[advances in food research] advances in food research volume 8 volume 8 || composition of wines. ii....

COMPOSITION OF WINES . I I . INORGANIC CONSTITUENTS

BY MAYNARD A . AMERINE

Department of Viticulture and Enology. College of Agriculture. University of Califomin. Dauis. California

I . Introduction . . . . . . I1 . General Methods of Analysis . .

1 . Effect of Minerals . . . . 2 . Balance of Ions . . . . . 3 . Ash . . . . . . .

a . Methods . . . . . . b . Amounts . . . . . .

4 . Alkalinity of the Ash . . . a . Methods . . . . . . b . Amounts . . . . . .

I11 . Anions . . . . . . . 1 . Boron . . . . . . .

a . Methods . . . . . . b . Significance . . . . . c . Amounts . . . . . .

2 . Bromide . . . . . . a . Methods . . . . . . b . Amounts . . . . . .

3 . Carbon Dioxide . . . . . a . Methods . . . . . . b . Amounts . . . . . . c . Factors Affecting Solubility . . d . Forms of Carbon Dioxide Present

4 . Chloride . . . . . . a . Methods . . . . . . b . Amounts . . . . . .

5 . Fluoride . . . . . . a . Methods . . . . . . b . Amounts of Fluoride Prescnt .

6 . Iodide . . . . . . . 7 . Oxygen . . . . . .

a . Methods . . . . . . b . Amounts . . . . . .

8 . Phosphate . . . . . . a . Methods . . . . . . b . Amounts of Phosphate Present .

9 . Silicate . . . . . . 10 . Sulfate . . . . . .

133

. Page . . . . . . . 135 . . . . . . . 136 . . . . . . . 137 . . . . . . . 138 . . . . . . . 138 . . . . . . . 138 . . . . . . . 139 . . . . . . . 139 . . . . . . . 139 . . . . . . . 140 . . . . . . . 141 . . . . . . . 141 . . . . . . . 141 . . . . . . . 142 . . . . . . . 142 . . . . . . . 142 . . . . . . . 142 . . . . . . . 143 . . . . . . . 143 . . . . . . . 143 . . . . . . . 144 . . . . . . . 148 . . . . . . . 149 . . . . . . . 150 . . . . . . . 150 . . . . . . . 150 . . . . . . . 151 . . . . . . . 151 . . . . . . . 152 . . . . . . . 152 . . . . . . . 153 . . . . . . . 153 . . . . . . . 153 . . . . . . . 153 . . . . . . . 154 . . . . . . . 1.54 . . . . . . . 156 . . . . . . . 156

134 MAYNARD A . AMERINE

Page a . Methods . . . . . . . . . . . . . 156 b . Sources of Sulfate . . . . . . . . . . . 157 c . Amounts of Sulfate Present 159

11 Sulfide and Mercaptans 159 a . Methods . . . . . . . . . . . . . 161 b . Source of Sulfide . . . . . . . . . . . 161

12 . Sulfurous Acid . . . . . . . . . . . . 162 . Methods . . . . . . . . . . . . . 162

164 171

IV . Cations . . . . . . . . . . . . . . 172 1 . Aluminum . . . . . . . . . . . . . 172 2 . Arsenic . . . . . . . . . . . . . 173 3 . Cadmium . . . . . . . . . . . . . 174 4 . Calcium . . . . . . . . . . . . . 174 5 . Copper . . . . . . . . . . . . . 176

a . Methods . . . . . . . . . . . . . 176 b . Sources and Effects . . . . . . . . . . 177 c . Effects of Copper . . . . . . . . . . . . 179 cl . Amounts of Copper . . . . . . . . . . 180

6 . Iron . . . . . . . . . . . . . . 181 a . Methods . . . . . . . . . . . . . 181 b . Source . . . . . . . . . . . . . 183 c . Effects . . . . . . . . . . . . . 186 d . Amounts . . . . . . . . . . . . . 188

7 . Lead . . . . . . . . . . . . . . 189 a . Methods . . . . . . . . . . . . . 189 b . Amounts . . . . . . . . . . . . . 189

8 . Magnesium . . . . . . . . . . . . . 191 9 . Manganese . . . . . . . . . . . . . 191

10 . Mercury . . . . . . . . . . . . . 193 11 . Molybdenum . . . . . . . . . . . . 193 12 . Potassium . . . . . . . . . . . . . 193

u . Methods . . . . . . . . . . . . . 193 b . Amounts . . . . . . . . . . . . . 194

13 . Radium . . . . . . . . . . . . . 195 14 . Rubidium . . . . . . . . . . . . . 195 15 . Silver . . . . . . . . . . . . . . 196 16 . Sodium . . . . . . . . . . . . . 196

a . Methods . . . . . . . . . . . . . 196 b . Amounts of Sodium . . . . . . . . . . 196

17 . Tin, Titanium, and Vanadium . . . . . . . . . 198 18 . Zinc . . . . . . . . . . . . . . 198

a . Methods . . . . . . . . . . . . . 198 b . Amounts . . . . . . . . . . . . . 198

V . Research Needs . . . . . . . . . . . . 199 Acknowledgments . . . . . . . . . . . . 200

. . . . . . . . . . . . . . . . . . . .

. . . . . . . b . Sulfurous Acid in Musts and Wines 13 . Sulfur: Elemental and Organic . . . . . . . .

References . . . . . . . . . . . . . 200

WINES: INORGANIC CONSTITUENTS 135

I . INTRODUCTION

The inorganic constituents of wines have received less attention than the organic components. This may be because they appear to be of less biochemical and physiological importance. Nevertheless, the minerals are of considerable significance in enology. Some are needed in the process of alcoholic fermentation. