also present. The tartrate contents of several types of wines are given in Table VIII.

3. Malic Acid

Interest in malic acid is primarily directed toward controlling its utilization by microorganisms. The central position of malic acid in enology has been most clearly documented by Ribbreau-Gayon and Peynaud (1938~). Not only do the varieties of grapes differ markedly in malic acid (see Peynaud 1938b, 1947c; Amerine and Winkler, 1943; Korotkevich, 1948; and Amerine, 1950-1951), but the per cent present is markedly affected by maturity and climatic conditions. Finally, malic acid usually undergoes a malo-lactic fermentation during the later stages of fermentation as well as during aging (CharpentiB, 1950).

Methods. The most common procedure for determining malic acid is that of per- manganate oxidation in a buffered solution to produce acetaldehyde as developed for musts and wines by Peynaud (1938b, 1946). By slow introduction of very dilute permanganate a recovery as high as 98% to 99.2% was reported, although Joslyn and Comar (1938) obtained lesser recovery from pure aldehyde solutions. The disadvan- tage of this procedure is the correction needed for the presence of tartaric acid. Amerine and Winkler (1943) and Amerine (1950-1951) were unable to obtain a con- stant acetaldehyde production from tartaric acid and preferred to remove most of it as potassium acid tartrate. Some coprecipitation of malic acid probably takes place.

Malic acid was determined colorimetrically with Pinerua’s reagent (@-naphthol in sulfuric acid) by Ghimicescu (1935a). The malic acid was separated in 70% alcohol. Nitschk6 (1952) also proposed a colorimetric procedure based on the red color produced in alkaline solution with a-naphthol. A standard curve is prepared; the color must be extracted with isooctyl alcohol and is sensitive to light. Sugars, tannins, and tartaric and lactic acids should be absent.

A polarographic procedure for determining malic acid was developed by Hennig and Burkhardt (1951). In i t they heated with alkali to convert the malic to fumaric acid. The polarographic procedure depends on the reduction of the double bond of fumaric acid using a dropping mercury cathode. Since this method may be used only on tannin- and sugar-free wines, Tanner and Rentschler (1953) removed these by passing the wine successively through a cation and anion exchanger. The acid was then washed from the anion exchanger. This appears to be a practical solution to many clarification problems.

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396 MAYNARD A. AMERINE

bntschler (1949) proposed using a pure culture of Bacterium gracile for its deter- mination by measuring the carbon dioxide produced. Only 90% of the malic acid could be fermented and even a t constant temperature there was a 6% to 8 % error. Each determination took about 3 to 4 hours.

Amounts Found. In green grapes Amerine (1950-1951) reported to 50% of the titratable acidity was due to malic acid and at maturity only 10% to 40%. The varieties differed markedly in malic acid from each other. Casale (1934) found the ratio tartaric acid/malic acid in Piedmont grape musts to vary from 0.5 to 3.0, whereas in California grapes Amerine and Winkler (1943) reported ratios of 1.3 to 4.4 a t Balling readings of 20" to 25". Flanzy (1948) showed the intense oxidation of malic acid that occurs in the fruit when the temperature goes above 29" C. (84.2" F.). Considerable tartaric acid was also oxidized; however, the acid tartrate resisted oxidation. Hennig and Burkhardt (1951) found less malic acid in the grapes in warm than in cool seasons and higher amounts in the varieties Miiller-Thurgan, Sylvaner, and White Riesling. Bobadilla and Navarro (1949) also studied the changes in malic acid content during maturation, during and after fermentation of sherry wines. They found the usual decrease during maturation, particularly when the grapes were exposed to the sun for a day after picking and prior to crushing-the usual Andalusian practice. During fermentation they observed the same decrease as had earlier investigators. Further decreases due to the malo- lactic fermentation were observed after fermentation and preceding fortification. A slight decrease occurred during the "flor " stage. Placing grapes in an atmosphere of carbon dioxide before crushing results in a decrease in the malic aicd content, according to Garino-Canina (1949).

Disappearance of 10% to 30% of the malic acid during alcoholic fer- mentation at a pH of 2.6 to 3.6 was demonstrated by RibBreau-Gayon and Peynaud (1946b). Peynaud (193810) showed a decrease of 9.9% to 14.5%. At a pH of above 3.6 destruction decreased. This decrease is attributed by Peynaud (1947~) to the splitting off of two hydrogen atoms and decarboxylation of the resulting oxalacetic acid to acetaldehyde, which, in turn, acts as a hydrogen acceptor and is reduced to alcohol. RibBreau-Gayon and Peynaud showed that the lactic acid formed is approximately equal to one-half the malic acid destroyed and that the destruction of citric acid does not start until the malic acid has prac- tically disappeared. Both glycerol and tartaric acid are attacked by cer- tain bacteria but not a t first by those causing the malo-lactic fermenta- tion. Rippel (1949) reported that the activity of Bacterium gracile was dependent on a catalyst of unknown nature derived from the grape. For historical and other information on the malo-lactic fermentation see Garino-Canina (1943) and Schanderl (1950). In Alsatian wines Lobstein

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COMPOSITION OF WINES 397

and Schmidt (1931) showed that the wines high in malic acid were low in lactic and vice versa. They indicated that the malo-lactic fermentation was frequently necessary in order to produce balanced wines. An example of the changes in acids during storage of a German white table wine in which a malo-lactic fermentation is occurring is given in Fig. 1.

%:::; 2.0 * - - - - o Malic Acid

--- Lactic Acid

0- - 0 Tartaric Acid

Volatile Acidity 0.. .... ... O I. I

O*'O 10 20 30 40 50 60 70 00 90 100 110

O*'O 10 20 30 40 50 60 70 00 90 100 110

TIME IN DAYS

FIG. 1. Changes in the malic, tartaric, lactic, and volatile acids during storage of a German white table wine (Kramer and Bohringer, 1940).

Rib6reau-Gayon and Peynaud (1938~) reported the normal range of malate in French wines was 0.067 to 0.268 g. per 100 ml. The malic acid content of various types of wines is given in Table IX.

4. Citric Acid It is now generally agreed that citric acid is a normal though minor

component of grapes and wines. Its accurate determination in musts and wines is difficult.

Methods. The quantitative determination of citric acid is occasionally important, ns several European countries limit the citric acid content. Cerasari (1950) has re- viewed the legal problems and has given a qualitative and quantitative procedure. The two procedures now commonly used for the determination of citric acid are the

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398 MAYNARD A. AMERINE

pentabromacetone and the permanganate oxidation. Von Fellenberg (1933) used the pentabromacetone procedure. His method was not free of empirical details, and the yield was only about 90% of the theoretical. Reichard (1934a) used it but reported that the temperature, amount of bromine, relation of bromide to citric acid, and amount of permanganate to add must be standardized. No interference with other acids was noted, but sugars must be fermented out (objectionable) or the citric acid separated as barium citrate. Good recovery of added citric was reported with a variety of wine types. See also Reichard and Bleyer as reported in Bleyer (1938).

Other studies of the methods for the determination of citric acid in wines were made by Pfab (1931) and Tarantola (1937a, b). The former used a semiquantitative

TABLE IX Malic Acid Content of Various Musts and Wines

Region Algeria Algeria Alsace

Bordeaux Bordeaux Bordeaux California France

(Nante) Hungary Portugal Spain

Spain

Switzerland Switzerland

Type of wine

Wh. table Table Table

Wh. table Red table Musts Musts

Wh. table Wh. table Table Fino

Oloroso

Wh. table Table

(Grams per 100 ml.) No. of Mini-

Source of data samples mum Fabre and BrBmond (1932) BrBmond (1937b) Heiduschka and Pyriki

Peynaud (1938b) Peynaud (1938b) Peynaud (1947~) Amerine (1950-1951)

(1930)

Huriez (1948) Torley (1942) Correia and SBrgio (1943) Bobadilla and Navarro

Bobadilla and Navarro

NitschkB (1952) Berner (1952)

(1952)

(1 952)

13 3

19

29 21 14 32

11 10

107 15

10

16 23

0.18 0.11 0.01

0.03 0.00 0.10 0.12

0.12 0.15 0.01 0.08

0.07

0.01 0.01

Maxi- mum 0.59 0 .18 0 .03

0 .40 0.05 0 .60 0.57

0.41 0.29 0 .38 0 .13

0.17

0 .73 0 .33

Aver- age 0.37 0.14 0.02

0.14 0.02 0 .30 0 .29

0 .20 0 .21 0.15 0 .09

0.12

0.20 0 .12

procedure, and the latter employed the Reichard (1934a) method with recoveries of 95% to 105%. Schindler and Koz&k (1934) studied several procedures for the deter- mination of citric acid in wines, criticizing features of all but recommending a rather complicated one based on conversion to pentabromacetone. The method of Cartier and Pin (1949) was developed with biological materials in mind. They converted the citric acid to pentabromacetone which was colorimetrically measured using the KonBtiani reaction. An accuracy of f 2 % with 0.1 to 1.2 mg. was claimed. Taufel and Mayr (1933) also showed that special attention must be paid to buffering, etc., in order to keep the acetonedicarboxylic acid produced in the keto form, as the enol form is more likely to undergo undesirable oxidation. They recovered 98.4% to 99.6% of the citric acid added. Mohler (1937) and von Fellenberg (1933), however, obtained a low recovery with the pentabromacetone method. Hargreaves el al. (1951) perfected the pentabromacetone procedure so as to be able to determine citric and d-isocitric acids.

The Kogan (1930) permanganate procedure, based on the oxidation of citric acid

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COMPOSITION OF WINES 399

to produce acetone, was modified by Taufel and Mayr (1933) and Peynaud (1938a) and later by Godet and Charrihre (1946). The latter introuced the permanganate a t a more regular rate to secure a slower and more even oxidation. They reported an accuracy of 2% and preferred the procedure to the pentabromacetone method, from which they could get only 91% to 92% recovery. Bartels (1933) also studied Kogan’s procedure and reported that while organic acids and sugars do not interfere, it was necessary to separate the citrate as the calcium or barium salt in the presence of alcohol and ammonia in order to avoid interference from glycerol. Recovery of 92% to 102% of the added citric was reported. Peynaud (1938a) reported an accuracy of better than 4%.

The method of Heiduschka and Sommer (1935) is longer, including heating with barium hydroxide and making to 50% alcohol to precipitate barium citrate, treating the precipitate with sulfuric acid, and eventually distilling off the acetone formed into iodine. A qualitative test using mercuric sulfate was also developed by Reichard (193413). A simple and rapid procedure for the detection of citric acid was given by Roleff (1952). This depended on the cloudiness developed in wines containing citric acid when bromine water and 1% vanadium pentoxide (dissolved in 1 + 3 sulfuric acid by warming) was added to charcoal-treated wines. Only 0.02% in 5 ml. was needed for a positive test, and the best results were obtained in the range 0.02% to 0.1%. Sugar, up t o 7%, did not interfere.

Occurrence. Citric acid, although present in only small amounts in musts, is of considerable biochemical interest. RibBreau-Gayon and Peynaud (1938d) found more in certain varieties than others. During ripening, citric acid decreased in four Bordeaux varieties and increased in one (Sauvignon blanc) (Peynaud, 1938a). On a per berry basis there was a decrease in two, no change in one, and an increase in two varieties. The average content a t maturity varied from 0.02% t o 0.03%.

Formation of 1 to 2 meq. per liter of citric acid at the expense of 166 g. of sugar during alcoholic fermentation was demonstrated by RibBreau- Gayon and Peynaud (1946b). Since only small amounts of citric acid are present in musts, this may result in a 40% increase during fermentation. Peynaud (1947~) attributes the increase in citric acid during fermentation to the direct action of the yeast on sugars. Saccharomyces ellipsoideus and Kloeckera apiculata were found by Gobis (1950) to produce citric acid by an oxidative mechanism. She noted that citric acid production, like higher alcohol and succinic acid production, may be associated with the protein metabolism of yeasts. For example, addition of ammonium sulfate decreased production of higher alcohols and citric acid. Addition of tartaric and formic acids increased citric acid formation. Decreases in citric acid during fermentation were shown by Tarantola (1937a) to depend on the organism present rather than on the absence of sulfur dioxide. In numerous Italian wines he found 0 to 0.478 g. per liter. Wines of low total acid also contained less citric acid.

RibBreau-Gayon and Peynaud (1938d) reported white wines to con- tain over four times as much as the reds-owing to bacterial utilization

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400 MAYNARD A. AMERINE

in the nonsulfited reds. The citric acid content of nonpasteurized wines was always less than that of the pasteurized checks. RibBreau-Gayon (1938a) noted that sulfur dioxide should always be added along with citric acid. Luthi (1949) reported that it increased the volatile acidity of Swiss red table wines 0.15% and should not be employed. Charpenti6 et al. (1951) find acetylmethylcarbinol, acetic acid, diacetyl, lactic acid, and 2,3-butylene glycol as the products. They propose a mechanism by which the degradation of citric acid proceeds through an oxalacetic- pyruvic acid stage. The pyruvic acid then reacts as follows to give the above products in the order listed:

2CHoCOCOOH + CHsCOCHOHCHs + 2CO2

2CHsCOCOOH + CHsCOCOCHs + 2C02 + 2H CHsCOCOOH + HnO + CHsCOOH + 2COt + 2H

CHsCOCOOH + 2H -+ CHsCHOHCOOH 2CHsCOCOOH + 2H + CHsCHOHCHOHCHs + 2CO2

They calculated the theoretical and actual amounts of the products formed according to this scheme and found good agreement.

The protective effect of citric acid against ferric phosphate cloudiness is well known. Verda (1940) claimed that addition of citric acid to wines decreased the loss of vitamins, particularly ascorbic acid.

A summary of the regulations of various countries limiting the use of citric acid was published by Berg and Schulze (1934). Mohler (1937) has reviewed the earlier work on the citric acid content of wines and con- siders up to 0.05% normal for wines. This is the French limit. As of 1937 Germany, Hungary, and Austria prohibited use of citric acid; Rumania, Yugoslavia, and Switzerland had the 0.05% limit; Italy and Spain a 0.10% limit; and Greece had no limit. The present United States limit is 0.05%, but under a more liberal section of the regulations almost un- limited amounts can be added. Buogo (1938) has reviewed the literature and finds no biochemical reason why wines containing this acid should be considered sophisticated, but believes that it should not be added in excessive amounts because of its flavor. This aspect of its use needs to be investigated further.

Amounts Reported. The amounts of citric acid reported in various wines are given in Table X. It is noteworthy that Tarantola (1937a) was unable to detect any citric acid in 18 of the 57 wines which he analyzed. This was obviously owing to bacterial decomposition during aging. Rodopulo (1952a) reported 0.023% citric acid in a Russian must and 0.035% in the fermented wine. Von Fellenberg (1933) found from 0.07 to 0.38 g. per liter in 4 authentic Rheinpfalz wines. In wines made from Spanish, Greek, or California raisins he reported 0.02 to 0.63 g. per liter.

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COMPOSITION OF WINES 40 1

In 14 Swiss wines 0.04 to 0.44 g. per liter were found, but fruit wines con- tained up to 2.94 g. per liter. In 60 samples from Bari, Italy, Buogo and Picchinenna (1938) reported 0.03% to 0.05% with an occasional sample up to 0.1%. Bobadilla and Navarro (1949) reported 0.03% to 0.30% in sherry wines. Little changes occurred during fermentation or during

TABLE X Citric Acid Content of Various Wines

(Grams per 100 ml.) No. of Mini-

Type of wine Source of data samples mum Table Lobstein and Schmidt 19 0.00

(1931) Wh. table Peynaud (1938a) 34 0.009 Red table Peynaud (193%) 26 0.003 Swt. table Peynaud (1950a) 6 0.017

Maxi- mum 0.02

Aver- age

0.01 Region

Alsace

France France France France

Germany

Germany

(Nante)

0.058 0.038 0.058

0.033 0.0076 0.039

Wh. table Table

Table

Wh. table Table Red table Wh. table Table Fino

(sugared)

(unsugared)

Huriez (1948) Mader (1936)

11 11

0.008 0.017

0.037 0.045

0.026 0.025

Mader (1936) 8 0.009 0.037 0.024

Germany Germany Germany Germany Italy Spain

Spain

Reichard (1936) Reichard (1934a) Reichard (1936) Wirthle (1931) Tarantola (1937a) Bobadilla and Navarro

Bobadilla and Navarro

Godet and CharriAre

Berner (1952) Berg and Schulze

Berg and Schulze

Berg and Schulze

Reichard (1936)

(1952)

(1952)

(1946)

(1934)

(1934)

(1934)

70 15 30 22 57 15

0.000 0.000 0.000 0.01 0.000 0.002

0.030 0.010 0.045 0.02 0.045 0.036

0.008 0.003 0.009 0.02 0.015 0.010

Oloroso 10 0.002 0.036 0.015

Switzerland Table 5 0.02 0.05 0.03

Switzerland Various

Table Wh. table

23 11

0.001 0.00

0.162 0.03

0.016 0.01

Various Red table 5 0.00 0.03 0.01

Various Swt. table 7 0.00 0.27 0.11

Various Dessert 26 0.000 0.103 0.024

aging under the “flor.” Piatkowska and Smreczyriska (1950) noted that the high citric acid content of current, bilberry (Vaccinium myrtillus), and gooseberry wines makes it possible to detect their addition to grape wines. However, as much as 30 % of fruit wine would have to be added, and since some countries do not control the citric acid addition t o grape wine, the addition of apple, cherry, or blackberry wines cannot be so detected.

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402 MAYNARD A. AMERINE

6. Succinic Acid

This acid is found in all fermented beverages, and in wine constitutes an important fraction of the fixed acidity. Generally about 1 % as much succinic acid as alcohol by volume is found in unfortified wines.

Methods. Espil (1937) separated the barium tartrate, malate, and succinate in 80% alcohol. These salts were then decomposed with hydro- chloric acid by evaporating to dryness with potassium sulfate. The tartaric and malic acids were separated by ether extraction and the succinic acid in the residue titrated. SBmichon and Flanzy (1932~) deter- mined succinic acid by oxidizing the other constituents and weighing the residual succinate after purification. No data on accuracy were given. The best study of the determination of succinic is that of Marignan (1944). (See also Jaulmes, 1951, and Amerine, 1952.) It is applicable primarily to sugar-free wines, but by extracting with ether prior to the permanganate oxidation it can be adapted to sweet wines. He oxidized the other acids with permanganate, extracted the residual succinic acid with ether, precipitated as silver succinate, and determined the residual silver.

Source. In pure cultures RibQeau-Gayon and Peynaud (1946b) showed that more succinic acid was formed at the start of the fermenta- tion than a t the finish and that the amount formed per gram of sugar fermented varied with the must and the yeast. Peynaud (1947~) found about 0.47 g. of succinic acid formed per 100 g. of sugar fermented and noted a fairly regular production during fermentation. He believes that it originates from sugars with acetaldehyde or pyruvic acid as the inter- mediate and not from amino acids. Bobadilla and Navarro (1949) found no changes in succinic acid during aging under a “flor.”

Amounts. Vasconcellos (1940b, 1941) has reported data on the per- centage of succinic acid in the sweet dessert wine, port. Although this author’s procedure had a maximum error of about lo%, in over 70% of the samples it was less than 5%. In eight samples where the original sugar content of the must was known, no direct relationship between the quality of sugar fermented and the amount of succinic acid formed was observed. In the studies of Genevois et al. (1948~) succinic acid in Bor- deaux wines varied greatly-from 48 to 106 millimoles per liter, average 75. The ratio of acetic acid to succinic acid, according to the yeast strain, varied from 0.4 to 4.3, but usually from 0.4 to 2.0. Anibal (1935) calcu- lated the ratio of succinic acid per liter times 100 divided by the glycerol content (grams per liter) for forty-three Argentinian table wines to vary from 0.46 to 2.79. Correia and Ribiero (1942) found the succinic acid, as per cent of the weight of alcohol produced, to vary from 0.68 to 2.25 in

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COMPOSITION OF WINES 403

114 Portuguese table wines. This was too variable to make the succinic acid : alcohol relationship of use for identification purposes. The succinic acid content of various types of wines is given in Table XI.

TABLE XI Succinic Acid Content of Various Wines

(Grams per 100 ml.) Type of No. of Mini- Maxi- Aver-

Region wine Source of data samples mum mum age Argentina Red and Wh. Anibal (1935) 43 0.035 0.195 0.069

Argentina France

(Nante) France France France Hungary Italy (Cirb)

table Table

Wh. table Swt. table Red table Dessert Wh. table Red table *

Portugal Table

Portugal Table

Portugal Red port Portugal Wh. port Spain Fino

Spain Oloroso

Switzerland Table * Av. alcohol 15.3.

Velazquez (1936) 39 0.04? 0.181 0.061

Huriez (1948) Peynaud (1950a) Peynaud (1950a) Peynaud (1950b) Torley (1942) Sallustro and Sculco

Correia and Ribeiro

Correia and Shrgio

Ramos and Reis (1945) Ramos and Reis (1945) Bobadilla and Navarro

Bobadilla and Navarro

Berner (1952)

(1937-1938)

(1942)

(1943)

(1952)

(1952)

11 6 6 8

10 26

114

105

38 19 15

10

13

0 .06 0.090 0.099 0.019 0.081 0.041

0.06

0 .05

0.005 0.005 0.079

0.094

0.047

0.11 0.130 0.116 0.101 0.207 0.073

0.225

0.67

0.127 0.050 0.140

0.142

0.097

0 .09 0.112 0.105 0.077 0.120 0.054

0.121

0.103

0.035 0.014 0.111

0.114

0.064

6. Lactic Acid

Lactic acid is not only a product of alcoholic fermentation but of the bacterial activity in wines. I n some red table wines i t is the pre- dominant acid. Its accurate determination is therefore of considerable interest.

Methods. The two most common procedures for the determination of lactic acid are the Moslinger procedure, or a modification of it, which depends on the solubility of barium lactate in 70% to 80% alcohol, or variations of the Espil (1936) technique, which is based on its oxidation in a buffered solution with permanganate and measure- ment of the acetaldehyde formed. Those standardizing lactic acid solutions should not forget that saponification is necessary. Hickinbotham’s procedure (1948) is conven- ient. Von Fellenberg (1931, 1932a) gave further details on hie earlier steam-distillation procedure for lactic acid, which may yield high results with red wines. Benvegnin and Capt (1932) compared several procedures for the determination of lactic acid, pre- ferring the Moslinger procedure for wines of normal lactic acid content. They obtained

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404 MAYNARD A. AMERINE

good results with the von Fellenberg (1932a) technique, especially for wines of low or high lactic acid and with sweet wines, but the technique is difficult. Modifications of the MGslinger-Bonifazi method were proposed by Fabre and Brdmond (1931rt), Velazques (1936), and Michel (1931). Errors of less than 0.2 g. per liter were reported by the former. BoFinjak (1938) compared various methods for lactic acid. The Mas- linger procedure could not be used on sweet wines nor with wines high in lactic acid, and losses occurred with Espil’s (1936) method. His best results were secured by extraction.

The micro-procedure of Ghimicescu (1935e) can also be used for larger amounts. It too is based on isolation of barium lactate in 80% alcohol and conversion to barium carbonate. Seiler (1941) pointed out that the Moslinger technique was not applicable to sweet or fruit wines. He questioned if a calculation of the original malic acid content based on determination of the final lactic acid content was justified.

The latest modifications of the Espil technique are given by Peynaud (19461, by Peynaud and Charpentid (1950) and by Koch and Bretthauer (1951). They reviewed the problem and suggested several modifications. They removed 2,3-butylene glycol by bringing the pH to 6 and evaporating t o dryness. By keeping the acidity low they kept aldehyde formation from glycerol to a minimum. Amerine (1950-1951) compared several procedures for the determination of lactic acid. Both oxidation and precipita- tion procedures gave satisfactory results.

A dichromate oxidation procedure for table wines was proposed by Sdmichon and Flanzy (1932b). No data on the accuracy of the procedure were given. A new pro- cedure by Krause (1948) is based on the solubility of calcium lactate and acetate in anhydrous methyl alcohol. The lactate and acetate were precipitated as silver salts and ashed, and the alkalinity of the ash was determined. By subtracting the acetic acid, the lactic acid content can be calculated. The procedure is said to be satisfactory for red and white wines, even if they contain sugar.

Colorimetric procedures may be subjected to errors from impurities. Hillig (1937) extracted, purified with charcoal, developed a color with ferric chloride, and estimated it photometrically a t 450 to 460 mp. The colorimetric procedure of Strohecker et al. (1938) employing veratrole is not satisfactory for wines, although Diemair et al. (1940) used it. It is based on evaporation of the volatile acids, precipitating most of the other organic acids in alcohol as barium salts. The glycerol and lactic acid remaining in solution are separated after removal of barium, with ether or an ether-alcohol mixture. The lactic acid was determined colorimetri- cally with veratrole and the glycerol measured after oxidation to formal- dehyde with fuchsin. This procedure seems too complicated for ordinary use, and Beer’s law is applicable for the veratrole-lactic acid color only up to 0.1 g. per liter.

The special problem of lactic acid determination in sweet wines was studied by Berg and Schulze (1931) using barium carbonate for removal of sugars. The results were only fair. A qualitative test for lactic acid was developed by Widmar (1931). He neutralized the volatile acid distillate with barium hydroxide and added alcohol under specific conditions. A small amount of precipitate which settled slowly indicated lactic.

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COMPOSITION O F WINES 405

Source. Rib6reau-Gayon and Peynaud (194613) and Peynaud (1947~) showed that 5 to 7 meq. per liter of lactic acid were formed at a pH of 2.6 to 7.0 with twelve different yeasts. The constant occurrence of lactic acid in fermentation products was also demonstrated by Durmishidze (1938). He showed that sugar not malic acid was its probable precursor in fermentation. The formation of lactic acid was intensively studied by Hohl and Joslyn (1941b). With a variety of yeasts they found lactic acid formation to parallel alcohol formation. While aeration showed no appre- ciable effect on lactic acid production, variations resulted from the use of different yeasts and media. Uchimoto (1951) found less lactic acid produced at lower temperatures than at high. Bobadilla and Navarro (1949) considered this acid more important to the flavor and body of sherry wines than tartaric or malic. During the period under the “flor” the lactic acid increased. The changes during storage were studied by Seiler (1943a). Lactic acid increased during the first four to seven months and then decreased; after bottling there was little change.

For detailed historical information on the malo-lactic fermentation, see Kramer (1941b), Vogt (1945), and Schanderl (1950). Reviews of the lactic acid content of wines are given by Anonymous (1940), Genevois and RibQeau-Gayon (1947), Amerine (1950-1951), and Fabre and Bremond (1932). The classification of the last-named authors on the basis of lactic acid content is interesting; young wines which have not under- gone a malo-lactic fermentation contain less than 0.1% and a pH of about 3.1; diseased wines have over 0.2% lactic acid and a pH of 3.3 or higher.

The amounts reported in various types of wines are indicated in Table XII.

Region Algeria

Algeria Alsace

Argentina California California

California

Czechoslovakia

TABLE XI1 Lactic Acid Content of Various Wines

(Grams per 100 ml.) No. of Mini-

Type of wine Source of data samples mum Table Fabre and 13 0.072

Table Br6mond (1937b) 3 0.074 Table Lobstein and 19 0.03

Table Velazquez (1936) 58 0.12 Table Hillig (1937) 17 0.11 Wh. table Amerine (1950- 17 0.08

Red table Amerine (1950- 4 0 .17

Wh. table Kopal (1938) 300 0.09

Br6mond (1932)

Schmidt (1931)

1951)

1951)

Maxi- Aver- mum age 0 .46 0 .19

0.128 0.092 0 .43 0.17

0.41 - 0.49 0 .29 0 .43 0 .19

0.25 0.21

0.41 0.24

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406

Region France

France

France

France

France Germany

Germany Germany Germany

Germany Germany Germany

Germany

Germany Germany Germany Germany Germany Hungary Hungary Italy (Cirb)

Italy Italy

Roumania

Russia

Spain

Spain

Switzerland Switzerland Turkey * Diseased wines..

MAYNARD A. AMERINE

TABLH XI1 (Continued)

Type of wine Table

Table *

Wh. table

Red table

Table Wh. table

Wh. table Wh. table Wh. table

Wh. table Wh. table Table

Table

Wh. table Wh. table Wh. table Table Wh. table Wh. table Table Red table

Table Table

Table

(sugared)

(unsugared)

Table

Fino

Oloroso

Wh. table Table Table

No. of Mini- Source of data samples mum

Chevalier (1930)

Chevalier (1930)

and Peynaud (1937a)

and Peynaud (1937a)

Hugues and 80 0.06

Hugues and 20 0.12

Rib6reau-Gayon 28 0.04

Rib6reau-Gayon 31 0.06

Peynaud (1950a) 12 0.07 Heiduschka and 29 0.06

Seiler (1933) 51 0.05 Alfa (1933) 46 0.03 Heide and Zeissett 24 0.12

Wirthle (1931) 22 0.05 Seiler (1935) 114 0.03 Mader (1936) 11 0.06

Pyriki (1930)

(1935)

Maxi- mum 0.29

0.37

0.25

0.38

0.25 0.46

0.42 0.50 0.39

0.41 0.34 0.19

Aver- age

0.14

0.23

0.10

0.20

0.17 0.28

0.13 0.19 0.22

0.18 0.084 0.10

Mader (1936) 8 0.07 0.14 0.09

Seiler (1936b) Seiler (1937) Seiler (1944) Hennig (1952) Seiler (1952) Torley (1942) Torley (1942) Sallusto and Sci

71 0.02 66 0.03

128 0.05 11 0.08 24 0.06 10 0.00 10 0.09

ulco 26 0.14

0.32 0.28 0.38 0.25 0.61 0.33 0.44 0.30

0.20 0.07 0.14 0.16 0.15 0.19 0.25 0.19

(1937-1938) Violante (1950) Garino-Canina

(1951a) &muleanu and

Ghimicescu (1936)

Voskobohikov (1931)

Bobadilla and Navarro (1952)

Bobadilla and Navarro (1952)

Nitschk6 (1952) Berner (1952) Akman (1951)

40 0.23 0.37 0.32 9 0.08 0.34 0.15

33 0.09 0.44 0.21

117 0.037 0.33 0.15

15 0.071 0.140 0.109

10 0.085 0.189 0.134

16 0.08 0.45 0.26 24 0.063 0.367 0.217 66 0.02 0.16 0.07

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COMPOSITION OF WINES 407

7. Other Fixed Acids SBmichon and Flaney (1933b) verified earlier work that glyoxylic acid

is a constituent of grapes (and even of wines). They used a Cannieearo reaction to produce glycolic and oxalic acid, determining the latter, assuming no oxalic acid was present originally. They reported 210 mg. per liter-this needs to be confirmed. Rodopulo (1952a) reported 0.0085 % oxalic acid in a must and 0.0087ojo in the wine. Ventre (1939) found up to 0.13% glucuronic and 1.0% gluconic acids in musts of diseased grapes. Sound vintages contained none or no more than 0.03 % of glucuronic acid. The acids were formed st the expense of glucose and fructose. Peynaud and Charpenti6 (1953) developed a colorimetric procedure for gluconic acid. In red wines from sound grapes they found only traces; however, thirty-seven Bordeaux white wines, all of which were produced from grapes with more or less Botrytis cinerea, contained 0.29 to 2.46 g. per liter (average 1.02). Other organic acids probably will be disclosed by application of suitable techniques. See also p. 465.

8. Volatile Acidity (Acetic Acid)

The primary volatile acid present in wines is acetic. The term volatile acid, a rather loose one, refers to their volatility with steam. Usually formic, butyric, and possibly other fatty acids are included as well as acetic, but lactic is not.

The determination is important, since the amount permitted in com- mercial wines is limited by law. The limits in this country are lower than those of most European countries. The Federal limits are 0.120 g. per 100 ml. as acetic and exclusive of sulfur dioxide for white table and dessert wines, and 0.140 for red table wines. Michel (1948a) proposed a limit for free and esterified volatile acidity of 0.187% (as acetic). Whether it is the acetic acid or ethyl acetate which gives a spoiled taste will be discussed under esters (p. 430). Under any circumstance a high volatile acidity usually means a high percentage of ethyl acetate. A review of the volatile acidity as a quality factor was given by Kramer (1941a).

Methods. The determination is complicated by the presence of carbon dioxide and sulfur dioxide and by the volatility of lactic acid. The volume of work is due not only to the analytical difficulties but to the desire to secure a simple and rapid procedure. Hugues (1930) and Ketelbant (1936) summarized the common methods used in France. Fonzes-Diacon and Jaulmes (1932) discussed the merits and defects of four common procedures, preferring their special rectification column procedure to S6mi- chon and Flanzy’s (1931a) method. They stressed that changes after sampling must be avoided and recommended salicylic acid to prevent changes during storage. A theoretical discussion of the distillation of various volatile fatty acids was made by Foucy (1932). His empirical procedure possibly does not take into account the varia- tions encountered in practice. Astruc and Caste1 (1932a) recommended for ordinary

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408 MAYNARD A. AMERINE

control work no defecation with alkali and distilling lO/llths of the volume of the diluted wine-possibly an oversimplification. Shmichon and Flanzy (1931a) found the principal sources of error to be: production of acids by pyrolysis, entrainment of lactic acid, and retention of free acid by the extract of the wine. Jaulmes (1935b) could not confirm the latter. However, individual components of the extract may reduce or increase the volatility of acetic acid. For example, organic acids and sugars increase it, whereas glycerol decreases it. He attributed the decrease in acidity in SBmichon and Flanzy’s experiment to growth of molds on the wine. Defecation with calcium oxide does not change the volatile acidity, or with wines it may increase it, owing to produc- tion of acetic acid. Addition of starch or gum arabic did not change the volatile acidity. The disadvantages of defecation with calcium oxide prior to the determination of volatile acids were studied by Jaulmes (1935a). High results owing to formation of formic and acetic acid from sugars were noted. A sidelight on the current methods for the determination of volatile acidity by steam distillation is Pozzi-Escot’s (1938) claim to priority.

Jaulmes (1934, 1951, 1952) has made a valuable theoretical and experimental study of the distillation of volatile acids. He considered the volatile acidity to consist of formic, acetic, propionic, butyric, and its higher homologs, such as isovaleric and capric. With the usual steam-distillation procedure, the results are frequently low, owing to dilution of the sample during distillation. He recommended adding a crystal of tartaric acid.

A detailed study of the influence of various factors affecting the rate of distillation of acetic acid from wines was made by Ionescu et al. (1933) and Ionescu and Popescu (1934). The speed of distillation is important; with a fixed speed the concentration of acid, the volume being distilled, and the amount distilled are also important. They recommended steam distillation of 10 ml. of wine, collecting 120 ml. of distillate in 50 minutes. The 50-minute limit was proposed owing to the slight volatility of lactic acid. The amount of lactic acid distilled depends on its concentration and the speed of the distillation. For the same speed of distillation and concentration in the wine, the volume of wine and the volume distilled governs the amount of lactic acid distilled. Acetic acid increased the volatility of lactic acid. Usually less than 0.005% of the volatile acidity is due to the lactic acid entrained during distillation. The conditions of distillation should always be stated-they prefer a modified Saunier-Gazenave tube. Mechanical entrainment must, of course, be prevented.

A collaborative study of the Association of Official Agricultural Chemists pro- cedure by Joslyn (1938b) revealed considerable discrepancies, probably mainly from differences in technique. Various theoretical problems were discussed. Further reports on collaborative analysis by Joslyn (1939) also showed variable results, but variation in the type of still did not seem to be important. He recommended further study of distillation methods. In a study of Peynaud’s (1937a) procedure, Joslyn (1940b) showed that the difference between the methods was not due to lactic acid. He sug- gested that the extent of neutralization and the period of contact may influence results by Peynaud’s procedure with wines of high sulfur dioxide content. Bringing the pH to 8 rather than 7 might be useful in decomposing more of the bound sulfur dioxide.

The micro-procedure of Ghimicescu (1935d) utilized steam distillation of 15 ml. of wine. A feature of his apparatus, found in recent American models also, is a method for removing the spent sample. See also Egorov (1951). Pavelka and Montini (1948) used a modified Pregl apparatus distilling 65 ml. from 10 ml. of wine. This appears to be too small an amount of distillate; however, the results obtained were very similar

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COMPOSITION OF WINES 409

to those with the method used in Europe where 200 ml. are distilled from 50 ml. of wine. The American practice of distilling 100 ml. from 10 ml. appears better. Use of superheated steam (260' C.) (500" F.) for distilling was proposed by Amadio and Paronetto (1936). They obtained values close to those of the official Italian distillation procedure.

Addition of sodium chloride prior to distillation was recommended by Jeanp6tre (1931) in order to increase the percentage distilled in the first 100 ml. Modified Caaenave apparatus for the determination of the volatile acidity were developed by G a d (1941) and Miconi (1952b). The latter's improvement is the large trap with pro- vision for rectification. A simplified formula for correcting for sulfur dioxide is also given. An all-glass apparatus and an adequate rectifying and scrubbing device to retain lactic acid were employed by Colombier and Clair (1938). They recommended a-napthalein as an indicator. Picozzi's (1947) apparatus was inadequately described but apparently allowed sufficient rectification to prevent appreciable distillation of lactic acid and had a special anti-spray trap.

Rather than distilling 100 ml. from 10 ml. of wine several short cuts have been proposed. Foucy (1932) used the 100-ml. distillate from 50 ml. of wine for determining the volatile acidity. Although he found a fairly constant fraction of the acids to distill from synthetic solutions, this is by no means true of wines of very variable composi- tion. Direct distillation of 72% of the wine and doubling the titration value has been tested by Violante and Imbrici (1949). On 34 of 35 samples their results were within f0.007% of those by steam distillation and the usual difference was f0.003. Procopio (194%) also distilled a fixed amount of the wine and applied an appropriate correction factor. Rentschler and Simmler (1949) proposed distilling 5 ml. of wine after addition of tartaric acid and tannin. The apparatus is simple, and the determination requires only 7 to 10 minutes.

Palieri (1952) distilled two 7.5-ml. portions from 20 ml. o iwine. The second 7.5-ml. portion was titrated and contained about 60% of the acetic acid, largely free of sulfur dioxide or lactic acid. In general, the amount of acetic acid present in the distillate was a function of the volume distilled, and a curve, y = $2, where y is the total amount present and z the per cent distilled, could be constructed.

The importance of carbon dioxide in the volatile acid determination was em- phasized by Marsh (1936). He recommended boiling the distillate for 1 minute and titrating hot. Removal of carbon dioxide is more difficult from sparkling wines. Pato and Salvador (1949) titrated the volatile acid distillate to a p H of 6.33 and then to 9. At a p H of 6.33, n (ml. 0.1 N NaOH) = 0.79A + 0.5C, where A is the volatile acidity expressed as acetic acid and C represents the bicarbonate content. At a p H of

9, N (ml. 0.1 N NaOH) = A + C. From this A = ':",.,". - They used bromocresol

and phenolphthalein as indicators. An early suggestion that entrainment of lactic acid may occasionally introduce

errors was made by Fonzes-Diacon and Jaulmes (1932), who recommended a rectifying column and rapid distillation to avoid the error. In order to prevent interference of lactic acid Ferr6 and Archinard (1935) made a double distillation. To reduce the lactic acid error Jaulmes (1951, 1952) employed a rectification tube, a 60-cm. Vigreux column (two theoretical plates). To reduce the carbon dioxide error, he used carbon- dioxide-free water.

Marcille (1934, 1935) proposed correcting for the sulfur dioxide in the distillate by iodine titration before and after desulfiting and gave an empirical equation for this. He admits that Jaulmes's (1934, 1951) procedure of determining both the free and

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410 MAYNARD A. AMERINE

combined sulfur dioxide is more practical and yields better results. Farrugia (1942) also recognized the dual nature of the correction to be made on the volatile acid distil- late owing to free and bound sulfur dioxide, but Fabre and Brkmond (1931b) in com- paring several methods corrected for only the free sulfur dioxide, as did Ferr6 and Archinard (1935). Bertin’s (1934) procedure of refluxing the wine to destroy the sulfur dioxide has been criticized as too long (30 minutes). Peynaud (1937a) neutralized to pH 8.5 with barium hydroxide, distilled, and corrected the acidimetric titration by subtracting one-half the sulfur dioxide found in the distillate. Carbon dioxide was removed by shaking under vacuum. Tarantola (1949) tested various procedures and recommended that of Jaulmes (1934), since those of Peynaud (1937b) and Marcille (1934) gave high values. Although the interference of sulfurous acid in the determina- tion of the volatile acidity is recognized by all, many analysts fail to make a correction for it or do not realize how much influence it may have. Procopio (1950a, b) has demonstrated how serious this omission may be with Italian wines. He distilled a por- tion of the wine and titrated. This distillate contains most of the sulfurous acid. The remaining liquid is brought to volume and distilled, and the distillate is titrated. The difference between the two represents, roughly, the sulfurous acid. At best the method seems too empirical, though simple and rapid. Mestre and Campllonch (1935) com- pared the results of several methods. They recommended dividing the volatile acid distillate into three parts, determining the total acidity, free sulfur dioxide, and total sulfur dioxide. The free sulfur dioxide plus one-half the total less the free is calculated as acetic acid and subtracted from the acetic as grams per liter. To reduce the sulfur dioxide Politova-Sovzenko and Dikhtyar (1948) recommend passing about 10 1. of air through 25 ml. of wine within an hour. Oxidizing the sulfurous acid was proposed by Perazzo and Arbecchi (1933) and Leggieri (1951). The latter treated the wine with hydrogen peroxide and barium chloride.

Origin. The most rapid period for formation of acetic acid during fermentation appears to be during the initial stages, according to Sal- varezza (1935-1937). Joslyn and Dunn (1941) and RibBreau-Gayon and Peynaud (1946b) confirmed this. The latter noted that after passing through a maximum more than half disappeared, varying with the yeast strain employed. Peynaud (1938~) observed that when acetic, propionic, or butyric acids were added to musts before fermentation only a slight amount of higher alcohol was present with acetic and considerable with the other acids-indicating their reduction during fermentation to their corresponding alcohols. The amount of acetic acid reduced was also shown by Peynaud (1939-40) to vary with the rH, the phosphate content, temperature, and the acidity of the media. He envisages the following scheme :

CHsCHO

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COMPOSITION OF WINES 411

Uchimoto (1951), however, found no correlation between volatile acid formation and the temperature of the fermentation. Joslyn and Dunn (1941) reported that the yields of formic and acetic acid in various atmospheres were as follows (grams per 100 ml.) :

Gas Formic Acetic Air 0.0489 0.0686 Oxygen 0.0273 0.132 Nitrogen 0.0162 0.0532 Carbon dioxide 0.0308 0.0492 Control 0.0289 0.0292

The effect also varied with the stage of fermentation. Activity of yeast dehydrogenase in oxidizing aldehydes, alcohol, and acetic acid are related to the changes in volatile acidity, but association or competitive action on these substrates and the influence of other acids may be important. The hypothesis of Joslyn and Dunn (1941) that acetic acid is formed by oxidation of ethyl alcohol was questioned by Peynaud (1947~). He postulated that acetic acid is formed by dismutation of acetaldehyde through the action of aldehydomutase. He also found that if dimedon was added to combine with the aldehyde, very little acetic acid was formed.

High volatile acidity is not always due to Acetobacter. Cappucci (1948) found volatile acidities of from 0.104% to 0.369% in new 1946 and 1947 wines. He attributed this to Saccharomyces apiculatus (KloeckeraQ) and Zygosaccharomyces sp. The rapidity with which volatile acidity can develop during fermentation under warm weather conditions was shown by Cruess (1936). He recommended 100 p.p.m. of sulfur dioxide to control the spoilage. Burdzhanadze (1951) showed that the alcohol lost during storage (owing solely to oxidation to acetic acid) was greater than could be accounted for by the acetic acid formed. Evaporation, decomposition of acetic acid, and oxidation of alcohol to other products probably account for the difference.

Since excess volatile acidity is prohibited by law, its reduction is of great interest. Two procedures have been proposed : refermentation or use of film yeasts. Ventre (1937), Peynaud (1938c, 1939-1940), and others have shown that acetic acid is reduced to alcohol during fermentation and that the lower the rH value, the greater the amount reduced. Various yeasts had different reducing properties. SBze (1938), Jaulmes (1952), and earlier workers had suggested the addition of high volatile wines to fermenting musts. An objection to the first procedure is the possible spread of infection and the spoiling of a potentially good wine.

The other procedure, use of a film-forming yeast, has been recom- mended by Marcilla et al. (1936), Cruess et al. (1938), Schanderl (1943), Bobadilla (1943), and more recently by Florenzano (1952), who found

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412 MAYNARD A. AMERINE

that both white and red wines could be so treated. The concomitant loss of alcohol was decreased by reducing the surface/volume ratio, but color and tannin were lost during the process. The claim that the organoleptic quality was increased should probably be considered only in relation to the removal of acetic acid. Peynaud (1938c), for example, objected to the use of film yeasts because of accumulation of aldehydes.

Both procedures assume that a wine once unfit for human consump- tion can thereafter be made fit for human consumption. Generally public health authorities forbid or frown on such practices. Possibly ion-exchange procedures might escape the legal and flavor problems. Patterson and Bawtenheimer (1930) found that deacetization with magnesium car- bonate occurred when all the acids, fixed as well as volatile, were neutral- ized. Magnesium acetate is only slightly volatile in the absence of a hydrolyzing agent.

9. Other Volatile Acids

SCmichon and Flanzy (19314 developed methods for formic, butyric, and propionic acids based on Duclaux’s method.

Formic Acid. Hohl and Joslyn (1941a) concluded that formic acid was “not a final by-product of alcoholic fermentation of sugar” by the strains of yeast tested by them. The indications from their data are that little would be formed at the high pH of California grape juice and that utilization during fermentation was greater than formation.

Seifert and Ulbrich (1930) found 0.023 to 0.089 g. of free formic acid per liter in 24 Austrian and Hungarian wines, a variable percent- age being esterified. Some of the formic acid may have originated from the long storage on the lees-decomposition of leucine being a possible source: CH(CH3)&H2CHOHCOOH = CH(CHJ2CH2CHO + HCOOH. The ratio of free formic acid to the volatile acidity was very variable. Villforth (1950-1951) reported about 50 mg. per liter in nine normal German table wines but found 270 and 460 mg. per liter in two Italian red wines. His procedure, based on a Duclaux separation, steam-distilling 250 ml. from 50 ml. of wine, however, gave a low but constant recovery of 44 to 46% with from 12.5 to 36.4 mg. Only dry wines can be used, as there is evidence for the formation of formic acid from invert sugar during steam distillation. He found the mousy taste of a gooseberry wine to be associated with a high formic acid content. Actually he stated that a polymerization of formaldehyde and acetaldehyde would produce the mousy odor. Hohl and Joslyn (1941a) used a steam-distillation procedure for formic acid but found lactic acid to interfere. They therefore pre- ferred the total-extraction mercury-reduction procedure of von Fellen- berg (1936).

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Butyric Acid. The presence and methods of determination of butyric acid in biological materials was reviewed by Grossfeld and Battay (1931). Detection of this acid in dilutions of 1/12,500 was reported. In five wines they reported 0 to 0.213 mg. per liter, average 0.088, using a potassium perchlorate procedure. Miermeister and Battay (1931), using the same procedure, found 0 to 0.60 mg. per liter, average 0.033, in seven authentic Greek sweet wines. In six Greek muscat wines, in which sophistication with the carob bean (St.-John’s Bread, Ceratonia siliqua) was suspected, 0.080 to 0.250 mg. per liter, average 0.143, were found. Berg and Schulze (1932) reported relatively large amounts of butyric acid in fermented beverages containing carob bean. Only small amounts were found in various European dessert wines. However, they considered it a normal constituent of sweet wines. A sensitive procedure for butyric acid was developed by Klinc (1935). In fifteen Jugoslavian wines 10 to 20 mg. per liter were reported. The wines were sound table wines of 9% to 11% alcohol and 0.06% to 0.08% volatile acidity. Wine vinegars contained up to 290 mg. per liter.

10. p H

The color, taste, clarity, and resistance to disease of a wine are closely related to its pH.

Methods. Morani (1930), Geloso (1931), Genevois and RibBreau-Gayon (1933), and RibBreau-Gayon (1938b) have given reviews of methods for determining the pH, the latter preferring the glass electrode. Von der Heide and Miindlen (1930) gave a good review of the methods available at that time. A comparison of the results obtained on four wines by five procedures follows:

Wine Method 1 2 3 4

Quinhydrone electrode 3.51 3.35 2.83 3.29 Hydrogen electrode 3.54 3.43 2.88 3.34 Diazoacetic acid ester

hydrolysis 3.48 3.37 2.82 3.31 Sucrose inversion 3.52 3.38 2.84 3.31 Colorimetric 3.38 3.26 - 3.26

Sulfur dioxide interfered with the hydrogen electrode procedure. They considered the quinhydrone method best, but, of course, the glass electrode was not easily available to them. Joslyn and Marsh (1935) showed that the hydrogen electrode was poisoned unless protected by an atmosphere of hydrogen. Measurements of the p H on de- alcoholized samples were less than on the original wine.

Fornachon (1946) has also reviewed the various procedures and found differences of 0.1 pH unit and more between the quinhydrone and glass electrodes, with the glass electrode values being more nearly correct. The quinhydrone electrode gave lower values because of the alcohol, but rsducing substances, such as sulfites and tannin, may result in high values. The compensation of the two errors results in approxi- mately correct results in some wines. RibBreau-Gayon and Peynaud (1937b) and

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Peynaud (19370) have applied the influence of pH on the hydrolysis of acetal as a method for the determination of the pH. The results for 26 samples by the acetal procedure averaged 3.19 and by the glass electrode 3.17.

An ingenious method for the determination of pH was devised by Bremond (193813). It consisted of two freshly cleaned platinum electrodes connected with an electrometer and with the two solutions by a salt bridge. One electrode was placed in wine plus quinhydrone and the other in potassium acid phthalate with quinhydrone. Sodium hydroxide was then added until the sensitive millivoltmeter, or capillary electrometer, showed no current. A table showing the pH for various amounts of sodium hydroxide added to the potassium acid phthalate solution was given.

Whereas the glass electrode gives results of adequate sensitivity in fortified wines, the influence of alcohol on the activity of the hydrogen ion is appreciable. For wines of 19% to 22% (vol.) of alcohol Ribeiro (1938) found the true pH to be about 0.1 pH unit below the observed value.

A method of capillary analysis was adapted to determine the pH by Boutaric and Bouchard (1935). The method is only an approximate one, since they diluted the wines 1/100. A pH indicator consisting of 2 volumes of saturated (aqueous) benzyl orange, 2 volumes of saturated (aqueous)a-dinitrophenol, and 5 volumes of 0.26 % (alcoholic) bromophenol blue was proposed by Marcilla and Feduchy (1943). The range waa from 2.8 to 4.6 with colors from orange to brown to gray to blue violet and a sensitivity of about 0.2 pH unit.

Roussopoulos (1930) used the following formula for calculating the pH based on

log A'(A - log A / ( A - X') - - ",:,, a t 35" C., where A is inversion of sucrose: pH = 2.19 -

the invert sugar (10.256) equivalent to 10 g. of sucrose (the amount used), X and X' the amount of invert sugar formed in equal times, and 100/94 a correction factor (2.19 is the pH of 0.1 N tartaric acid a t 35" C.).

In Grapes and Wine. Crisci (1931) studied the increase in pH during ripening of grapes and the changes in the juice during pressing-the first press was lower in pH than the second. Gerasimov (1931) also studied the pH changes during ripening. He reported that addition of amino acids during fermentation decreased the pH, but amides and ammonia were without influence. He also correctly interpreted the changes in pH and titratable acidity caused by the malo-lactic fermentation.

The importance of pH in the fermentation and stability of the cham- pagne wines of France was studied by Franpot (1945). He found no direct relationship between pH and titratable acidity, but he found that the relatively low pH of these wines was an important quality factor. The optimum pH for fermentation for a number of wine yeasts was studied by Burgvits and Hochberg (1936). They found 3.0 to 3.61 to be the best for speed of fermentation. With low pH musts too much sulfur dioxide should not be added lest the pH be reduced so low as to delay fermenta- tion. The influence of the pH on the rate of fermentation was also investi- gated by Casale (1930b, c). Whereas a pH of 3.3 to 4.0 favored the rate of fermentation, the best utilization of sugar occurred a t pH's as low as 2.8. Lactic acid formation was favored by higher pH values. Decreases

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COMPOSITION O F WINES 415

in pH commonly occurred during fermentation, the decrease being greater the higher the original pH. At pH’s below 2.5 Casale (1930a) found cell division and alcohol formation to be restricted, possibly be- (’&use of changes in enzyme activity. When 60 strains of Saccharomyces ellipsoideus were inoculated into samples of the same must, the resulting wines had pH’s of from 3.08 to 3.30 in the study of Goes and Correia (1942).

The spoilage bacteria of dessert wines isolated by Fornachon (1943) were very sensitive to a pH of below 3.5; this is probably the primary reason why so many European wines are relatively resistant to bacterial spoilage. A decrease of pH during growth of the film yeast in sherry pro- duction was reported by Marcilla et al. (1936). The changes in pH during the malo-lactic fermentation are summarized by Schanderl (1950).

Influence on Taste. Crisci (1930) showed that pH and acid taste were more related than pH and total acidity, but that the presence of other substances, alcohol, sugar, tannin, etc., modified the acid taste. The un- dissociated organic acids also have an influence-when they are added to wine the acid taste increases, but the pH remains nearly constant. Like- wise when a wine is diluted, the pH changes little, but the acid taste is greatly reduced. Wines vary from one to the other in this respect. Al- though Gerasimov (1931) and others stated that the acid taste is related more to the pH than to the total acidity, in his study this was limited to old Crimean wines of the same total acidity. The influence of alcohol, sugar, tannin, etc., made the relation less exact. The general relationship of acidity and pH to taste and disease resistance is indicated in the follow- ing data of Biedermann (1951) for Swiss table wines:

Total acid, % as tartaric pH Taste Disease resistance

1 0 -1 8 2 7 Very acid Very good 0 6 -1.2 3 . 1 Acid Good 0 4 -0 9 3 5 Average Normal 0 35-0 6 3 8 Flat Poor 0 25-0 4 4 1 Very flat Very poor

Gerasimov (1931) , Genevois and RibBreau-Gayon (1933) , and Berg (1939) showed that wines are so buffered that there is no simple relation between the pH and the titratable acidity. Bremond (1937~) has also amply demonstrated this. The importance of a relatively low pH to the appearance and flavor of French sparkling wines was emphasized by Frangot (1945). The possible influence of pH on various chemical changes in wines during aging was stressed by Gentilini (1952). The importance of the pH to the color and disease resistance of port was stressed by Ribeiro (1938). The pH of a potassium acid tartrate-10 ’% alcohol solution

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is about 3.5. Biedermann (1951) has shown that in wines of below 3.5, precipitation of potassium acid tartrate causes a decrease in the pH, whereas in wines of above 3.5, an increase in pH results. Dissolving the salt in wines causes the opposite changes. Under winery conditions the actual amount of pH variation with bitartrate precipitation is small and of little importance to the taste and biology of either grape juice or wines.

TABLE XI11 pH of Various Types of Wines

Region wine Source of data samples mum mum age Type of No. of Mini- Maxi- Aver-

Alsace California California California Croatia Croatia France France France France Germany Italy

Table Wh. table Red table Dessert Table Table * Table Table Dessert Sparkling Sparkling Wh. table

Portugal Dessert t Portugal Dessert $ Portugal Dessert 0 Portugal Table Spain Fino

Spain Oloroso

Switzerland Table * Wine grape varieties. t Experimental dessert wines. $ Red ports for export. 0 White ports for export.

Fabre and Br6mond (1932) Amerine (1947) Amerine (1947) Amerine (1947) Peretid (1950) Suc6vid (1950) Peynaud (1947~) Peynaud (1950a) Peynaud (1950b) Hennig (1952) Hennig (1952) Dalmasso and Dell’Olio

Ribeiro (1938) Ribeiro (1938) Ribeiro (1938) Correia (1943) Bobadilla and Navarro

Bobadilla and Navarro

Berner (1952)

(1937)

(1952)

(1952)

13 187 282 315 104 136 103 12 8 5 19 145

13 20 17 264 15

10

25

2.96 3.03 3.05 3.14 3.03 3.10 2.83 3.24 3.07 2.76 2.81 2.90

3.60 3.50 3.50 2.94 3.22

3.19

2.95

3.30 3.89 3.97 4.40 4.33 4.40 3.73 3.56 3.40 3.06 3.10 3.50

3.90 3.85 3.75 3.91 3.63

3.42

3.75

3.11 3.44 3.54 3.82 3.07 3.67 3.28 3.37 3.31 2.29 2.96 3.10

3.70 3.64 3.61 3.56 3.34

3.28

3.31

Crisci and Michielini (1932) demonstrated that small changes in pH had an influence on the efficiency of decolorizing charcoals and the clarifying properties of gelatine. In both cases the efficiency was greater a t higher pH’s of about 3.4 to 3.8 compared to lower (to 2.73) and higher (to 5.97) values. The influence on the pH of the wines of addition of 0 to 520 p.p.m. of sulfur dioxide to musts was indicated by the results of Pato and Sousa (1938). They found the pH of the resulting wine to vary from 2.87 to 2.54 following addition of 0 to 520 p.p.m. Such low pH values are not common in northwestern Europe or in this country.

Gerasimov (1931) reported in 202 Crimean wines a pH range of 3.0

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COMPOSITION OF WINES 417

to 3.93 with 84% of the samples between 3.2 and 3.6. In 14 wines of 27 or more years of age the pH was higher, 3.40 to 3.88. The pH of 42 Italian wines was reviewed by Morani (1930) and varied from 2.92 t o 3.60. Other European wines were as low as 2.65 and as high as 3.78. The pH’s of various types of wines are summarized in Table XIII.

Bufer Capacity. The buffer capacity, dB/dpH, where B is the milli- liters of 0.1 N sodium hydroxide added per liter, was used by Morani (1930) in his studies to detect addition of mineral acids. In Bordeaux red wines it varies from 35 to 45, according to Genevois and Ribereau-Gayon (1935a). In sweet wines at pH’s of 9 and over alkaline glucosates are formed. They concluded that the buffer capacity was of little analytical interest but noted that the buffer capacity to a pH of 4 was a measure of the organic acid content of the wine. In red wines the coefficient to a pH of 10.5 is a measure of the phenolic compounds and appears to increase with the amount of color. In white wines it is a function of increasing sugar content. In Bordeaux wines with pH’s of 2.7 to 3.5 no relationship of the pH to the quality or origin of the wine was found.

The extraordinary buffer capacity of wines has been observed by many investigators. Rippel (1949) noted the difficulty in changing the pH, either by biological or chemical means, but Schanderl (1950-1951) believed his results with calcium carbonate might be in error, since Schanderl found an increase in pH from 3.4 to 4.2 when the titratable acidity was reduced from 0.78 % to 0.38 %. Rippel (1949) showed that the buffer capacity increased during the alcoholic fermentation-owing to absorption of buffer substances by the yeast. Similar changes due to the malo-lactic fermentation were also reported, but no detailed studies on different types of wines have been made. Differences between wines of warm and cold seasons suggests that such studies should be made.

The buffer capacity of wines is largely owing to the buffer capacity of the organic acids they contain. The following data of Kramer and Bohringer (1940) are for 0.5% solutions of four acidic substances and a mixture; they show the change in pH with dilution with water:

48.5 mole % tartaric Dilution, Potassium acid + 51.5 mole %

% Tartaric acid tartrate potassium acid tartrate Mnlic 0 2 . 2 5 3 . 5 2 2 . 9 7 2 . 4 0 5 2 . 2 5 3 . 5 0 2 . 9 7 2 . 4 0

10 2 . 2 6 3 . 5 1 2 . 9 3 2 . 4 2 15 2 . 2 8 3 .51 2 . 9 1 2 . 4 4 20 2 . 3 0 3 . 5 3 2 . 9 0 2 . 4 6 30 2 . 3 3 3.5L 2 . 9 1 2 . 4 8 50 2 . 4 2 3 . 5 6 2 . 9 6 2 . 5 5 75 2 .61 3 .63 - 2 . 7 3 87 .5 2 . 8 1 3 . 6 8 - 2 .94

Lactic 2 . 5 1 2 . 5 1 2 . 5 2 2 . 5 4 2 . 5 6 2 . 5 8 2 . 6 5 2 . 8 6 3 . 0 2

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These results show that the pH changes least with a mixture of tartaric acid and potassium acid tartrate. Addition of sugar, alcohol, or gelatine generally raised the pH values and on dilution, even up to 50 %, the pH's remained higher. Morani (1930) correctly noted the influence of strong acids on the buffer capacity of wines. Morani and Marimpietri (1930) gave

10 W 30 40 50 Bo 70 0 90 100110 120 130140 I 5 0 Mllliequlv. NaOH adCd

FIG. 2. Titration curve and buffer capacity of a wine. The total acidity is equal to about 107 meq. (after Vergnes from Jaulmes, 1951).

further data on this point. They found the buffer capacity to be very variable between various wines. The buffer capacity of grape juices and wines was studied by Berg (1939). The relation of the titration curve and the buffer capacity is indicated in Fig. 2. The increase in buffer capacity above a pH of 9 is owing to tannins, coloring material, and other poly- phenolic compounds.

VI. CARBOHYDRATES Fructose and glucose are the chief sugars present in grapes. Pentoses

and sucrose have also been found. Related compounds present in wines

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include pectins, dextrins, caramel, and mannite. The sum of the dissolved non-volatile material in wine is called the extract.

1. Hexoses

The alcohol of wines is derived from the fermentation of sugars. Little new information on the types and concentrations of sugars present has been reported in the period under review.

Methods. The modified Lane and Eynon procedure with Soxhlet's reagent is now widely used for the determination of reducing sugars in wines. The main problem is the removal of interfering nonsugar materials. More experiments on recovery of added sugar should be employed, as suggested by Joslyn (1950). Ribeiro (1946) recommended addition of lactic acid and use of subacetate of lead as the clarifying agent. He recog- nized that basic lead acetate alone gives low results (owing to fructose absorbed in the basic lead precipitate); hence the addition of lactic acid, which lowered the p H and did improve the recovery to nearly 100%. The SBmichon and Flanzy procedure of defecating the wine with a mercuric salt was criticized by Pluchon (1937) as giving high results with wines containing sucrose or pectins. He clarified with mercuric sulfate and then with alkali and zinc powder. The procedure seems not to be used nowadays though the results reported were good. Jaulmes (1951) prefers mercuric acetate. Cunha and Ribeiro (1945) studied various volumetric and gravimetric pro- cedures for determining reducing sugars in dessert wines. The Lane and Eynon pro- cedure gave the best results, and since there is usually more fructose than glucose in dessert wines expressed the results as fructose. A modification of the Lane and Eynon procedure for the rapid determination of reducing sugars in musts was proposed by Gentilini (1950). Satisfactory agreement with gravimetric procedures was obtained on eighty-five wines.

A volumetric copper procedure and the usual copper gravimetric method on wines gave comparable results, providing details of the volumetric procedure were exactly followed, according to Kalberer (1930). Geiss (1938) proposed using a Pulfrich photometer to measure the blue color remaining after the reaction of Fehling's solution and the sugar. Lehmann (1940) used volumetric and gravimetric procedures with Fehling's solution, and Ghimicescu (1937) gave a micro-method. Von Fellenberg (1932b) found differences between his iodometric procedure and the gravimetric copper method, where wines contained reducing substances not precipitated by lead acetate.

JiinEnez and Mendivelz6a (1939) used a mixed reagent of alkaline copper sulfate and potassium ferricyanide. The sugar solution was added while boiling until the color turns green, methylene blue being used as the indicator. The method is probably overly sensitive, as are most procedures employing ferricyanide. For example, while GCorgacopoulos and Costopoulos (1952) favored the ferricyanide method for deter- mining the sugar in musts and wines, it gave appreciably higher results than the copper procdires when the sugar content was above 6%. Vartan'gn (1951) also employed alkaline ferricyanide and used methylene blue as the indicator. Amerine (1952) used ferrous orthophenanthroline as the indicator. Alexis (1933) proposed determining the residual sugar of red wines by heating to 100" C. (212" F.), adding sodium chloride and acetic acid, making alkaline with carbonate, adding iodine and titrating the remainder after 2 hours. Just what was determined by this procedure is not clear but certainly more than the residual sugar. Kielhofer (1953) calculated the approximate sugar

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content of normal wines from data on the specific gravity of the must and wine and gave tables to facilitate the calculation. A qualitative procedure was proposed by Trauth (1949). This consisted of extracting with ether and petroleum ether and tasting the residue.

Sidersky (1942) determined the total reducing sugar and the polarization. He reported the polarizing value times 0.1122 as “active” fructose and the total sugar less the “active” times 0.3548 as “inactive” fructose. The difference between the total sugar and sum of the “active” and “inactive” fructose was reported as glucose. A simple procedure for determining fructose in grape juice before and during fermenta- tion and in sweet wines was presented by Prillinger (1952~). It is based on heating 2 hours at 50” C. (122” F.) in an alkaline copper sulfate solution. He added sodium chloride to precipitate coloring material and other suspended material that might react with the iodine-added to determine the excess copper.

The value of the Zeiss refractometer for determining the soluble solids content of must in comparison with a Mohr specific gravity balance or with the Ochsle hydrom- eter was indicated by Buxbaum (1932) and Gerum (1932). Kramer (1935) stated that a t least ten single berries should be used in determining the sugar content of the must by means of a hand refractometer. Actually many more berries should be used (see Amerine, 1952). The utility of the Zeiss refractometer in determining per cent sugar in the grapes was shown by Zweigelt (1938). He also indicated that single berries were not suitable samples. The conversion of refractometer readings to Ochsle degrees is explained by Bohringer (1943). The equation x = 4.25y, where y is the refractometer reading and z the degree Ochsle, fits the data quite well. He recommends the hand refractometer for field studies, particularly with hybrids. Palieri (1951) has proposed it also as a rapid means of determining the sugar content of sweet wines when the alcohol content is known. Although his formula apparently works fairly well for the sweet table wines of Castelli Romani (near Rome), it is not applicable to California dessert wines.

The hydrometer designed by the Klosterneuberg station, near Vienna-commonly called the Babo hydrometer-reads per cent sugar. Gentilini and Carli (1950) used this on 390 Venetian musts on which the sugar content was determined by Fehling’s solution. The degree Babo read about -0.13 below the true value but was so variable that they recommended that it not be used. Barini-Banchi (1952) has also shown that the Babo hydrometer usually gives low results in comparison with copper-reduction procedures-no doubt owing to the variable amount of nonsugar solids in the musts. He also found that the refractometer reading less 3 is also usually lower than the chemical results.

Calculation of the sugar content of dessert wines when the alcohol and specific gravity are known was reported by Berg (1932). A table of the Wine Institute (see Amerine, 1952) gives similar data. Procopio (194813) has developed nomograms to facilitate calculating the sugar content from the density, alcohol, and extract con- tents. On seventeen wines the calculated sugar varied from -0.17 to +0.90 from that determined.

The problems of quantitative analyses of sugar in concentrate were indicated by Garoglio and Barini-Banchi (1940). In general there was slightly more fructose than glucose in the concentrate, Good agreement between the soluble solids calculated from the refractive index and those calculated from the density were obtained.

Source. The fructose and glucose content of ripening French grapes wm measured by Alexis (1936) at intervals of three to four days and the

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COMPOSITION OF WINES 42 1

glucose/fructose ratio decreased from 1.40 to 1.01. In an extensive study of the fructose and glucose contents of Hungarian grapes Szab6 and Rakcsinyi (1935) showed that a t the beginning of the ripening of the grapes glucose predominated. During ripening fructose increased more rapidly than glucose, until in overripe grapes it amounted to 56% of the total reducing sugar. Fructose equaled or exceeded glucose when the total sugar was about 17%. Drying or cooking of grapes did not change the ratio. This is surprising when one considers the heat sensitivity of fructose. In unripe grapes Sidersky (1942) reported a glucose/fructose ratio of above 1, but this varies with variety and origin. Espinosa (1943) showed the glucose to decrease from 86 % of the total reducing sugar to about 47% during ripening. In thirty varieties the ratio a t maturity varied from 0.87 to 0.96, average 0.90.

The increase in per cent sugar in grapes attacked by Botrytis cinerea is well known. SisakGn and Marutfan (1948) reported that the glucose/ fructose ratio generally decreased during ripening, but their data were variable. For a recent summary of the process see Schanderl (1950).

I n Fermentation. While most yeasts ferment glucose more rapidly than fructose, not all do so. The fact that the Sauternes’ strain of yeast ferments fructose faster than glucose has been known for some time. Normally glucose ferments more rapidly, even though fructofuranose has an affinity for hexokinase twice that of any form of glucose. The explana- tion, according to Gottschalk (1946), is that the cell walls of this strain are more permeable to fructose than to glucose. It is strange therefore that Kniphorst and Kruisheer (1937) should find a genuine French Sauternes with 72.4% of its residual sugar as fructose. Straub (1934) reported the fructose content of seven Sauternes to amount to 66.7% of the total sugar. In the drier neighboring wines of the Graves region seven samples averaged 55.7% fructose. In nine fortified wines, such as port, the fructose amounted to 50% to 65% of the total sugar content. Clavera and Oro (1932) reported the glucose to exceed the fructose in Mhlaga wines. Dubaquie and Debordes (1935) noted that with certain yeasts when the must was treated with monobromacetic acid nearly all the fructose fermented before the glucose. A yeast isolated from concen- trate or previously treated with monobromacetic acid behaved in the same way. They also reported data on the production of alcohol and the per cent residual glucose and fructose for several yeasts.

The most extensive study of the changes in fructose and glucose during fermentation appears t o be that of Szab6 and Rakcsinyi (1935). They showed with Hungarian musts that the glucose was fermented much more rapidly than the fructose in musts of 17% to 20% total reducing sugar. Both sugars fermented a t the same rate a t 20% to 25% sugar, and

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glucose fermented less rapidly than fructose at higher per cent sugars. This accounts for the fact that there is more glucose than fructose in the very sweet Tokay essence type of wine. The presence of added alcohol did not influence the rate of fermentation. Since concentrate has an equal or higher fructose than glucose, imitation wines, prepared by adding con- centrate to the dry wine, did not show the expected high dextrose content. Espinosa (1943) obtained similar results in Argentina. During fermenta- tion the glucose/fructose ratio declined from about 0.9 to 0.2.

Although grapes seldom contain enough sugar to slow down fermenta- tion, Mathieu (1938) reported such an instance for the RhBne region of France.

In Wines. The dangers of excessive residual reducing sugar in red wines were considered by Dubaqui6 and Debordes (1931). A rapid pro- cedure for the detection of excess sugar was developed. They considered 0.2 % the permissible maximum limit and recommended chemical analyses of the new wines rather than tasting.

An increase in residual sugar during the first six years of aging was noted by Perre and Michel (1947). This they attributed to hydrolysis of glucosidesmainly of the oenin. The enzymes responsible were reported more prevalent in some years than in others. In two dry Swiss table wines Godet and Martin (1946) reported 0.026% and 0.024% glucose and 0.036 % and 0.022 % fructose, respectively.

In three ports Muttelet (1930) reported the following percentages of fructose and glucose, respectively: 5.15 and 3.97, 5.38 and 4.02, and 5.40 and 4.00. The excess of fructose indicates either that the grapes were harvested late, when fructose was in excess, or that the yeasts employed fermented glucose more rapidly than fructose, or both. Ribeiro (1938) found the glucose to exceed the fructose in other Portuguese dessert wines, as the following data for the glucose/fructose ratio indicate:

No. of samples Minimum Maximum Average 13 * 0 .3 0.6 0 . 4 20 t 0 .6 0 . 8 0 . 7 17$ 0.4 0.9 0 .7

* Experimental dessert wines-lower sugar than oommeroial samplea. t Red ports for export. t White ports for export.

No differences in flavor, aroma, or carbonation of the dry finished sparkling wine were observed by Goresline and Champlin (1938) in fer- mentations with sucrose (cane and beet), glucose, anhydrous glucose, and commercial invert sirup. When used for the final sweetening dosage, differences in flavor between the sugars did occur in the wine.

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2. Pentoses and Related Compounds

The compounds generally regarded as being present include pentoses such as arabinose and methyl pentose; rhamnose; pentosans such as araban and methyl pentosans; and acids such as ascorbic and dihydroxy- maleic. In a study of the composition of the residual sugar in seventeen “dry” table wines von der Heide and Burkard (1935) showed that the total reducing sugar varied from 0.07% to 0.567%, of which 0.025% to 0.5% was due to fructose and the remainder was largely arabinose. Actually arabinose appears to have been determined in only four wines, but the values do agree well with those obtained by subtracting the fructose from the total reducing figure.

By dealcoholizing and refermenting, Tarantola (1948, 1950b) found about 0.05% to 0.18% nonfermentable reducing substances which he found to be pentoses. I n 89 samples of Italian red and white wines he reported from 0.036% to 0.199% pentoses (as arabinose). White wines averaged lower than reds, and some pentoses were extracted from the stems and skins when the must was fermented with them. I n 8 wines 0.020% to 0.038% pentosans were reported. The fermentable residual sugar in “dry” wines of moderate alcohol content was found to be fruc- tose. Canals and Collet (1939) on the basis of polarimetric studies con- sidered that invert sugar, not fructose, was the residual sugar in dry red table wines. No reference to the possible arabinose content was made. A very slight residual rotation was due to tartrate. Torricelli (1941) re- ported 0.05% to 0.11% pentoses (calculated as arabinose) in 41 natural white wines. When contact of the pomace with the wine was prolonged, an unidentified glucoside was found, called the “ Tresterfaktor.” Using both the arabinose content and the “Tresterfaktor,” he was able to identify 20 or 21 wines made from pomace. A micro procedure for the determination of pentose and colorimetric procedure for the unidentified glucoside were given. Torricelli (1943) has also determined the arabinose content of natural Swiss white wines. The range was from 0.43 to 1.14 g. per liter, the average 0.62. Genevois el al. (1949a) reported only 0.05 to 0.09 g. per 100 milliliter of pentose in 4 sweet Bordeaux table wines. Peynaud’s (1950a) values for pentose indicate that from a quarter to a half or more of the residual sugar is pentose. In 6 red table wines he reported 0.05 to 0.07 g. per 100 ml. and in 6 sweet white table wines 0.05 to 0.10, average 0.8. Finally, Jaulmes (1951) reported 0.04 to 0.13 g. per 100 ml. of arabinose in 5 red wines of Southern France.

Torricelli (1943) reported less than 0.05% rhamnose in wines and Jaulmes (1951) gave a range of 0.015% to 0.03%.

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3. Sucrose

Sucrose is added of necessity to musts in eastern United States and in northern European countries to increase the sugar enough so that the alcohol content of the resulting wine will fall in an acceptable range. The presence of considerable amounts of unfermented sucrose in sweet wines is usually considered sophistication. Details of the official German pro- cedure for the detection of sucrose in wines were given by Jahr (1931). The particular point made was that the clarification should be the same for the sucrose determination as for the reducing sugar determination. He used animal charcoal and lead acetate. A method for detecting sucrose was devised by Krauze (1933) based on destruction of hexoses with peroxide and conversion of sucrose to hydroxymethylfurfural. This gives a blue color with diphenylamine.

In Russian grapes S i s a k h and Marutkn (1948) reported 0.2% to 1.5% sucrose in 26 varieties. They used both acid hydrolysis and ester hydrolysis. The sucrose decreased in Isabella grapes during ripening, but the results with the Malbec variety were variable. No specific test as to the identity of the hydrolysis product appears to have been made. Small amounts of sucrose was reported in both immature and mature grapes by Venezia and Gentilini (1935).

Although sucrose may be found in wines made of non-Vitis vinifera grapes, it is usually found only in traces in wines made of Vitis vinifera varieties. Muttelet (1930) has confirmed this for three authentic samples of port wine. I n these he reported a very slight increase in reducing power following inversion-amounting to 0.024% to 0.038% as sucrose. The colorimetric diphenylamine test was negative, and there was little change in polarization following inversion. He concluded that those samples had not had sucrose added. Botelho (1935) also found no sucrose and normal glucose and fructose contents in an authentic Portuguese port. In eight genuine MBlaga wines Clavera and Oro (1932) found no sucrose. Godet and Martin (1946) reported 0.011% and 0.015% sucrose in two Swiss wines. Lobstein and Schmidt (1931) reported 0.0 to 0.15 g. per 100 ml. (average 0.06) in nineteen Alsatian table wines.

4. Related Compounds

Dextrins. Reducing sugar was determined before and after acid hydrolysis under pressure by Herrero (1943) and the difference X 0.9 expressed as dextrins. The amounts found were less than 0.1%. Bucci (1940) gave a technique for demonstrating dextrins in wine.

Caramel. Presence of caramel, a product of sucrose dehydration, is usually considered evidence of sophistication in wines and its addition is

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prohibited in some countries. Many tests for detection of caramel have therefore been devised. Mastbaum (1933) rejected the resorcinol test for detecting caramel in wine, as pure muscat wines of Portugal gave the test (possibly because they contained hydroxymethylfurfural, see p. 385). Various qualitative tests for caramel were reported by Fetzer (1938). A procedure for detecting addition of caramel to wine, based on precipita- tion of the caramel with an ether-alcohol mixture, was developed by Milos (1942). The test is not quantitative, as some caramels do not pre- cipitate quantitatively in such mixtures. A quantitative colorimetric procedure more specific than that of Milos based on use of Lovibond slides was developed by Mallory and Love (1945). Coal tar and vegetable dyes, wool extractive matter, and natural colors did not interfere. The chief advantage of their procedure is that the caramel is isolated in a relatively pure form. 7 he use of Lovibond slides is a disadvantage. A modification of the Marsh test for caramel was developed by Clapp and was reported on by Valaer (1945). The use of cyclohexanol plus methyl propyl ketone as the solvent is new. Valaer (1948) has reviewed the available procedures for the detection of caramel in wines. If care is used the Milos or Mallory-Love tests should not give positive results when caramel is absent. Since, in certain cases where oak chips or certain dyes have been used, the Marsh reagent may show a positive test, confirmatory tests should be employed. The Mathers (see Valaer, 1948) test is simpler. After separating the caramel the 2,4-dinitrophenylhydrazine test is used to confirm its presence. Scott (1946) preferred the Love and Mallory procedure. He reported that owing to aging or heating caramel-reacting materials are present in some normal California wines. The possi- bility that the Maillard reaction may be responsible is also to be considered.

Torricelli (1945) decolorized grape juices with animal charcoal and then examined them under a quartz-filtered ultraviolet light. Those pre- pared from raisins or concentrate had a strong luminescence. Pasteuriza- tion of grape juice at 85" C. (185" F.) for 30 minutes did not result in a positive test.

Mannitol. Whereas mannitic fermentations are seldom a problem where sulfur dioxide, pure yeasts, and temperature control are employed, Martucci (1941) has reported them in Argentina. He recommended con- trol of the must acidity, since a high pH also favored such spoilage. A complicated polarimetric procedure for mannitol (a sugar alcohol) in wines was presented by Salani (1937). Formation of mannite during dialysis of musts a t low temperatures (8" to 10" C. (46.4" to 50" F.)) in the presence of chloroform was reported by Barbera (1933b) (possibly owing to enzyme action).

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6. Pectins Methods. Barbera (1933a) extracted the pectin material of dried grapes with boiling

water and then fractionated it into an alcohol-insoluble fraction (xylan-araban?) and an alcohol-soluble fraction. Methyl alcohol was rapidly produced by pectase. His terminology is now somewhat outdated. To differentiate the pectins and the gums Peynaud (1952) made the alcohol content of the acidified must 80%. The impure pectin and gum precipitate was dissolved in hot water and reprecipitated. After a second purification it was dissolved. An aliquot sample was then placed in a platinum dish, dried, and weighed. The contents were ashed and the weight subtracted to get that of the pectins plus gums. Another aliquot of the purified pectin was titrated to determine the pectic acid and was then subtracted to determine the amount of esteri- fied pectin. These two subtracted from the net pectin plus gum weight gave the amount of gum. The milliequivalent weight of pectic acid was taken as 176 and of esterified pectic acid as 190. In a comparison with the usual calcium precipitation method, he found this procedure to give lower results. The methods used by NBgre et al. (1947) for pectic material has been shown by Peynaud (1952) to yield results two to nine times too high, owing to entrainment of insoluble calcium salts. Solms et al. (1952) have given a procedure for determining pure pectin and per cent esterification of grape pectin. They found two water-soluble polyuronides in grapes-one with the usual equivalent weight and a low degree of esterification and the other of much higher equivalent weight, though of the same components. The latter was not readily precipitable as the calcium salt.

Composition. SQmichon (1933) reported 12.86% methoxy in a purified pectin from grapes and 5.71 % mineral material-possibly calcium pectate. He reported a large increase in pectin content when grapes were allowed to become overripe and maintained that the increase in pectin, per se, was related to the increase in quality. This is difficult to believe from what we know of the solubility of pectin in wines. The dextro- rotatory substance in wines (insoluble in methyl alcohol) yielded uronic acids, galactose, and glucose in Parisi and Della Barba’s (1931) study- possibly from pectin. Barbera (1933~) separated from wines a methyl alcohol-soluble and -insoluble substance. The first he found to be pectin, and the latter was a uronic acid. A study of the pectins of wines was made by von Fellenberg (19444. He reported polygalacturonic and galactu- ronic acid (5.9 and 10.0 mg. per 100 ml.), araban (12.8 and 6.9), and arabinose (26.8 and 69.0) in a white dry wine and a wine prepared from “botrytised ” grapes. Using paper chromotography Solms et al. (1952) found galacturonic acid, galactose, mannose, arabinose, and rhamnose in pectin from Swiss musts. Von Fellenberg (1944b) gave a method of separating “ furfuroids” (from protopectin?). The “furfuroid ” content was higher in wines made from moldy grapes.

Amounts. Peynaud (1951b) reported the following fractionation of pectins and related materials in grapes (grams per liter) :

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Total pectin Pectic acid Gums or Variety material Free Esterified arabans

Merlot 1.77 0 .07 0 . 1 9 1.51 SBmillon 4 .43 0 . 0 2 0 . 1 4 4 . 2 7 Cabernet franc 1.22 0.08 0.37 0 . 7 7

The degree of purity of the total pectin material is much less in grapes than in peaches and other fruits. Hauptmann (1952a) reported 97 mg. per 100 ml. of calcium pectate in Riesling musts in September and 78.2 mg. a month later. Further data were reported by Peynaud (1952), who found the following average amounts of pectins and gums in Bordeaux musts and wines (grams per liter) :

N ~ . of Pectic acid samples Free Esterified Gums

Musts 8 0 .07 0 . 4 3 1 . 3 2 Musts* 2 0 . 0 2 0 . 1 3 3 . 7 2 White table 5 0 . 0 2 0 . 0 4 0 .59 Red table 5 0 . 0 2 0 . 1 3 0 . 9 3

* From grapes attacked by Bofrytis cinersa.

He concluded that pectins played no role in the mellowness of wines, since most of the pectin was lost during fermentation or during the first two months after fermentation. This agrees with the conclusion reached by Amerine and Joslyn (1951). The value, 0.05% for total pectic acid, is somewhat lower than most of the values reported by them or by Solms et al. (1952), who found 0.056% to 0.355% pure pectin (average 0.171) in thirteen Swiss musts of which an average of 31.4% was esterified. The gums, however, constitute about 0.1% of the wine. Peynaud calls these osanes or polysaccharides such as araban or galactan. More work needs to be done as to their identity and the changes which they undergo during aging. Franpot and Geoffroy (1951) also separated the pectins and the gums. They found three to four times as much in the press as in the free- run juice. During fermentation from 30% to 90% of the pectins were precipitated.

Removal. Use of pectolytic enzymes as an aid to the clarification of grape juice has been studied by Willaman and Kertesz (1931) and Mehlitz and Scheuer (1934). Hickinbotham and Williams (1940) and Besone and Cruess (1941) used commercial preparations successfully for clarifying the must. The resulting wines also clarify more rapidly. Cruess and Kilbuck (1947) added the enzyme to the crushed grapes to increase the juice yield. They obtained 6.5% more free-run juice when one part of the enzyme was added to 1000 of the crushed grapes, which were then allowed to stand overnight. They claimed the wines cleared more rapidly,

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were fruitier in bouquet, and yet matured more than twice as rapidly as untreated wines. Kilbuck et al. (1949) used amounts as low as 200 to 300 p.p.m. They reported the wines matured more rapidly. Little increase in methyl alcohol content was found. Finally Cruess et al. (1951) confirmed that in some cases treated samples were darker than untreated, particu- larly if the enzyme was added to the crushed grapes. They also found that the addition of galacturonic acid hastened darkening. Since galacturonic acid is a product of pectic enzyme activity on pectin, this would suggest a reason for the darkening of some treated wines. Considerable variability in results was obtained. This agrees with Testa and Maveroff’s (1949) results in Argentina, where they found regional and varietal differences. The galacturonic acid content of six white wines was determined by Cruess et al. (1951). Before treatment with pectic enzymes it varied from 3.1 to 8.0 mg. per 100 ml., average 5.3, and after from 6.0 to 14.1, average 10.1.

The value of pectolytic enzymes in aiding filtration was demonstrated by Geiss (1939) and Procopio (1949). Paronetto (1948) reported 50 t o 100 g. per hl. of a pectin-splitting enzyme (Biozim) reduced the pectin- gum content of two wines from 0.640 g. per liter to 0.580 and 0.504, respectively. The organoleptic data were conflicting.

Hauptmann (1952b) recommended a preparation low in pectase for red wines so that the extract and ash content of the wine would not be too high. With the proper enzyme he found the red wines of better color and flavor. For white wine clarification no protease should be present. Better clarification and freedom from protein cloudiness in the bottle was reported for the treated wines.

6. Extract

The meaning of the term “extract” has been debated since 1890. While it obviously means the nonvolatile soluble solids, it is difficult to specify analytically. Godet (1949) and Jaulmes (1951) have summarized the arguments and clarified the issue. At present extract is usually deter- mined by formula based on the specific gravity, by evaporation, or by hydrometer readings on the dealcoholized wine. None of the procedures is entirely satisfactory.

Formulas. The indirect determination of extract content may be represented by s.g. wine + s.g. water = s.g. alcoholic distillate + s.g. of the extract solution, where 8.g. is the specific gravity. This formula reduces to

s.g. extract = (s.g. wine + 1) - s.g. distillate

and has been modified by many later workers. Roussopoulos (1933) recommended a specific gravity procedure based on drying 48 hours under vacuum over PzOF,. His formula is the usual one. Ghimicescu (1938) used the formula (D - D1)2.685 to

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COMPOSITION OF WINES 429

calculate the extract, D being the density of the wine and D1, the density of the distillate (both by pycnometer). On 45 Roumanian table wines, he obtained an average extract value of 2.55 as compared to 2.60 for the drying procedure. The Rome convention of 1935 (Anonymous, 1935) defined extract as based on the densimetric method, using the specific gravity of the wine and the alcoholic distillate at 15O C. (59" F.). The actual formula used may be Schermann, Houdart, Dujardin-Salleron, or Roussopoulos, etc. The Dujardin-Salleron method sometimes gives higher and sometimes lower results than the dry extract obtained after 6 hours on a boiling water bath. Houdart's formula is (D - D ) K , where D is the density of wine at 15' C., D', the density of a water-alcohol mixture of the same per cent as wine, and K is 2.062. For 170 Alsatian wines Percher (1938) found K to vary from 1.079 to 2.591, average 2.198. For MBlaga wines Clavera and Oro (1932) found it to vary from 2.50 to 2.68. The best direct procedure in their study was i n aacuo at a low temperature. Laganne

(1938) discussed the various formulas and proposed

the extract in grams and s the sugar content. Percher (1938) preferred the Houdart value.

In determining the extract content based on density measurements the contraction is most difficult to determine. Jaulmes (1951) and Godet and Deuel (1947) have given approximate formulas for making this correction. Godet and Deuel (1947) noted that to account for the contraction which takes place when water and alcohol are mixed this formula should read

(q - 8, x 2.062 -k l, where is 2.663

Dextrsat = (Dprine - Daloohad + 1 - (Cwine - [cdaohol + CaxtraotI).

e e - 1 Jaulmes (1951) expressed the extract in grams per liter as 1,000- (De - l),

where e is the density of the extract. This takes into account the water of hydration which reduces the volume but not the increase in volume when a substance is dissolved in water. This means that the final contraction, D f , equals the contraction of the water less the increase in volume due to dilution and that the Jaulmes formula should read

(De - 1 - c). Godet and Deuel (1947) established that the Cf equals 1,000 - (De - 1) - ( p - v ) for volume of extract in 1 ml. From this they find the extract in

grams per liter to equal (De - 1 - C), where D is the density of the dry

extract. This is essentially the same as the corrected Jaulmes formula. Unfortunately, e, D , or the contraction of water or the final contraction cannot be measured. Grivas (1952) proposed making two dilutions and calculating from these the extract. For- mulas are given.

Tarantola (1947a) used the Windisch tables in preference t o those of the Acker- mann. The errors in direct procedures using sweet wines or wines of high volatile acidity are outlined. The indirect extract determination is usually higher than the direct, according t o von der Heide and Zeisset (1935), but with very high glycerol contents the opposite may occur, and they determined both in studying possible sophistication. A useful table for calculating the extract from the specific gravity was published by von der Heide and Mandlen (1933). Very useful tables relating the density and the per cent alcohol of wines were given by Pato (1938). These include temperature corrections and the relation between the density of the wine, its per cent alcohol, and its extract content. A similar table is given by Anonymous (1944).

Evaporation. Von Fellenberg (1944a) using artificial extract solutions showed con- stant weight losses up to 7 hours when drying at 103' to 105" C. (217.4" to 221" F.) ;

e e - 1

D

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however, he believed the direct procedure to be better than the indirect and proposed a formula a + 2(a - b), where a is the weight after 4 hours drying at 105" C. (221" F.) and b is the weight after 6 hours drying a t 105" C. (221' F.). He neutralized the extract before heating and subtracted the weight of the potassium hydroxide used for neu- tralization. Boinjak's (1936) study of the methods of determining the extract content has received little attention because of its isolated place of publication. He reported good results if the samples were dried in vacuum over sulfuric acid, providing the sugar content is below 0.8%. Indirect procedures were best for sweet wines. Percher (1938), however, did not find drying at 100" C. (212' F.) to yield consistent results owing to the influence of the per cent moisture in the air and the loss of glycerol. Drying 48 hours in a vacuum at 50" C. (122' F.) gave slightly better results than 60 to 120 hours. Fischl's (1942) direct method gave results to within 0.8%. Moreover, the empirical direct heating procedures involved more or less changes in various con- stituents: tartaric to metatartaric, malic to malonic, caramelization of sugars, etc.

The various methods for determining the per cent dissolved solids were discussed by Malvezin (1934) and Ay (1936). The latter described the various hydrometers and indicated their defects. The densimetric procedures were preferred to the direct evaporation methods of extract determination by Krombach (1948). The official French 6-hour evaporation procedure gave low results, and the Association of Official Agricultural Chemists procedure of evaporating 235 hours and the densimetric method gave concordant results. The value of the refractometer for determining the extract content is emphasized by Vetscher (1947), Bohringer (1951a), and Jilke (1951).

Miscellaneous. A review of his work showing that living wine yeasts form triose phosphates which are intermediaries in the fermentation process was made by Kiessling (1949). He reported that addition of a mycelium extract of Aspergillus sp. increased formation of triose phos- phates. At the beginning of fermentation the triose phosphate content decreased.

Markley et al. (1938) found nonacosane, hentriacontane, and sitosterol in the saponified bloom of Concord (Vitis Zabrusca) grapes. Gatet (1939a) identified a substance in grapes whose hydrazone was insoluble in hot alcohol but soluble in sodium carbonate and which is believed to be a furfural derivative. He also reported an aldehydic substance whose hydrazone was insoluble in hot sodium carbonate but soluble in alcohol. The presence of iodine-reducing substances other than sulfur dioxide, aldehydes, or sugars in wines has long been known. Muth (1933) shows that most of these are present in the grape but that some are produced by fermentation.

VII. ESTERS

Very little work on the esters of wines had been done since the classic studies of Berthelot in the last century until the Bordeaux enologists began their studies in the early 30's. The result of this work seems to relegate the esters to a secondary role in wine quality, except for ethyl acetate as a spoilage product. This is contrary to the rather loose state- ments often found in the literature.

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Methods. Espil el al. (1933) proposed extracting esters from wines in a continuous liquid-liquid extractor. Direct saponification of wines in the presence of sugars leads to formation of volatile acids. Esters of the fatty acids are easily distilled, but esters of polyhydroxy acids are more difficult. Because of the unfavorable partition coeffi- cient, esters are more difficult to quantitatively extract from wines. Espil and Peynaud (1936), however, obtained satisfactory extraction of neutral esters using freshly distilled neutral petroleum ether. Ethyl ether is unsatisfactory, since it extracts colored saponifiable materials. Dangoumau and Debordes (1937) obtained less satis- factory results, but Espil and Peynaud (1937) and Genevois (1937) indicated that this was due to an insufficient extraction. For the accurate determination of total esters and neutral esters the extraction procedure should be used. However, the determination of total esters, as outlined by Peynaud (1937b), is rather lengthy, and normally only the neutral esters are determined (Amerine, 1944). The neutral esters may be frac- tionated into volatile and nonvolatile neutral esters. Peynaud (1937b) has determined in the latter the ethyl tartrate, malate, and citrate, as distinguished from the ethyl lactate and succinate. The acid esters may be calculated by difference between the total esters and the neutral esters. It is also possible to determine the ethyl acid tartrate by determining the tartrate content before and after saponifying the acid ester by the racemate procedure (Jaulmes, 1951).

Because extraction procedures require special equipment and considerable time, the simpler distillation procedures have been investigated for the neutral esters and particularly for the neutral volatile esters. Peynaud (1937b, 1938d), Grandchamp and Vollaire-Salva (l939), Archinard (1939), and Peynaud (1939a) each have developed a procedure. In the first Peynaud (1937b) procedure the wine was distilled at a p H of 7.5, the distillate neutralized, excess base added and later back-titrated. In the second (1938d) the wine was buffered to a pH of 6.3 and about 15% distilled into base. After saponification the solution was acidified and distilled. The Archinard (1939) method is similar to the former except the distillate is received in base and the saponi- fication carried out at a temperature of not over 50" C. (112' F.) After saponification a n equivalent amount of acid was added and the excess titrated with base. The speed of distillation should be slow and care taken to remove carbon dioxide. Archinard (1940) developed a distillation procedure which Jaulmes (1951) considers the most rapid and accurate of the direct distillation methods. In it 50 ml. of wine were neu- tralized, buffered with 25 ml. of a pH 7.5 phosphate buffer, and distilled into a 150-ml. volumetric containing 20 ml. of 0.1 N alkali and 115 ml. of water. Excess sulfuric acid was added to an aliquot, the solution boiled and back-titrated with alkali. Grand- champ and Vollaire-Salva's (1939) method is admittedly approximate, being based on fist determining the volatile acidity. Another aliquot is saponified, then acidified and distilled. The difference in the two represents the neutral esters. None of these pro- cedures have given satisfactory recovery in the present author's laboratory, although Peynaud (1938d) obtained similar results by his second distillation procedure and by ether extraction. Reis (1946) favored distillation over extraction procedures, since he obtained low results on pure solutions. Peynaud (193713) and Amerine (1944), possibly with longer and better extraction, did not find this to be the case. Roubert (1951) determined amyl acetate in the vapors condensed during fermentation by a nephelo- metric procedure.

Diethyl tartrate is rapidly saponified by lead acetate, but ethyl acid tartrate resists saponification even when heated, according to Hartmann (1939).

Source. Espil et al. (1933) studied the speed of esterification of the various acids present in wine at 10% alcohol and in 0.1 N solution at

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100" C. (212" F.). The K X lo4 a t pH 3 and 4 were: acetic, 12 and 3.5; propionic, 10 and 5.0; butyric, 6 and 2.5; lactic, 250 and 60.0; succinic, 120 and 50.0; malic, 110 and 45.0; and tartaric, 40 (pH 3). The primary esterification is by bacteria, although some results from yeast activity. Even so, equilibrium is seldom reached, even in very old wines. For example, Espil et al. (1933) obtained the following results:

Acetic Ethyl acid, acetate, Coefficient of esterification

Year Alcohol, % pH millimoles/l. millimoles/l. Actual Calculated 1893 14.8 3.94 29.4 1900 11.0 3.60 17.5 1907 10 .2 3.30 20.6 1914 11.1 3.50 19.4 1925 10.1 3.63 19.2 1930 9 . 2 3.30 17.8 1933 10.0 3.77 15.6 1934 11.5 3.20 19.0 1936 10.6 3.60 11.2

3 . 1 1 . 7 1 . 8 2 . 0 1 . 9 1 .4 1 . 4 1 . 8 1 .o

10.9 9 . 4 8 . 5 9 .9 9 . 6 7 . 5 8 . 4 8 . 9 8 . 7

14.6 11.7 11.2 11.8 11.1 10.4 11.0 12.1 11.4

Formation of neutral and acid esters of the polyhydric acids is essen- tially a chemical reaction and proceeds very slowly. The following data of Espil et al. are indicative of this:

Neutral esters,

Year Alcohol, % pH millimoles/l. 1893 12.6 3 .35 0.75 1914 11.1 3 .60 0.60 1926 10.7 3.23 0 .40 1933 11.4 3.68 0.30 1934 12 .2 3.50 0.20 1935 10.6 3.60 0.00

Ethyl acid tartrate,

millimoles /l. 1.60 1.60 1.25

trace 0.00

-

The rate of esterification of acetic, propionic, citric, butyric, malic, succinic, lactic, and tartaric acids at three different pH's over a 30- to 60-day period was determined by Espil and Peynaud (1936). They showed that none of the ethyl esters of the polyhydric alcohols contribute to the aroma and would not even if present at ten times their normal amounts. Tomaghelli (1937) studied the rate of esterification of the system acetic acid-ethyl alcohol and that of saponification of the system ethyl acetate-water at 100" C. (212" F.) for 500 hours and a t 150" C. (302" F.) for 320 hours.

The most extensive investigations of the ester content of wines were made by Peynaud (193713). Although other alcohols than ethyl are present in wines, they are present in very small amounts. Glycerol is, of course, present in larger amounts but forms very little esters. As a matter of fact,

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only ethyl acetate was found to be an important ester from the organo- leptic point of view. I n wines the limits of esterification were never reached. Citric, for example, was only very slightly esterified a t the pH of wine. Lactic and succinic approached the limits of esterification most nearly and rayidly. Esterase was a negligible factor in wine esterification. Pasteurization did not increase ester content but esterification was very slow at 15" C. (59" F.) compared to 30" C. @So F.). Prolonged oxidation did not increase the ester content. The esters of simple acids formed during fermentation may have some slight effect on bouquet. More likely oxidizable petroleum-ether-soluble materials, such as tannoids or coloring matter, are responsible. Peynaud's work has been briefly reviewed in Italian by Procopio (1949). Peynaud (1938d) proposed a limit of 220 mg. per liter of ethyl acetate, in lieu of the present limits on the volatile acidity. (See also Peynaud, 1936a, 1939a, and Michel, 1948a.) This was based on the demonstration (1) that addition of pure acetic acid to wine does not produce a spoiled character; (2) that subjecting a moderately spoiled wine to a vacuum reduces the spoiled smell and the ethyl acetate content without changing the per cent acetic acid; (3) that adding pure ethyl acetate gives a spoiled character; and (4) that heating a wine con- taining acetic acid (no spoiled odor) in a sealed tube gives a spoiled odor while check samples a t room temperature show no such odor. Cellar samples with a badly acescent odor, a low volatile acid content, and a high ethyl acetate content were also observed. Grandchamp and Vollaire- Salva (1939) also reported wines of high acetic acid content which did not smell spoiled owing to their low acetate content and, vice versa, wines of low volatile acidity which had an acescent character. Gentilini (1947), however, found no correlation between ethyl acetate content and the volatile acidity in forty Italian wines. Moreover, the organoleptic tests were more in agreement with the volatile acidity than the ethyl acetate content, and he rejected an ethyl acetate limit as an indication of quality in Italian wines. He did find that wines high in ethyl acetate were usually also high in acetic acid.

West et al. (1951) have made a similar study on beer, where they reported a range of 23 to 55 mg. per liter of volatile esters, as ethyl acetate, average 40.7. They found no relationship between ester content and aroma, flavor, or foaminess.

Most of the neutral esters formed in wine result from biological activity. Uchimoto (1951) , however, showed that neutral esters were produced in slightly higher amounts at lower fermentation temperatures (less loss?). Even after many year's aging (up to 50) only about 7501, of the theoretical ester content was reached in the studies of Peynaud (193713) and Rib6reau-Gayon and Peynaud's (1936). The acid esters are

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formed by slow chemical activity, and esterification is more rapid at the lower pH’s. Approximately half the total esters found by Peynaud in Bordeaux wines were acid esters.

Yeasts as producers of esters have been of interest to those who believe esters contribute to wine quality. Gomes (1945), for example, isolated Hansenula anomala var. Spjarerica (Naegeli) Dekker from port grapes. This yeast produced 959 p.p.m. of esters in 45 days but only 3.5% of alcohol. Unfortunately the volatile acidity and aldehyde content were greatly increased. Tabachnick and Joslyn (1953) showed that ethyl acetate was the ester produced by this yeast, that ester production was favored at a pH of below 3, that the nitrogen source was relatively un- important, and that under aerobic conditions the ester is accumulated in the fermentation of glucose and is itself utilized. They suggest that the high ester yields indicate an energy-consuming reaction and not the reversal of a simple esterase hydrolysis. Popova (1948) found that esterase preparations from Oidium lactis, Botrvtis cinerea, and Aspergillus oryzae show high synthesizing and hydrolyzing ability. The synthesizing power is enhanced in oxidizing media. Wines were found to contain a weak esterase activity. Addition of mold esterase increased the syn- thesizing activity, as shown by an increase in ester content in young and aged wines. Wines treated with mold extracts also showed an increased enzymatic activity. Popova claimed that the principal role of the extracts belongs to the esterases because, owing to their action, glycerol and esters among other substances are formed, and these enhance the quality of well-aged wines. This is doubtful, to say the least.

A polemic has developed in Russia on the formation and importance of the carbonic acid ester diethylpyrocarbonate in sparkling wines. Parfent’ev and Kovalenko (1951, 1952) refuted Rosenfeld’s (1952) con- cept that diethylcarbonate is only condensed carbon dioxide in alcohol. They note that it has been synthesized and its physical properties determined. Kozenko (1952) reported the amount of carbonic acid ester to be 0 in musts and to increase during fermentation. In still wines about 9 mg. per liter were found, whereas in sparkling wines 125 mg. per liter were noted. I n a bottled sparkling wine 53 mg. were reported before opening, 42 mg. at 18 days after opening, 32 a t 60 days, and 26 a t 90 days after opening. The subject is, however, by no means settled; see, for example, Merzhanian (1951, 1952).

Amounts. The part which esters play in the olfactory quality of wines inspired the classical studies of Berthelot on esterification. Some claim that esters are important, but others admit only that ethyl acetate is a spoilage product and detracts from the quality. Reis’s (1946) results (see Tables XIV and XV) lend some support to those who believe quality and

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higher esters are related-the four-year-old and special quality ports have the highest ester content. But most of the work reported does not substantiate any such claim. In six Russian wines Oparin and Manskaya (1939) reported 1.1 to 3.6 meq. per liter of neutral esters (average 2.2) and 1.8 to 4.5 of acid esters (average 3.6). The neutral esters increased

TABLE XIV Total Neutral Esters in Various Types of Wines

(Milligrams per liter as ethyl acetate)

Region California California California France France France France Germany Portugal Portugal Portugal Spain

Type of wine Wh. table Red table Dessert Red table Swt. table Dessert Sparkling Sparkling Port (export) Port (old) Port (young) Sherry

Source of data Amerine (1947) Amerine (1947) Amerine (1947) Peynaud (1950a) Peynaud (1950a) Peynaud (1950b) Hennig (1952) Hennig (1952) Reis (1946) Reis (1946) Reis (1946) Bobadilla and Navarro

(1952)

No. of Mini- samples mum

79 80 60 170

124 93 6 132 6 141 8 112

13 155 40 103 33 114 4 598

12 229 25 540

Maxi- mum

553 725 730 229 273 336 292 351 334 924 422

1350

TABLE XV Total Volatile Neutral Esters in Various Types of Wines

(Milligrams per liter as ethyl acetate) Type of No. of Mini- Maxi-

Region wine Source of data samples mum mum California Wh. table Amerine (1947) 79 8 234 California Red table Amerine (1947) 60 61 228 California Dessert Amerine (1947) 124 17 201 France Red table Peynaud (1950a) 6 132 229 France Swt. table Peynaud (1950a) 6 141 274 Spain Sherry Bobadilla and Navarro 25 50 840

(1952)

Aver- age 209 400 333 186 21 1 209 246 207 195 693 332 826

Aver- age

73 112 104 188 211 344

more during ten years aging of a dessert wine (from 2.0 to 4.7 meq.) than did the acid esters (2.0 to 3.4). Reichard (1951) reported 15 to 350 mg. per liter of volatile esters in German wines. The total and volatile neutral esters of a number of different wines are given in Tables XIV and XV.

VIII. POLYHYDROXYPHENOLS

The tannins and coloring matter are the primary heterocyclic poly- phenolic compounds found in wines. They are similar in their chemical and oxidation-reduction properties. The tannins, furthermore, play an

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important role in the taste of wines, particularly of the reds. Their anti- biotic properties are less well established. The color of wines is one of their most important attributes from the consumer’s point of view. In grapes the tannins may be conaidered as phlobatannins-the phlobaphene- producing tannins. These are polyhydroxy flavinacoles and are thus basically derivatives of the heterocyclic benzopyrylium chloride nucleus from which the color pigments-anthocyanidins, flavones, and flavanols- are likewise derived.

1. Tannins

The phlobatannins of grapes are usually classified as pyrocatechol tannins because they give a green color with ferric chloride. Gatet (193913) pointed out that the polyphenols are colorless at an rH of below 14 and highly colored at an rH of above 23.

Methods. A large number of procedures for determining the tannin content of wines have been proposed. Reviews of the various methods were made by Collier (1935), Ghimicescu and Gheorghiu-Vieriu (1938), and Diemair et al. (1951). The primary problem is to distinguish the tannins from the other polyhydroxyphenolic compounds. The standard procedure is to determine the amount of permanganate reduction before and after treatment with charcoal. The charcoal removes the tannins and color; hence the difference between the two titrations represents the reduction due to them. This is known as the Neubauer-Loewenthal method. Durmishidze (1948b) and others have noted that the substances determined by the Neubauer-Loewenthal method are frequently erroneously reported as “tannins,” even though other oxidiza- ble substances are included, particularly in high oenidin red wines. As a correction he introduced the term “coefficient of oxidation of anthocyanin.” From the total oxidiza- ble substances the ether-soluble oxidizable substances were deducted. A correction coefficient for oenotannin was also introduced. The formula is:

E T = 0.00588 (2 - b.006y5 - p )

where T is the amount of tannin in grams per liter, Z: the milliliters of 0.1 N perman- ganate used for oxidation of tannins and coloring matter in the first titration of the wine according to the Neubauer-Loewenthal procedure, E the amount of oenidin ih grams per liter, and p the amount of 0.1 N permanganate required for the oxidation of that portion of ether extract which is absorbed by bone charcoal. Data obtained with this formula are in Table XVI. Vasconcellos (1940a) uses a factor of 0.00173 instead of the more commonly employed factor of 0.00416 for converting perman- ganate titration values to tannin in the Neubauer-Loewenthal procedure. He also uses gelatine or casein to remove tannin, claiming that charcoal also removes non-tannin- oxidizable substances. NBgre (1939a, b) has differentiated the oenotannin content- that precipitated by zinc-from the total tannoid-that precipitated by lead. The difference between the two he calculated as the polyphenol-non-tannin material. Sampaio (1946) precipitated the tannins with ammoniacal zinc acetate and oxidized the washed precipitate with permanganate using sodium sulfoindigotate as an indi- cator. The results obtained are naturally lower than when titrating all the perman- ganate-oxidizable material.

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A rather lengthy procedure, based on determining the copper-reducing value before and after removal of tannins, was devised by Astruc and Caste1 (1932b). The macro-method of Ghimicescu and Gheorghiu-Vieriu (1938) is based on the reducing ability of tannin for Fehling’s solution before and after detannising a sample of wine, the cuprous oxide being determined. It is not certain that the basic lead acetate used does not remove some sugar, which would vitiate the determination.

The Folin-Denis reagent was used by Rosenblatt and Peluso (1941) for the colori- metric determination of tannin in wines. Careful attention to details of temperature, time, and concentration is necessary, but the procedure is reported accurate to within

TABLE XVI Tannins in Red Wines*

Ether- Neubauer- soluble

Sample and Loewenthal Oenidin substances Oenidin,

date ml. 0.1 N KMnO4/1. t3.A Saperavi, 1946 930 130.6 100 0.908 Saperavi, 1916 360 65.0 85 0.452 Saperavi, 1915 305 74.4 75 0.519 Saperavi, 1894 365 57.6 75 0.400 Saperavi, 1891 310 51.3 80 0.357 Saperavi, 1887 460 70.8 95 0.492 Kaberne, 1942 560 80.0 80 0.556 Kaberne, 1917 480 70.3 65 0.489 Kaberne, 1898 285 70.3 85 0.489 * Durmishidze (1948b). t Corrected for oenidin and ether-soluble substances.

Tannin and color

(Neubauer- Loewenthal), Tannin, t

g.P. g.A. 3.869 4.112 1.500 1.234 1.270 0.915 1.520 1.366 1.290 1.050 1.920 1.739 2.330 2.352 2.000 2.026 1,190 0.762

0.5%. A similar procedure was given by Diemair el al. (1951). They proposed pre- cipitation of the tannins with lead acetate and gelatine, ,dissolving the precipitate in phosphoric acid and sodium phosphate, adding sodium tungstate and sodium car- bonate. The amount of blue color produced by the reduction of the tungsten by tannin (etc.?) was used as a measure of the tannin present (1-cm. cell with an 5-68 filter). Results were from 20% to 60% lower than by the Neubauer-Loewenthal method. Lang (1951) also used phosphotungstic acid. Pro (1952) modified the similar Association of Official Agricultural Chemists (1950) method to increase speed and accuracy so that the color density follows Beer’s law more closely.

The polyphenolic compounds of musts and wines rapidly fix bromine, and bromine titration may be used to measure them. Gatet and Genevois (1938) used this property to show that the amount of polyphenols was three times greater in the press juice than in the free-run. The method has been developed further by RibBreau-Gayon and Mauri6 (1942) and MauriE (1942). A substance extractable by ethyl acetate which consumes 8 bromine atoms per molecule is found in wines and grape berries. Genevois (1951) reported that the bromine consumption indicated 1.2 to 2.5 millimoles of catechol per liter and 4 to 6 millimoles of oenidin were present. The “catechol” may represent demethoxylated oenidin. Tarantola (1951) also used ethyl acetate for the separation of tannin from color. He reported that only 9.4% to 24.6% of the per- manganate required for oxidizing the tannin plus coloring matter of red wines was due to the ethyl acetate-extractable (tannin) material. For white wines this was 18.0% to

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61.9%. In the red wines the tannin content was not correlated with the color. The permanganate index, for example, varied from 4.7 to 12.9 with colors of 41 to 330. RibBreau-Gayon and MauriB (1942) reported that wines with a high permanganate/ color ratio were more astringent than those with a low ratio.

A photoelectric colorimeter was used by Faure and Pallu (1936) for the color of the tannin-iron complex. Kretzdorn (1949) also tested an iron chloride procedure, but citric acid (1% to 3%) interfered. The hide-powder method was applied to dealcohol- ized wines by Ponte and Gualdi (1931). Feigl and Feigl (1946) proposed use of a,a’- ferrous dipyridyl sulfate or a,a’-ferrous phenanthroline sulfate for the colorimetric identification of tannin. Synthetic tannins did not react and seven red and white wines gave positive tests.

Brugirard and Tavernier (1952) used the property of true tannins of flocculating a solution of 1% gelatine in 10% sodium chloride for their tannin determination in cider. They determined the total tannoids ( T ) by the Neubauer-Loewenthal procedure, then precipitated the true tannin in a buffered solution with 2.0% cinchonine sulfate, and determined the non-tannin polyphenols (t’) in the centrifugate. T - t’ thus equals the true tannins. Since the tannin content decreases with time, Fessler (1947) noted that the age of the sample should be stated along with the tannin results. Rentschler and Hauser (1950) precipitated the catechin tannins in a hot acid solution with formaldehyde, filtered, washed with alcohol and ether, dried and weighed. The anthocyanin pigments were reported not to interfere.

Source. Diemair et al. (1951) found the tannins of grape leaves and stems to be catechin tannins. In wines resorcinol and pyrocatechol were demonstrated in the tannin fraction. During the growing season, May to October, the tannin content of the leaves increased from 0.1% to 0.5%, and in the stems there was a sharp rise from 0.1% to 0.6% in July followed by a continuous decrease. In the berries, after an increase of from 0.2% to 0.4% in May and June, the tannin content decreased to 0.05%. When the seeds were crushed with the fruit, an increase occurred in August; and they showed this to be due to a large increase in tannin occurring a t this time in the seeds. During fermentation of white grapes the tannin content decreased. Dur- mishidze (1950d) also followed the changes in tannin content. During ripening he reported a decrease in the tannin fractions in the clusters, in the seeds, and particu- larly in the flesh and skin of the fruit. The composition of the tannin complex also changed, the ratio of water-soluble fractions to polyphenol catechols decreasing. However, the decrease in total tannin was not due to transformation of one type of tannin to another. The varieties differed in total tannin as well as in the ratios of the tannin fractions. Tannin diminution continued during storage of grapes.

The investigation of tannins by Durmishidze (194813) has shown that the ether-soluble substances (polyphenols and catechols) pass from the pulp into the fermenting must during the early stages of fermentation and that the amount in the wine is independent of the duration of fermenta- tion. The ether-soluble tannins remained essentially unchanged during the aging of wines. The amounts of tannin and oenidin increased with the duration of fermentation (contact with the skins). The accumulation of these substances is quite regular. There is a reduction in oenidin and ta.nnin during the aging of wine. They showed that the main part of the tannin complex in Rkatsiteli, Mtsvane, and Saperavi wines are the

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tannins of the catechin group, 63.1% to 76.0%. The data in Table XVII are typical.

Politova-Sovzenko (1947) reported the isolation of seven different catechin tannin materials from a white wine, but the original article is not available as to details. Ponte and Gualdi (1931) on the basis of compara- tive analysis by three different methods also concluded that the tannins of wines are exclusively of the catechin type. Durmishidze (1950a) isolated d-catechin by extracting with dry ethyl acetate, drying with sodium sulfate and under carbon dioxide a t reduced pressure, and pre- cipitating three times with chloroform and purifying with lead. The

TABLE XVII Catechin, Mixed, and Precipitable Tannins*

Variety Catechin Mixed of grape Material tannin, % tannin, %

Rkatsiteli Leaves 66 .2 17.8 Rkatsiteli Skin 76.0 15.8 Rkatsiteli Stems 74.0 18.4 Rkatsiteli Seeds 76.0 20 .8 Mtsvane Leaves 72.4 10.6 Mtsvane Skin 68.3 23.2 Mtsvane Stems 72.3 20.7 Mtsvane Seeds 74.5 23.8 Saperavi Leaves 63.1 20.9 Saperavi Skin 72.5 20.5 Saperavi Stems 70 .4 23 .4 Saperavi Seeds 70.6 27.1 * Durrnishidze (1948h). t According t o the Fisher-Bergman procedure.

Precipitable f tannin, %

16.0 8 . 3 7 . 6 3 . 2

17.0 8 . 5 7 . 0 1 .7

16.0 7 . 0 6 . 2 2 . 3

d-catechin was identified from its acetyl and methyl derivatives. Later, Durmishidze (1951) isolated Z-gallocatechin, which he found to constitute 45% to 54% of the total tannin. This compound and d-catechin do not make up the whole of the tannin complex, since the summation of the optical activities of the two do not add up to that of the crude material (+75"). It is particularly interesting to note that the skins are lower than the seeds in Z-gallocatechin. Durmishidze also showed that whereas 1-gallocatechin increased during ripening, d-catechin decreased. He sug- gested oxidation of the former to the latter.

Using his differential methods for distinguishing tannins from poly- phenol non-tannins, NBgre (1942-1943) found that the latter were mainly dissolved at the beginning of the fermentation and the former a t the end. In ciders the tannins constitute 32% of the total tannoids and 77.5% in perrys, according to Brugirard and Tavernier (1952). It is not often that sufficient tannins are found in grape juice to cause clouding. Such a case occurred in Austria in 1951 according to Prillinger (1952a). Pectin-

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splitting enzymes were of no value but gelatine-fining prevented reoccur- rence. Qualitative tests showed catechin tannins to be responsible. According to Schanderl (1950), 0.2% t o 1.0% tannin is slightly inhibiting on fermentation, but it was less toxic to normal wine yeasts than to Kloeckera types. However, the use of small amounts of tannin in spar- kling wine production is common and occasions no difficulty. NBgre (1939a) reported that 200 p.p.m. of sulfur dioxide in the must did not increase the tannin content of the wine but that addition of gallotannin did result in better-colored wines. It is not hydrolyzed during fermenta- tion. Use of tannin did not inhibit wild yeast or bacterial growth in fermentation in the study of Turbovsky et al. (1934).

TABLE XVIII Tannin and Coloring Matter Content of Various Types of Wine

Type of No. of Mini- Maxi- Region wine Source of data samples mum mum

California Wh. table Amerine (1947) 399 0.02 0 . 1 3 California Red table Amerine (1947) 282 0.10 0.38 California Wh. Dessert Amerine (1947) 407 0.01 0 .11 California Red Dessert Amerine (1947) 81 0.04 0 .16 Italy Table Lucchetti (1941) 12 0,011 0.310 Germany Wh. table Diemair et al. (1951) 90 0.004 0.064 Spain Montilla Casares and Gonzalee 51 0.005 0.174

Various Red table Diemair et al. (1951) 42 0.019 0.100 Various Dessert Diemair et al. (1951) 51 0.008 0.072

(1953)

Aver- age

0.052 0.21 0.05 0 .08 0.129 0.022 0.067

0.058 0.028

Decrease in tannin during aging owing to combination with protein was claimed by Beridze (1948). Since the protein content of wines is small and the decrease in tannin rather large, this hardly seems to be an ade- quate explanation. Joslyn and Comar (1941) showed that there is a gradual decrease in tannin as aldehydes are formed and that sulfur dioxide inhibits this decrease. Removal of tannins with casein or activated charcoal in the preparation of pharmaceutical wines was recommended by Ross (1942). Removal of excess tannin in white wines by means of gelatine-fining was recommended by Moreau and Vinet (1937). Rent- schler and Hauser (1950) reported that addition of 0 to 1000 mg. of gelatine per liter reduced the tannin content from 0.165% to 0.025%. Zlataroff and Poppoff (1937) studied the inhibitory effect of red and white wines on enzymes such as lipase, oxidase, peroxidase, invertase, and urease. The effect is attributed to the tannins. NBgre (1939a) also con- sidered tannin of some value in determining the resistance of wines to disease. Turbovsky et al. (1934) found tannin did retard the growth of spoilage bacteria (Lactobacillis) and considered that 0.05 g. of tannin per 100 ml. of wine improved low-tannin white and red wines. Nowadays tannin is seldom used. Cruess (1935) called attention to the influence of

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COMPOSITION O F WINES 44 1

tannin in the flavor of red wine and noted that low-tannin wines are more subject to disease than high-tannin wines. Fornachon (1943) reported similar results with fortified wines in Australia.

Amounts. I n fifty-six genuine red ports Vasconcellos (1940a) found 0.01 % to O.l6y0 tannin. In sixteen white ports the range was from 0.01 % to 0.04%. These values should be multiplied by 2.4 to be comparable to those of the Neubauer-Loewenthal procedure. Other values are reported in Table XVIII.

2. Color-Red Wines

The color of red wines has been studied much more than that of whites. The importance of color to the commercial value of red wines was stressed by Vogt (1935), Winkler and Amerine (1938), and others.

Methods. Many methods for measuring the color of red wines have been employed. The best are those based on optical transmission. However, other procedures have been more popular because of the labor involved in spectrophotometric procedures. Roos (1930) stated that the color density of a red wine is more important commer- cially than the tint. He used a standard of permanganate and dichromate and diluted the wine with 0.5% sulfuric acid until the colors matched, the number of milliliters of acid solution added being a measure of the color. The procedure has several faults- many wines are less acid than 0.5% and the tint will change. Using a color standard, Vogt (1935) reported on the color value of various German wines. Comparisons with the color standard were made a t six different depths and the average value calculated. Color values from 5 to 1470 were reported. The limitations of this method of expression of color were indicated by Amerine and Joslyn (1951) and Winkler and Amerine (1938). Kielhofer (1944) modified the Vogt color standard to give a better comparison as follows: 78 mg. alizarinastroviolet B, 14 mg. brillantcrocein MOO, and 4 mg. Griin PLX made up to a liter. Winkler and Amerine (1038) compared the Lovibond slides, color standards, the Dujardin-Salleron “vino ” colorimeter, and spectrophotometric data. They appear to have been the first to use transmission-curve data for the calcu- lation of brightness (luminance), dominant wavelength, and purity of wines. For data on the principles involved see Mackinney and Chichester (1954). Nedeltscheff and Kondareff (1941-1942) used 1 % Bordeaux red for specifying the color. The ratio of the optical density measured a t 480 mp and 640 mp was found by Boutaric et al. (1936) to be a good measure of the color of red wines. They gave transmission curves on six red wines. Mixtures of two wines gave values close to the calculated optical density a t three different wavelengths. However, with dilution the color density does not obey Beer’s law, particularly in highly colored wines. During neutralization the optical density increases and then decreases. Boutaric et al. (1937) also studied tthe effect of dilution on the optical density and found that it decreased more rapidly than would be indicated by Beer’s law. This they interpret as indicating that the color is not in true solution but present in a colloidal condition as micelles. On dilution the equi- librium between the micelles and the intermicellar liquids is disturbed (e.g., the micelles are broken up) and the optical density decreases.

Faure and Pallu (1935) determined the optical density at 460 mp with a photo- electric colorimeter and proposed the color unit ROB, which is K times the optical density, where K is chosen so that the 100 ROB is a standard red wine color. There is no assurance that i t would be satisfactory for a variety of wines of varying purity,

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luminance, and dominant wavelength. Korotkevich (1951) measured the color formed by making a diluted wine basic as a measure of the intensity of the original color present. A Pulfrich photometer with an 843 filter for whites and an S53 for reds was employed.

Genevois (1951) reviewed the methods used for color. He suggested bromination or titration with titanium trichloride at a high pH. Zinc has been used for anthocyanin reduction. However, oxidation of acidulated wine by means of permanganate is the commonest procedure.

Components. The primary anthocyanins of V . vinifera grapes appear to be the monoglucoside oenin and some diglucoside. Levy et al. (1931) found a small amount of delphinidin and its 3’-methyl ester in the Fogarina (i.e., Fogaruna?) grape. The absorption curve of natural and synthetic oenin chloride (malvidin) from 420 mp. to 600 mp. and the distribution numbers in a special solvent were identical for the synthetic and natural product. The picrate consisted of only about 45% oenin- the remainder may be petunidin (delphinidin 3’-methyl ester) and delphinidin.

In V . labrusca it may be a mixture of oenin and monomethoxy- delphinidin monoglucoside or, as Brown (1940) pointed out, a mixture of oenin, delphinidin monoglucoside, and monomethyoxydelphinidin mono- glucoside. In V . rolundifolia Brown (1940) reported the red color is probably a 3,5-diglucoside of 3’-O-methyldelphinidin, which he named muscadinin. The anthocyanin isolated by Cornforth (1939) from an Australian wild grape vine, Vitis hypoglauca F.v.M. was oenin and con- tained little or no delphinidin or its methyl esters. It therefore resembles the European species more than the American. Sastry and Tischer (1952b) identified chlorophyll, water-soluble yellow pigments, and carotene in addition to anthocyanins in the skins of Concord (V . labrusca) grapes. The anthocyanin was oenidin 3-monoglucoside. In paper chroma- tography studies, anthocyanidin and the diglucoside were identified. Tannins, especially those from grapes or grape stems, had a protective influence on the destruction of the anthocyanins by ultraviolet light.

The color of hybrids of American and European species of grapes was studied by Violante (1948). Although his procedure was not critical, he believed that his transmission curves justified concluding that hybrids contained a mixture of anthocyanins of both parents. He noted particu- larly the blue color in V . rupestris hybrids. Sudario (1953) reported the red color of American species of grapes and of their hybrids to have a lower methoxy content than that of V. uinifera grapes. The methoxy con- tent of the color of the wines was lower and the differences between species less. Variable rates of loss of color from wines by different varieties of grapes were reported by Amerine and Winkler (1947), who concluded that a mixture of pigments were probably present.

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Separation of the anthocyanins by partition chromatography was reported by Spaeth and Rosenblatt (1949, 1950), who utilized columns of silicic acid with 10% phosphoric acid as the immobile aqueous phase and a mixture of phenol and toluene as the nonaqueous phase. Following separation the anthocyanidins were quantitatively determined by means of optical density measurements. Mathers (1951) purified prior to chro- matographing. He used calcium chloride-methyl alcohol to precipitate the color, dissolving in phosphoric acid-isopropyl alcohol, adding ether, and passing the solution through a silicic acid column.

Vil'Lrns and Taranova (1950) separated oenin and oenidin by a modi- fied picrate method (oenidin is precipitated but oenin is not) and the extinction coefficient was determined at 520 mp. The sum of the extinction coefficients was only a little less than that of the wine itself. Durmishidze (1948a) measured the oenidin content by dealcoholizing, and freeing of other pigments and of glycerol, pectin, and mannitol. The color and tannin are then separated as lead salts and the methoxy content determined by the Zeisel procedure. He reported 4% to 6 % oenidin in the skins of red grapes and 0.06% in red wines. Durmishidze and Khachidze (1952) pre- pared pure oenidin by the picrate method from the skin of the Saperavi grape and constructed a table for the conversion of photometer values to concentration. They used a 50% alcohol solution at a pH of 1.2 to 1.4. Oenin and oenidin were separated with amyl alcohol. By this method only anthocyanins and anthocyanidins which have not changed color can be determined. Vil'gms and Taranova (1951) also absorbed the wine pig- ments on absorbent cotton previously washed with ether and dried in vacuum. On passage of red wine through cotton columns two zones were formed. Elution with acidified water (pH 1 to 2) removes the oenin and with acidified 50% ethyl alcohol (pH 1 to 2) removes the oenidin. At higher pH values the pigments are unstable. Both eluates were made up to volume with alcohol, and the extinction values were determined with the Pulfrich spectrophotometer a t 530 mp (filter S53).

The oenin and oenidin contents of several wines were as follows:

Wine and date Saperavi, 1946 Saperavi, 1949 Saperavi, 1949 Saperavi, 1949 Saperavi, 1949 Saperavi, 1949 Dneprooskoe, 1949 Dneprooskoe, 1949 Dneprooskoe, 1949

Treatment hTone None Steam, 1 hr. at 95" C. (203" F.) Dry air, 7 days at 28" C. (82.4' F.) 3 months storage Dry air, 15 days at 48" C. (118.4" F.) None Dry air, 7 days at 28" C. (82.4" F.) Dry air, 15 days at 48" C. (118.4' F.)

Oenin, W.P.

288 317 245

81

115 101 83

-

-

Ocnidin, mg./l.

260 300 190 165 134 39 50 44 45

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444 MAYNARD A. AMERINE

Source. The source of white and red wines is derived from grape pig- ments. Ducellier (1935) found the pigment in a state of granulation or in solution in the cells of the hypodermis of white-juice varieties. Amerine and De Mattei (1940), in order to release the color, used very hot water or steam to destroy the semipermeability of the cells. Quantitative data on the time-color relationship for temperatures of 70" to 90" C. (158" t o 194" F.) were reported by Joslyn et al. (1929). Sastry and Tischer (1952a) studied the influence of heating Concord grapes for varying periods a t 170", 210", and 250" C. (338", 410", and 482" F.). After 63 minutes a t the highest temperature there was pigment destruction but less under nitro- gen or in the dark than in air. Both the mono- and diglucosides of the anthocyanidin decreased. Using pure monoglucoside solutions even greater effects of temperature and oxidation were observed.

Removal of the aglucon fraction results in cessation of oxygen absorp- tion, according to Chogovadze (1948). At high fermentation temperatures the aglucon fraction increased-not only from the skins but from hy- drolysis of tannins. This also occurred during heating, the source in this case being leuco compounds.

Kaczmarek and Weise (1942) compared the transmission curves of musts, fermenting musts, and wines. They found differences in the shape of the curves between varieties, and in the height of the curves between grapes of different maturity or grapes grown in different regions. The changes in color with variations in pH were studied by Casale (1930d). He found the isoelectric point for the color change of oenin to be p H 5.4 to 5.8.

Aging and Fining Egects. The function of the anthocyanins in the aging of wines has been stressed by Genevois (1951). He reported pro- gressive demethoxylation during the first three years ; the pigments gradually become colloidal and are no longer reversibly reduced by hydro- sulfite. Genevois postulated that the latter was a result of demethoxyla- tion which gives an acidic orthodiphenol compound that condenses with other compounds. According to Heide (1940) precipitation of red wine color depends on the fining agent used, amount of sulfur dioxide and iron, and other factors.

Detection of Sophistication. In Europe where red wines of full color are desired, and the lack of maturity tends to prevent full color development, addition of foreign coloring matter is occasionally practiced. Various methods have been devised for the detection of such additions.

The absorption spectra of dye solutions and colored wines were compared by Casamada (1931). The differences found were too small to allow conclusions as to adulteration. The color absorption curve from 430 to 750 mp. of wines and of artificial colors was determined by Mon-

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COMPOSITION OF WINES 445

tequi (1933), and the possibility of detecting Bordeaux red by this means was considered. On dilution he did find that the optical density of wine obeys Beer’s law. Violante and Bemporad (1937) determined the spectral absorption curves of red wines and various artificial colors. They showed that the log of the molar-extinction coefficient is independent of concen- tration and might be used to detect adulteration.

Use of elderberry (Sambucus nigra and S. Ebulus) juice for coloring red wines, particularly port, is an ancient practice. Waser et al. (1932) determined the absorption curve from 200 to 560 mp and demonstrated that elderberry wine could be detected from the shape of the absorption curve in the region of 250 to 350 mp. A chromatographic technique with aluminum oxide was developed by Popov (1947-1948) for detecting elderberry pigments. Whortleberry, kermes, beet, cochineal, and twenty- four acidic, basic, or substantive dyes could also be detected, either alone or in admixture with elderberry juice.

To detect hematin, basic and acid fuchsin, scarlet red, and Bordeaux B and R in wines Gentilini (1939, 1941) absorbed on magnesium oxide and used acetone as the washing liquid. Ajon (1943) used aluminum hydroxide for detecting artificial color. Mohler and Hammerle (1935) separated the natural pigments of red wines from artificial colors by passing them through aluminum oxide. The artificial colors passed through easily, whereas the anthocyanins were strongly adsorbed. The absorption curve showed a maximum at 513 to 518 mp and a minimum at 410 to 413 mp for the wine pigments, and a maximum at 517 mp and minimum at 438 mp for the artificial colors. Mohler and Hammerle (1936) also used chromatographic columns to detect white wine in red. The eleutant from zones 1 and 2 were colorimetrically and spectrophoto- metrically compared for untreated wines and untreated wines to which 50% decolorized wine had been added. Both indicated about 50% dilution. A sort of primitive paper chromatography was used by Venezia (1940) for detecting foreign colors, such as Bordeaux red, in wines. Ruf (1952b) used paper chromatography to detect red beet, whortleberry, blackberry, elderberry, Bordeaux red (synthetic and vegetable), and synthetic raspberry color in a red wine.

To determine whether a white wine was made even partially from red grapes or had been decolorized by charcoal, von der Heide (1932) mixed 10 ml. of wine and 3 to 5 ml. of 10% hydrochloric acid, a pink or red color so indicating. The procedure is not new.

Various procedures for detecting addition of organic dyes were studied by Conceiggo (1942). The Arata procedure was sensitive to 0.002 mg. per liter, and a simplified modification could detect 0.01 mg. According to Ferrari (1939, 1942) addition of artificial colors can be detected by adding

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silver nitrate to a wine containing potassium bromide-a brown silver bromide precipitate indicated a pure wine and a red precipitate a basic artificial color. To detect artificial colors in wines, Maravalhas (1935) acidified, then shook them with xylene. The xylene is then absorbed on filter paper and examined. A capillary luminescence procedure for detect- ing added color in red or white wines was developed by Kocsis el al. (1941). This consists of allowing 2 ml. of wine to spread onto a Schleicher and Schull No. 602 filter paper, then examining the paper under ultraviolet light. By this means they could demonstrate addition of cochineal, elder- berry, or mallow leaves in red wines and of caramel or safflower (an extract of saffron) to white wines. Karamboloff (1932) tested for the presence of added colors by adding 3 to 5 ml. of 30% hydrogen peroxide to 5 ml. of wine on a watch glass. Natural wines turn yellow within 15 minutes, whereas those to which artificial colors have been added remain red. However, hybrids (such as Othello) were decolorized only in 24 hours.

A new procedure for the detection of elderberry color was developed by Wobisch and Schneyder (1952). It is based on the fact that there is only one OH group on the benzopyrylium portion of oenidin, whereas there are two on the elderberry chrysanthemin pigment. With the dihydroxy colors borate forms a red addition compound as follows: "c"=~=o OH

vc\ 0 C o - c ~ H ~ ~ o ~ H +

Therefore when borates are added to red wines in alkaline solutions, the color remains blue, but if the wine contains elderberry color, there is a shift to the red.

The special problem of detecting grape wine in berry wine has arisen in this country because of the cheaper price of the former. The per cent transmittance of authentic acidified and unacidified grape and fruit wines in the ultraviolet and visible regions of the spectrum was determined by Beyer (1945). When the curves from acidified and unacidified samples were plotted on the same graph, the curves cross to the right of 590 mp

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COMPOSITION O F WINES 447

in red grape wines (except for wines of the variety Pinot noir) and to the left in red berry wines. If one calculates the ratio of the spectral trans- mittance a t 590 rnb before and after addition of acid, a ratio of over 1 indicates grape wine and less than 1 indicates berry wine (except for the low-color variety Pinot noir). With berry juices and wines Yang and Wiegand (1950) reported a marked change in the shape of the absorption curve during aging, as indicated in Fig. 3. This shows a marked reduction in the ratio of the extinction coefficient at 515 mp and 340 mp.

1.0 1 3 E5'5'E340 Months 1.039 1 I Year 0.586 2 Years 0.424 3 Years 0.280

3 Mo.

1 I I

400 500 600 M I 0

FIG. 3. Ratio of the extinction coefficients Es~s/Etro for a loganberry wine (Yang and Wiegand, 1950).

3. White Wines

No carotene or xanthophyll was found in white wines by Peyrot (1934). From a study of the spectral absorption curve he concluded that white musts contain a red pigment, which decreases rapidly during vinification and rarely appears in the finished wine. The absorption spectra of a white wine and of solutions of quercitin and quercitrin were found by Peyrot not to be similar. He did find that a 0.008% solution of cyanine (a reduction product of quercitin) gave a curve similar to that of wine. The properties of the flavonols and other pigments of white wines are reviewed by Genevois (1951). In normal white wines they are stable, but in old white wines exposed to air there is a darkening and precipita- tion of the color. Genevois (1934a) attributed the slight fluorescence of white wines to be due to 0.04 to 0.1 mg. per liter of flavine and lumi- flavine. The fluorescent material was extracted by trichlorethylene. He believed the flavine might arise from the musts or yeasts.

Chromatographic analysis was used by Williams and Wender (1952) to identify isoquercitrin in Vitis vinifera. Isoquercitrin is the glucoside of quercetin, and its isolation appears to be new. Previously quercitrin,

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the rhamnoside of quercetin, had been reported. To detect foreign coloring matter in white wines, Ajon (1943) added potassium alum and sodium hydroxide to bring to the isoelectric point. A colored supernatant liquid after centrifuging was considered a positive test.

IX. NITROGENOUS COMPOUNDS

Much of the available information concerning the nitrogenous sub- stances in wines has been obtained during the period under review. With chromatographic techniques even more rapid progress can be anticipated. Since most of the papers have been on the nitrogen complex as a whole, the various compounds will be discussed together, except in the sum- maries of the analyses.

1. Methods Methods for determining total (by Kjeldahl) protein, ammonia, phosphotungstic-

precipitable, basic and amino nitrogen in musts and wines were developed by Muth and Malsch (1934). Peynaud (1939b) and Shcherbakov (1940) reviewed the pro- cedures. For total nitrogen Reichard (1943) used hydrogen peroxide and sulfuric acid. Total nitrogen in musts and wines was rapidly determined by Garcfa and Freyre (1951) by wet ashing with selenium and perchloric acid and distilling into Nessler’s reagent. Results comparable to those obtained by the regular Kjeldahl procedure were obtained on 1 ml. in about 10 minutes.

Amino Acids. Castor and Guymon (1952) and Castor (1953b) used microbiological assay techniques. Ribbreau-Gayon and Peynaud (1947a) gave a colorimetric tech- nique for tryptophane and utilized the Sbrensen procedures for amino nitrogen. Muth and Malsch (1934) used the Willstiitter technique for amino nitrogen. Sisakian and Bezinger (1949), Valaire and Dupont (1951), and Liithi and Vetsch (1952) used paper chromatography for identifying and roughly determining the amino acids in grapes and wines.

Proteins. Almeida (1948) has used a polarograph to identify certain proteins. From the similarity of the curves obtained with the extract of a port wine and pure solutions of albumins or globulins, he was able to estimate the protein content. A port wine deposit showed a relatively high protein content. He did not find peptones.

2. In Grapes

The changes in total nitrogen, ammonia, and amide nitrogen in five Bordeaux varieties during the ripening period of 1937 and 1938 was reported by Peynaud (1939~). On a volume basis the total and amide nitrogen increased during ripening. On a per berry basis all three in- creased. Whereas Casale (1935-1937) believed the ratio total nitrogen/ ammonia to be fairly unique for each variety, Peynaud did not find it so specific. Casale reported 5 to 120 mg. per liter of ammonia and 56 to 670 mg. of total nitrogeii in Piedmont musts, whereas Peynaud found 19 to 144 of ammonia and 156 to 870 of total nitrogen. There was more variation between localities than between varieties in the latter’s study. A review of the nitrogen fractions present in musts and wines was given

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COMPOSITION OF WINES 449

by Genevois and Rib6reau-Gayon (1935b). The total nitrogen content of Bordeaux wines varied from 300 t o 600 mg. per liter. New wines of different regions have varying amounts of ammonia and the varieties of grapes from the same region also differ in total nitrogen content. Wines made from insect-injured grapes had abnormally high nitrogen contents.

Wines from the same variety growing on granitic soils contain more nitrogen than those from schistic soils, according to Oliveira (1942). The decrease in nitrogen content of grapes attacked by Botrytis cinerea is very large, and this may favorably influence the stability of the resulting sweet wine. Schanderl (1950) has summarized the data on the subject. Barbera (1933~) believed the amino acids in wines were not primarily derived from the yeast but from the fresh grapes.

3. In Fermentation and Aging

The importance of the nitrogenous components of the must t o the fermentation and clarification, aging, and character of the resulting wine has been known for many years. However, quantitative data on many of the nitrogenous compounds are lacking, particularly on their specific relationship to fermentation, clarification, aging, or the character of the final wine.

Tarantola (194713) has made a contribution in this direction. He dis- cussed the influence of time of pressing on nitrogen content and the utilization of ammonia and amino acids in the early stages of fermentation when proteolytic enzymes are also active. Later changes are outlined and the results of other investigators evaluated. Valaize (1949) studied the disappearance of ammonia during fermentation in musts to which 0, 100, and 300 mg. per liter of ammonium phosphate had been added. Typical results, as milligrams per liter of ammonia, were:

Amount No. 1 No. 2 No. 3 added Must Wine Must Wine Must Wine

0 82.6 8 . 4 63 .0 7 . 0 61.6 6 . 3 100 102.2 7 . 7 82 .6 7 . 6 85 .4 6 . 3 200 135.8 6 . 3 9 8 . 0 7 . 0 119.0 4 . 9

It is obvious that the added ammonia is used up. No changes in the com- position of the wine were noted. He recommends use of ammonium phos- phate for cold musts.

The total nitrogen content of musts and their wines was not influenced by fertilizing the vineyards, according to Niehaus (1938). Loss of nitrogen occurred between 12 and 48 hours after fermentation started; 50.7% t o 58.5% of the total nitrogen was removed by fermentation. Yeast strains had little influence on the amount lost, but aeration increased yeast

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growth and nitrogen removal. Contact of the new wine with the lees increased its nitrogen content.

Hennig and Oshke (1942) and Hennig (1944) reported that several forms of nitrogen (total, protein, ammonia, amino, humic, and phospho- tungstic acid) all decreased during fermentation and then increased. Only amide and residual nitrogen decreased. While the nitrogen content is generally lower in a good (warm) year in Germany, the relationship can not be used for judging quality. Blue fining (addition of potassium ferro- cyanide to remove copper and iron) and gelatine-tannin fining decreased the nitrogen content slightly-8.4 to 26.6 mg. per liter less of total nitrogen in blue-fined wines. The yeasts appear not to add any protein material to young wines, but bacteria rapidly use up the amino acids.

Saenko (1951) showed that small amounts of nitrogen (194 mg. per liter from ammonia, amino acids, or autolyzed yeasts) stimulated the growth of the sherry film. Addition of ammonia (60 to 120 mg. per liter) reduced the period of film formation by 3 to 4 days and increased the film mass by 50% to 70%. The stimulated growth of the film also hastened the appearance of the sherry taste. For a pH of 3.1 to 3.2 more ammonia may be added, up to 120 mg. of nitrogen per liter (1.25 ml. of 20% am- monia per liter). This will raise the pH to the optimum, 3.3 to 3.4, for the film growth. For wines with a pH of 3.3 to 3.4 the amount of ammonia must be reduced to 60 mg. of nitrogen per liter. He concluded that addi- tion of ammonia would increase the production of finished sherry wine, improve the quality, and reduce losses, because a rapid growth of the sherry film reduces the danger of an acetic acid fermentation.

The changes in nitrogenous substances in sparkling wines during: fermentation in bottles and subsequent storage on the yeast were in- vestigated by Oparin et al. (1945, 1946, 1947). Fermentation is rapid during only the first 20 to 30 days. They found that practically all the yeast cells died about 80 to 90 days after fermentation started. The dead yeast cells, however, released enzymes (proteases), and subsequent changes in the nitrogenous substances occurred. These involved trans- formations which caused the Kjeldahl-nitrogen content to decrease between 110 and 255 days and after 370 days returned to normal. So, apparently, nitrogen compounds of unknown structure were formed, which escaped detection by the Kjeldahl method. Before fermentation about half of the nitrogen present in the wine is not precipitated by tannin and is also not determinable by the Van Slyke method. The nature of these nitrogenous substances is unknown. Most of the nitrogen trans- formation were at their expense. As the fermentation proceeded there was an increase of amino and basic nitrogen. After 300 to 350 days, the proteases are practically inactive, and no further changes in the nitrog-

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COMPOSITION OF WINES 45 1

enous compounds were observed. Oparin and Bezinger (1949) found a nitrogen compound in sparkling wines that was not hydrolyzed by proteolytic enzymes. Its amino acid content was also higher than that of proteins, and it gave a test for reducing sugar. They believed that during aging in the presence of yeasts a high molecular weight nitrogen-carbo- hydrate compound is formed. High molecular weight nitrogen compounds from bottle-fermented sparkling wine were isolated by concentrating under vacuum, dialyzing, reconcentrating, and precipitating in 88 % alcohol. These were apparently formed from carbohydrates and amino acids and polypeptides in the presence of yeast autolysate. They also reported free amino acids and polypeptides in sparkling wines and found that as much as 40% of the total nitrogen content could be accounted for by these. Independent confirmation of the changes in nitrogen content during the aging of sparkling wines comes from Schanderl (1950). He reports that after nine to thirteen months of aging, about one-third of the nitrogen content of the yeast is found in the wine. This he naturally associates with autolysis of the yeasts, as very large decreases in the amount of yeast in the deposit in the bottles occurred during the same period.

Castor (1950) reported a rapid decrease in amino acids during the early stages of fermentation, but several of the amino acids increased in the latter stages of fermentation, probably from autolysis. Addition of ammonium ion showed a “sparing” effect for arginine and leucine but not for glutamic acid or the other amino acids. Schaefer (1939) believed the amino acids to be important to the character of the wine. On the basis of a study of the nitrogen fractions Oliveira (1942) considered that a relation between quality and the per cent nitrogen had been demon- strated with port wines.

4. In Clouding

The colloidal nature of the nitrogenous material in Bordeaux white wines was noted by Rib6reau-Gayon (1932). As much as 26 mg. per liter of heat-coagulatable, negatively charged colloidal material, called albuminoids, was found. These can be eliminated by heating, by adding acids or tannin, by aging, by ultrafiltration, or by adsorption on kaolin.

A cloudiness followed by a precipitate in bottled wines, 80% of which was organic, was described by Kielhofer (1942). A more detailed study of the protein-clouding of 47 German wines produced in 1947 was made by Kielhofer (1948-1949). Organic fining agents were not effective, and silicic acid was recommended. Aging and blue fining were of some value. This clouding was not associated with heavy metals and did not occur until a temperature of about 20” to 25” C. (68” to 77” F.) was reached.

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Clouding reoccurred only when the wine was raised to a higher tempera- ture. Kielhofer (1949) reported bentonite reduced the nitrogen content 49 to 59 mg. per liter, but increased the mineral content 240 mg. per liter, probably owing to the absorption of exchangeable sodium, calcium, potas- sium, and magnesium. Ultrafiltration through a protein-tight membrane also reduced the nitrogen content but did not prevent turbidity when the wine was warmed. Heat- and tannin-precipitable, alkali-soluble material containing 6.4% to 11.8% nitrogen was found in certain German wines by Kielhofer (1951). He considered it a protein hydrolysis product, as i t could not be removed by ultrafiltration. He has also reported (1948) that the turbidity probably includes tannins. Roleff (1948) believed the tur- bidity of the 1947 wines due to high calcium content-possibly from the glass. Roleff (1949) noted that the changes in pH during heating might influence the proteins and that protein turbidity could be caused by a protein-tannin precipitate. However, Schmid and Nestle (1949) did not find the calcium differences in the 1947 wines to be great enough to cause cloudiness. Furthermore, they reported turbidity in wines which were not in contact with glass.

Archinard (1937, 1939) did not consider ammonia to be a measure of spoilage in wines, although French law sets a maximum of 200 mg. per liter.

5. Amounts

One of the first to fractionate the nitrogen compounds of wine was Barbera (1933~). He reported only three-ammoniacal, amide and amine, and total nitrogen. His data indicate the possible amount of amino acids in wine and also how much is removed by fermentation. The first exten- sive fractionation of the nitrogenous material in wines was that of Muth and Malsch (1934). The following indicates some of their results (as milligrams per liter) :

Protein Ammonia Geisenheimer

Geisenheimer

Geisenheimer

Geisenheimer t

(1931) 13.3 45.0

(1932) 10.5 19.1

(1930) 11.2 35.9

(1904) 7 . 3 15.9 * Without amino before hydrolysis. t An audese, a wine of late-piaked grapes.

Amino before and

Phospho- after Total by tungstic hydrolysis Humin Sum* Kjeldahl

313.6 223.3 274.5 9 . 2 655.6 665.8

145.4 - 194.2 9 . 8 379.0 376.8

221.0 203.7 251.1 8 . 6 530.8 536.5

120.9 120.2 148.0 9 . 1 294.2 301.2

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In Swiss wines Godet and Martin (1946) reported 0.0656%, 0.0531%, and 0.1425% of nitrogen as protein. Mestre and Mestre (1935) frac- tionated the organic nitrogenous materials in musts and wines. The pro- cedures used were not very specific, but tryptophane, glycine, cystine, leucine, and arginine were tentatively identified in musts, and the last two also in wines. When wine spirits are added prior to fermentation much of the nitrogen is precipitated; this had an adverse effect on the quality of the wines. However, when pure alcohol was used, no harmful effect on quality was noted. Venezia (1935) determined the amino nitrogen content of musts (116 to 358 mg. per liter) and of wines (56 to 245 mg. per liter). Red musts and wines were generally higher than whites. He sug- gested that the association of amino nitrogen and the yeast might explain differences between the odor of wines of different origins (and varieties?). Gentilini (1937) reported a total nitrogen of 0.0360% in a Cabernet franc wine. Of this 0.0015% was ammonia nitrogen, 0.0019% amide nitrogen, 0.018% amino nitrogen, and 0.015% protein nitrogen. The methods used may account for some of the results.

Using paper chromatography Sisakzn and Besinger (1949, 1950) identified glutamic acid, alanine, valine, and proline as the amino acids present in wines to the greatest degree. Lesser amounts of aspartic acid, serine, and threonine were found and identification of phenylalanine was doubtful. Later Sisakgn et al. (1950b) reported tryptophane in eight wines, varying in amount from a trace to 6.4 mg. per liter (average 1.6). In two Kakhetinskikh wines they reported a total nitrogen of 207 and 330 mg. per liter, of which 45% and 46.6%, respectively, were amino nitrogen. The Van Slyke diazotation procedure for amino nitrogen gave lower results than the determination of the free amino acids. The poly- peptide content of one sample was 13% of the total nitrogen.

Castor and Guymon (1952) reported 7 to 10 mg. per 100 ml. each of leucine, isoleucine, and valine in a grape juice of Vitis vinifera and less than 2 mg. in the resulting wine, Castor (195313) reported glutamic acid in the largest amounts in five of seven varieties (26.5 to 160.7 mg. per 100 ml.). Arginine was found in higher amounts in two varieties (7.0 to 113.0). The amounts of the other fourteen amino acids reported by him were usually below 10 mg. per 100 ml., and lysine, methionine, glycine, and cystine were present a t 2 mg. or less. From 75% t o 90% of the amounts originally present were removed by fermentation, except for glycine, lysine, and cystine, which showed little change during fermenta- tion. After fermentation five amino acids were returned in small amounts, presumably owing to yeast autolysis, namely, valine, isoleucine, leucine, tryptophane, and tyrosine. Durmishidze and Mosiashrili (1948) showed that a triose and not pyrotartaric acid was the hydrogen acceptor in the

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diaminization of glutamic acid. When glutamic acid was added to musts, the succinic and acetic acid and glycerol contents were proportionally increased.

The importance of amino acids to Bacterium gracile, one of the bac- teria in the malo-lactic fermentation, was stressed by Luthi and Vetsch (1952). A summary of the amino acid reports to date follows:

Sisaksn and Valaise and Liithi and Reich* Besinger Dupont Vetsch

Amino acid (1950) (1949) (1951) (1952) - Yes Yes Alanine -

Arginine Yes Yes Aspartic acid Yes Yes

Cystine Yes Glutamic acid Yes Yes - Yes

- Yes Yes Glycine - Yes Histidine Yes

Isoleucine - - Yes(?) - - Yes ( 1) - Leuoine Yes

Lysine Yes Methionine Phenylalanine - ? - Yes Proline Yes Yes Yes Yes

Yes - Yes Serine - Yes Theonine - Yes

Tr yptophane Yes Yest Tyrosine Yes Valine - Yes Yes Yes

- - - -

- - -

- -

- - - - - - -

- - -

- Yes -

* It is not clear from the text whether Reich actually determined these or not. t Sisakzn et al. (1950b).

Castor (1950, 1953b)

Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes

-

-

- Yes Yes Yes

The amounts of total nitrogen, amino nitrogen, amide nitrogen, ammonia nitrogen, and other nitrogen fractions are given in Tables XIX, XX, XXI, XXII, and XXIII.

X. ENZYMES, VITAMINS, AND AROMATIC CONSTITUENTS

Because the chemical composition of enzymes is poorly defined, they will be omitted from this review. For a summary of information on the enzymes in grapes and wines see Delp (1932), Requinyi and S o b (1935), Baglioni et al. (1935-1937), Casale and Garino-Canina (1935-1937), Venezia (1937), Manskaya (1939), Manskaya and Emel’yanova (1939), Oparin and Manskaya (1939), Hussein and Cruess (1940a, b), Hussein el a2. (1942), Cruess (1943), Ribdreau-Gayon (1943), Osterwalder (1945), Garino-Canina (1945-1946), Rodopulo (1948), Durmishidze (1950b, c), Popova and Puchkova (1950), Rentschler (1950), Rodopulo (1950a, b), and Tarantola (19504.

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Region Bordeaux Bordeaux Bordeaux France France France Germany Germany Germany Germany Italy

Portugal Roumania

Spain

Spain

Switzerland Switzerland

Region Bordeaux Bordeaux France France France Germany Portugal

Region Bordeaux Bordeaux France France Germany Portugal

TABLE XIX Total Organic Nitrogen Content in Various Types of Wine

(Grams per liter) Type of No. of Mini- Maxi-

wine Source of data samples mum mum Red table Peynaud (1939b) 35 0.143 0.666 Wh. table Peynaud (193913) 36 0.077 0.247 Table Peynaud (1950a) 12 0.168 0.394 Table Valaize and Dupont (1951) 72 0.100 0.952 Dessert Peynaud (1950b) 8 0.147 0.256 Sparkling Hennig (1952) 14 0.248 0.514 Wh. table Hennig (1944) 19 0.314 0.734 Wh. table Reichard (1943) 50 0.560 0.980 Wh. table Remy (1932) 10 0.294 0.908 Sparkling Hennig (1952) 43 0.102 0.666 Wh. table Dalmasso and Dell’Olio 145 0.046 0.201

Dessert Oliveira (1942) 64 0.106 0.215 Table , Sumuleanu and 33 0.23 0.71

Fino Bobadilla and Navarro 15 0.110 0.318

Oloroso Bobadilla and Navarro 10 0.200 0.318

Table Godet and Martin (1946) 3 0.111 0.240 Table Berner (1952) 8 0.420 0.825

(1937)

Ghimicescu (1936)

(1952)

(1952)

TABLE XX Amino Nitrogen in Various Types of Wine

Aver- age

0.330 0.185 0.246 0.473 0.191 0.379 0.493 0.766 0.491 0.262 0.102

0.152 0.39

0.209

0.261

0.156 0.590

(Grams per liter) Type of No. of Mini- Maxi- Aver-

wine Source of data samples mum mum age Red table Peynaud (1939b) 35 0.041 0.131 0.080 Wh. table Peynaud (1939b) 36 0.010 0.067 0.034 Red table Peynaud (1950a) 12 0.021 0.055 0.038 Table Valaize and Dupont (1951) 73 0.059 0.165 0.083 Dessert Peynaud (1950b) 8 0.021 0.070 0.039 Wh. table Hennig (1944) 19 0.068 0.196 0.108 Dessert Oliveira (1942) 58 0.018 0.061 0.032

TABLE XXI h i d e Nitrogen in Various Types of Wine

(Grams per liter) Type of No. of Mini- Maxi- Aver-

wine Source of data samples mum mum age Red table Peynaud (1939b) 35 0.001 0.006 0.003 Wh. table Peynaud (1939b) 36 0.001 0.007 0.003 Red table Peynaud (1950a) 12 0.001 0.003 0.002 Dessert Peynaud (1950b) 8 0.001 0.006 0.003 Wh. table Hennig (1944) 19 0.001 0.004 0.003 Dessert Oliveira (1942) 11 0.002 0.008 0.002

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456 MAYNARD A. AMERINE

TABLE XXII Ammonia Nitrogen (as Ammonia) in Various Types of Wine

Type of No. of Mini- Maxi- Aver- Region wine Source of data samples mum mum age

Bordeaux Red table Peynaud (1939b) 35 0.001 0.071 0.018 Bordeaux Wh. table Peynaud (1939b) 36 0.000 0.014 0.005 France Dessert Peynaud (1950b) 8 0.010 0.031 0.015

France Table Valaize and Dupont (1951) 73 0.017 0.201 0.101* France Table Archinard (1937) 8 0.007 0.069 0.020 Germany Wh. table Hennig (1944) 19 0.003 0.028 0.007 Portugal Dessert CJliveira (1942) 35 0.011 0.030 0.016 Roumania Table Vumuleanu and 33 0.002 0.048 0.009

Spain Fino Bobadilla and Navarro 15 0.004 0.026 0.012

Spain Oloroso Bobadilla and Navarro 10 0.008 0.035 0.021

Switzerland Table Godet and Martin (1946) 3 0.012 0.026 0.014 Switzerland Table Berner (1952) 8 0.014 0.037 0.027 * There is no clear explanation for these high values.

TABLE XXIII Other Nitrogen Fractions in Various Types of Wine

(Grams per liter)

Fraction Region Source of data samples mum mum age

France Table Peynaud (1950a) 12 0.009 0.019 0.012

Ghimicescu (1'336)

(1952)

(1952)

No. of Mini- Maxi- Aver-

Humin Germany Hennig (1944) 19 0.005 0.018 0.009 Peptone * France Peynaud (1950b) 8 0.008 0.018 0.014 Peptonet France Peynaud (1950a) 12 0.013 0.032 0.020 Phosphotungstic Germany Hennig (1944) 19 0.006 0.034 0.018 Protein France Peynaud (1950b) 8 0.001 0.011 0.003 Protein Germany Hennig (1944) 19 0.008 0.025 0.013 Protein Switzerland Godet and Martin 3 0.009 0.023 0.014

Nitrates Roumania Vumuleanu and 33 0.003 0.010 0.005 (1946)

Ghimicescu (1936)

Residual Germany Hennig (1944) 19 0.007 0.016 0.010 *Listed as peptone and polypeptide and does not include protein. t Probably includes protein and polypeptide.

Among those reported are : oxidase, tannase, invertase, pectinase, ascorbase, catalase, peroxidase, dehydrase, polyphenoloxidase, esterase, and a proteolytic enzyme.

1. Vitamins

Merzhangn (1930) reviewed what little was known of the vitamin content of grapes and wines in 1930; these were mainly qualitative studies of ascorbic acid content. A summary of Randoin's work on the

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COMPOSITION OF WINES 457

vitamin content of French wines was given by Hugues (1934). Minz and Sirianni (1934) concluded that grapes contained only small amounts of vitamin A, thiamin, and riboflavin, moderate amounts of ascorbic acid, and no vitamin D. Parro (1948) summarized Portuguese studies on the vitamin content of wines and recommended further studies in which the ecological factors would be considered. On the basis of her studies Morgan (1941) concluded that grapes supply (on the average) only 3% of the daily nutritive requirements (of vitamins, calcium, and iron) for adults.

Addition of vitamins to wines has occasionally been recommended. Ascorbic acid added to wines was retained rather poorly according to Randoin and Gallot (1941)-only 7.5% after two months. Addition of tannin did not affect the retention of ascorbic acid. Vetscher and Losa (1947) added 100 to 200 mg. per liter of ascorbic acid and 50 to 100 mg. per liter of thiamin to champagne cuv6es before bottling. Little influence on odor or composition was noted with ascorbic acid, but thiamin resulted in a deterioration in flavor.

Use of vitamins as accessory growth factors was studied by RibBreau- Crayon and Peynaud (1952). They added 25 micrograms per liter of biotin, 10 mg. of inositol, and 0.5 mg. of thiamin, and a mixture of all three. Each accelerated the growth of yeast, but thiamin alone was as good as the combination. RibBreau-Gayon et al. (1952a) isolated a sub- stance from an extract of Botrytis cinerea or Aspergillus sp. which favored yeast growth and increased the amount of glycerol and succinic acid formed. Rib6reau-Gayon et al. (1952b) also found fermentation inhibitors in the Botrytis extract. Use of thiamin when the fermentation starts slowly was recommended by them; however, it would seem that more data on its influence on quality should be obtained.

Ascorbic Acid. The practice of adding green walnut hulls or their pressed juice to wines is an ancient one. It has usually been considered that this was done to add color and flavor, but Jeroch (1947) suggested that the high ascorbic acid content of the hulls might be the basis of the practice.

To determine the total ascorbic acid, Genevois (1938) recommended reduction of dehydroascorbic acid with cystine, fixing the cystine with formaldehyde, and titration with dichlorophenolindophenol. Gerasimov and Vinogradova (1931) measured the ascorbic acid content of 150 Crimean grapes and 40 wines, using the colorimetric Bezsonov procedure. Onokhova (1937) tested 74 varieties in Russia for ascorbic acid. The cultivated sorts had only 2 to 5 mg. per 100 ml. of juice and the wild sorts 7.5 t o 12.5. Cahill (1933) reported that the hexuronic acid isolated from grapes had no antiscorbutic value and might be 5-ketogluconic acid. More likely i t was dehydroxyascorbic acid.

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458 MAYNARD A. AMERINE

The reducing property of the juice of nearly ripe grapes is largely due to ascorbic acid, according to Genevois (1938) and Genevois et al. (1938b), but another oxidation-reduction system is also present. This second system, with a high rH, is responsible for the darkening of musts. Gatet (193913) emphasized the influence of the ascorbic acid on the oxidation- reduction potential of the grape berry. Arutunyan (1939) reported grape leaves to be an excellent source of ascorbic acid-4,000 I.U. per kilogram -and recommended them as a possible source for the food industries. Kramer and Satterfield (1942) reported no ascorbic acid in a red and white wine of Scuppernong grapes after one year storage. Verda (1940) showed that addition of citric acid did not improve the retention of ascorbic acid in wine. Lesnovskaya and Vecher (1939) recommended storage, filtering, and bottling wines without access of air to prevent loss of ascorbic acid.

Schon et al. (1939) reported 1.8 mg. per 100 ml. of ascorbic acid in Portuguese red wines-slightly less than in the fruit. However, Scheurer (1944) reported 135 mg. per kilogram of grapes of ascorbic acid but only 3.6 mg. per kilogram in the wine. Ascorbic acid decreased from 134 mg. per kilogram of grapes to 3.6 mg. per liter of wine in Lodi’s (1943) investi- gation. This was probably due to enzymic oxidation. Rather extensive data on the ascorbic acid content of Italian grapes were reported by Venezia (1938, 1944), who believed that fresh grapes might have thera- peutic value. The ascorbic acid contents of a number of varieties of grapes from several other authors have been recently summarized by Amerine and Joslyn (1951). They showed quantities of 1.2 to 18.3 mg. per liter.

Vitamin A . Daniel and Munsell (1932) in rat tests reported small amounts of vitamin A in fresh grapes but none in commercial grape juices. Unsulfured, soda-dipped, dehydrated raisins retained their vitamin A and B contents rather well in the tests of Morgan et al. (1935). Sun-drying or storage, even in air and when frozen, allowed rapid loss, and if they were treated with sulfur dioxide prior to drying, the B was also lost. Schon et al. (1939) found little vitamin A or carotenoid pigment (about 0.005 mg. per liter) in a Portuguese red wine. Lodi (1943) reported 0.715 mg. per kilogram of carotene in grapes and none in the wines. The skins and seeds contained most of the carotene. Loss during fermentation is due to precipitation and enzymatic oxidation.

Thiamin. Lane et al. (1942) reported raw grapes to contain 0.67 mg. per kilogram and raisins, 1.06 mg. Flavier (1939) reported 0.5 to 0.8 mg. per kilogram in green Cabernet and Sauvignon blanc grapes, 0.2 to 0.4 in ripe grapes, and 0.05 to 0.11 after fermentation. Daniel and Munsell (1932) reported fair amounts of vitamin B in two varieties of grapes but little or none in commercial grape juices. When thiamin was added to

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COMPOSITION OF WINES 459

grape juices or wines, i t was retained according to Perlman and Morgan (1945). About 50% of the thiamin was destroyed by sulfiting the must before fermentation or filtering through bentonite after fermentation, according to Perlman and Morgan (1945).

The thiamin decreased from 0.316 mg. per kilogram to 0.007 in one case and from 0.134 to 0.07 in another in Lodi’s (1943) study. Esterifica- tion to cocarboxylase may be a cause of the decrease. Genevois and Flavier (1938-1939) reported 3d to $i of the thiamin present as the free base and the remainder as the phosphoric ester, although in an occasional wine as much as % was esterified. They reported less than 0.2 mg. per liter in most wines but two of thirty has 0.3, which seems very high.

Thiamin (B,) was shown by Schanderl (1950) to increase rapidly for 8 weeks in sparkling wine production. For 44 weeks thereafter it de- creased. As much as 0.23 mg. per liter were present at 8 weeks but only about 0.05 mg. at 52 weeks. Schanderl(l950) has summarized some of the German results as follows: fresh grape juice, 0.120 to 0.268 mg. per liter; commercial grape juice, 0.027 to 0.135; white wine 0.013 to 0.150; and red wine, 0.133 to 0.266. Morgan et al. (1939) reported 3 t o 4 I.U. of thiamin per 100 ml. in red and white table and dessert wines, or about

as much as in the original grape juices. Randoin (1936) found the B vitamins were preserved best in wines prepared as simply as possible and with a minimum of manipulation. Pasteurization was particularly harmful to their retention. Cailleau and Chevillard (1949) determined the thiamin of nine red and white French wines. They reported 0.008 to 0.086 mg. per liter, with an average of 0.034. Sisakgn et al. (1950a) reported 0.043 mg. per liter of thiamin in a new wine and 0.025 after growth of a film yeast.

RiboJEavin. Flavier (1939) found little riboflavin (about 0.05 mg. per kilogram) in green or ripe Cabernet and Sauvignon blanc grapes, but 0.3 to 0.5 mg. per liter after fermentation. The high percentage of yeast in the small Bordeaux barrels may explain the variable amounts. Riboflavin is easily destroyed by light, and about 50% is lost by sulfiting the must before fermentation or by filtering through bentonite, according to Perlman and Morgan (1945). Since white Bordeaux wines are usually marketed in clear glass bottles, this may also account for some of the variation. Riboflavin was found by Morgan et al. (1939) to be higher in white (1.00 to 1.50 mg. per liter) than in red wines (0.27 to 0.90). Perlman and Morgan (1945) also reported added riboflavin to be retained by both grape juices and wines, except when they were stored in clear glass bottles exposed to the light (for sixteen months), where it was largely destroyed. No difference in the riboflavin content of diploid and tetraploid grapes of the same variety was found by Smith and Olmo (1944). I n Lodi’s

to

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460 MAYNARD A. A M E R I N E

(1943) report the riboflavin content in grapes was 0.141 mg. per kilogram and 0.098 mg. per liter in the wine. Cailleau and Chevillard (1949) found 0.08 to 0.145 mg. per liter (average 0.210) in eleven French wines. Sisakgn et al. (1950a) reported the riboflavin to decrease from 0.182 mg. per liter before fermentation to 0.167 mg. after fermentation, and 0.087 mg. after six months under a film. An older sherry had only 0.063 mg.

The changes in several vitamins during alcoholic fermentation are shown in Fig. 4.

Other Vitamins. Pyridoxine was found by Perlman and Morgan (1945) in amounts of 0.83 to 1.82 mg. per kilogram of grape juice and 0.66 to

J U

0

0

LL 40-

I-

$ 6 0 -

50-

y 30 - LT w

a 2 0 -

I0 -

0 % I I I I 0 3 6 10 17 24 31 45 60 75 86 97 106

DAYS OF FERMENTATION

FIG. 4. Changes in carotene, thiamin, riboflavin, and ascorbic acid during fer- mentation (Lodi, 1943).

0.72 mg. per kilogram of wine. Pyridoxine added to grape juices or wines was well retained during storage. In eleven French wines Cailleau and Chevillard (1949) reported 0.2 to 1.2 mg. per liter (average 0.67).

Pantothenic acid was reported in grape juices and wines by Perlman and Morgan (1945) in amounts of 0.007 to 0.100 mg. per liter. When added to either, it was retained during storage. Smith and Olmo (1944) found significantly higher amounts of pantothenic acid in the juice of tetraploid compared to diploid varieties. Labrusca X vinifera interspecific hybrids were also higher in this vitamin than vinifera hybrids.

Cailleau and Chevillard (1949) found 0.70 to 1.90 mg. per liter (aver- age 1.08) of nicotinic acid in eleven French wines. Teply et al. (1942) found 0.28 mg. per 100 g. of nicotinic acid in fresh Sultanina grapes (1.84

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COMPOSITION O F WINES 46 1

mg. per 100 g. on a dry basis). Popova and Puchkova (1948) used Lacto- bacillus arabinosus for assay of nicotinic acid as did Sisakfan et al. (1950a), who reported 2.34 mg. per liter in a must, 1.69 during fermentation, and 0.72 to 0.90 after growth of a film yeast on the wine. They reported, however, that higher alcohols and tryptophane interfered by reducing growth of the bacteria. Castor (1953b), however, reported an unknown inhibitor factor present in musts where little tryptophane and no higher alcohols are present.

Considerable vitamin Bg was reported by Perlman and Morgan (1945) in wines after seven months storage. Castor (1953a) also reported biotin and p-aminobenzoic acid. Inositol has been identified by German workers and recently also by Castor (1953a).

The need of these vitamins for yeast growth was questioned by Wik6n and Richard (1951-1952), who made 120 successive transfers of the Fendant strain of yeast on a strictly chemical medium with no sign of diminished growth or viability. They also reported that (+)-biotin and meso-inositol when added in amounts of 0.0025 to 0.025 mg. per liter and 0.25 to 2.5 mg. per liter, respectively, only slightly stimulated growth. They concluded that the Fendant strain of yeast employed in Switzerland is an auto-autotrophic strain capable of synthesizing its cellular con- stituents from glucose-mineral-salt media. Similar results were obtained with other strains except that meso-inositol stimulated growth more.

However, Ribkreau-Gayon and Peynaud (1952) believe that the thiamin stimulates growth sufficiently to be considered of some use in winery practice. Considering the rate of fermentation actually observed in wineries, a t least in California. I ts use may be rather limited.

Wines have a component which strengthens capillary resistance, according to Lavollay and Sevestre (1944). This they attributed to the so-called vitamin P. A summary of the vitamin content of wines is given in Table XXIV.

2. Aromatic Constituents

While enologists have been interested in the odorous constituents of grapes and wines for many years, Hennig and Villforth (1942) and Hennig (1943, 1950-1951) seem to have made the first systematic studies on the subject. They extracted wine with pentane and after hydrolysis identified the alcohols and acids. They reported the following aldehydes, ketones, and related compounds (formaldehyde, acetaldehyde, propion- aldehyde, cinnamaldehyde, vanillin, acetone, methyl ketone, acetyl- methylcarbinol, and acetal-caproaldehyde and higher members of the series, benzaldehyde, and furfural were not positively identified but probably also occur) ; alcohols (methyl, ethyl, isopropyl, isobutyl, isoamyl, and a-t,erpineol-n-propyl, n-heptyl, and sec-nonyl (2-nonanol)

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462 MAYNARD A. AMERINE

are also probably present) ; acids (formic, acetic, propionic, n-butyric, caproic caprylic, capric, and lauric-isobutyric, isovaleric, and oenanthic are probably present). The alcohols and acids are present mainly as esters, since little free acid or alcohol was found.

S o b et al. (1948) have also undertaken studies in this field. They reported three aldehydes (oenanthaldehyde (heptanol) , acetaldehyde, and

TABLE XXIV Vitamin Content of Various Types of Wines

Must, Wine, micrograms/ micrograms/

Source Vitamin 100 g. 100 g. 30-57 * 0-12 Morgan et al. (1939)

0-24 Perlman and Morgan (1945) . . . . . . . 15-30 Genevois and Flavier (1938-

Thiamin. . . . . . . . . . . . . .

Riboflavin. . . . . . . . . . . . .

Pyridoxin . . . . . . . . . . . . .

Pantothenic acid. . . . . . .

7 . 4 0.8-8.6t . . . . . . . . . .

. . . . . . . 0-27.2 11 pl45t 27-50 25-122t

6-22 8 . . . . . . . 5-40 *

Nicotinic acid. . . . . . . . . .

14.1 1 . . . . . . .

40 $ . . . . . . . 83, 182 89, 150 . . . . . . . . . . . . . .

9 . 3 7 . 5

8.0-45.0* . . . . . . . . . .

0-12.5** 88, 70, 72 40-110 7-45 I

20-120*

1939) Scheurer (1944) Cailleau and Chevillard (1949) Watt and Merrill (1950) SisakGn et al. (1950a) Morgan et al. (1939) Perlman and Morgan (1945) Perlman and Morgan (1945) Genevois and Flavier (1938-

Scheurer (1944) Schon et al. (1939) Cailleau and Chevillard (1949) Watt and Merrill (1950) SisakGn et al. (1950a) Perlman and Morgan (1945) Perlman and Morgan (1945) Perlman and Morgan (1945) Cailleau and Chevillard (1949)

1939)

85-210* Cailleau and Chevillard (1949) . . . . . . . . . . Watt and Merrill (1950) . .

* Per 100 ml. t In experimental samples after 1 month’a storage. $ Per 100 g. of edible portion. a Average of wines = 5.34. ** Average of wines - 4.10.

In commeraial wines.

propionaldehyde), nine acids (acetic, lactic, propionic, butyric, valerianic, caproic, caprylic, capric, and pelargonic) , and six alcohols (ethyl, propyl, butyl, amyl, hexyl, and heptyl). More recently Holley (1951) reported isolation of nine volatile components from Concord grapes; details are lacking.

Haagen-Smit et al. (1949) extracted the constituents in a volatile oil

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COMPOSITION O F WINES 463

from fresh Zinfandel grapes. This variety was not a happy choice for the study, as the aroma of this grape is not distinctive and only after fer- mentation can its berrylike character be identified. They isolated ethyl alcohol (244 g. per 1000 g.), acetaldehyde (1.8 g.), acetic acid (0.0053 g.), n-butyric acid (0.003 g.), n-caproic acid (0.0015 g.), glyoxylic acid (0.118 g.), n-butyl phthalate (2.25 g.), leaf aldehyde (0.327 g.), sulfur (0.004 g.), acetylmethylcarbinol (0.013 g.), waxy substances (0.024 g.), and a carbonyl compound (0.024 g.).

The identification of lauric acid as one of the characteristic con- stituents of wine distillates was probably first made by Grossfeld and Miermeister (1928). They reported 5.8, 19.0, and 20.0 mg. per liter in three table wines (or 47.5, 163.8, and 183.4 mg. per liter of alcohol). They also reported 20.5 mg. per liter of caprylic acid (or 198 mg. per liter of absolute alcohol).

Chauvet (1950) has given a useful summary of the sources of the odorous constituents in wine and their importance to the quality. Chauvet considered the vinous odor to be due mainly to esters of lauric acid- concentrations of 1 in 40,000 being found in new wine. The propionic and butyric acids he believed might be attributed to enzymatic action on the oils of the grape seed or to enzymatic action on the amino acids. The tannins may be involved in the odor of red wines, particularly of wines stored in new oak casks, and their antioxidant effect may prevent oxida- tion of desirable aromatic principles already present. Esterification of fixed acids, such as tartaric or succinic, he does not consider important in the development of the “aged ” bouquet-because they develop slowly and because they have very little odor. The roselike odor of certain Beaujolais wines he attributed to p-hydroxyphenylethyl alcohol, derived from phenylalanine. Valaize and Dupont (1951) reported that Paris added phenylalanine to a must and secured the roselike odor. Presence of p-hydroxyphenylethyl alcohol in fermented rice wine was reported by Shimamoto and Sugayama (1951).

Schanderl’s (1938) experiments showed that the character of Rhinkand Moselle wines was derived entirely from the grape. Use of various strains of yeast to produce the characteristic flavors of these wines was unsuccess- ful. However, the sherry wine odor or “Sudweinbukett” can be obtained by using the proper type of yeast. The distinctive odor produced by film- forming yeasts has been noted by all who use them. The dry Spanish sherry wines owe most of their characteristic odor to these yeasts. Consult Shcherbakov (1941), Saenko (1947, 1948), Creuss (1948), and Fornachon (1953). Joslyn (1938a) showed that electrolysis produced a sherrylike flavor although not equal in all respects to the Spanish product. He also suggested simultaneous electrolysis and heating. Neubauer (1941)

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464 MAYNARD A. AMERINE

pointed out that production of aroma by yeasts could be hastened by aeration, particularly in producing a ‘‘ sherrylike ” odor.

Ravaz (1935) has indicated, and most enologists agree, that the pre- dominant factor in determining the characteristic quality of a wine is variety. Mezzadroli et al. (1931), however, reported a case where Barbera grapes fermented with “ Barbera” and “Chianti ” strains of yeast pro- duced wines with different bouquets. Peynaud (193713) believes the bou- quet is probably due to substances in the skin which are conditioned by variety as well as soil and climatic conditions.

Prillinger (1952b) believed that the odorous substances produced during fermentation should not be lost. He absorbed them on activated charcoal; they appeared to be esters and aldehydes and were not char- acteristic of the variety of grape. Smaller amounts were obtained in long, slow, low-temperature fermentations. Although these fermentation odors were considered favorable to the character and balance of young wines, they were not important in aged wines or in wines to which oxygen had been added. To prevent covering up the delicate fermentation odor he recommended keeping the sulfur dioxide content low.

In studies with synthetic solutions Kutal’ova (1931) showed that addition of amino acids or ammonium salts gave distinctive odors in the fermented product. I n the presence of lactic acid or ammonium salts a winelike character was produced, with glycine a yeast odor, with leucine a fruitlike odor, and with alanine a wine or yeast odor. Procopio (19488) has proposed a process for increasing the aroma of wines and brandies by addition of a yeast hydrolysate. This was said to accelerate aging changes and to result in wines of greater intensity of odor. Similar results during aging appear to be inherent in Russian work on tank fermentations.

Rib6reau-Gayon (193th) showed that the development of bouquet in wines took place only in the bottles in the absence of oxygen, i .e . , under reducing conditions. Lehmann (1943) has indicated the effect of alcohol, acids, and the soluble solids on flavor. The paper by Nelson (1937) on the flavor of alcoholic beverages adds little information.

XI. SUMMARY

The relatively constant relation between the major by-products of alcoholic fermentation was apparently first recognized by Genevois (1936). He found that the equation g = 5s + 2a + h, where g is the num- ber of moles of glycerol, s the number of moles of succinic acid, a those of acetic acid, and h of acetaldehyde, theoretically expressed the relation. The actual analysis showed g to be less than the equation indicates and it is usually calculated as 0.9 g. Genevois et al. (1946; 1947a, b; 1948a, b, c; 1949a, b, c) , Peynaud (1948a) , Peynaud and RibBreau-Gayon (1947), and

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COMPOSITION OF WINES 465

Genevois (194913, 1950) have reported on the subject. Their final equation -5s + 2a + b + 2m + h = 0.9g(Z), where s, a, h, and g are as above, b is the moles of the 2,3-butylene glycol, and m is the moles of the acetyl- methylcarbinol-has been shown to be valid for various yeasts and for musts of varying composition. A large number of wines have been tested and found to conform fairly well with this equation. With different yeasts, however, the relative amounts of acetic acid, succinic acid, 2,3-butylene glycol, and glycerol varied considerably. Also by changing the fermenta- tion conditions the ratios between the by-products could be varied. These relations were also shown to apply to fortified wines by Genevois et al. (194%). They showed Z/g to vary from 0.88 to 0.94 and b /g X 1,000 from 108 to 128. In laboratory and commercial fermentations s varied from 5 to 9 millimoles per liter; a was 10 to 12 in commercial fermentations and 4 to 12 in laboratory fermentations; and b varied from 5 to 10 in commer- cial fermentations and from 3 to 6 in laboratory fermentations. The ratio a/s was 0.4 to 2 under normal fermentation conditions and 1 to 3 when the fermentation conditions were varied. Likewise b/g was usually 4 to 9, but by changing the fermentation conditions varied from 7 to 12. Many of the results of their research may be of practical importance in winery operation. They found, for example, that the acetic acid/succinic acid ratio is very different for grapes fermented on the skins compared to those fermented off the skins. Genevois (194913) has also suggested the possible formation of 1,4 butanedial and the following acids as minor secondary by-products of alcoholic fermentation: d l citramalic, 7-hy- droxybutyric (4-hydroxybutanoic), isocitric, aconitic, oxyglutaric, and glutaric. See also p. 407.

Of more theoretical interest has been the study of the quantity of water fixed by various secondary products of alcoholic fermentation. Genevois et al. (1949b) showed that the amount fixed, e , equals a + 2s + 4c, where c is the citric acid.. With 29 French yeasts on grape juice e varied from 15 to 26, average 19. With the same yeasts on a sucrose media e varied from 26 to 35, average 29. Another interesting theoretical relationship was their discovery that e/g is nearly constant at 1/3 with a variety of yeasts on two media. I n this respect, at least, the yeasts appear limited. Finally they have shown that Aa = a + 2s - g/3. When A is between 3 and 10 there is a presumption of formation of acetic acid by anaerobic bacteria and not as a by-product of alcoholic fermentation. Even with various types of yeasts Genevois et al. (1948a) found the fermentation balance was maintained. These included succinogenic, glycologenic, and acetogenic yeasts. Addition of acetaldehyde during fermentation in- creased the succinic acid and 2,3-butylene glycol content, but the effect varied with the yeast.

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466 MAYNARD A. AMERINE

Perhaps the outstanding advances made in this period have been in the greater quantization of data and the welcome biochemical interpre- tation which has been applied to it. This has been true particularly of the new and better data on a number of the minor constituents. The applica- tion of new analytical techniques will certainly aid in future work. Many important gaps exist in our knowledge. The relation between the various acids, cations, and the buffer capacity of musts and wines should be delineated. Data on the substances which contribute to the characteristic odor of many wines are almost completely lacking. And finally, there is a pressing need for more specific and accurate methods for the determina- tion of practically all of the organic constituents of wines-both methods for control purposes and accurate research procedures.

ACKNOWLEDGMENTS I am greatly indebted to members of the library staff for their patience and dili-

gence in locating and checking the references, particularly Patricia L. Golton, Shirley Hopkinson, Mrs. Aileen R. Jaffa, Sara B. Schreiber, and Louise B. Wheeler. I am also grateful to my colleagues, Mr. Harold W. Berg and Professors J. G. B. Castor, M. A. Joslyn, and A. D. Webb who have read all or portions of the manuscript and to Mrs. Angelo Arnold who has faithfully typed the various “editions l 1 of the manuscript. The errors which remain, however, are the author’s.

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Akademiix Nauk-Institut Biokhimii. 1947-1950. Biokhimix vinodelig. A kademiia ind. agr. biol. 19, 180-181.

Nauk S.S.S.R., Moscow, Vol. 1, p. 208, 1947; Vol. 2, p. 183, 1948; Vol. 3, p. 246, 1950.

Akiya, S., and Sasao, H. 1951. Determination of methanol in wine by chromotropic acid. J . Pharm. SOC. Japan 71, 1325-1326; C. A . 46, 2234 (1952).

Akman, A. V. 1951. Die Weine Ankaras. Deut. Vein-Ztg. 88, 101-102. Alessandrini, E. 1933. Dosage de l’aloool isopropylique dans les boissons alcooliques

Alexis, E. 1933. Le dosage du sucre restant dans les vins rouges. Ann. fals. et fraudes

Alexis, E. 1936. Influence de la date des vendanges sur la qualit6 des vins d’Aramon

Alfa, J. 1932. Ergebnis der amtlichen Weinstatistik. V e i n u. Rebe 14, 181-191. Alfa, J. 1933. Ergebnis der amtlichen Weinstatistik. Wein u. Rebe 16, 175-183. Almeida, H. de. 1948. Estudo polarogrhfico de algunas protefnas puras. Anais inst.

Almeida, H. de. 1950. Estudo polarogrhfico do aldefdo ac6tico no vinho do Parto.

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Amerine, M. A. 1947. The composition of California wines a t exhibitions. Wines &

Amerine, M. A. 1948. Hydroxymethyl furfural in California wines. Food Research 13,

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Amerine, M. A., and Dietrich, W. C. 1943. Glycerol in wines. J . Aesoc. Ofic. Agr. Chemists 26, 408-413.

Amerine, M. A., and Joslyn, M. A. 1951. Table Wines: The Technology of Their Pro- duction in California. University of California Press, Berkeley.

Amwine, M. A., and Webb, A. D. 1943. Alcohol-glycerol ratio of California wines. Food Reseaech 8, 280-285.

Amerine, M. A., and Wheeler, L. B. 1951. A Check List of Books and Pamphlets on Grapes and Wine and Related Subjects, 1938-1948. University of California Press, Berkeley.

Amerine, M. A., and Winkler, A. J. 1941. Maturity studies with California grapes. I. The Balling-acid ratio of wine grapes. Proc. Am. SOC. Hort. Sci. 38, 379-387.

.4mcrine, M. A., and Winkler, A. J. 1943. Maturity studies with California grapes. 11. The titratable acidity, pH, and organic acid content. Proc. Am. SOC. Hort. Sci.

hmerine, M. A., and Winkler, A. J. 1947. Relative color stabilities of the wines of cer- tain grape varieties. Proc. Am. SOC. Hort. Sci. 49, 183-185.

Anibal Burgoa, P. 1935. Estudio comparativo del contenido normal en glicerina de 10s vinos argentinos. Rev. fac. cien. q u h . univ. nacl. La Plata 10, 95-104.

.4nonymous. 1933. Roumanie. MBthodes officielles d’analyses des vim. Bull. ofice idern. vin 6(67), 54-92.

Anonymous. 1934. Minister0 dell’agricoltura e delle foreste. Metodi ufficiali di analisi per le materie che interessano l’agricoltura. I1 (Part I). Mosti, vini, birre, aceti, sostanze tartariche, materie tanniche. Instituto Poligrafico dello Stato, Roma.

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2,3-butanediol. Inds. agr. et aliment. (Paris) 70, 397-398.

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468 MAYNARD A. AMERINE

Antoniani, C., and Cioffi, R. M. 1949. Transaminazione in vivo nei lieviti alcolici.

Antoniani, C., and Gugnoni, S. 1941. L’acetilmetilcarbfnolo nei vini. Ann. chim. appl.

Ant-Wuorinen, O. , and Kotonen, E. 1935-1937. Bestimmung des Methylalkohol- gehaltes in Alkohol und alkoholhaltigen Getranken. 2. Untersuch. Lebensm. 69,

Archinard, P. 1937. La limite de 20 mgr. d’NHs admise par la loi pour caracteriser les vins impropres h la consommation. Est-elle justifibe? Rev. viticult. 87, 339-343.

Archinard, P. 1939. Le dosage de l’ester acetique et les vins alteres impropres B la consommation. Ann. fals. et fraudes 32, 254-260.

Archinard, P. 1940. MBthodes rapides de dosage des esters neutres dans les boissons fermentbes. Ann. fals. et fraudes 85, 76-85.

Arutunyan, L. A. 1939. Antiscorbutic property of grape leaves (transl.). Voprosy pi taniz 8, 54-57.

Association of Official Agricultural Chemists. 1950. Official and Tentative Methods of Analysis of the Association of Official Agricultural Chemists. Association of Official Agricultural Chemists, Washington, 7 Ed.

Astruc, H., and Castel, A. 1932a. Contribution B 1’6tude du dosage des acides volatils dans les vins. Ann. chim. anal. et chim. appl. 14, 145-152.

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Ay, H. 1936. Die Methoden zur Bestimmung des Mostgewichtes und des Saure- gehaltes im Most. Wein u. Rebe 18, 161-172.

Azevedo, M. P. de. 1942. 0 Auxiliar do Analista. Edi@o do Instituto do Vinho do PBrto, PGrto.

Baglioni, S., Casale, L., and Tarantola C. 1935-1937. L’attivitA proteolitica del succo d’uva. Annuar. R. staz. enol. sper. Asti (2)2, 203-219.

Balavoine, P. 1939. Sur la mustimbtrie. Mitt. Gebiete Lebensm. u. Hyg. 30, 331-335. Balavoine, P. 1943. Contribution B l’appr6ciation des vins de MAIaga. Mitt. Gebiele

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Barbera, G. 1933a. Ricerche sperimentali sulla pectina dell’uva. Ann. tern. agrar. 6,

Barbera, G. 193313. Sulla formazione della mannite nei mosti dializzati a bassa tem- peratura in presenza di cloroformio. Ann. chim. appl. 23, 470-473.

Barbera, G. 1933~. Sulla sostanze estrattive dei vini. I. Pectine e gornme. 11. Corn- ponenti nitrogeni. Ann. chim. appl. 23, 95-99, 115-120.

Barini-Banchi, G. 1948. Determinaeione dell’alcool nei vini mediante il metodo di ossidazione cromica. Ann. chim. appl. 38, 423-428.

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1-37.

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COMPOSITION OF WINES 469

Mostgewicht und Alkoholgehalt und deren Nutzanwendung bei der Verbesserung der Moste. Wein u. Rebe 16, 107-118.

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Benvegnin, L. 1934. DBchets dans la manutention des vins. Ann. agr. Suisse 1934,

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Benvegnin, L., Capt, E., and Piguet, G. 1951. Trait6 de Vinification. Librairie Payot, Lausanne, 2nd Ed.

Benz, G. 1931. Berechnung der ursprunglichen Oechslegrade im angegorenen Trauben- most. Wein u. Rebe 13, 63-66.

Berg, P. 1932. Die Bestimmung der Susse in Dessertweinen nach Baum6-Graden. Wein u. Rebe 14, 175-180.

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Berg, P., and Schulze, G. 1934. Ein neues Pentabromaceton-Verfahren zur Bestim- mung der Citronensilure im Wein. 2. Untersuch. Lebensm. 67, 605-613.

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Bergman, H. F., and Magoon, C. A. 1945. Tartrate content of Maryland-grown American grape varieties. Proc. Am. Sac. Hort. Sci. 46, 253-254.

Beridze, G. I. 1948. The aging of Kakhetinski wine on the pomace (transl.). Vinodelie a’ Vinogradarstvo S.S.S.R. 8(8), 11-14.

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rertrand, G., and Silberstein, L. 1950-1952. Sur la teneur des vins en m6thanol. Compt. rend. acad. agr. France 36, 59-61, 191-192; 38, 162-163; see also Ann. inst. Pasteur 82, 668-675 (1952).

1173-1 184.

23, 46-64.

388-4 13.

350-352.

et fraudes 26, 103-105.

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226, 365-367 (1948.)

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470 MAYNARD A. AMERINE

Besone, J., and Cruess, W. V. 1941. Observations on the use of pectic enzymes in wine making. Fruit Products J . 20, 365-367.

Beyer, 0. F. 1945. Report on the spectrophotometric examination of wines. J. Assoc. O&. Agr. Chemists 28, 471-475.

Bicalho, N. dos Santos. 1933. Analise de vinhos. (MBtodos sequidos no Laboratorio Bromatolgico de Dep. Nacional de Sadde Publica.) Rev. SOC. brasil. chim. 4,63-73.

Biedermann, W. 1951. Die pH-hderungen bei der Abscheidung von Weinstein aus Getranken. Mitt. Gebiete Lebensm. u. Hyg. 42, 476-482; see also Schweiz. 2. Obst- u . Weinbau 61, 193-195 (1952).

Bleyer, A. 1938. Alkoholische Genussmittel. Handbuch der Lebensmittelchemie. J. Springer, Berlin, Bd. 7.

Bobadilla, G. F. de. 1943. Aplicaciones industriales de las levaduros de flor. Agri- cultura (Madrid) 12, 203-207.

Bobadilla, G. F. de, and Navarro, E. 1949. Vinos de Jerez. Estudios de sus Acidos, desde el period0 de madurez de la uva hasta el envejecimiento del vino. Bol. inst. nacl. invest. agron. Spain 9(21), 473-519.

Bobadilla, G. F. de, and Navarro, E. 1952. Vinos de Jerez. Contribuci6n a1 estudio de sus caracetlsticas. An4lisis de varios tipos de vinos. Bol. inst. nacl. invest. agron. Spain 12 (27) , 377-395.

Bodendorf, K. 1930. Ein einfacher Nachweis des Isopropylalkohols in Spirituosen. 2. Untersuch. Lebensm. 69, 616-617.

Bohringer, P. 1943. tfber die Bestimmung des Refraktometerwertes von Pfiilzer Trauben mittels des Zeiss'schen Handrefraktometers. Gartenbauwiss. 17, 505-520.

Bohringer, P. 1951a. Bestimmung des Alkohol- und Extraktgehaltes von trockenen

Weinen aus der Refraktion bei 20" C. und dem Gewichtsverhiiltnis Y L 200. 2.

Lebensm.-Untersuch. u. -Forsch. 93, 65-75. Bolcato, V., D'Orazi, F., and Pasquini, G. 1941. Alcune miscure sperimentali

sull'alcole trasportato dalla COa delle fermentazione alcolica. Zndustria saccar. ital. 34, 357-364.

Bonaterra, R. 1949. Study of the method of evaluation of higher alcohols by colori- metric determination based on the furfural-sulfuric acid reaction. Applied to distilled beverages (transl.). Rev. fac. cienc. qutm. univ. nacl. La Plata 24,125-133; C . A . 47, 3516 (1953).

Bordas, F., and Roelens, E. 1930. Corrections alcoomhiques pour les tempBratures au-dessous de zBro. Ann. fals. el fraudes 23, 263-283.

Bordas, F., and Touplain, F. 1930. &Etude sur 1'alcoomBtrie. Ann. fals. et fraudes 28,

Bognjak, I. 1935. Priifung und Vergleich der Methoden zur Analyse des Weines. I. Ftir die Verwerfung des indirekten Extraktes bei der Analyse vergorener Weine und seine Ersetzung durch das Vakuumextrakt. Jahresber. Oenol. Stat. Aker- bauminist. Jugoslav 1, 175-235, 281-287.

Boinjak, I. 1938. Priifung und Vergleich der Methoden zur Analyse des Weines. 11. Milchsiiurebestimmungsmethoden. Jahresber, Oenol. Stat. Ackerbauminist. Ju- goslav 2, 131-216.

Botelho, J. C. 1935. gtudes sur le vin de porto. Ann. chim. anal. el chim. appl. [3] 17,

Botelho, J. C. 1938. Dosage de l'oxymbthylfurfurol dans le vin de porto. Son r81e dans la sophistication. Ann. chim. anal. et chim. a p p l . [3] 20, 203-205; see also Rev. viticult. 89, 202-205 (1938).

20"

84-102.

49-63, 179-180.

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COMPOSITION OF WINES 47 1

Botelho, J. C. 1939. Dosage rapide de l’alcool du vin au moyen du picnometre de Mendelejeff. Ann. chim. anal. et chim. appl. [ 3 ] 21, 203-205.

Boutaric, A., and Bouchard, J. 1935. Sur une mBthode simple pour 1’Btude de I’aciditB des vins exprimBe par la concentration en ions hydrogene. Compt. rend. acad. agr. France 21, 737-743; see also Bull. ofice intern. vin 8(86), 44-49 (1935).

Boutaric, A., F e d , L., and Roy, M. 1936. Recherches spectrephotomBtriques sur la couleur des vins. Compt. rend. 203, 1142-1144; see also Ann. fals. et fraudes 30,

Boutaric, A., FerrB, L., and Roy, M. 1937. Recherches spectrophotomBtriques sur la dilution et le melange des vins. Compt. rend. 204, 343-344.

BrBmond, E. 1937a. Bilan complet e t repartition des substances ionisables contenues dans les vins. Bull. SOC. chim. France [5] 4, 296-305.

BrBmond, E. 1937b. Bilan complet et repartition des substances ionisables contenues dans les vins. Ann. fals. et fraudes 30, 136-146.

BrBmond, E. 1937c. Contribution ?i l’fitude Analytique et Physico-chimique de 1’AciditB des Vins. La Typo-Litho et Jules Carbonel RBunies, Alger.

BrBmond, E. 1938a. Qtude analytique et physico-chimique de l’acidit6 des vins. Ann. ferment. 4, 86-102.

BrBmond, E. 1938b. Nouveau dispositif de mesure du p H des vins. Ann. agron. 8, 371-379, 557-558; see also Ann. fals. et fraudes 32, 85-95 (1939).

Brockmann, M. C., and Stier, T. J. B. 1948. Influence of temperature on the produc- tion of glycerol during alcoholic fermentation. J . Am. Chem. SOC. 70, 413-414.

Brockmann, M. C., and Werkman, C. H. 1933. Determination of 2,3-butylene glycol in fermentations. Znd. Eng. Chem., Anal. Ed, 6, 206-207.

Brown, W. 1,. 1940. The anthocyanin pigment of the Hunt Muscadine Grape. J . Am. Chem. SOC. 62, 2808-2810.

Brugirard, A., and Tavernier, J. 1952. Sur le dosage des matieres tannoides dans les cidres et les poirbs. Ann. fals. et fraudes 46, 108-110.

Brune, H. 1948. Der qualitative Nachweis von Methanol neben khan01 in Tinkturen und alkoholischen Get rhken nach DenigBs. 2. Lebensm.-Untersuch. u. -Forsch. 88, 274-278.

Bucci, F. 1940. Sulla ricerca destrina nei vini. Ann. chim. appli. 30, 533-539; see also Prog. vinic. olea. Ztal. 26, 37-40 (1949).

Biirgi, J. 1932. Zur Bestimmung der hoheren Alkohole nach Komarowsky-v. Fellen- berg (Mikromethode). Mitt. Gebiete Lebensm. u. Hyg. 23, 94-95.

Buhrer, N. E. 1950. Mktodo prltico para diferenciar vinhos de uva de outros vinhos de frutas, especialmente de laranja. Anais assoc. qubm. Brazil 9, 104-105.

Buogo, G. 1938. L’acido citrico costituente normale dei vini genuini. Probabile sua funzione. Raffronto con l’acido tartarico. Atti 10th congr. intern. chim. Rome 4,

Buogo, G., and Picchinenna, D. 1938. L’acido citrico nei vini genuini della provincia di Bari. Ann. chim. appl. 28, 427-431.

Burdzhanadze, V. F. 1951. On acetic acid and sugar-alcohol balance in wine making (transl.). Vinodelie i Vinogradarstvo S.S.S. R . 11(3), 12.

Burgvits, G. K., and Hochberg, R. B. 1936. Uber die Wirkung der Wasserstoffionen- konaentration des Mostes auf Weinhefe (transl.). Arch. biologitscheskich Nauk. 43, 39-47.

Buscar6ns Ubeda, F. 1941. Sobre 10s componentes de alto punto de ebullici6n del fuse1 de orujo de uva y RU approvechamiento industrial. Anales jbs. y q d m . Madrid 37,

196-209 (1937).

487-494.

356-369, 371-383.

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472 MAYNARD A. AMERINE

Buxbaum, W. 1932. Mostgewichtsbestimmung auf optischem Wege mit Hilfe des

Cahill, W. M. 1933. Recherches sur le facteur antiscorbutique. Bull. soc. chim. biol.

Cailleau, R., and Chevillard, L. 1949. Teneur de quelques vim franpais en aneurine,

Cambitzi, A. 1947. Formation of racemic calcium tartrate in wines. Analyst 72,

Campllonch Romeu, I. 1945. Ejercicios de AnBlisis de Vinos: mostos, mistelas, t&rtaros, vinagres y alcoholes. Sociedad Enol6gica del PenadBs, S. A., Vilafranca del PanadBs, 5th Ed.

Canals, E., and Collet, H. 1939. Essai polarimetrique des vins. J . pharm. et chim. 29,

Canals, E., and Vergnes, P. 1940. Coefficient tampon des vins. Bull. SOC. chim. France

Cappucci, C. 1948. Osservazione sulle probabili cause della inconsueta aciditd volatile di alcuni vini della regione Emiliano-Romagnola. Riv. viticolt. e enol. (Conegliano)

Cartier, P., and Pin, P. 1949. Microdosage de l’acide citrique. Bull. SOC. chim. biol. 31,

Casale, L. 1930a. La fermentazione alcoolica nei liquidi ad elevata concentrazione idrogenionica. 111. Ann. chim. appl. 20, 357-361.

Casale, L. 1930b. Influenza che esercitano i prodotti della fermentaaione sulla velocith di moltiplicazione della cellula di li6vito. 11. Ann. chim. appl. 20, 353-357.

Casale, L. 1930c. Influenza del valore pH del mezzo sulla fermentazione alcoolica. I. Ann. chim. appl. 20, 336-353.

Casale, L. 1930d. Ricerche fisico-chimiche sulle materie coloranti delle uve e dei vini rossi. Ann. chim. app. 20, 559-566.

Casale, L. 1934. Esperienze de fermentazione a bassa temperatura. Congr. intern. quim. pura apl. 9(V), 254-259; see also Annuar. R . staz. enol. sper. Asti (2) 2, 1-5

Casale, L. 1935-37. Esame critico, tecnico e pratico della varietd delle uve da vino coltivate in Piemonte, in Lomhardia ed in Liguria. Annuar. R. staz. enol. sper. Asti (2) 2, 67-104.

Casale, L., and Garino-Cnnina, E. 1935-37. Ricerche sugli enaimi del vino e del mosto. Annuar. R. staz. enol. sper. Asti (2) 2 , 239-250.

Casamada Maurl, R. 1931. Espectros de absorci6n en el ultra-violeta y la investigaci6n de colorantes artificialcs en 10s vinos. Mem. acad. cienc. artes Barcelona 22,

Casares, R., and Gonzales de Rivera, C. 1953. Contribuci6n a1 estudio de 10s vinos de la zona de Montilla y Moriles (Espaiia). Anales bromatol. (Madrid) 6, 23-67.

Castor, J. G. B. 1950. Biochemical events during vinous fermentation. Proc. Am. Soc. EnoZogists 1960, 21-37, 104.

Castor, J. G. B. 1953a. B-complex vitamins of musts and wines as microbial growth factors. Appl. Microbiol. 1, 97-102.

Castor, J. G. B. 1953b. The free amino acids of musts and wines. Food Research 18,

Castor, J. G. B., and Guymon, J. F. 1952. On the mechanism of formation of higher

Cerasari, E. 1950 (i.e. 1951). Sul contenuto e sulla determinazione dell’acido citric0

Zeiss’schen Handzuckerrefraktometers. Wein u. Rebe 14, 171-174.

16, 1462-1471.

riboflavine, acid nicotinique et acide pantothhique. Ann. agron. 19, 277-281.

542-543.

385-390.

[5] 7, 231-234.

1, 386-388.

1176-1183.

(1 935-3 7).

251-256.

139-145, 146-151.

alcohols during alcoholic fermentation. Science 116, 147-149.

nei vini. Ann. triest. cura univ. Trieste Sez. 2 20, 127-139.

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Ccrutti, G. 1951. Sull’originc e sul contenuto in alcool metilico dei vini italiani. Ann. sper. agrar. (Rome) (N.S.) 6, 331-335.

Ccrutti, G., and Vcdani, A. 1951. Sulla detcrminaaione dcl nictanolo nei vini e nei fermentatio ttlcolici. Ann . sper. agrar. (Rome) (N.S.) 6, 419-421.

Charles, E. 1930. Sur la presence et le dosage dc l’ethanal dans les vins. Ann. fals. et fraudes 23, 153-154.

Charles, E. 1938. Dosage de l’alcool iiibthylique ou dc l’alcool isopropylique en prdscnce d’alcool 6thylique. 18th Congr. chim. ind. Nancy 1, 38C-48C.

Charpentie, Y. 1950. La fermentation malolactique des vins blancs de la Gironde. Bull. ofice intern. vin 23 (231), 61-64.

Charpentie, Y., Ribdreau-Gayon, J., and Peynaud, E. 1951. Sur la fermentation de l’acide citrique par les bacteries malo-lactiqucs. Bull. SOC. chim. biol. 33,1369- 1378.

Chauvct, J. 1950. L’arBrne des vim fins. Bull. inst. natl. appel. orig. vins et eaux-de-vie 34, 8-17.

Chelle, L., Dubaquid, J., and Vitte, G. 1936. Sur la presence de l’acetonc et son dosage dans les alcools de vin. Bull. soc. pharm. Bordeaux 74, 112-126.

Chogovadae, S. K. 1948. Role of the aglucon fraction of coloring matter and tannin materials in the wine-maturing process (transl.). Vinodelie i Vinogradarstvo

Churchward, C. R. 1953. Spirit content of wine by ebullioscope. Australian Brewing and Wine J . 71(5), 4, 6, 8.

Churchward, C. R., and Johns, B. G. 1940. Use of the Dujardin-Sallcron ebulliometer for the determination of the alcoholic strength of wines. Australian Chem. Inst . J . & Proc. 7, 18-30.

Cioffi, R. M. 1948. Sul contcnuto in alcoli superiori dci vini Italiani. Riv. viticolt. e enol. (Conegliano) 1, 341-343.

Cioffi, R. M. 1949. Studio dell’infiuenza di alcuni inibitori ensimatici sull andamento del process0 di “fermcntazione alcoolica dcgli aminoacidi ” Riv. viticolt. e enol. (Conegliano) 2, 121-123.

Clavera,.J. M., and Moreno Martin, F. 1936. Influencia del alcohol metflico en la dosificaci6n de 10s alcoholes superiores en 10s aguardientes. Anales SOC. espa8. fis. y quim. 34, 507-512.

Clavera, J. M., and Oro L6pca, M. 1932. Los az6cares y el extract0 seco en 10s vinos de MAlaga. Anales SOC. espaii. f i s . y quini. 30, 140-144.

Collier, D. 1935. Sur le dosage des tanins du vin. A n n . fals. et fraudes 28, 208-224. Colombier, L., and Clair, E. 1936. La dbtcrmination du degr6 alcoolique des vins.

Ann. fals. et fraudes 29, 411-416. Colornbier, L., and Clair, E. 1!)38. Quclqucs observations sur la d6termination de

I’acidit6 volatile dcs vins. Ann. fals. et fraudev 31, 414-418. Col$escu, I. H., Nichitovici, V., Dobrcscu, J., Iliescu, L., Tomescu, F., and Moldovan,

E. 1941. Beitrag zur Kenntnis der Zusammensctzung der Hybridenweine direkter Eraeugung. Analelc Inst . Cercetari Agron. Ronimllniei 13, 3-1 1 .

Conceipso, A. de B. F. da. 1942. Pcsquiza do corantes orgdnicos sintbticos nos vinhos. Anais inst. super. agron., Univ. tic. Lisbou 13, 191-197.

Cordebard, H. 1939. Titrimetric determination of organic substances by chromic oxidation. Use of stable nitro-chromic solutions (transl.). J. pharm. chim. 30,

Cornforth, J. W. 1939. The anthocyanin of Vi t i s hypoglauca F.v.M. J . Proc. Roy.

Correia, E. M. 1943. Riqueaa em Bcido fosf6rico e ferro de alguns vinhos de pasto

S.S.S.R. 8(6), 14-17; C. A. 44, 9619.

263-272.

SOC. N . S . Wales 73, 325-328.

portugueses. Anais inst. super. agron., Univ. tic. Lisboa 14, 327-334.

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Correia, E. M., and Ribeiro, E. C. 1942. Riqueza em &cido succhico e glicerina dos vinhos comuns portugueses. Anais inst. super. agron., Univ. tbc. Lisboa 13,155-164.

Correia, E. M., and Sbrgio, R. J. de R. 1943. Riqueza em Acidos orghicos de alguns vinhos portugueses. Anaiu inst. super. agron., Univ. t6c. Lisboa 14, 351-357.

Correia, E. M., and Vilas, M. A. 1943. Subsidio para o estudo das caracterfsticas ffsicas, qufmicas e ffsico-quhicas dos vinhos da regiao demarcada de Colares. Anais inst. super. agron., Univ. t b . Lisboa 14, 359-360.

Cosmo, I. 1950. Ulteriori indagini sui vini rosati e cerasuoli delle Venezie. Ann. sper. agrar. (Rome) 4, 803-817; see also Annuar. staz. sper. viticolt. e enol. (Conegliono)

Crisci, P. 1930. Intorno alla pretesa proporzionalith fra il p H e il sapore acido delle soluzioni acquose con speciale riguardo ai vini. Ann. chim. appl. 20, 566-583.

&isci, P. 1931. I1 p H nell’uva-sua misura e sua interpretazione. Ann. teen. agrar.

brisci, P., and Michielini, L. 1932. Sul comportamento della forza acida dei vini e mosti d’uva rispetto ad alcune operazioni tecniche. I. Chiarifacazione e de- colorazione. Ann. chim. appl. 22, 663-666.

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.

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Cruess, W. V. 1942. Research in enology. Proc. Znst. Food Technol. 1942, 152-161. Cruess, W. V. 1943. The role of microorganisms and enzymes in wine making. Ad-

Cruess, W. V. 1947. The Principles and Practice of Wine Making. Avi Publishing Co.,

Cruess, W. V. 1948. Investigations of the flor sherry process. Calif. Agr. Ezpt. Sta.

Cruess, W. V. 1950. Minor constituents of vinous fermentation. Proc. Am. SOC. Enologists 1960, 28-36.

Cruess, W. V., and Kilbuck, J. 1947. Pectic enzymes in wine making. Wines & Vines 28(8), 23-24; see also Rev. quim. ind. argentina 2 , 22-24 (1948).

Cruess, W. V., O’Neal, R., Chong, G., and Uchimoto, D. 1951. The effect of pectic enzymes in wine making. Proc. Am. SOC. Enologists 1961, 59-75.

Cruess, W. V., Weast, C. A., and Gillilland, R. 1938. Summary of practical investiga- tions on film yeast. Fruit Products J . 17, 229-231, 251.

Cunha, J. D. S. da. 1947. Mdtodo expedito para determinaggo do oximetilfurfural no vinho do PBrto. Anais inst. vinho PGrto 8, 49-54.

Cunha Ramos, M. da, and Ribeiro, M. de B. 1945. A determinagfio dos agdcares redutores no vinho do PBrto. Comun. 18th congr. Luso-espafi. par progress0 cienc. Cdrdoba 1944, Supl. Caderno inst. vinho PGrto No. 63, 9-36.

Cunha, V. 1939. Tentativa para dosagem de glicerina nos vinhos. Arquiv. hig. sazide ptiblica (Sdo Paulo) 4, 65-66; see also Ann. SOC. pharm. chim. Sit0 Paulo 3, 13-15 (1939).

Cusmano, I. 1949. Confront0 tra alcuni ebulliometri usati in pratica per la deter- minazione del grado alcoolico del vino. Riv. vilicolt. e enol. (Conegliano) 3,335-340.

Dalmasso, G., and Dell’Olio, G. 1937. I vini bianchi tipici dei colli Trevigiani. Annuar. staz. sper. vitocolt. e enol. (Conegliano) 7 , 3-115; see also Ann. sper. agrar. (Rome) 26, 4-93 (1937).

Dangoumau, A., and Debordes, G. 1937. Sur l’extraction, la separation et le dosage des esters du vin. Bull. soc. ehim. France [5] 4, 911-918.

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New York, 2nd Ed.

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COMPOSITION OF WINES 475

Daniel, E. P., and Munscll, H. E. 1932. The vitamin A, B, C, and G contents of Sultanina (Thompson Seedless) and Malaga grapes and two brands of commercial grape juice. J . Agr. Research 44, 59-70.

De Astis, G. 1933. Recherche5 BbulliomBtriques e t les lois de 1’6chelle alcooliques. Bull. ofice intern. vin 6(58), 47-65.

De Astis, G. 1941. Variations du degrB alcool--6bulliomBtrique aux diverses pressions et altitudes. Bull. ofice intern. uin 14(146), 91-96.

Delp. 1932. uber die Enzyme des Weines und die organischen Sauren im Wein und Weinessig. Deut. Essigind. 36, 219.

Dicenty, D., Requinyi, G., Palinkas, S., Srabb, E., Sobs, E., Rakcsanyi, L., and Wettstein, E. 1935. Le point de vue hongrois. 4th Congr. intern. vigne et uin, Lausanne, 1935 I, 179-192; see also Magyar Ampelol. lhkonyv. 12, 1-88 (1938).

Diemair, W., Janecke, H., and Krieger, G. 1951. uber eine methode der Gerbstoff- bestimmung in der Rebe und im Wein. 1-11. 2. anal. Chem. 133, 346-359.

Diemair, W., and Klcber, J. 1941. Beitrag zur Kenntnis der Bildung von Acetyl- methylcarbinol und 2,3-Butylenglycol bei der Garung. 2. Untersuch. Lebensm.

Diemair, W., Riffart, H., and Mollenkopf, K. 1940. Die stufenphotometrische Bestimmung von Milchsiiure und Glycerin im Wein. 2. anal. Chem. 118,189-201.

Dubaqui6, J. 1932. Potasse et compos-6s tartriques dans les vins. Ann. fals. et fraudes 26,280-285.

DubaquiB, J., and Debordes, G. 1931. Du sucre restant dans les vins rouges. Ann. fals. et fraudes 24, 477-484.

Dubaquie, J., and Debordes, G. 1935. Antiscptiqucs et fermentation Blective. Ann. ferment. 1, 33-40.

Dubrowskaja, V. P. 1946. Determination of alcohol (transl.). Vinodelie i Vino- gradarstvo S.S.S.R. 6(4), 40-41.

Duccllier, G. 1935. L’augmentation de la couleur des vins par le brassage automatique. Rev. viticult. 83, 266-269.

Dujardin, J., Dujardin, L., and Dujardin, R. 1938. Notice sur les Instruments dc PrBcision Appliques A l’oenologie. Dujardin-Salleron, Paris, 6th Ed.

Dupont, G., and Dulou, R. 1935. Sur la presence d’alcool butylique secondaire actif dans certains fusels. Compt. rend. 200, 1860-1861.

Durmishidze, S. V. 1938. Formation of lactic acid in ordinary yeast fermentation (transl.). Biokhimiya 3, 308-320.

Durmishidze, S. V. 1948a. Determination of oenidin in grapes and wines (transl.). Biokhimiya 13, 16-22.

Durmishidze, S. V. 1948b. Quantitative determination of tannin in red grapes and wines (transl.). Biokhimii?l vinodeli2 2, 169-176.

Durmishidze, S. V. 1950a. d-Catechin in the composition of grape tannin (transl.). Doklady Akad. Nauk. S.S.S.R. 73, 987-990; C. A . 46, 719 (1951).

Durmishidze, S. V. 1950b. Oxidizing enzymes in wine grapes (transl.). Vinodelie i VCnogradarstvo S.S.S.R. 10(8), 29-30.

Durmishidze, S. V. 1950c. The polyphenoloxidase of grapes and its role in wine tech- nology (transl.). Biokhimiya 16, 58-66.

Durmishidze, S. V. 1950d. Transformation of tannin compounds in grape clusters in the process of ripening (transl.). BiokhimiG vinodeZi& 3, 7-24.

Durmishidze, S. V. 1951. l-Gallocatechin in the composition of tannins of grapes (transl.). Doklady Akad. Nauk. S.S.S.R. 77, 859-862; C . A . 46, 8089 (1951).

Durmishidze, 8. V., and Khachidze, 0. T. 1952. Photometric determination of rcd

81, 385-404.

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476 MAYNARD A. AMERINE

pigments in grapes and wine (transl.). Vinodelie i Vinogradarsfvo S.S.S.R. l 2 ( l ) ,

Durmishidze, S. V., and Mosiashrili, G. I. 1948. Triose as a hydrogen acceptor in the process of diaminisation of glutamic acid during alcoholic fermentation (transl.). BiokhimiG vinode1iG 2 , 143-148.

Durodie, J., and Roelens, E. 1942. CaractBrisation de l’alcool butylique secondaire et absence de l’alcool isopropylique dans les fractions de diverses huiles essentielles de vin distillant au voisinage du point d’Ebullition de l’alcool isopropylique. Bull. soc. chim. France [5] 9, 822-825.

Eckert, A. 1950. Sitsung des Ausschusses fur Weinforschung in Rudescheim. Z. Lebensm.-Untersuch. u. -Forsch. 90, 445-448.

Egorov, I. A. 1951. New method for determining volatile acids in wine (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 11 (3), 44.

Emiliani, E. 1938. La determinazione ebulliometrica del grado alcoolico nei vini dolci. Ann. chim. appl. 28, 409-412.

Errichelli, E. 1952. Un nuovo ebullioscopio. Riw. viticolt. e enol. (Conegliano) 6,389-391. Errichelli, U. 1950. L’acidith volatile dei vini in rapport0 alla determinazione dell’alcool

col metodo per distillasione. Riv. viticolt. e enol. (Conegliano) 3, 99-105, 135-138. Espil, L. 1936. Les constituants des vins. Glycerine et acide lactique. Bull. SOC. chim.

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des esters de l’alcool Bthylique. Enzymologia 4, 88-93. Espil, L., and Peynaud, E. 1936. Dosage des esters neutres dans lea milieux de fer-

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Bull. SOC. chim. France [5] 4, 904-906. Espinosa, N. A. 1943. Variaci6n de las proporciones relativas de glucosa y levulosaen

la uva y sus derivados. Industria y quim. 6 , 155-173, 213-219. Etienne, A. D. 1950. Determination of alcohol in wines and liqueurs. J . Assoc. Ogic.

Agr. Chemists 33, 1015-1020. Etienne, A. D. 1952. Determination of alcohol in wine and the effect of temperature

on the determination. J . Assoc. Ogic. Agr. Chemists 36, 66-67, 454-455. Etienne, A. D., and Breyer, G. F. 1951. Determination of alcohol in wines and liqueurs.

Wines & Vines 32(4), 63-64; see also Soap, Perfumery & Cosmetics 26, 1284- 1286 (1952).

18-20.

Ettinger, I. 1947. New micromethod for alcohol. Wines & Vines 28(11), 31. Fabre, J.-H. 1936. ProcBdBes Modernes de Vinification. 11. Analyse des vins e t inter-

pretation des rBsultats analytique. “La Typo-Litho ” et Jules Carbonel RBunies, Alger, 3rd Ed.

Fabre, J.-H., and Bremond, E. 1931a. Le dosage de l’acide lactique dans les vins. Ann. fals. et fraudes 24, 474-477.

Fabre, J.-H., and Bremond, E. 1931b. Influence de l’anhydride sulfureux sur le dosage de l’acidite volatile des vins. Ann. fals. et fraudes 24, 345-349.

Fabre, J.-H., and Bremond, E. 1932. L’acide lactique dans les vins d’AlgCrie. Ann. fals. et fraudes 26, 99-110, 157-170.

Fabre, J.-H., and BrBmond, E. 1935. A study of different methods of estimating alcohol in wines (transl.). Congr. intern. tech. chim. ind. agr., Bruxelles 3,308-315.

Fhbregues Soler, J. M. de, and Mestre Jane, A. 1948. MBtodos analiticos para el

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COMPOSITION OF WINES 477

Acido thrtarico de 10s vinos y residuos de 10s mismos, y ensayos realieados con un procedimiento conductometrico. Bol. inst. nacl. invest. agron. Spain 18, 189-239.

Fantoni, P. 1949. Apparecchio per la determinaeione del grado alcoolico dei vini nella pratica cnologica. Rend. ist. super. Sanitd 12, 740-747.

Farrugia, A. J. 1942. Influencia del anhidrido sulfuroso en el dosaje de la acidea volhtil en 10s vinos y metodo para la determinacih de la acides volhtil libre do SO2 en 10s vinos. Anales asoc. qutm. argentina 30, 47-48.

Fatome, M. 1935. Dosage du glycerol dans les vins. Ann. ferment. 1, 291-297; see also Bull. ofice intern. vin 8(90), 47-53 (1935).

Faure, A., and Pallu, R. 1935. Mesure de la coloration des liquides, application aux vins. Ann. fals. et fraudes 28, 5-9.

Faure, A., and Pallu, R. 1936. Le photo-densimhtre S.N.P. Ann. fals. et fraudes 20,

Federico, L., and Cioffi, R. M. 1947. Sulla determinaeione degli alcoli superiori nei vini e fermentati analoghi. Chimica e industria (Milan) 29, 298-299.

Feigl, F., and Feigl, H. E. 1946. Reagbo senslvel e seletiva para Acido thnico e outros taninos. Brazil, Ministbrio agr., Dept. nacl. produciio mineral, Lab. produciio mineral, Bol. No. 24, 25-30; see also Ind. Eng. Chem., Anal. Ed. 18, 62-63 (1946).

Fellenberg, Th. von. 1929. Zur kolorimetrischen Bestimmung der hoheren Alkohole in Spirituosen. Modifikation der Methode Komarowski-von Fellenberg. Mitt. Gebiete Lebensm. u. Hyg. 20, 16-29.

Fellenberg, Th. von. 1931a. Milchsaurebestimmung in Wein. Mitt. Gebiete Lebensm. u.

Fellenberg, Th. von. 1931b. Mikrobestimmungen von Glycerin, 2,3-Butylenglycol und Milchsaure in Wein durch Verdampfen bezw. durch Dampfdestillation. Mitt. Gebiete Lebensm. u. Hyg. 22, 231-248.

Fellenberg, Th. von. 1932. Titrimetrische Zuckerbestimmung in Wein. Mitt. Gebiete Lebensm. u. Hyg. 23, 77-81.

Fellenberg, Th. von. 1933. Citronensaurebestimmung in Wein. Mitt. Gebiete Lebensm.

Fellenberg, Th. von. 1935. Oxymethylfurfurol-Mikrobestimmung durch Chromsaure- verbrennung; Oxymethylfurfurol in Sussweinen. Mitt. Gebiete Lebensm. u. Hyg. 26, 249-257.

Fellenberg, Th. von. 1936. Ameisensaure in Fruchtsaft und Sirup. Mitt. Gebiete Lebensm. u. H y g . 27, 182-200.

Fellenberg, Th. von. 1937. Die Bestimmung des Methylalkohols in alkoholischen Getranken. Compt. rend. 5th congr. intern. tech. chim. ind. agr. 1, 184-196.

Fellenberg, Th. von. 1943. Glycerinbestimmung in Sussweinen und Weinen. Mitt. Gebiete Lebensm. u. Hyg. 34, 344-364.

Fellenberg, Th. von. 1944a. Beitrag zur Untersuchung von Mistellen und Sussweinen. Mitt. Gebiete Lebensm. u. Hyg. 36, 77-93.

Fellenberg, Th. von. 1944b. Nachpriifung des Verfahrens von A. Torricelli Bum Nachweis von Tresterwein in Weisswein. Mitt. Gebiete Lebensm. u. Hyg. 56,

Ferrari, C. 1939. Applicaeioni dell’analisi capillare. 1. Riconossimento di coloranti

Ferrari, C. 1942. Nuevo metodo per il riconoscimento di tracce di coloranti artificiali

Ferrari, V. 1949. Contributo alla messa a punto di un metodo di dosaggio chimico

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Ferre, L. 1931. L’aciditB des vins e t la nouvelle reglementation. Ann. fals. et fraudes

F e d , L. 1943. Aciditat der Champagnermoste und -weine im Jahre 1942. Schweiz.

FerrB, L. 1945. Fermentation malo-lactique. le Vigneron Champenois July, 1945; see

Ferr6, L., and Archinard, P. 1935. A propos du dosage de l’acidit6 volatile des vins.

FerrB, L., and Michel, A. 1938. Dosage de la glycerine dans les vins. Ann. fals. et

Ferrh, L., and Michel, A. 1947. Hydrolyse de la matiere colorante des vins. Casse

Fessler, J. H. 1941. Alcohol determination by dichromate method. Wines & Vines

Fessler, J. H. 1947. Some technical notes on tannin content in wines. Wine Rev. 16(5),

Fetser, W. R. 1938. Analysis of caramel color. Znd. Eng. Chem., Anal. Ed. 10,340-353. Filaudeau, G. 1933. Projet de methode officielle internationale pour l’analyse des vins.

Filipello, F. 1951. Correlation of fortifying brandy with wine quality. Proc. Am. Sac.

Fischl, P. F. 1942. The determination of alcohol and extract in wines. Food Manufac-

Fischler, M. 1937. Mostgewicht-Alkoholgehalt bei badischen Weinen. Wein u. Rebe

Fischler, M. 1938. tfber die Besiehungen swisehen Mostgewicht und Alkoholgehalt bei badischen Weinen. Wein u. Rebe 20, 193-194.

Flaney, M. 1934a. Nouvelle methode de microdosage de l’aleool mhthylique en prbs- ence de quantites importantes d’alcools homologues. Compt. rend. 196, 94-97.

Flanzy, M. 193413. Presence de l’alcool methylique dam les alcools de vin, de mare et de fruit. Compt. rend. 198, 2020-2022.

Flaney, M. 1935a. Sur les mbthodes de recherche de dosage de l’alcool methylique dans les liquidcs et les milieux naturels. Ann. fals. et fraudes 28, 146-158.

Flansy, M. 193513. Nouvelle m0thode de dosage de faibles quantites d’alcool methylique in presence d’alcool bthylique. Ann. fals. et fraudes 26, 260-277.

Flansy, M. 1948. Les acides organiques dans les raisins e t les vins. Ann. agron. 18,

24, 75-80.

Weinztg. 61, 289-293.

Bull. ofice intern. vin 16(171/174), 142-144 (1945).

Ann. fals. et fraudes 26, 9-15.

fraudes 31, 85-94.

hydrolasique. Compt. rend. acad. agr. France 33, 239-241.

22(4), 17-18.

12-13.

Ann. fals. et fraudes 26, 420-423.

Enologists 1961, 154-156.

ture 17, 198-199.

19, 83-84.

60-64. Flansy, M. 1951. L’alcool methylique dans les vins. Vignes et Vins 6(17), 28-30; (18),

27-30. Flansy, M., and Banos, M. 1938. Presence du propanol-2 dans les alcools de vin.

Compt. rend. 206, 218-219; see also Ann. fals. et fraudes 31, 418-419 (1936). Flansy, M., and Boudet, V. 1949. Les pertes d’alcool. Vitic. Aboric. 96, 104-107. Flavier, H. 1939. Evolution des vitimines B1 et Bz au cours de la maturation du raisin

et de la fermentation alcoolique. Compt. rend. soc. biol. 130, 499-500. Fleury, P., and Fatome, M. 1935. Dosage du glycerol en presence des sucres par

l’aeide periodique. J . pharm. et chim. 21, 247-266. Florentin, D. 1948. MBthodes Actuelles d’Expertises Employees au Laboratoire

Municipal de Paris . . . 111. Boisons et derives immbdiates. Donod, Paris, 2nd Ed.

Florenzano, G. 1952. La corresione dell’acidith volatile nei vini per via biologica. Atti accad. ital. vite e vino 3, 215-235.

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Flygare, H. 1949. Zur Bestimmung der Gesamtsauren in Most und Wein. Wein u. Rebe 31, 19.

Fontanelli, G. 1941. Ricerche sull’aciditrl fissa e volatile dei vini. Ann. facoltd agrar. univ. Pisa (N.S.) 4, 353-364.

Fonzes-Diacon, H., and Jaulmes, P. 1932. Sur I’acidit6 volatile des vins. Ann. falsif. et fraudes 26, 149-152; see also Bull. ofice intern. vin 4(33), 95-101 (1931).

Fornachon, J. C. M. 1943. Bacterial Spoilage of Fortified Wines. Australian Wine Board, Adelaide.

Fornachon, J. C. M. 1946. The p H of wines. Examination of glass and quinhydrone values. Ind. Eng. Chem., Anal. Ed. 18, 790-793.

Fornachon, J. C. M. 1953. The accumulation of acetaldehyde by suspensions of yeasts. Australian J . Biol. Sci. 6 , 222-223.

FOUCY, J. 1932. Sur le dosage de I’acidit6 volatile des vins. J. pharm. et chim. 16,

Frangot, P. 1945. Acidit6 total e t acidit6 d e l e des moiits e t des vins de Champagne. Bull. ofice intern. oin 18 (167/170), 114-118 (from le Vigneron Champenois 1945).

Frangot, P., and Geoffroy, P. 1951. Les pectines e t les gommes dans les moats e t les vins de Champagne. le Vigneron Champenois 72(2), 54-59; see also Bull. ofice intern. vin 24(242), 94-96 (1951)A

Frolov-Bagreev, A. N., and Agabal’ianG, G. G. 1951. Chemistry of Wine (transl.). Pischepromizdat, Moscow; for review see Vinodelie i Vinogradarstvo S.S.S. R.

Gahl, L. 1941. Verbesserung des Volatimeters von Cazenave-Saunier. Kisdrlet. Kozlem.

Gadzhiev, D. M. 1940. A new method for determining tartaric, malic andsuccinic acids in wine. (transl.) Vinodelie i Vinogradarstvo S.S.S.R. 1(9/10), 21-22.

Garcia de Angulo, J. R., and Freyre, E. 1951. Notas de un metodo para determination del nitrogen0 total en mostos y vinos por colorimetria. Bol. inst. nacl. invest. agron. Spain, 11, 403-414.

Garino-Canina, E. 1933. I1 2-3 butilenglicole e l’acetilmetilcarbinolo nei vini e negli aceti. Ann. ehim. appl. 23, 14-20; see alsoldnnuar. R. staz. enol. sper. Asti 1,235-

Garino-Canina, E. 1943. La fermentation de l’acide malique dans la technique oenologique. Bull. ofice intern. vin 16(159), 63-76.

Garino-Canina, E. 1945-1946. La catalasi nell’uva e nel mosto. Ann. accad. agr. Torino 99, 95-97.

Garino-Canina, E. 1948. Etudes des mEthodes r6centes d’analyse des vins en vue de leur unification internationale. 7th Congr. intern. inds. agr., Paris, 1948 1, (Q2),

Garino-Canina, E. 1949. Fermentazione vinaria con dettagli biochimici del process0 della fermentazione del mosto d’uva. Ann. sper. agrar. (Rome) (N.S.) 3, 343-350; see also Bull. oflce intern. vin 21(204), 55-61 (1948).

Garino-Canina, E. 1950. Unification des m6thodes d’analyse et d’apprhciation des vins. 6th Congrks intern. oigne et vin, Athknes, I, 661-671; National Repts, pp. 671-717; see also Bull. ofice intern. oin 24(243), 4-60 (1951).

Garino-Canina, E. 1951a. I grandi vini da arrosto della Valtellina. Atti accad. ital. vile c vino 3, 157-164.

Garino-Canina, E. 1951b. Per l’unificazione internazionale del servizio repressione frodi nella preparazione e ma1 commercio del vino. Atti accad. ital. vite e vino 3,

376-382.

12(5), 62-63 (1952).

44, 147-150.

241 (1932-34).

B 1-9.

124-137.

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480 MAYNARD A. AMERINE

Garoglio, P. G. 1941-1942. Trattado de Enologia; enciclopedia vitivinicola moderna. “Prog. vinic. ed olea., Firenze,” 5 v. (Vol. V. Analisi chimica, chimico-fisica e merceologica dei mosti, vini, derivati e sottoprodotti.) (See also his Nuovo Trat- tat0 di Enologia, Sansoni Edizioni Scientificke, Firenze, 3 v. 1953.)

Garoglio, P. G., and Barini-Banchi, G. 1940. Saccarimetria dei mosti concentrati. Pros. vinic. ed olea. 16, 2782-2784.

Gatet, L. 1939a. Qtude du pouvoir r6ducteur des jus de fruits au cours de la matura- tion. Enzymologia 6, 375-386.

Gatet, L. 1939b. Recherches biochimiques sur la maturation des fruits. Ann. physiol. phys. biol. 16, 984-1064.

Gatet, L., and Genevois, L. 1938. Indice de brome du glucose et des substances ph6noliques. Application 8. l’ktude de la maturation du raisin. Bull. SOC. chim. France [5] 6 , 578.

Gatet, L., and Genevois, L. 1941. Sur le pouvoir rkducteur des vins. Bull. SOC. chim. France [5] 8, 485-487.

Geiss, W. 1938. Zuckerbestimmung in Weinen und Siissmosten auf photometrischen Wege mit Hilfe des Zeiss’schen Pulfrich-Photometers. Wein u . Rebe 20, 181-187.

Geiss, W. 1939. Versuche zur Klarung der filtrationsfordernden Wirkung des Filtragols bei Apfel- und Traubensaft. Wein u . Rebe 21, 70-82.

Geloso, J. 1931. Relation entre le vieillissement des vins et leur potentiel d’oxydo- reduction Ann. brass. el dist. 29, 177-181, 193-197, 257-261, 273-277.

Genevois, L. 1934a. Recherche de la flavine dans les vins blancs. Bull. SOC. chim. France [5] 1, 1503-1504.

Genevois, L. l934b. La solubilit6 des tartrates de potassium e t de calcium dans les solutions alcooliques acides, les modts et les vins. Ann. brass. et dist. 32, 310-315,

Genevois, L. 1936. Acide succinique et glyc6rhe dans la fermentation alcoolique.

Genevois, L. 1937. Sur la saponification des esters en milieu neutre. Bull. soc. chim.

Genevois, L. 1938. Les substances rkductrices au cours de la maturation du raisin.

Genevois, L. 1949a. Acides organiques et du vin. Rev. ferment. ind. aliment. 4, 67-76. Genevois, L. 194913. Les Bquations de la fermentation alcoolique. Inds. agr. et aliment.

(Paris) 66, 329-335. Genevois, L. 1950. Essais de bilans de la fermentation alcoolique due aux cellules de

levures. Biochim. et Biophys. Acta 4, 179-192. Genevois, L. 1951. Les produits secondaires de la fermentation; acides organiques

des vins; matihres colorantes e t vieillissement des vins. Rev. ferment. ind. aliment. 6, 18-25, 43-47, 88-96, 111-115.

Genevois, L. 1952. Formation des alcools supErieurs et de leurs ddrives aux cours de la fermentation alcoolique. Inds. agr. et aliment. (Paris) 69, 27-32.

Genevois, L., Espil, L., Peynaud, E., and Rib6reau-Gayon, J. 1938a. Dosage des acides organiques et des esters dans les modts et les vins. 18th Congr. chim. ind. Nancy 1, 1320-1330.

Genevois, L., and Flavier, H. 1938-1939. Dosage des vitamines BI et Bz dans quelques vine de la Gironde. PTOC. verb. dun . SOC. sci. phy. nat. Bordeaux 1938-39, 72-73.

Genevois, L., and Gatet, L. 1940. Formation et 6volution biologique des acides organiques dans le raisin Saint-amilion A Cognac. Rev. viticult. 02, 243-247,

326-328, 337-343.

Bull. soc. chim. biol. 18, 295-300.

France [5] 4, 1506-1508.

Bull. 8oc. chim. France [5] 6 , 580-597.

259-263.

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COMPOSITION OF WINES 48 1

Genevois, L., Gatet, L., and Cayrol, P. 1938b. Analyse des substances rbductriees par formation de complexes; acide ascorbique dans les moats e t les vins. 18th Congr. chim. ind. Nancy 1, 93c-94c.

Genevois, L., Peynaud, E., and RibBreau-Gayon, J. 1946. Sur un bilan des produits secondaires de la fermentation alcoolique. Compt. rend. 223, 693-695.

Genevois, L., Peynaud, E., and Ribkreau-Gayon, J. 1947a. Bilan sur produits sec- ondaires de la fermentation alcoolique. Rev. ferment. ind. aliment. 2 , 193-199.

Genevois, L., Peynaud, E., and RibBreau-Gayon, J. 1947b. Sur un bilan des trans- formations de l’bthanal ajout6 8. une fermentation alcoolique. Compt. rend. 224,

Genevois, L., Peynaud, E., and Ribbreau-Gayon, J. 1948a. Action du milieu sur lea produits secondaires de la fermentation alcoolique des levures elliptiques. Compt. rend. 226, 126-128.

Genevois, L., Peynaud, E., and Ribbreau-Gayon, J. 1948b. Bilans des produits secondaires de la fermentation alcoolique dans les vins rouges de la Gironde. Compt. rend. 226, 439-440.

Genevois, L., Peynaud, E., and Ribereau-Gayon, J. 194%. La fermentation alcoolique des vins doux naturels. Compt. rend. 227, 227-228.

Genevois, L., Peynaud, E., and Ribbreau-Gayon, J. 1949a. La fermentation alcoolique des vins blancs de la Gironde. Compt. rend. 229, 479-480.

Genevois, L., Peynaud, E., and RibCreau-Gayon, J. 1949b. Sur la quantit6 d’eau fixbe par les produits de la fermentation alcoolique et sur une relation empirique entre la quantit6 d’acides et de glycerol form&. Compt. rend. 229, 777-778.

Genevois, L., Peynaud, E., and Rib6reau-Gayon, J. 1949c. Sur une relation num6rique entre les divers produits secondaires de la fermentation alcoolique. Bull. soc. chim. biol. 31, 369-373.

Genevois, L., and RibQeau-Gayon, J. 1933. Les Bquilibres ioniques dans les mohts e t les vins. Ann. brass. et dist. 31, 273-277, 289-294, 305-311.

Genevois, L., and Ribbreau-Gayon, J. 1935a. Coefficients tampons de quelques vins. Bull. S O C . chim. France [5] 2, 1286-1287.

Genevois, L., and Ribbreau-Gayon, J. 1935b. Sur les substances azot6es des mohts e t des vins. Ann. ferment. 1, 541-546; see also Bull. ofice intern. vin. 9(94), 36-41 (1936).

762-763.

Genevois, L. and RibBreau-Gayon, J. 1947. Le Vin. Hermann & Cie., Paris. Gentilini, 1,. 1937. Di alcuni carboni in enologia. Annuar. staz. sper. vilicolt. e enol.

(Conegliano) 7 , 301-337. Gentilini, L. 1939. Contributo all0 studio dell’analisi cromatografica applicata alle

materie coloranti naturali del vino. I. Ann. chim. appl. 29, 169-183. Gentilini, L. 1941. Studio dell’analisi cromatografica applicata a1 riconoscimento di

alcuni dei pih comuni sofisticanti del colore dei vini rossi. Annuar. staz. sper. niticolt. e end. (Conegliano) 10, 59-72.

Gentilini, L. 1947. L’acetato di etile e l’aciditii volatile nei vini spunti e acescenti. Annuar. slaz. sper. viticolt. e enol. (Conegliano) 13(1), 2-8; see also Ztal. vinic. ed agr. 37(10), 112-114; ( l l) , 125-128; ( la) , 137-139 (1947).

Gentilini, L. 1950. Procedimiento cuprometrico rapido per il dosaggio degli zuccheri riduttori nel inosto d’uva. Ann. sper. agrar. (Rome) (N.S.) 4, 213-217; see also Annuar. slaz. sper. viticolt. e enol. (Conegliano) 14(2), 213-217 (1950-51).

Gentilini, L. 1952. I1 p H in enologia. Riv. viticolt. e enol. (Conegliano) 6, 423-429. Gentilini, L., and Carli, E. 1950. Corrispondenza fra gradi Babo e contenuto zuc-

cherino reale nei pih comuni mosti d’uva del veneto. Ann. sper. agrar. (Rome)

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482 MAYNARD A. AMERINE

(N.S.) 4, 1049-1067; see also Annuar. staz. sper. viticolt. e enol. (Conegliano)

Georgacopoulos, MM., and Costopoulos, J. 1952. Dosage des sucres par la methode au ferricyanure. Bull. ofice intern. vin 26(258), 114-120.

Gerasimov, M. A. 1931. Die aktuelle Aeiditat des Traubensaftes und des Weines. Magarach. Krvmskaa zonal’naa o p g t n a s stanssi^a PO vinogradamtvu i vinodeliu, Trudy 2, 1-42; see also Bull. ofice intern. vin 6(48), 22-27 (1932); Ann. fals. et fraudes 26, 353-355 (1932).

Gerasimov, M. A., and Vinogradova, N. I. 1931. Der Gehalt des Vitamins C im Traubensafte und im Wein. Magarach. K r y m s k a a zonal’naa opytna& stanszi& PO vinogradarstvu i vinodeliu, Trudy 3, 1-21.

Gerum, J. 1932. Die Bestimmung der Oechslegrade mit Hilfe des Zeiss’schen Ein- tauchrefraktometers. W e i n u. Rebe 14, 235-238.

Ghimicescu, G. 1935a. Microdosage colorim6trique de l’acide malique dans les vins. Ann. sci. univ. Jassy 21, 321-325.

Ghimicescu, G. 1935b. Microdosage colorim6trique de l’acide tartrique total dans les vins. Ann. sci. uniu. Jassy 21, 326-329.

Ghimicescu, G. 1935c. Microdosage colorim6trique du bitartrate du vin. Ann. sci. univ. Jassy 21, 343-345.

Ghirnicescu, G. 1935d. Microdosage de l’acide volatile dans les vins. Ann. sci. univ. Jassy 21, 306-314

Ghimicescu, G. 1935e. Une micromethode pour le dosage du acide lactique dans les vins. Ann. sci. univ. Jassy 21, 315-320.

Ghimicescu, G. 1935f. Une nouvelle microm6thode pour le dosage colorim6trique de la glycerine dans les vins. Ann. sci. univ. Jassy 21, 346-351.

Ghimicescu, G. 1937. Microdosage des sucres dans le vin. Mikrochemie 22, 201-207. Ghimicescu, G. 1938. Sur le dosage de l’extrait sec du vin, du vinaigre, e t de 1s bibre.

Ann. sci. univ. Jassy 24, 87-90. Ghimicescu, G., and Gheorghiu-Vieriu, A. 1938. Microdosage de la tanin dans le vin.

Mikrochemie 26, 187-191. Gierer, S., and Hoffmann-Ostenhof, 0. 1951. Eine kolorimetrische Mikromethodik

zur quantitativen Bestimmung der Fuselalkohole bei Garversuchen. Mikro- chemie 38, 232-236.

Gobis, L. 1950. Richerche sul mecanismo di formaeione dell’acido citric0 nel corso della fermentaeione alcoolica. Ann. sper. agrar. (Rome) (N.S.) 4, 569-578.

Gobis, L., and Farfaletti-Casali, P. L. 1952. I1 contenuto in acetilmetilcarbinolo e glicol butilenico nei vini e il suo significato enologico. Riv. viticolt. e enol. (Cone- gliano) 6, 297-300.

Godet, Ch. 1949. Sur l’unification des mbthodes d’analyse des vins. Bull. ofice intern. vin 22(223), 60-66; see also 7th Congr. intern. ind. agr., Paris, 1948 1(&2), 1-7 ( 1948).

Godet, C., and Charribe, R. 1946. Sur le dosage de l’acide citrique dans lea vins, jus de fruits, concentrb, etc. Mitt . Gebiete Lebensm. u. Hyg. 37, 317-326.

Godet, C., and Deuel, H. 1947. Les poids sp6cifiques de l’extrait du vin. Mitt . Gebiete Lebensm. u. Hyg. 38, 5-11.

Godet, C., and Martin, L. 1946. Contribution la connaissance des vins suisses. Mitt . Gebiete Lebensm. u. Hyg. 37, 327-342.

Goes, L. A. de A., and Correia, E. M. 1942. Influbcia de raga de levedura (Saech. ellipsoideus) como elemento a considerar na correcpfio da concentraqb hidro- geni6nica dos mostos. Anais inst. super. agron., Univ. tdc. Lisboa 13, 171-175.

14(4), 1-19 (1950-51).

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COMPOSITION OF WINES 483

Goldbach, N. J., and Opperschaum, R. Z. 1950. Zum toxikologischen Nachweis des Methylalkohols als p-Brombenzosauremethylester. Z. Lebensm.-Untersuch.

Gomes, J. V. M. 1941. Doseamento do Alcool por destilaqb nos vinhos do PBrto.

Gomes, J. V. M. 1945. Microflora duriense; leveduras produtoras de esteres. Anais

Goresline, H. E., and Champlin, F. M. 1938. Sugars in champagne production. Ind.

Got, N. 1947. Les Vins Doux Naturels. Chez I’Auteur, Perpignan, France. Gottschalk, A. 1946. Mechanism of selective fermentation of d-fructose from invert

sugar by Sauternes yeast. Biochem: J. 40, 621-626. Grandchamp, L.-E., and Vollaire-Salva, J. 1939. Dosage rapide des esters des acides

gras volatils. Ann. fals. et fraudes 32, 244-247. Grivas, G. 1952. Le dosage de I’extrait du vin d’aprb le poids specifique de la solution

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Grossfeld, J., and Battay, F. 1931. Versuche uber Nachweis, Bestimmung und Vorkommen der Buttersaure in Lebensmitteln. Z. Untersuch. Lebensm. 61, 129- 161.

Grossfeld, J., and Miermeister, A. 1928. Vorkommen, Nachweis und Bestimmung von Laurinsaure in alkoholischen Getranken. Z. [Jntersuch. Lebensm. 66, 167-187.

Guimarks, A. F. 1950. Doseamento do Acid0 tar thico no vinho do PBrto. Anais. insl. vinho Pdrto 11(1), 59-72.

Guittonneau, G., BBjambes, M., and Tavernier, J. 1941a. Sur la presence et l’origine de l’ac6tylmBthylcarbinol e t du butanediol 2-3 dans les cidfes normands. Ann. ferment. 6, 159-167.

Guittonneau, G., Tavernier, J., and BBjambes, M. 1941b. Sur la presence et l’origine de l’ac6tylm6thylcarbinol et du butanediol 2-3 dans les cidres normands. Les Aerobacter en cidrerie. Compt. rend. 213, 257-259.

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Anais inst. vinho Pdrto 2, 305-359.

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Eng. Chem. SO, 112-113.

26(258), 121-123.

Guntz, A. A. 1950. Echangeurs d’ions et oenologie. Chim. anal. 32, 246-248. Guymon, J. F. 1951. Report on methanol. Colorimetric determination of methanol in

solutions containing ethyl alcohol. J. Assoc. Ofic. Agr. Chemists 34, 310-328. Guymon, J. F. and Heitz, J. E. 1952. The fuse1 oil content of California wines. Food

Technol. 6, 359-362. Gvaladze, V. Z., and Rodopulo, A. 1946. Acetylmethylcarbinol as indicator of the

beginning of acetic acid fermentation in wines. (transl.) Vinodelie i Vinogradarslzw

Haagen-Smit, A. J., Hirosawa, F. N., and Wang, T. H. 1949. Chemical studies on grapes and wines. I. Volatile constituents of Zinfandel grapes (Vitis vinifera var. Zinfandel). Food Research 14, 472-480.

Hall, N. A., Krupski, E., and Fischer, L. 1952. Methanol in Washington wines. Am. J. P h a m . 124, 343-350.

Hanak, A. 1932. Prazisionsdestillations-apparat. Chem.-Zgt. 66, 984. Hargreaves, C. A., Abrahams, M. D., and Vickery, H. B. 1951. Determination of

Hartmann, B. G. 1939. Report on (the analysis of) wines. J. Assoc. 0, f i r . Agr. Chem.ists

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Hauptmann, K. H. 1952a. Action des enzymes de filtration dans la fabrication des jus

Hauptmann, K. H. 195213. Fermentierungsprobleme bei der Weinbereitung. Angew.

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Heide, C. von der, and Mandlen, H. 1930. Vergleichende Bestimmungen der Wasser- stoffionen-Konzentration im Wein nach verschiedenen Verfahren. Wein u. Rebe

Heide, C. von der, and Mandlen, H. 1933. Tafeln zur Ermittlung des Alkohol- und Extraktgehaltes des Weines aus den Spezifischen Gewichten von Alkohol- Wassermischungen und von Saceharoselosungen bei 20°, bezogne auf Wasser von 4". Z. Untersuch. Lebensm. 66, 338-341.

Heide, C. von der, and Zeisset, W. 1935. Die Extraktbestimmung im Wein. 2. Unter- such. Lebensm. 69, 138-145.

Heide, E. 1940. Etwas uber Farbstoffausscheidungen bei Rotweinen. Weinland 12,

Heiduschka, A., and Pyriki, C. 1930. Untersuchung von 1928er Traubenweinen des Weinbaugebietes Pillnitz-Lossnitz-Meissen-Seusslitz. Z . Untersuch. Lebensm. 69, 104-109.

Heiduschka, A., and Sommer, H. 1935. Citronensaurebestimmung im Wein. Pharm. Zentralhalle 76, 593-595.

Heitz, J. E., Roessler, E. B., Amerine, M. A., and Baker, G. A. 1951. Certain factors influencing the composition of California-type sherry during baking. Food Research 16, 192-200.

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1934, 26-27.

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258-260, 281-283, 569-570; 89, 29-30.

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Hozumi, T., and SatB, M. 1950. Studies on alcoholic beverages by paper partition chromatography. I. Detection of reducing sugars of sake and wines. J . SOC. Brewing Japan 46,322-325.

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Hugues, E., and Chevalier, R. 1930. L’acidit6 lactique de quelques vins de 1’Herault. Ann. fals. el fraudes 23, 214-216.

Hunk&, B. 1938. Schnellmethode zum Nachweis von Verfalschungen geistiger Getranke mit Methylalkohol. Kisdrletuggi KiizZernhyek 41, 111-112; Bee also Chem.-Ztg. 62, 240 (1938).

Huntenburg, W. 1936. Exakter Nachweis des Oxymethylfurfurols in Sussweinen. 2. Untersuch. Lebensm. 71, 332-337.

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Iribarne, J. V. 1941. La determinaci6n de aldehidos en vinos. Anales asoc. q u h .

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Jacquin, P., and Tavernier, J. 1952. Emploi de l’ac6tate d’isopropyle comme solvant dans le dosage du glycerol par oxydation periodique. Inds. agr. et aliment. (Paris)

Jahr, H. 1931. Beitrag zur Bestimmung des Rohrzuchers in Susswein. 2. anal. Chem.

Jakovliv, G. 1952. Essai de caracterisation chromatographique des fruits dans les aliments sucres et les boisson. Znds. agr. et aliment. (Paris) 69, 223-225.

Jauker, H. 1937. Vber das Vorkommen und die Bestimmung von Methylalkohol in Giirungsprodukten. Dissertation, Pharmakognostischen Institut, Universitat Tartu.

Jaulmes, P. 1934. La dktermination de l’acidit6 volatile des vins. Ann. fals. et fraudes

Jaulmes, P. 1935a. La defecation B la chaux et le dosage de l’acidit6 volatile des vins. Ann. fals. et fraudes 28, 540-545; see also Bull. pharm. Sud-Est 39, 235-241 (1935).

Jaulmes, P. 1935b. L’influence des matikres extractives sur la distillation des acides volatils du vin. Ann. fals. et fraudes 28,590-599; see also Bull. pharm. Sud-Est 39, 314-325 (1935).

Jaulmes, P. 1950. Appareil pour la separation des produits entrainables par la vapeur d’eau: alcool, acidit6 volatile, ammoniaque, etc. Ann. fals. et fraudes 43,

Jaulmes, P. 1951. Analyse des Vins. Librairie Coulet, Dubois et Poulain, Montpellier, 2 Ed.

Jaulmes, P. 1952. L’acidit6 volatile et son dosage. Rev. agr. Afrique du Nord 60,27-31, 4.2-50.

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Jaulmes, P., and Espezel, R. 1935. Le dosage de l’acetaldehyde dans les vins e t les spiritueux. Ann. fals. et fraudes 28, 325-335.

Jaulmes, P., and Marignan, R. 1953. Consbquences de l’adoption de la temperature de r6f6rence de 20’ pour la definition du degr6 alcoolique des vins et des spiritueux. Ann. fals. et fraudes 46, 208-212.

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Jaulmes, P., and Slizewicz, L. 1943. Les rbgles oenologiques et la methode officielle de dosage des acidit6s totale e t h e des vins. Bull. SOC. chim. France [5] 10, 59-60.

Jeanpbtre, J. 1931. Un am6lioration du procBd6 Landmann pour la determination de l’acidit6 volatile du vin. Mitt. Gebiete Lebensm. u. Hug. 22, 94.

Jeroch, 0. P. 1947. The use of walnut extracts for vitaminizing wines (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 7(1), 17-18.

Jilke, W. 1950. Beitrag zur Statistik der Rheingauer Moste des Herbstes 1948. 2. Lebensm.-Untersuch. u. -Forsch. 91, 418-422.

.Jilke, W. 1951. Uber die Anwendbarkeit refraktometrischer Methoden bei der Unter- suchung von Wein, weinahnlichen und weinhaltigen Getranken. 2. Lebensm- Untersuch. u. -Forsch. 93, 357-362.

Jim6nez de Abeledo, M. E. 1937. Determinaci6n de acidez total en vinos. Anales asoc. qufm. argentina 20, 81-93.

Jimbnea de Abeledo, M. E., and Mendivelaba, G. 1939. Determinaci6n de azucar reductor en vinos. Anales asoc. qufm. argentina 27, 1-20.

Joslyn, M. A. 1938a. Electrolytic production of rancio flavor in sherries. Znd. Eng. Chem. SO, 568-577.

Joslyn, M. A. 1938b. Report on volatile acids in ines. J. Assoc. O@c. Agr. Chemists

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Joslyn, M. A. 1940a. The by-products of alcoholic fermentation. Wullerstein Lab.

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Joslyn, M. A. 1949. Chemistry of alcoholic fermentation. Proc. Wine Tech. Conf. (Davis) 1949, 86-88.

Joslyn, M. A. 1960. Methods in Food Analysis, Applied to Plant Products. Academic Press, New York.

Joslyn, M. A., and Amerine, M. A. 1941. Commercial production of dessert wines. Calif. Agr. Expt. Sta. Bull. 661, 1-186.

Joslyn, M. A., and Comar, C. L. 1938. Determination of acetaldehyde in wines. Znd. Eng. Chem., Anal. Ed. 10, 364-366.

Joslyn, M. A., and Comar, C. L. 1941. Role of acetaldehyde in red wine. Znd. Ens. Chem. 33,919-928.

Joslyn, M. A,, and Dunn, R. 1941. Acid metabolism of wine yeast. I. The relation of volatile acid formation to alcoholic fermentation. J. Am. Chem. SOC. 60, 1137- 1141.

Joslyn, M. A., Farley, H. B., and Read, H. M. 1929. Effect of temperature and time of heating on extraction of color from red-juice grapes. Ind. Eng. Chem. 21, 1135- 1137.

Joslyn, M. A., and Marsh, G. L. 1935. Methods of wine analysis. I. Comparisons of direct and indirect methods of determining alcohol, extract, and total acid in dry wine, J. Assoc. Ofic. Agr. Chemists 18, 307-313.

Joslyn, M. A., Marsh, G. L., and Fessler, J. 1937. A comparison of several physical methods for the determination of the alcohol content of wine. J . Assoc. OJic. Agr. Chemists 20, 116-130.

Kacsmarek, A., and Weise, R. 1942. Physikalisch-chemische Untersuchungsmethoden fur die Rebenzuchtung. I. Uber das Absorptionsspektrum als Hilfsmittel bei dcr Rotweinzuchtung. Gartenbauwiss. 16,314-357.

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Kalberer, 0. E. 1930. Die Anwendbarkeit der titrimetrischen Zuckerbestimmunds- methode Bruhns fiir Obst- und Traubenweine. Mitt. Gebiete Lebensm. u. Hyg. 21, 114-115.

Karamboloff, N. 1932. Eine neue ( 1 ) Rbaktion, um das Vorhandensein von Kunst- farben in den Weinen festzustellen. Wein u. Rebe 14, 5 (see original in Ann. Univ. Sofia 10, 207-218, 1931-32.)

Katar’gn, T. G. 1951. Accomplishments of Magarach Institute (All-Union Scientific Research Institute of Wine Manufacture and Viticulture) (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 11(6), 58-59.

Ketelbant, E. 1936. Dosage des acides volatils dans les liquidcs ferment&. Ann. ferment. 2, 109-127.

Kielhofer, E. 1937. Die Kellerbehandlung des Weins. Erkenntnisse und technische Fortschritte im letzten Jahrzehnt unter besonderer Berucksichtigung der mittel- europakchen Weinbaugebiete. Forschungsdienst 4, 331-341, 382-391.

Kielhofer, E. 1942. Troubles albuminoxdes du vin. Bull. ofice intern. vin 16(152),

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Kielhofer, E. 1953. Die Bestimmung des Gehalts an unvergorenem Zucker in der Praxis. Deut. Wein-Ztg. 89, 163-164.

Kielhofer, E., and Gunther, P. 1937. Vber die Beaiehungen zwischen Mostgewicht, Zuckergehalt, Zuckerzusatz und Alkoholgehalt beim unreifen 1936er Mosten des Moselgebietes. Wein u. Rebe 19, 33-45.

Kiessling, W. 1949. Formation d’acides triosephosphoriques au cours de la fermenta- tion due aux levures vivantes. Inds. agr. et aliment. (Paris) 66, 111-118.

Kilbuck, J. H., Nussenbaum, F., and Cruess, W. V. 1949. Pectic enzymes: invcstiga- tions on their use in making wines. Wines & Vines SO@), 23-25.

Kilp, W., and Deplanque, R. 1934. In welchem Stadium der Giirung beginnt die Fuselolbildung. 2. Spiritusind. 67, 306, 308, 313-314, 316; see also Brennerei Ztg.

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Kniphorst, L. C . E., and Kruisheer, C. I. 1937. Die Bestimmung von 2-3-Butylen- glykol, Acetylmethylcarbinol und Diacetyl in Wein und anderen Garungs- produkten. 2. Untersuch. Lebensm. 73, 1-19; 74, 477-485.

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Koch, J., and Bretthauer, G. 1951. Uber eine zuverlassige Methode zur Bestimmung der Milchsaure in Sussmost und Wein. 2. anal. Chem. 132, 346-356.

Kocsis, E. A., CaokBn, P., and Horvai, R. 1941. Weinfarbenuntersuchung mittels Capillar- Luminescenz-Analyse. 2. Untersuch. Lehensm. 81, 316-321; see also ibid. 84, 332-340 (1942).

Kogan, A. J. 1930. Uber die Bestimmung der Citronensaure bei Gegenwart anderer organischer Substanzen. 2. anal. Chem. 80, 112-122.

Kondareff, M. 1940. Bilanz und Verteilung der organischen Sauren in dem sud- bulgarischen Weinen. 2. Untersuch. Lebensm. 80, 527-542; see also 2. Landwirt. Versuchsstat. Sofia 9 (1939).

Konek, F., and Wettstein, E. 1934. Verfahren zur quantitativen Trennung und Bestimmung der im Wein enthaltenen organischen Sauren. Magyar Tudombmyos Akaddmia, Budapest, Matematikai ds termdszettundomdnyi drtesto. 61, 305-324; see also Magyar Ampelol. Ibkonyo 9, 429-439 (1935).

Kopal, S. 1937. Chemick6 SloIenE Ceskos1ovenskJ;ch v h . NBkladem ministerstva zemtidtilsvi republiky Ceskoslovenski, Praha.

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Korotkevich, A. V. 1948. Relative acidity of musts and wines (transl.). Biokhimiz?a uinodeli; 2, 149-168.

Korotkevich, A. V. 1949. Determination of alcohol in table wines by ebulliometry (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 8(10), 40; C. A . 44, 273 (1950).

Korotkevich, A. V. 1951. Determination of wine color by a photometer (transl.). Vinodelie i Vinogradarstvo S.S.S. R. 11(1), 20-22.

Korotkevich, A. V., and Arbuzova, E. M. 1949. The determination of glycerol in dry wines (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 9(7), 29-31.

Kozenko, E. M. 1952. On the contents of stable esters of carbonic acid in wines (transl.). Vinodelie i Vinogradarstvo S.S.S. R. 12(4), 25-28.

Kramer, M., and Satterfield, G. H. 1942. Ascorbic acid content of four varieties of raw wines. Food Research 7, 127-129.

Kramer, 0. 1935. Die Bestimmung des Mostgewichtes mittels des Zeiss’schen Hand- zuckerrefraktometers. Wein u. Rebe 17, 275-281.

Kramer, 0. 1941a. Enstehung und Bedeutung der fluchtigen Sauren im Wein. Wein- land 13, 41-44, 72-75.

Kramer, 0. 1941b. Die Milchsaure im Wein. Weinland 13, 93-94, 122-123, 134-137. Kramer, 0. 1942. Neuere Probleme der Kellerwirtschaft. Forschungedienst 16, 525-537. Kramer, O., and Bohringer, W. 1940. Untersuchungen und Versuche uber die Saure-

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Krause, H. 1948. Neues Verfahren zur Bestimmung der Milchsaurc. Weinbau. Wissenschaftl. Beih. 2, 297-307.

Krauze, S. 1933. Zur Frage des Nachweises von geeuckerten Weinen. Mitt . Gebiete Lebensm. u. HYg. 24, 79-90.

Kretzdorn, H. 19-19. Beitrag zum Gerbstoffnachweis nach Nessler und Barth. Deut. Wein-Ztg. 86, 11-12.

Krombach, H. 1948. Essais comparatifs des mkthodes de dosage de l’extrait sec sur des vins de la Moselle. 7th Congr. intern. inds. agr., Paris 1(&2), D 1-3.

Kruisheer, C. I., Vorstman, N. J. N., and Kniphorst, L. C. E. 1935. Bestimmung des Oxymethylfurfurols und des Lavulosins in Portwein und anderen Sussweinen. 2. Untersuch. Lebensm. 69, 570-582.

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liutal’ova, T. 1931. Die Roue der Aminosauren bei der Gestaltung des Weinbouquetes. Odessa. fientrol’na naukovo-doslidchot vinogrado-vinorotcha stanGi2, Pratsi 4,

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Lagneau, C. 1945. Le contrble legal en oenologie. Bull. ofice intern. uin 18(167-170), 54-74.

Lakkopoulos, A. A. 1939. The determination of citric acid in musts by the method of electrical conductivity (transl.). Prakt. Akad. Athenon 14, 547-553.

Lambert, M., and Neish, A. C. 1950. Rapid method for estimation of glycerol in fer- mentation solutions. Can. J . Research 28B, 83-89.

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Lang, W. 1951. tfber die quantitative Bestimmung von Gerbstoffen. Pharmazie, Berlin, 6, 137-140.

Larsen, H. J. 1951. Vereinfachte Siiure -Bestimmung. Weinbau. Wissenschajtl. Beih. 6, 381.

Lavollay, J., and Sevestre, J. 1944. Le vin consid6r6 comme un aliment riche en vitamine P. Compt. rend. acad. agr. France 30, 259-261; see also Bull. ofice intern. vin 17(163-166), 82-84 (1944).

Leggieri, C. L. 1951. Nuovo sistema di dosaggio dell’acidith volatile del vino con diretta esculsione dell’anidride solforosa. Controllo del limite consentito d i Sot. Chimica (Milan) 6 , 157-159.

Legkov, P. 1931. Die colorimetrische Bestimmung des Glyzerins. Odessa. !?sentral’na naukovo-doslidchol vinogrado-vinorotcha slant&, Pratsi 4, 88-91.

Lehmann, E. 1940. Zur Zuckerbestimmung im Wein. 2. Untersuch. Lebensm. 79, 270. Lehmann, E. 1943. Die Geschmacksstoffe des Weines. Schweiz. Wein-Ztg. 61, 89-90. Leonoel, C. P. 1946. Microdosage de l’alcool mbthylique dans les milieux alcooliques

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C in fruit-berry wines (transl.). Nauch. -Isoledovatel. Inst. Pishchevo’l Prom., Sbornik Molodykk Nauch. Rabotnikov 1939, 35-47; C. A . 36, 4280 (1942).

Levy, L. P., Posternack, T., and Robinson, R. 1931. Experiments on the systhesis of the anthocyanins. VIII. A systhesis of oenin chloride. J . Chem. SOC. 1931, 2701- 2715; see also ibid. 2715-2722).

Lherme, G. 1933. Les 6bullioscopes et le degr6 des vins blancs. Ann. fals. et fraudes

Lobstein, E., and Schmidt. 1931. Le vignoble Alsacih et ses vins. Ann. fals. el fraudes

Lodi, M. 1943. Untersuchungen tiber den Gehalt von Carotin, Vitamin BI, Bz, und C bei der alkoholischen Giirung der Weinbeeren. Vitamine u . Hormone 4, 443-455.

Lucchetti, E. 1941. Un’inchiesta sui vini de Montecarlo (Lucca). Ann. facoltcl agrar. univ. Pisa (N.S.) 4, 216-230.

Luckow, C. 1931. Nachprtifung von Alkoholometern. Wein u. Rebe 13, 267-269. Luckow, C. 1935. Die Bestimmung des Alkohol- und Extraktgehaltes mit Hilfe des

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COMPOSITION OF WINES 49 1

Luthi, H., and Vetsch, U. 1952. Papierchromatische Bestimmung von Aminosauren in Weinen. Schweiz. 2. 0bst.-und Weinbau 61, 390-394, 405-408.

Maaskant, L. 1936. Quantitative Bestimmung von Furfurol und Oxymethylfurfurol mit p-Nitrophenylhydrazin. Rec. trau. chim. 66, 1068-1070.

Mackinney, G., and Chichester, C. 0. 1954. The color problem in foods. Advances in Food Research, 6, 301-351 (1954).

Mader, 1936. Der Einfluss der Veredlung auf die chemische Zusammensetzung des Mostes und des Weines. Wein u. Rebe 17, 250-258.

Mallory, G . E., and Love, R. F. 1945. Determination of caramel in wine, dis- tilled spirits, vinegar, and vanilla extract. Znd. Eng. Chem., Anal. Ed. 17,

Malvezin, P. 1931. Les methodes d’analyse et l’expertise 16gale. Bull. ofice intern. uin

Malvezin, P. 1934. A propos du dosage de l’extrait sec des vins. Ann. fals. et fraudes

Manskaya, S. M. 1939. Aging of wine (transl.). Priroda l989(9), 74-80; C. A . 86,3989 (1942).

Manskaya, S. M., and Emel’yanova, M. P. 1939. Oxidation processes in wine (transl.). Biokhimiya 4, 581-592.

Maravalhas, N. 1935. Novo processo rapido para a determinaqb das substancias colorantes artificiaes nos vinhos. Rev. chim. ind. (Rio de Janeiro) 4, 480.

Marcel, M., and Bastisse, E.-M. 1942. Sur la technique de determination du titre alcoolique des vins, cidres, bihres, etc. Compt. rend. acad. agr. France 28, 382-383.

Marcilla Arrazola, J. 1934. Sobre la caracterizaci6n de vinos por el an&lisis qufmico. C O T L ~ T . intern. quim. pura apl. 9(VI), 352-366.

Marcilla Arrazola, J., Alas, G., and Feduchy Marifio, E. 1936. Contribucih a1 estudio de la levaduras que forman velo sobre ciertos vinos de elevado grado alcoholico. Anales Centro Invest. Vinicolas 1, 1-230.

Marcilla Arrazola, J., and Feduchy Marifio, E. 1943. Una mezcla de indicadores de pH, especialmente adecuada para la industria enol6gica. Inst. nacl. invest. agron. Cuaderno (Spain), 24, 37-59.

Marcille, R. 1933. Observations sur les nouvelles mkthodes officielles de dosage des acidites dans lea vins. Ann. fals. et fraudes 26, 286-292; see also Bull. ofice intern. vzn 6(67), 39-44 (1933).

Marcille, R. 1934. Dosage de l’acidit6 volatile des vim sulfit6s. Ann. fals. et fraudes

Marcille, R. 1935. Dosage de l’anhydride sulfureux libre dans lea vins. Ann. falsif. el fraudes 28, 93-96; see also Bull. ofice intern. vin 8(84), 49-52 (1935).

Marcille, R. 1937. Observations sur les mkthodes d’analyse des vins ayant fait l’objet de la convention internationale de Rome. Ann. fals. et fraudes 30, 299-304.

Mariani, A. 1950. La determinazione di piccole quantith di alcole metilico nell etilico. Rend. ist. super. SanitB 13, 154-166.

Marignan, R. 1944. Le Dosage de 1’Acide Succinique dans les Vins. Imprimerie A. Quillet, Montpellier.

Markley, K. S., Sando, C. E., and Hendricks, S. B. 1938. Petroleum ether-soluble and ether-soluble constituents of grape pomace. J . Biol. Chem. 123, 641-654.

Marsh, G. L. 1936. The peculiarities of carbon dioxide in wine. Wine Rev. 4, 17-18. Marsh, G. L., and Joslyn, M. A. 1935. Precipitation rate of cream of tartar from wine.

Marsh, G., and Kean, C. 1951. Applications of chromatographic methods to organic

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Ind. Eng. Chem. 27, 1252-1257.

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Martucci, J. 1941. La manita en 10s vinos. Vinos, ViAas y Prutas 37, 165-166. Mastbaum, H. 1933. Uber den Nachweis von Caramel in Sussweinen. Chem.-Ztg. 67,

Mathers, A. P. 1949. Detection of tartaric acid and tartrates in wine. J. Assoc. Oflc.

Mathers, A. P. 1951. Report on chromatographic studies of wines and distilled spirits.

Mathers, A. P., Beck, J. E., and Schoeneman, R. L. 1951. Polarographic determination

Mathers, A. P., and Schoeneman, R. L. 1952. Polarographic determination of benzalde-

Mathieu, G. 1938. Observations sur la fermentation alcoolique h. Chgteauneuf-du-

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Mauri6, A. 1942. Lea compos6s phholiques du vin. (Mati6res colorantes et tannofdes).

McCharles, 0. H., and Pitman, G. A. 1936. Methods of wine analysis. Ind. Eng.

Mehlitz, A., and Scheuer , M. 1934. Ober enzymatische Klarung von Fruchtsaften und

Melcher, B. 1947. Zur Bestimmung der Gesamtsaure. Mitt. Gebiete Lebensm. u. Hyg.

Merzhanfan, A. A. 1930. Uber den Vitamgehalt von Trauben und Traubenweinen Wein u. Rebe 11, 404-408; see also ibid. 12, 67-76 (1930).

Merzhan&n, A. A. 1951. On the behavior of diethyl esters of pyrocarbonic acid in sparkling and gassified wines (transl.). Vinodelie i Vinogradarstvo S.S.S.I?.

Merzhanfan, A. A. 1952. Regarding some remarks on the theory of champagnization (transl.). Vinodelie i Vinogradarstvo S.S.S. R. l2(2), 23-25.

Mestre Artigas, C., and Campllonch Romeu, I. 1935. Determinaci6n de la acidez volatil real en 10s vinos. Bol. inst. nacl. invest. agron. Spain 1, 181-196.

Mestre Artigas, C., and Campllonch Romeu, I. 1942. La producci6n de aldehidos en la fermentaci6n de mostos sulfitados y su influencia en 10s vinos. Bol. inst. nacl. invest. agron. Spain 6, 1-16; see also Bull. oflce intern. vin 16 (155), 82 (1943).

Mestre Artigas, C., and Garcia Barcel6, J. 1947. Perfeccionamiento de 10s m6todos electroqulmicos aplicables a 10s an&lisis de 10s vinos. Bol. inst. nacl. invest. agron. Spain 16, 101-124.

Mestre Artigas, C., and Mestre JanE, A. 1935. Contribuci6n a1 estudio de la evoluci6n de las substancias nitrogenadas del mosto en la fermentaci6n. Bol. inst. nacl. invest. agron. Spain 1(2), 9-32.

Mestre Artigas, C., and Mestre Jan6, A. 1939. Estudio comparativo de fermentaciones de mostos a moderadas y bajas temperaturas. Bol. inst. nacl. invest. agron. Spain

Metra, M., Lesage, L., and Descatoire, F. 1938. L'isopropanol. Sa recherche dans lea

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Agr. Chemists 32, 417-421.

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Pape. Compt. rend. acrcd. agr. France 24, 592-596.

SOC. chim. France 151 1, 411-419.

Bull. ofice intern. vin 16(153), 41-49.

Chem., Anal. Ed. 8, 55-56.

Siissmosten. Biochem. 2. 268, 345-354; see also ibid. 276, 66-85, 86-90 (1935).

38, 299-301.

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2(3), 31-43.

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preparations. Am. Scientist 40, 482-492, 517.

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Mezzadroli, C., Amati, A., and Sgargi, L. 1931. Influenza della razza del fermcnto alcoolico sulla qualitb e sul bouquet del vino. Giorn. biol. appl. ind. agr. 1, 161- 171.

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Michel, A. 1931. Dosage de l’acide lactique dans les vins. Ann. fals. et fraudes 24,

Michel, A. l948a. Considerations sur le dccret du 28 juin 1938 fixant le taux maximum de l’acidit6 volatile des vins propres S la consommation. Ann. fals. et fraudes 41,

Michel, A. 194813. La reaction de Fiehe applique6 b la caracterisation de jus dc raisin chauffcs (pasteurises, desulfites et concentres). Ann. f a k . et fraudes 41, 208-21 1.

Miconi, C. 1948. La . . . dificile detcrminazione dell’acidith totale dei mosti e dci vini. Riv. viticolt. e enol. (Conegliano) 1, 123-124.

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Miermeistcr, A., and Battay, F. 1931. Die Verfalschugen von Sussweinen und ihr Nachweis durch Bestimmung der niederen Fettsiiuren (Buttersaure). 2. Unter- such. Lebensm. 61, 161-171.

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Mohler, H., and I-Iammerle, W. 1936. Uber den Nachweis von Weisswein in Rotwein

Montequi, F. 1933. El color del vino. Anales soc. espafi. f;s. quim. 31, 663-668. Morani, V. 1930. La. ricerca delle aggiunte di acidi minerali nel vino mediante il

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Moreau, L., and Vinet, E. 1937. Le tanin dans les vins blanc. Rev. viticult. 86, 65-69. Moreno Martin, F. 1934. Influencia del alrohol metilico en la dosificaci6n de alcoholes

superiores en agardientes y licores. Congr. intern. quim. pura apl. 9(VI), 272-273. Morgan, A. F. 1941. A nutritivp index of fruits. Fruit Products J. 21, 75-77. Morgan, A. F., Field, L. K., and Nichols, P. F. 1935. The vitamin content of Sultanina

(Thompson Seedless) grapes and raisins. J. Nutrition 9, 369-382. Morgan, A. F., Nobles, H. L., Wiens, A., Marsh, C. L., and Winkler, A. J. 1939. The

B vitamins of California grape juices and wines. Food Research 4, 217-219. Moureu, H., and Dod6, M. 1934. Recherche et dosage du butylCneglycol2-3 dans les

jus de fermcntation. Bdl . assoc. chim., sucr., dist. 61, 247-250. Mursaeva, A. M., and BrailovskaG, A. E. 1952. Crystallization of atrtrates in grape

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Hug. 27, 27-40.

70, 193-195.

2. Untersuch. Lebensm. 7 , 186-189.

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Muth, F. 1933. Vber die Bindung von Jod in ungeschwefelten Mosten und Weinen. Bericht Lehr- u. Forschungsanstalt Wein-, 0bst.- u. Gartenbau, Geisenheim 1933,3-4.

Muth, F. 1934. Mostgewicht und Alkoholgehalt der Weine. Wein u. Rebe 16,239-244. Muth, F., and Malsch, L. 1934. Versuche zur Aufstellung einer Stickstoffbilanz in

Muttelet, C. F. 1930. Les sucres des vins de Porto. Ann. fals. et fraudes 23,

Nedeltscheff, N., and Kondareff, M. 1941-42. Untersuchung von Mavrudweinen und

NBgre, E. 1939a. Contribution oenologique h 1’6tude des matiBres tannoides. Compt.

NBgre, E. 193913. Dosage de l’oenotannin. Ann. jals. et fraudes 32, 175-178. NBgre, E. 1942-1943. Les matiBres tannoides et la composition des vim. Bull. ofice

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rev., National Research Council of Canada, Praire Regional Lab., Saskatoon. Neish, A. C. 1951. Analysis of mixtures of a simple aliphatic alcohols by partition

chromatopgraphy. Can. J . Chem. 29, 552-557. Nelson, E. K. 1937. Flavor of alcoholic beverages. Food Research 2, 221-226. Nelson, E. K., and Wheeler, D. H. 1939. Natural aging of wine. Ind. Eng. Chem. 81,

Neubauer, A. 1911. Verfahren zur Aromatisierung von Beerensaften und Weinen. 0bst.-u. Cemuseverwert.-Ind. 28, 373-375.

Newton, W., and Munro, F. L. 1933. The determination of alcohol and extract in wine by means of the density and refractive index. Can. Chem. Met. 17, 119-120.

Niehaus, C. J. 1934. The determination of alcohol by means of the ebulliometer. S. African Wine Ann. (Special Ed. Wine and Spirit) 4, 1693-1697.

Niehaus, C. J. 1937. Sugar-alcohol ratio in South African musts and wines. Xci. Bull. Dept. Agr. S. Africa 161, 1-11.

Niehaus, C. J. 1938. The nitrogen content of South African musts and wines. Sci. Bull. Dept. Agr. S. Africa 172, 1-15.

NitschkB, E. 1952. MBthode de dosage colorimBtrique de l’acide malique dans les vins e t les modts. Mitt. Gebiete Lebensm. u. Hyg. 43, 50-57.

Noguero G6mez, E. 1942. Analisis de vinos. MBtodos empleados en el Laboratorio de Bromatalogfa del Ministerio de sanidad y asistencia social. Rev. sanidid y asis- tencia social (Venezuela) 7 , 573-590.

Oliveira, A. J . de 1941. Estudo estatfstico de algumas caracterfsticas q u b c a s do vinho do Parto. Anais inst. vinho Pdrto 2 , 389-442.

Oliveira, F. P. de 1942. Subsfdios para o estudo das substhncias azotadas nos vinhos do PGrto. Anais inst. vinho Pdrto 3(1), 107-156.

Onokhova, N. P. 1937. Grapes as a source of vitamin C. Bull. A p p l . Bot., Genet., Plant Breeding U.S.S. R. Suppl. 84(II), 195-200.

Oparin, A. I., and Bezinger, E. N. 1949. The nitrogen constituents of wine. I. Nitrogen compounds of high molecular weight in champagne (transl.). Biokhimiya 14,

Oparin, A. I. , Besinger, E., and Batsyna, I. 1945. Transformation of nitrogenous sub- stances in champagne during processing (transl.). Biokhimiya 10, 311-325.

Oparin, A. I., Kursanov, A. L., Saenko, N. F., and Bezinger, E. N. 1946. Biochemical

Traubemosten und -weinen. 2. Untersuch. Lebensm. 68, 487-500.

205-207.

Rotweinstocken. Ann. Fac. &on. Univ. Sofia 20, 41-49.

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1279-1281.

291-301.

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COMPOSITION OF WINES 495

processes in champagne during the secondary fermentation period (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 6(5), 12-19; C. A . 40, 1630 (1946).

Oparin, A. I., Kursanov, A. L., Saenko, N. F., and Bezinger, E. N. 1947. Biochemical processes taking place in champagne during after-bottling maturation (transl.). BiokhimiG vinodeliz’a 1, 134-157.

Oparin, A. I., and Manskaya, S. M. 1939. Oxidation in the fermentation of tea and the aging of wine (transl.). Sbornik Akad. Nauk S.S.S.R. Prezidentu Akad. Nauk S.S.S.R. Akad. V . L. Komarovu 1939, 588-600.

Osborn, G. H., and Mott, 0. E. 1952. The determination of higher alcohols in whiskey and other potable spirits. Analyst 77, 260-262.

Osterwalder, A. 1945. Weitere Beitrage zur Kenntnis des Braunwerdens der Weine. Ann. agr. Suisse 69, 573-605.

Osterwalder, A. 1952. Uber die durch Bakterien verursachte Zersetzung von Wein- saure und Glyzerin im Wein. Ann. agr. Suisse 66, 181-197.

Palieri, M. G. 1950. Aciditti volatile e distillato alcoolico. Riv. viticolt. e enol. (Cone- gliano) 3, 354-356.

Palieri, M. G. 1951. Nuovo metodo per la determinazione rapida degli zuccheri nei vini. L’ltalia Agricola 88, 781-783.

l’alieri, M. G. 1952. La determinazione dell’aciditti volatile con i metodi per distilla- zione parziale a fiamma diretta. Riv. vitivolt. e enol. (Conegliano) 6 , 392-399.

Parfent’ev, L. N., and Kovalenko, V. I. 1951. On the potential role of pyrocarbonate esters in the formation of champagne characteristics in sparkling wines (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 11(3), 16-19.

Parfent’ev, L. N., and Kovalenko, V. I. 1952. On the question regarding the theory of champagnization (transl.). Vinodelie i Vinogradarstvo S.S.S. R . 12(4), 28-29.

Parisi, E., and Della Barba, L. 1931. Acido uronico, glucosio e galattosio, componenti di alcune sostanze otticamente attive contenute nei vini completamente fer- mentati. Giorn. biol. appl. ind. chim. 1, 95-102.

Parro, A. da C. 1948. Brhve esquisse d’un plan d’btudes sur la richesse en vitamines des mohts et des vins du Portugal. Bull. ofice intern. vin 21(204), 83-88.

Paronetto, L. 1938. La determinazione dell’alcole nei vini liquorosi e vermut per ossidazione cromica. Ann. chim. appl. 28, 164-169.

Paronetto, L. 1948. Alcune prove di vinificazione in bianco con un nuovo prodotto enzimatico. Riv. viticolt. e enol. (Conegliano) 1, 377-380.

Paronetto, L. 1950. La determinazione ebulliometrica nei vini dolci. Riv. viticolt. e enol. (Conegliano) 3, 223-228, 254-258.

Pato, M. d. S. 1932. Qufmica-fisica aplicada aos mostos e aos vinhos. Revista agronb mica (see Estacao Viti-vintcola da Beira Litoral, SBr. A, Bol. 1, 1-59. 1932).

Pato, M. d. S. 1935. Considerations sur la correction de l’acidit6 des moQts au point de vue technologique et au point de vue Bconomique. CongrPs International de la Vigne et du Vin, Lausanne.

Pato, M. d. S. 1938. Tabelas para a determina@o do extract0 s&co dos vinhos portu- gueses, por densimetria. Direcqlo Geral Serviqos Agricolas, Repartipgo Estud., Infor. e Prop., Lisbo4.

Pato, M. d. S. 1944. Importance d’un dosage rigoureux de l’acide tartrique. Bull. ofice intern. uin 17(161), 57-74.

Pato, M. d. S., and Salvador, A. R. N. 1949. Mbtodo para a titulaggo dos 4cidos vol4teis dos vinhos com deduptio do 4cido carb6nico. Anais junta nacional vinho 1, 107-122; see also Bull. ofice intern. vin 21(204), 70-82 (1948).

Pato, M. d. S., and Sousa, T. T. de 1938. Da influhncia do anidrido sulfuroso na

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496 MAYNARD A. AMERINE

correc@o Bcida dos mostos. 5th Congr. intern. vinha e vinho, Lisboa; see also ibid. rapports 11, 94 (1938).

Patterson, W. E., and Bawtenheimer, J. W. 1930. Volatility of magnesium acetatein wines. Can. Chem. Met. 14, 287-288.

Pavelka, F., and Montini, L. 1948. Eine Bestimmung der fliichtigen Siiuren in Wein mittels der Apparatur von Pregl-Parnas. Milcrochemie 33, 333337,

Pavolv-Grishin, S. I. 1940. Determination of glycerol in grape wines (transl.). Vino- delie i Vinogradarstvo S.S.S.R. 1(5), 9-10; C. A. 37, 558 (1943).

Penniman, W. B. D., Smith, D. C., and Lawshe, E. I. 1937. Determination of higher alcohols in distilled liquors. Ind. Eng. Chem., Anal. Ed. 9, 91-95.

Perard, J. 1939. Le bilan de la fermentation alcoolique est-il a reviser. Bull. assoc. chim., sucr., dist. 66, 251-252.

Perard, J. 1940. A propos du bilan de Pasteur. Bull. assos. chim., sucr., dist. 87, 250- 251.

Perarso, A. A,, and Arbecchi, A. C. 1933. Acides volBtil de 10s vinos que contienen anhidride sulfuroso. Anal. asoc. quim. argentina 21, 156-158.

Percher, G. 1938. L’extrait sec des vins. Ann. agron. 1, 63-66; see also Ann. fals. et fraudes 31, 468-472 (1938).

Perdigon, E. 1941. Semi-microdosage du 2,3-butyl&ne glycol dans les liquides de fermentation par oxydation periodique. Ann. ferment. 6, 143-158.

PeretiE, M. 1950. Les vins de la Croatie Nord, vendange 1948. Biljne proizvodnje 4. Perlman, L., and Morgan, A. F. 1945. Stability of B vitamins in grape juices and

Petri, W. 1932. Neuere Forschungsergebnisse aus der Weinforschungsanstalt fur

Pettigiani, A. E. 1943. Los alcoholes superiores en 10s vinos Argentinos. Rev. fac.

Peynaud, E. 1936a. L’acetate d’dthyle dans les vins atteints d’acescence. Ann.

Peynaud, E. 1936b. Le dosage de l’acide tartrique dans les moats et les vins par les

Peynaud, E. 1937a. Le dosage de l’acidite volatile des vins sulfites. Ann. fals. el

Peynaud, E. 1937b. Etudes sur les phenomhes d’esterification. Rev. viticult. 86, 209-

113-116, 185-188, 242-249, 278-296, 297-301, 344-350, 362-364, 383-385; for a summary see Ann. ferment. 3, 242-252 (1937).

Peynaud, E. 19370. Methode chimique simple pour la determination du pH des vins. Ann. fals. et fraudes 30, 390-400.

Peynaud, E. 1938a. L’acide citrique dans les modts e t les vins de Bordeaux. Bull. ofice intern. vin 11(118), 33-41.

Peynaud, E. 193813. L’acide malique dans les modts et les vins de Bordeaux. Ann. fals. et fraudes 31, 332-347; see also Rev. viticult. 90, 3-12, 25-30 (1939).

Peynaud, E. 1938c. Comportement des acides gras volatils pendant la fermentation alcoolique. Rev. viticult. 88, 88-90.

Peynaud, E. 1938d. Le dosage de l’ac6tate d’bthyle dans les vins. Ann. fals. et fraudes

Peynaud, E. 1939a. Acetate d’6thyle et acescence. Rev. viticult. 90, 321-327. Peynaud, E. 193913. L’arote aminb et l’arote amid6 dans les vins de Bordeaux. Ann.

fals. et fraudes 32, 228-243; see also Bull. SOC. chim. France [5] 6, 784-785 (1939).

wines. Food Research 10, 334-341.

Mosel, Saar und Ruwer. 2. Untersuch. Lebensm. 64, 177-205.

cienc. qu‘im. univ. nacl. La Plata 18, 95-104.

ferment. 2, 367-384.

mdthodes au racemate. Ann. fals. et jraudes 29, 260-273.

fraudes 30, 225-231.

215,227-231,248-253, 299-301, 394-396, 420-423, 440-444,472-475; 87, 49-52,

31, 158-162.

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Peynaud, E. 1939c. Sur les variations de l’azote du raisin au cours de la maturation. Rev. viticult. 90, 189-195, 213-225.

Peynaud, E. 1939-1940. Sur la formation et la diminution des acides volatils pendant la fermentation alcoolique en anakrobiosc. Ann. ferment. 6, 321-337,

Peynaud, E. 1946. Etude des mkthodes de dosage des constituants de l’aciditk des vins. Chim. anal. [4] 28, 111-117, 127-135.

Peynaud, E. 1947a. L’acktylm6thylcarbinol e t le 2,3-butyl&n6glycol dans les milieux de fermentation alcoolique. Rev. ferment. ind. aliment. 2, 150-158, 189-196.

Peynaud, E. 194710. Applications de l’oxydation pkriodique 8, l’analyse des vins dosages du glyckrol, du 2,3-butylAn6glycol des sucres r6siduaires des vins rouges, de l’acide tartrique. Bull. ofice intern. vin 20(196), 38-51.

Peynaud, E. 1947c. Contribution 8, 1’6tude biochimique de la maturation du raisin et de la composition des vins. Inds. agr. et aliment. (Paris) 64,87-95, 167-188,301- 317, 399-414; also printed by Imprimerie G. Sautai et Fils, Lille (1948), and sum- marized in Rev. viticult. 92, 177-180, 271-272 (1946) and Bull. ofice intern. vin

Peynaud, E. 1948a. Bilans des produits secondaires de la fermentation alcoolique.

Peynaud, E. 1948b. Dosage du glycerol dans les vins par oxy8ation periodique. Ann.

Peynaud, E. 1950a. Analyses complbtes de douze vins de Bordeaux. Ann. agron. Ser.

Peynaud, E. 1950b. Analyses complbtes de huit vins doux naturels. Ann. agron. Ser.

Peynaud, E. 1951a. Note sur le dosage de l’acide d-tartrique par la m6thode au rac6mate 8, l’acide d’un extrait de Bauhimia reticulata D. C. Bull. SOC. chim. France [5] 18, 911-912.

Peynaud, E. 1951b. Sur les matibres pectiques des fruits. Inds. agr. et aliment. (Paris)

Peynaud, E. 1952. Sur les matihres pectiques des modts de raisin et des vins. Ann. fals . et fraudes 46, 11-20.

Peynaud, E., and Charpentik, Y. 1950. Note sur le dosage de l’acide lactique dans les boissons fermentkes. Ann. fals. et fraudes 45, 246-252.

Peynaud, E., and Charpentik, Y. 1953. Dosage de l’acide gluconique dans les modts et les vins provenant de raisins attaques par le Botrytis cinerea. Ann. fals. et fraudes

Peynaud, E., and Lafon, M. 1951a. Note complkmentaire sur les corps acktoiniques des eaux-de-vie. Ann. fals. et fraudes 44, 399-402.

Peynaud, E., and Lafon, M. 1951b. Presence et signification du diacbtyle, de l’ac6toYne et du 2,3-butanediol dans les eaux-de vie. Ann. fals. et fraudes 44, 264-283.

Peynaud, E., and Lafon, M. 1952. Bilans des produits secondaires de la fermentation alcoolique pour divers genres de levures et dans des conditions diffbrentes d’akra- tion. Inds. agr. et aliment. (Paris) 69, 397-408.

Peynaud, E., and Ribkreau-Gayon, J. 1947. Sur les divers types de fermentation alcoolique ddterminEs par diverses races de levures elliptiques. Compt. rend. 224,

Peyrot, E. 1934. Sulla probabile quantith e qualitti delle principali sostanze coloranti nei vini bianchi. Studio comparativo per curve di assorbimento. Ann. chim. appl.

385-401.

20(191), 34-51 (1947).

Inds. agr. el aliment. (Paris) 66, 99-108.

fals. el fraudes 41, 384-402.

A, 1, 252-266.

A, 1, 382-388.

68, 609-615.

46, 14-21.

1388-1390.

24, 512-519.

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Pfab, H. 1931. Die Bestimmung der Zitronensiiure im Wein. Dissertation, Tech- nischen Hochschule, Dresden.

Piatkowska, K., and Smreczyxiska, A. 1950. The citric acid content of native fruit and berry wines, and the influence of addition of these on the citric acid content of grape wines (transl.). Roczniki Pailstwowego Zakladu Hig. 1, 345-353.

Piazza, J., and Rouzaut, R. 1939. Determinacidn rtipida de graduciones alcoh6licas en vinos y cervezas con destilador a espiral. Anales inst. invest. cient. y tecnol., univ. nacl. litoral (Santa Fb, Argentina) 9, 82-86.

Piccoli, T. 1933. Recherche de l’alcool methylique dans les vinaigres de vin adulteres au moyen de vinaigres l’alcool e t produits provenant de la distillation pyrogenee (transl.). Atti 4th congr. naz. chim. pura ed appl., Rome, 1933, 773-775.

Picozzi, A. 1947. Method for determining volatile acidity in wines. Proc. 11th Conf. Pure and Appl. Chem., London 1947 3,207-209.

Pluchon, J. P. 1937. Modification ti la methode de defecation des vins. Ann. fals. et fraudes 30, 344-350.

Podkletnov, N. E. 1951. Determination of small quantities of tartaric acid (in musts and wine) (transl.). Vinodelie i Vinogradarstvo S.S.B.R. 11(10), 19.

Politova-Sovzenko, T. K. 1947. ttber die Gerbstoffe des Weinmostes (transl.). Vino- delie i Vinogradarstvo S.S.S. R. 7(12), 18-20.

Politova-Sovzenko, T. K., and Dikhtyar, P. 0. 1948. Determination of volatile acid in wines having a high sulfur dioxide content (transl.). Vinodelie i Vinogradarstvo

Ponte, A. and Gualdi, G. 1931. Tannin in wines and its estimation. J . Intern. SOC. Leather Trades Chem. 16, 151; for original see Boll. ugiciale staz. sper. ind. pelli mat. concianti 1931, 391-407.

Pool, A., and Heitz, J. E. 1950. Correlation of fortifying brandy with wine quality. Proc. Am. SOC. Enologists 1960, 101-105.

Popov, A. D. 1947-1948. Detection of elderberry pigments and some other foreign natural and synthetic coal-tar dyes in red wine (transl.). Ann. univ. Sofia, facult.

Popova, E. M. 1948. Esterases of molds and their influence upon the aging of wine (transl.). BiokhimiG vinodeli& 2, 115-125.

Popova, E. M., and Puehkova, M. G. 1948. Microbiological determination of nicotinic acid in wines (transl.). Biokhimia vinodelia 2, 117-182.

Popova, E. M., and Puchkova, M. G. 1950. Role of esterase in the aging process of champagne wines (transl.). Biokhimih Vinodelih 3, 69-84.

Poux, C. 1949. Sur le microdosage de l’acide tartrique dans les vins et dans les monts. Ann. fals. et fraudes 42, 439-443.

Poux, C., and Ournac, A. 1949. Oxydation des acides tartriques et formique par l’acide periodique. Znds. agr. et aliment. (Paris) 66, 503-507.

Pozzi-Escot, E. 1938. Mi tecnica en determinaci6n de la acidez volatil de 10s vinos, hoy metodo oficial en Francia; mi dispositivo experimental recomendado. Rev. cienic. (Peru) 40(424), 299-302.

Pozzi-Escot, E. 1949. Bur une methode precise de dosage de l’alcool par distillation. Inds. agr. et aliment. (Paris) 66, 119-121.

Prado, L. de. 1934. Nuevo micrometodo de dosage del glicerol en 10s bebidas fer- mentadas. Anales farm. y bioqutm. 6, 98-106.

Prange, G. 1941. Mikroalkoholbestimmung in Obsterzeugnissen. Vorratspfige u. Lebensmittelforsch. 4, 553-572.

Prfilat, C. E., and Mendivelzda, G. 1934. Ensayo de un m6todo rcfactometrico para

S.S.S.R. a@), 32-33; C. A . 44, 9620 (1950).

S C ~ . 44, 31-110.

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determinacibn de alcohol y extract0 en vino. Anales asoc. quim. argentina 22,

Prillinger, F. 1952a. Gerbstoffe als Ursache von Triibungsercheinungen von Suss- mosten. Mitt . hoheren Bundslehr- und Versuchsanstalt f u r Wein- und Obstbau (Klosterneuberg) 2, 197-199.

Prillinger, F. 1952b. Uber die fluchtigen aromastoffe bei der Vergarung von Trauben- most. Mitt . hbheren Bundeslehr- und Versuchsanstalt f u r Wein- und Obstbau (Klosterneuberg) 2, 160-164, 188-191; see also Moser, L. 1952. Weinblatt 46, 220-222.

Prillinger, F. 1952c. Titrimetrische Methode zur Fruktosebestimmung. Mitt . hoheren Bundeslehr- und Versuchsanstalt f u r Wein- und Obstbau (Klosterneuberg) 2, 20-23.

Pritzker, J. 1940a. Zur Bestimmung des Glyzerins in Sussweinen. Mitt . Gebiete Lebensm.

Pritzker, J. 1940b. Uber die Zusammensetzung und Beurteilung von Malaga und Mistellen. Mit t . Gebiete Lebensm. u. Hyg. 31, 230-233.

Pritzker, J., and Jungkunz, R. 1930a. Entstehung, Vorkommen und Nachweis des 2,3-Butylenglykols in Wein und Obstwein. 2. Untersuch. Lebensm. 60, 484-489.

Pritzker, J., and Jungkunz, R. 1930b. Vber Vorkommen und Nachweis des 2,3- Butylenglykols in Wein, Obstwein und anderen vergorenen Siften. Mitt . Gebiete Lebensm. u. Hyg. 21, 236-243.

Pro, M. J. 1952. Report on spectrophotometric determination of tannin in wines and whiskies. J . Assoc. Ofic. Agr. Chemists 36, 255-257.

Procopio, M. 1939. I1 grado ebulliometrico dei vini dolci. Ann. chim. appl. 29, 74-77. Procopio, M. 1948a. Innesto proteico nei mosti zuccherini (taglio proteico). Riv.

uiticolt. e enol. (Conegliano) 1, 80. Procopio, M. 1948b. Interpretazione del valore della densith nei vini dolci ai fini della

valutazione degle zuccheri. Riv. viticolt. e enol. (Conegliano) 1, 329-334. Procopio, M. 1948c. Simplificazione e standardizzazione del metodo Kleiber-Wiegner-

Magasanik per la determinazione dell’acidith volatile nei vini. Riv. viticolt. e enol. (Conegliano) 1, 381-385.

76-77.

U . Hyg. 31, 223-229.

Procopio, M. 1949. Eteri del vino. Riv. uiticolt e enol. (Conegliano) 2, 157-160. l’rocopio, M. 1950a. Determinazione diretta dell’acidith volatile dei vini contenenti

anidride solforosa. Riv. viticolt. e enol. (Conegliano) 3, 59-64. I’rocopio, M. 1950b. Determinazione diretta e rapida della reale aciditii volatile dei

vini contenenti anidride solforosa e stima indiretta di questa ultima. Riu. viticolt. e enol. (Conegliano) 3, 92-98.

Procopio, M. 1950c. Interpretazione della densith dei vini dolci a duplice finalith. Riv. viticolt. e enol. (Conegliano) 3, 321-325.

Procopio, M. 1950d. Valori ebulliometrici inconsuetamente anomali . . . Riu. viticolt. e enol. (Conegliano) 3, 139-145.

Prosstosserdov, N. N., and Taranova, R. D. 1949. Hydroxymethylfurfural in grape wines (transl.). Vinodelie i Vinogradarsluo S.S.S.R. 9(11), 43-44.

Ramos, M. da C., and Oliveira, H. T. de 1949. Estudo cromatogr6fico das mat6rias tinturiais do vinho do PBrto, tendo como primeiro objectivo a pequisa da baga. Anais inst. vinho PGrto 10(1), 11-24.

Ramos, M. da C., and Reis A. M. L. de C. 1945. Determinagh do 2,3-butilenoglicol no vinho do PBrto. Anais inst. vinho Pdrto 6(2), 11-31.

Randoin, L. 1936. Vitamines, jus de raisin et vins. Bull. SOC. sn’ent. d’hyg. aliment. ration d’homme 24, 18-40; see also Bull. ofice intern. vin 7(72), 62-74 (1932).

Randoin, L., and Gallot, S. 1941. Recherches experimentales sur la vitaminisation

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artificielle d’aliments naturels de consommation courante. Bull. SOC. chim. biol.

Rankine, B. 1952. The determination of the alcohol content of wine by pycnometer.

Ravaz, L. 1935. Les facteurs de la qualit6 et les pratiques culturales. Prog. agr. et vit.

Reich, P. 1950. Wein-Kompendium fiir den Artz. Wissenschaftliche Verl. Ges., Stuttgart. pp. 39-40.

Reichard, 0. 1934a. Bestimmung der Citronensiiure als Pentabromaceton und ihre Anwendung auf Wein. 2. Untersuch. Lebensm. 68, 138-172.

Reichard, 0. 1934b. Uber die Bestimmung der Citronensaure in Wein. 2. anal. Chem. 99, 138-142; see also ibid. 99, 81-96.

Reichard, 0. 1936. Citronensiiure-Bestimmung und -Gehalt im Wein. 2. Untersuch. Lebensm. 72 , 50-63.

Reichard, 0. 1943. Die Bestimmung des Stickstoffgehaltes von Wein und Traubensaft und ihr Gehalt, ein Beitrag zur Neubearbeitung der amtlichen Anweisung fur die Untersuchung von Wein und Most. 2. Untersuch. Lebensm. 86, 164-169.

Reichard, 0. 1951. Die Sinnenpriifung (Organoleptik) von Wein und ihr diagnostischer Wert. Deut. Wein-Ztg. 87, 340-342, 379-380, 402-404; see also Deut. Lebensm.- Rundschau 47, 103-110 (1951).

Reid, V. W., and Truelove, R. K. 1952. The colorimetric determination of alcohols. Analyst 77, 325-328.

Reis, A. M. L. de C. 1946. Esteres no vinho do PBrto. Anais inst. vinho PGrto 7 ,

Remy, E. 1932. Zusammensetzung badischer Weissweine der Jahrgiinge 1930-1932. Z . Untersuch. Lebensm. 64, 548-553.

Rentschler, H. 1949. Die biochemische Bestimmung der xpfelsaure. Mitt. Gebiete Lebensm. u . Hyg. 39, 30-35.

Rentschler, H. 1950. cber das Braunwerden der 1950er Weine. Schweiz. Z . Obst- u . Weinbau 69, 455-458.

Rentschler, H., and Hauser, F. 1950. Uber die Beeinflussung des Gerbstoffgehaltes von Weinen durch Gelatin Schonung. Schweiz. 2. Obst- u. Weinbau 69, 406-408.

Rentschler, H., and Simmler, H. 1949. Ein einfaches Verfahren zur Bestimmung der fllichtigen Siiure in Getriinken. Schweiz. 2. Obst- u. Weinbau 68, 367-370.

Requinyi, G., and S O ~ S , I. 1935. The inverting effect of some Hungarian wine yeasts (transl.). Magyar Ampelol. lhkonyv 9, 411-412.

Ribeiro, M. B. 1938. Subsfdios para o estuda da alcalinidade das cinzas nos vinhos do PBrto. Anais. inst. super. agron., Univ., t6c. Lisboa 9, 253-326.

Ribeiro, M. B. 1946. Eliminaqa dos redutores nLo apdcares nos vinhos do PBrto. Anais inst. vinho P6rto 7 , 51-68.

Rib6reau-Gayon, J. 1932. Sur les matihres albuminoides des vins blancs. Ann. falsif. et fraudes 26, 518-524, 602-609; see also Ann. brass. et dist. 31, 44-48, 62-64, 78-80 (1933).

23, 429-436.

Australian Brewing and Wine J . 70(6), 3-4, 6.

104, 489-494.

69-93.

Rib6reau-Gayon, J. 1938a. Les acides du vin. Progr. agr. et vit. 110, 226. Ribbreau-Gayon, J. 193813. La mesure du pH des vins. Rev. viticult. 88, 411-415,

Ribereau-Gayon, J. 193%. Sur les phenom&nes de reduction dans les vins. Bull. SOC.

Ribereau-Gayon, J. 1943. Les diastases en oenologie. Bull. ofice intern. vin 16(160),

434-440.

chim. France [5] 6 , 953-954.

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Ribbreau-Gayon, J. 1947. Trait6 d’oenologie. Librairie Polytechnique Ch. Bbranger, Paris et Liege.

RibCeau-Gayon, J. 1949. Les m6thodes rbcentes d’analyse des vins et leur unification. Bull. ofice intern. vin 22(218), 36-40.

Ribbreau-Gayon, J., and Maurib, A. 1942. Les composbs phbnoliques du vin. (Matihres colorantes et tannofdes). Bull. ofice intern. vin 16(150), 60-76.

Ribbreau-Gayon, J., and Peynaud, E. 1936. Estbrification chimique et biologique des acides organiques du vin. Bull. SOC. chim. France [5] 3, 2325-2330.

Ribbreau-Gayon, J., and Peynaud, E. 1937a. L’acide lactique dans les vins de Bor- deaux. Ann. fals. et fraudes 30, 339-344.

Ribereau-Gayon, J., and Peynaud, E. 1937b. Une inethode chimique simple pour la determination du pH des vins. Bull. SOC. chim. France [5] 4, 1627-1628.

Ribbreau-Gayon, J., and Peynaud, E. 1938a. Bilan de la fermentation malolactique. Ann. ferment. 4, 559-569.

Ribbreau-Gayon, J., and Peynaud, E. 1938b. La deacidification des vins par les bactbries. Compt. rend. acad. agr. France 24, 600-605.

Ribbreau-Gayon, J., and Peynaud, E. 1938~. L’acide malique dans les moats et les vins de Bordeaux. Bull. SOC. chim. France [5] 6, 1276-1277.

Ribereau-Gayon, J., and Peynaud, E. 1938d. Les teneurs en acide citrique des moQts et des vins de Bordeaux. Bull. SOC. chim. France [5] 6, 226-227.

Ribbreau-Gayon, J., and Peynaud, E. 1946a. Analyse et contrble des vins. Compt. rend. acad. agr. France 32, 528-530; see also Bull. ofice intern. vin 19(187), 29-31 (1946).

RibBreau-Gayon, J., and Peynaud, E. 1946b. Sur la formation des acides acbtique, lactique et citrique au cours de la fermentation alcoolique. Compt. rend. 222, 457-458; see also Bull. o&e intern. vin 19(183), 47-48 (1946).

Ribbreau-Gayon, J., and Peynaud, E. l947a. Analyse et Contrale des Vins. Librairie Polytechnique Ch. Beranger, Paris et LiCge.

Ribereau-Gayon, J., and Peynaud, E. 194713. Le 2,3-butylhnbglycol dans les boissons fermentbes. Bull. SOC. chim. France [5] 14, 894-896.

Ribereau-Gayon, J., and Peynaud, E. 1947c. Sur le dosage et la chimie de l’bthanal et de ses combinaisons dans les vins et les alcools. Ann. Inst. Pasteur 73, 777-796.

RibCreau-Gayon, J., and Peynaud, E. 1952. Sur l’emploi en vinification de quelques activeurs vitaminiques de la fermentation. Compt. rend. acad. agr. France 34, 444-448.

Ribbreau-Gayon, J., Peynaud, E., and Lafourcade, 5. 1952a. Formation d’ inhibiteurs et d’activeurs de la fermentation alcoolique par diverses moisissures. Compt. rend.

Ribbreau-Gayon, J., Peynaud, E., and Lafourcade, S. 1952b. Sur la formation de substances inhibitrices de la fermentation par Botrytis cinerea. Compt. rend. 234,

Rippel, K. 1949. Der biologische Saureabbau im Wein. Arch. Mikrobiol. 14, 509-531;

Roche, M. 19 18. Sur le dosage des aldbhydes. Inds. agr. et aliment. (Paris) 66,281-283. Rocques, J. 1!)50. A propos de la determination du degre alcoolique des vins. Ann.

Rodopulo, A. K. 1948. The oxydizing enzymes of musts and of wines (transl.).

Rodopulo, A. K. 1950a. Oxidizing enzymes of champagne varieties of grapes and

a54,251-253.

478-480.

see also Dmt. botan. Ges. 60, 108-117 (1943).

fals. et jraudes 43, 344-346.

Vinodelie i Vinogradarslvo S.S.S. R . 8, 8-9.

musts (transl.). BiokhimiG vinodelii^a 3, 43-52.

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Rodopulo, A. K. 1950b. Polyphenoloxidase system in grapes and juice (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 10(3), 35-37; C. A . 46, 6794i (1951).

Rodopulo, A. K. 1951. Oxidation of tartaric acid in wine in the presence of salts of heavy metals (activation of oxygen by iron) (transl.). Zzuest. Akad. Nauk S.S.S.R., Ser. Biol. 1961(3), 115-128.

Rodopulo, A. K. 1952a. Di- and tricarboxylic acids in must and wine (transl.). Vinodelie i Vinogradarstvo S.S.S. R . la(@, 8-11.

Fbleff, H. 1948. Triibungserscheinungen in 1947er Wein. Deut. Weing-Ztg. 84, 263- 264; see also ibid. 86, 265-266 (1949).

Roleff, H. 1949. Ursache der Wiirmetriibung bei 1947er Weinen. Deut. Wein-Ztg. 86, 12-13; see also ibid. 80, 197-198 (lY50), and Chem. Zentr. 1960 I, 1162, 1920.

Roleff, H. 1952. Schnellmethode sum Nachweis und sur Schfitzung von Citronensiiure in Weissweinen. Deut. Wein-Ztg. 88, 34-36; see also Corriere Vinicole 21(36), 1, 3 (1952).

Romano, E. 1951. Sul contenuto in 2,3-butilenglicol di alcuni vini italiani. Ann. sper. agrar. (Rome) (N.S.) 6, 779-783.

Roos, L. 1930. Mesure de la couleur des vins rouges. Ann. jals. et jraudes 23,207-211; see Progr. agr. et vit. 93, 374-377 (1930).

Rosenblatt, M., and Peluso, J. V. 1941. Determination of tannins by photocolorimeter. J. Assoc. Ofic. Agr. Chemists 24, 170-181.

Rosenfeld, P. M. 1952. On some questions regarding the theory of champagnisation (transl.). Vinodelie i Vinogradarstvo S.S.S. R. l2 ( l ) , 34-36.

Rosenthaler, L., and Vegezsi, G. 1953. Zur Kenntnis der Komarowskyschen Reaktion. Die Branntweinwirtschaft 76, 68-69; see also Mitt. Gebiete Lebensm. u. Hyg. 43,

Ross, S. L. 1942. Detannating wines for pharmaceutical use. Am. J. Pharm. 114, 200-204.

Roubert, J. 1951. Sur l’estimation rapide des esters insolubles a l’eaux contenus dans les alcools de rhcup6ration des gas de fermentation. Vignes et Vins 6, 20-21.

Roussopoulos, N. C. 1930. Vber ein einfaches chemisches Bestimmungs verfahren der wahren Aciditfit des Mostes. Prakt. Akad. Athenon 6, 359-362.

Roussopoulos, N. C. 1933. Sur les diffhrentes m6thodes de dosage de l’extrait sec du vin. Ann. fals. et fraudes 26, 582-594.

Rouzaut, R. 1939. Determinacih cuantitativa de alcohol en meaclas por medio del destilador a espiraI y movimiento exc6ntrico. Anales inst. invest. dent. g tecnol., univ. nacl. litoral (Santa Fd, Argentina) 9, 87-95.

Ruf, W. 1952a. Die Papierchromatographie als Hilfsmittel bei der Untersuchung von Weinen. Deut. Wein-Ztg. 88, 304.

Ruf, W. 1952b. Vber die Anwendung der Papierchromatographie s u m Nachweis von Fremdfarbstoffen im Wein. 2. Lebensm.-Untersuch. u. -Forsch. 94, 190-194.

Ruspini, Arnoldo. 1936. Valores de la acides real de 10s vinos Argentinos. Anales asoc. quim. argentina 24, 51-59.

Rustia, A. 1949. Sui coefticienti per la deterrninasione dell’alcool totale nei vini dolci e nei mosti in fermentazione. Riv. viticolt. e enol. (Conegliano) 2, 161-165.

Srtburov, N. V., Kalebin, M. I., Khakhinn, L. P., and Danilova, A. 1938. A compara- tive investigation of different methods for the determination of fruit acids (transl.). Nauch. Zapiski Inst. Narodnogo Khoz. im Plekhanova 1938 1, 3-50;

370-388 (1952).

C . A . 54, 1407-1408 (1940). Saenko, N. F. 1947. The Xeres yeast. (trans.) BiokhimiG vinodeliz 1, 98-126. Saenko, N. F. 1948. The change of the oxidation-reduction potential and the composi-

tion of wine aged under the sherry film (transl.). Biokhimiz UinodeliG 2,86-100

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Saenko, N. F. 1951. Accelerating the growth of sherry (yeast) film on wine (transl.). Vinodelie i Vinogradarstvo S.S.S. R. 11(1), 12-15.

St. Mokranjac, M., and Radmib, S. 1951. Prilog pitanju odredivanja rnetilalkohola (metanola) i njegova sadrzaja u rakijama. [Contribution la question de 1% determination du methanol e t son contenu rlans les eaux-de vie.] Acta pharma- ceutica Jugoslavica 1, 97-1 10.

Salani, R. 1937. Contributo allo studio della determinazione polarimetrica della mannite nei prodotti naturali che la contengono. Znd. saccar. ital. SO, 16-21.

Sallusto, F. 1935. Sul rapport0 cremore:alcool nei vini e nelle vinacce. 11. Ann. chini. appl. 8, 130-142.

Sallusto, F. 1936-37. Sulla composizione de alcuni vini genuini dell’Italia Meridionalc. Ann. Jac. agrar. Portici, R. univ. Napoli [3] 8, 3-33.

Sallusto, F. 1938-39a. I vini della Tunisia. Ann. fuc. agrar. Portici, R. univ. Napoli [3]

Sallusto, F. 1938-39b. Vini tipici della Lucania. Ann. Jac. agrar. Portici, R . univ. Napoli [3] 10, 87-111.

Snllusto, F., and Di Natale, G. 1938-39. L’enologia in provincia di Siracusa et i vini da taglio del territorio di Pachino. Ann. jac. agrar. Portici, R . univ. Nupoli [3]

Sallusto, F., and Sculco, U. 1937-38. I vini di Cirb (Catanzaro). A,nn. fac. agrar. Portici, R. univ. Napoli [3] 9, 121-154.

Salvarezza, M. 1935-37. L’acidith volatile dei vini riel corso della fermentazione. Annuar. R . staz. enol. sper. (Ast i ) [2] 2 , 287-395; see also Ztalia Agricola 74, 135-141 (1937).

Sampaio, A. V. de. 1946. Contribuiqio para a dosagem do tanino nos vinhos. Rev. inst.

Sampietro, C., and Invernizzi, I. 1940. Dosaggio dell’alcool nel vino e soafanze

Sannino, F. A. 1948. Tratado de Enologia. G. Gili, Buenos Aires. Sapondzhian, S. O., and Gevorkian, Kh. S. 1953. Determination of acetal in wine

(transl.). Vinodelie i Vinogradarstvo S.S.S. R. 13(1), 13-15. Sastry, L. V. L., and Tischer, R. G. 1952a. Behavior of the anthocyanin pigments in

Concord grapes during heat processing and storage. Food Technol. 6, 82-86. Sastry, L. V. L., and Tischer, R. G. 1952b. Stability of the anthocyanin pigments in

Concord grape juice. Food Technol. 6, 264-268. Savary, M. 1940. .4 propos du bilan de I’asteur. Bull. assoc. rhirn. sucr., dist. 67,

Schaefer, F. 1939. Uber die Verwendung von Sudweinliefen bei der Herstellung von weinhahnlichen Getranken. VorratspfEege u. Lebensmittelforsch. 2, 662-666.

Schanderl, H. 1938. Die Nutzbarmachung des oxydativen Stadiums der Hefe bei der Trauben- und Beerenweinbereitung sowie in der Brennereipraxis. VorratspJlege u. Lebensmittelforsch. 1, 456-469.

Schanderl, H. 1943. Sur la d6sac6tification des vins par voie biologique. Progr. agr. et vit. 120, 187-189.

Schanderl, H. 1950. Die Mikrobiologie des Weines. Eugen Ulmer, Stuttgart. Schanderl, H. 1950-1951. Uber den Einfluss des Entsauerns, verschiedener Schon-

ungen und des Lichtes auf das rH und pH der Weine. Wein u. Rebe 26, 118-128. Schemer. 1944. Les vitamines du vin. La terre vaudoise. Bull. ofice intern. vin 17(163-

166), 159; see also MLd. el Hyg. June 4, 1943. Schindler, J., and KozAk, K. 1934. Contribution A la recherche et au dosage de I’acide

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10, 112-132.

10, 209-236.

AdolJo L U ~ Z 6 , 107-115.

alcooliche col refrattometro ad immerzione. Ann. chim. appl. SO, 381-387.

165- 167.

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Schmid, C., and Nestle, K. Th. 1949. Trubungerscheinungen in 1947er Weinen. Eine Erwiderung auf die Veroffentlichung von H. Roleff. Deut. Vein-Ztg. 86,

Schmitthenner, F. 1937. Fiinf Jahrzehnte mikrobiologische Forschung im Weinfache. Eine fachgeschichtliche Darstellung. Wein u. Rebe 19, 65-82, 93-106.

Schon, K., Gouveia, A. J. A. de, and Coelho, F. P. 1939. Determinagces quantitativas de vitamina A, ergosterol, vitamina BZ (lactoflavina) e vitamina C por metodos ftsico-qufmicos. Estudo do vinho tinto da Bairrada. Rev. fac. c ihc. Univ. Coimbra 8, 130-147.

Schulek, E., and R ~ Z S R , P. 1939. &hylalkoholbestimmung nach vorangehender Reinigung der Alkoholdampfe durch Adsorption. 2. anal. Chem. 117, 400-414.

Schumakov, A. 1930. Der Einfluss der Dosen und der Zeit der Beimischung von SOz auf die Bildung des Glyzerins bei der Weingarung. Odessa. fientral’na naukoco- dosvidna uinorobcha stan%; . . . , Pratsi 2(2), 22-28.

41-42.

Scott, T. 1946. Some notes on caramel. Wines & Vines 27(7), 23. Seifert, W. 1938. Die Chemie des Mostes und Weines. J. Diemer, Mains. Seifert, W., and Ulbrich, M. 1930. Formic acid, a constituent of the volatile acidsof

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Seiler, F. 1932. Nachpriifung des Verfahrens der Weinsaurebestimmung in Most und Wein. 2. Untersuch. Lebensm. 64, 285-288.

Seiler, F. 1933. tfber die Zusammensetzung von 1931er Naturweinen des Mosel- weinbaugebietes. Wein u. Rebe 16, 135-140.

Seiler, F. 1935. Uber die Zusammensetzung von naturreinen Weinen der Jahrgange 1932 and 1933 der Mosel, Saar und Ruwer und den Saureabbau dieser Weine. Wein u. Rebe 17, 37-45.

Seiler, F. 1936a. tfber die Beziehungen zwischen Mostgewicht und Alkoholgehalt bei Moselweinen. Wein u. Rebe 17, 267-274.

Seiler, F. 1936b. Zusammensetzung von naturreinen 1934er Weinen der Mosel, Saar und Ruwer. Wein u. Rebe 17, 357-365.

Seiler, F. 1937. Zusammensetzung von 1936 Naturweinen der Mosel, Saar und Ruwer. Wein u. Rebe 19, 163-166.

Seiler, F. 1938. Uber die Beziehungen zwischen Mostgewicht und Alkoholgehalt bei 1936er Weinen des Moselweinbaugebietes. Wein u. Rebe BO, 118-1 19.

Seiler, F. 1941. Die Bestimmung dcr Milchsaure im Trauben- und Obstweinen. VorratspJEege u. Lebensmittelforsch. 4, 506-512.

Seiler, F. 1943a. Die Auswertung des Milchsauregehaltes der Weine fur den Saure- abbau. 2. Lebensm.-Untersuch. u.-Forsch. 86, 84-88.

Seiler, F. 1943b. Die Bestimmung der Weinsaure im Most und Wein. 2. Untersuch. Lebensm. 86, 507-511.

Seiler, F. 1944. Zusammensetzung von 1942er Naturweinen der Mosel und ihrer Nebenfliisse. 2. Lebensm.-Untersuch. u.-Forsch. 87, 52-59; see also ibid. 87, 60-61.

Seiler, F. 1952. Zusammensetzung von 1950er naturreinen Moselweinen. Deut. Wein-Ztg. 88, 236-238.

SBmichon, L. 1933. Lea pectines des raisins et le moelleux des vins. Bull. ofice intern uin 6(67), 44-53.

SBmichon, L. 1948. Rapport sur l’eonologie. Bull. ofice intern. vin 21(204), 30-51. SQmichon, L., and Flanzy, M. 1930a. Dosage de la glycerin dans lea vins et lea boissons

Sitmichon, L., and Flanzy, M. 1930b. fitude des substances acides entrant dans la ferment6es. Ann. jals. et fraudes 23, 583-602.

composition des vins. Ann. jals. et fraudes 23, 5-19.

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COMPOSITION OF WINES 505

SBmichon, L., and Flanzy, M. 1931a. Les acides volatiles. Ann. fals. et fraudes 24,

SBmichon, L., and Flanzy, M. 1931b. La recherche et le dosage de l’alcool mbthylique. Ann. fals. el fraudes 24, 80-87.

SEmichon, L., and Flanzy, M. 1932a. Application de l’oxydation chromiqueA quelques diacides. Compt. rend. 194, 2063-2065.

SBmichon, L., and Flansy, M. 1932b. Dosage de l’acide lactique dans les vins e t dans les jus de fruits. Ann. fals. et fraudes 26, 414-416.

SEmichon, L., and Flanay, M. 1932c. Dosage de l’acide succinique dans les vins e t les liquides ferment&. An71. jals. et fraudes 26, 416-419.

Si:michon, L., and Flanzy, M. 1932d. fitude des acides organiques des vins e t des jus fruits naturels ou ferment&. Ann. agron. (N.S.) 2, 199-214; see also Ann. brass. et d i d . 30, 217-222, 236-239 (1932).

SEmichon, L., and Flanzy, M. 1933a. Dosage de I’acide tartrique dans les moQts et dans les vins. Ann. fals. et fraudes 26, 403-406.

SBmichon, I,., and Flanzy, M. 1933b. Sur les acides organiques des jus de raisin. Compt. rend. 197, 198-201; see also Ann. agron. (N.S.) 2, 504-528 (1932).

S6michon, L., and Flanzy, M. 1934. Au sujet de l’application des d6crets relatifs au degrB minimum des vins. Ann. fals. et fraudes. 26, 92-93.

SPze, R. de 1938. Sur l’abaissement de l’acidith volatile des vins. Rev. viticult. 88, 339-345, 357-363.

Shcherbakov, M. F. 1940. A method for determining nitrogen compounds (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 1 (5), 8-9; C. A. 37, 2877 (1943).

Shrherbakov, M. F. 1941. A great achievement in the Soviet wine making (transl.). Doklady VsesoiuznoE Akademii S.-KH.-Nauk 1941(1), 29-31.

Shimamoto, T., and Sugayama, J. 1951. Tyrosol (p-hydroxyphenylethyl alcohol) in Japanese wine, sake. J . Sci. Research Inst. (Tokyo) 46, 139-143.

Sidersky, D. 1942. Le rapport du dextrose au lEvulose dans les moQts de raisin. Bull. assoc. chim. sum., dist. 69, 234-277.

SisakLn, N. M., and Bezinger, E. N. 1949. Separation and determination of amino acids in wines (transl.). Doklady Akad. Nauk. S.S.S.R. 69, 572-576.

SisakGn, N. M., and Besinger, E. N. 1950. Amino acids in grape wines (transl.). BiokhimiG vinodeliz 3, 185-195.

Sisaksn, N. M., Egorov, I. A., and Saakgn, R. G. 1950a. On the intensity of the bio- chemical reactions in sherry wine production (transl.). Biokhimii^a vinodeliiu S,

SisakLn, N. M., Egorov, I. A,, and Saaksn, R. G. 1950b. Tryptophan and the vita- mins of the B group in grape wine (transl.). BiokhimiG vinodeli& S, 96-101.

Sisaksn, N. M., and Marut& S. A. 1948. Sugars in grapes (transl.). BiokhimiG vinodeli& 2, 56-68.

Smith, M. B., and Olmo, H. P. 1944. The pantothenic acid and riboflavin in the fresh juice of diploid and tetraploid grapes. Am. J . Bot. 31, 240-241.

Solms, J., Buchi, W., and Deuel, H. 1952. Untersuchungen iiber den Pektingehalt einiger Traubenmoste. Mitt. Gebiete Lebensm. u. Hyg. 43, 303-307.

S o b , I., Rakcsanyi, L., and Zsolt, J. 1948. Hongrie, oenologie. BUZZ. ofice intern. v i n

Spaeth, E. C., and Rosenblatt, D. H. 1949. Partition chromatography of antho-

Spaeth, E. C., and Rosenblatt, D. H. 1950. Partition chromatography of synthetic

516-534.

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21(204), 52-55.

cyanidins. Science 110, 258.

anthocyanidin mixtures. Anal. Chem. 22, 1321-1326.

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Steuart, D. W. 1934. The determination of tartaric acid in cider. Analyst 69, 532-633. Stradelli, A. 1951. Evaporazione di alcol durante la fermentazione dei mosti. Riv.

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SLtdario, E. 1949. Analisi del Vino e la Ricerca delle Sofisticazioni. Casa Ed. Mares- calchi, Casale Monferrato.

Sudario, E. 1953. Le sostanze coloranti nelle uve degli ibridi produttori diretti. Ann. sper. agrar. (Rome) (N.S.) 7, 157-163.

Sulser, H. 1951. Anwendung der Papierchromatographie auf lebensmittelchemisehe Probleme. I. Grundlagen und Methodik. 11. Unterscheidung von Obstwein und Wein (with 0. Hogl). Mzlt. Cebiete Lebensm. u. Hyg. 42, 376-394, 395-405.

Sumuleanu, C., and Ghimicewu, G. 1935. Quelques Nouvelles Micro-Mbthodes pour 1’Analyse des Vins. Opinia, Jassy.

Sumuleanu, C., and Ghimicescu, G. 1936. L’analyse de quelquee vins naturels de Roumanie. Annales sci. Univ. Jassy 22, 194-255.

Swaby, R. J. 1943. Extraction of citrates and tartrates from fruit. Agr. GUZ. N . S. Wales 64, 571-573, 580.

Szab6, I., and Rakcsdnyi, L. 1935. The ratio of dextrose and Ievulose in the grape, in the must and in the wine (transl.). Magyar Ampelol. Eukonyu. 9,346-361; see also 6th Congr. intern. tech. chim. ngr. I, 936-949 (1938); C . A. 80, 1507 (1936).

Tabachnick, J., and Joslyn, M. A. 1953. Formation of esters by yeast. I. The produc- tion of ethyl acetate by standing surface cultures of Hansenula anomala. J . Bacteriol. 66, 1-9.

Taufel, K., and Mayr, F. 1933. Zur quantitativen Ermittlung der Citronensaure durch Uberfuhrung in Aceton. 2. anal. Chem. 93, 1-20.

Tanner, H., and Rentschler, H. 1953. Die quantitative Bestimmung der xpfelsaure in siissen und vergorenen Getranken. Schweiz. 2. Obst- u. Weinbau 62, 74-77.

Tarantola, C. 1934. Determinazioni delle aldeidi nel vino con il fotometro di Pulfrich e con il colorimetro fotoelettrico. Ann. chim. appl. 24, 615-625.

Tarantola, C. 1937a. L’acido citric0 nei vini italiani. Ann. tech. agrar. 10, 1-23; see also Annuar. R. staz. enol. sper. As t i [2] 2, 183-202 (1935-37), and Bull. inst. oeno.?. A lgk ie 10, 138-139 (1937).

Tarantola, C. 1937b. Dosage de l’acide citrique dans les vins. Bull. inst. oenol. AZgBrie

Tarantola, C. 1947a. La determinaaione dell’estratto nei vini. Prog. vinic. ed ozea.

Tarantola, C. 1947b. Le sostanxe azotate nei mosti e nei vini. Zndustrie Agrarie

Tarantola, C. 1948. Le sostanze riduttrici infermentescibili dei vini. Riv. vitimlt. e

Tarantola, C. 1949. La determinazione dell’acidit8 volatile nei vini in presenza di

Tarantola, C. 195Oa. T,’invertasi nei vini. Riv. viticolt. e enol. (Conegliano) 8, 229-232,

10, 88-92.

23(6/7), 7-14.

22(9/10), 7-18.

enol. (Conegliano) 1, 44-47.

anidride solforosa. Riv. viticolt. e enol. (Conegliano) 2, 193-199.

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COMPOSITION OF WINES 507

Tarantola, C. 195Ob. Pentosi e pentosani nei vini e bilancio dei carboidrati fermente- scibili e infermentascibili. Riv. viticolt. e enol. (Conegliano) 3, 287-292, 315-320.

Tarantola, C. 1951. I constituenti polifenolici del vino. Atti accad. ital. vile e vino 3,

Tartaglia, A. 1950. Difference in the ethyl alcohol content of Salento wines determined by the Malligand and by distillation methods (transl.). Coltimtore e giorn. vinicolo ital. 94, 156-168, 177-179; C. A . 46, 1722 (1951).

Teixeira Jdnior, E. do V. 1940. 0 etanal no vinho do PArto. Anais inst. vinho PGrto 1,

Teply, L. J., Strong, F. M., and Elvehjem, C. A. 19-12, Distribution of nicotinic acid in foods. J. Nutrition 23, 417-423.

Ter-Karapetian, M. A. 1952. The biological oxidation of ethyl alcohol into acetalde- hyde by the method of immersed dispersed culture. Acad. Sci. U.S.S.R. 83,

Testa, J., and Maveroff, h1. 1949. Las enzimas en la clarificacih de 10s mostos. Anales inst. vino (Cuyo) 1, 45-69.

Thaler, H., and Roos, W. 1950. tfber die Bestimmung des Glycerins im Wein mittels Perjodsaure. Z. anal. Chem. 131, 24-27.

Tomaghelli, A. A. 1937. Constante de equilibrio y color de reaccidn para el sistema: acido acetico, alcohol etilico, acetato de etilo y agua. Rev. fac. cien. qufm. univ. nacl. La Plata 12, 107-111.

Tomaghelli, -4. A. 1942. Microdeterminaci6n del alcohol en vinos. Anales asoc. quim. argentina 30, 30.

Tbrley, D. 1942. Szerves savak mennyisege magyar borokban. (The amount of organic acids in IIungarian wines.) Mezdgazdasdgi Kutatdsok 16, 310-320; C. A . 38, 6041 (1944).

Torricelli, A. 1941. A la recherche d’un nouveau prockde d’investigation pour deceler les vins fraud6s. Mitt. Gebiete Lebensm. u. Hyg. 32, 211-216.

Torricelli, A. 1943. A la recherche d’un nouveau procede d’investigation pour dbceler les vins fraiidbs. Mitt. Gebiete Lebensm. u. Hyg. 34, 115-127, 158-168.

Torricelli, A. 1945. Un moyen de differencier les jus de raisins frais des jus prepares par dilution de concentrks de raisins frais ou secs. Mitt. Gebiete Lebensm. u. Hyq.

Trauth, F. 1949. Ein Verfahren zum raschen qualitativen Nachweis von Siisstoff im Wein. Weinbau, Wissenschaftl. Beih. 3, 106-108.

Trauth, F., and Bitssler, K. 1936. Ein Beitrag zur Frage der Beziehungen zwiwhen Mostgewicht und Alkoholgrhalt und deren Nutzanwendung bei der Verbess- erung der Moste. Z . Untersuch. Lebensm. 72, 476-498.

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Trost, F. 1935. Sugli alcoli superiori dei cognacs. Ann. chim. appl . 26, 660-668. Turbovsky, M. W., Filipello, F., Cruess, W. V., and Esau, P. 1934. Observations on

the use of tannin in wine making. Fruit Products J . 14, 106, 121, 123. Twight, E. H. 1951. The pycnometer in alcohol determination. Wines & Vines 32(5),

TJchimoto, D. 1951. Effect of temperature on certain products of vinous fermentation. Thesis for M. S., liniversity of California, Bprkeley; see also Food Research 17,

Valaize, H. 1949. Nouveaux essais sup l’utilitk du phosphate d’ammoniaqur en

Valaize, H., and Dupont, G. 1951. Les acides aminks et le bouquet des vins. Inds. agr

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vinification. Inds. agr. et aliment. (Paris) 66, 349-352.

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508 MAYNARD A . h M E I t I N E

Valaer, P. 1945. Caramel and other artificial coloring matter in alcoholic liquors. J . Assoc. Ofic. Agr. Chemists 28, 467-470.

Valaer, P. 1947. Methods of analysis of wine. J . Assoc. Ofic. Agr. Chemists 30, 327- 331.

Valaer, P. 1948. Report on caramel in wines and distilled liquors. J . Assoc. Oflc. A p . Chemists 31, 178-184; see also ibid. 75-77.

Valaer, P. 1949. Report on chromatographic adsorption of wines. J . Assoc. Ofic. Agr. Chemists 32, 155; see also ibid. 33, 319-320 (1950).

Vartan’Gn, M. D. 1951. Rapid method for determination of sugar in wine (transl.). Vinodelie i Vinogradarstvo S.S.S. R. 11(7), 21.

Vasconcellos e Lencastre, A. Q. de. 194Oa. ConsideragiXoes sobre taninos e sua deter- minaqgo nos vinhos do Pbrto. Anais inst. vinho Pdrto 1, 203-289.

Vasconcellos e Lencastre , A. Q. de. 1940b. Doseamento do Acido succhico nos vinhos do Pbrto. Anais inst. ivinho PBrto 1, 291-294.

Vasconcellos e Lencastre, A. Q. de. 1941. 0 Acido succhico e 0s vinhos do Parto. Anais inst. vinho Pdrto 2, 243-304.

Vasconcellos e Lencastre, A. Q. de. 1946. Doseamento da glicerina no vinho do Pbrto e nos vinhos de pasto. Anais inst. vinho Pdrto 7, 31-48.

Velazquez, E. 1936. Contribuci6n a1 estudio del acido lactico en vinos argentinos Rev. fac. cien. qiiim. univ. nacl. L a Plata 11, 65-68.

Venezia, M. 1935. Osservarioni e studi sull’azoto in combinarione amminica nei mosti e nei vini. Annuar. R. staz. sper. viticolt. e enol. (Conegliano) 6, 103-110.

Veneria, M. 1937. Sull’invertasi nei vini. Annuar. R. staz. sper. viticolt. e enol. (Coneg- liano) 7, 283-299.

Venezia, M. 1938. Sull’acido ascorbic0 (Vitamina C) nell’uva e nel vino. Annuar. R. staz. sper. viticolt. e enol. (Conegliano) 8, 67-82.

Venezia, M. 1939-40. La fermentazione glicerica del mosto d’uva. Azione di un attivatore (fattore 2). At t i R. Zst. Veneto Sci., Lettere, Ar t i ZZ 00, 563-587.

Venezia, M. 1940. Sur une m6thode pratique pour d6celer les colorants artificiels dans les vins i-ouges. Bull. ofice intern. uin 13(140), 97-101.

Venezia, M. 1944. Propriht6s alimentaires e t caracthristiques biologiques du raisin. Bull. ofice intern. vin 17(6), 50-59.

Venezia, M. 1949. Sul grado ebulliometrico dei vini dolci. Ann. sper. agrar. (Rome)

Venezia, M., and Gentilini, L. 1935. Sulla distribuzione del saccarosio nella vite. Ann. chim. appl. 26, 203-215.

Venezia, M., and Gentilini, L. 1941. Ricerche sulla fermentazione glicerica del mosto dluva. Annuar. R. staz. sper. viticolt. e enol. (Conegliano) 10, 283-309; see also Ital. vitic. ed agr. 28, 529-532 (1938).

Ventre, J. 1936. Les lewres en vinification. Progr. agr. et vit. 106, 111-115, 135-140,

Ventre, J. 1937. Acidit6 volatile e t fermentation. Ann. ferment. 3, 447-465; see also

Ventre, J. 1939. Contribution hiochimique it 1’6tude des vins eud6mis6s. Ann. ferment.

Ventre, J . 1946-1947. Trait6 de Vinification, Pratique et Rationnelle. 2 v. Poulain,

Verda, A. 1940. Sull’aggiunta dell’acido citric0 nei vini. Ann. chim. appl. SO, 209-214. Vetscher, A. S. 1947. The determination of alcohol and of extract in wines using a sugar

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6, 13-44, 74-92.

Montpellier.

refractometer (transl.). Vinodelie i Vinogradarstvo S.S.S. R. 7(2), 33-35.

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Vetscher, A. S., and Losa, V. M. 1947. The influence of vitamins C and B, on cham- pagnes (transl.). Vinodelie i Vinogradarslvo S.S.S. R. 7(5), 9-11.

ViBles, P. 1939. Sur un dosage iodom6trique de l’acidit6 des vins. Bull. soc. chim. France [5] 6, 1127-1129.

Vil’Gms, V. V., and Taranova, R. D. 1950. A quantitative determination of the color- ing material of red wines (transl.). Vinodelie i Vinogradarslvo S.S.S.R. 10(4),

Vil’sms, V. V., and Taranova, R. D. 1951. Chromatographic method of separating

Villforth, F. 1940. Die quantitative Bestimmung des Gehaltes an fltichtigen Aldehyden

Villforth, F. 1950-51. Die Bestimmung der Ameisensaure im Wein. V e i n u . Rebe 26,

Violante, C. 1948. Richerche spettrofotometriche sulla materia colorante delle uve.

Violante, C. 1950. L’acido lattico nei vini dell’Irpinia. Riv. viticolt. e enol. (Conegliano)

Violante, C., and Bemporad, G. 1937. Ricerche spettrofotometriohe sulla materia colorante dei vini. Nota 1. Curve tipiche di alcuni vini dell’Irpinia e dei pih comuni coloranti artificiali. Ann. chim. appl. 27, 399-406.

Violante, C., and Imbrici, D. 1949. La determinazione dell’acidith volatile per distil- lazione diretta. Riv. viticolt. e enol. (Conegliano) 2, 329-334.

Vogt, E. 1934. Mostgewicht und Alkoholgehalt. Z . Untersuch. Lebensm. 68, 473-486. Vogt, E. 1935. Untersuchungen uber die Farbe der Rotweine. Wein u. Rebe 17,

Vogt, E. 1945. Weinchemie und Weinbereitung. J. Diemer, Mainz, 2d Ed. Vogt, E. 1952. Bildung von hoheren Alkoholen wahrend der Garung. Land- und

Hauswirtschaftl. Auswertungs-und Informationsdienst, Bericht Gartenbau-Forsch. 16, 93.

Volmar, Y., and Clavera, J. M. 1931. Los indicadores fluorescentes en las medidas de acidez de 10s vinos tintos. Anales SOC. espail. fk. quim. 29, 247-254; see also ibid. 490-493 and 494-496 for a polemic.

Voskobohikov, I. 1931. Materiale zum Stadium der ohemischen Zusammensetzung der Wein der Weinbaustation in Odessa. Odessa. %entral’na naukovo-doslidchoz vinogrado-vinorobcha stan&&, Pratsi 4, 55-87.

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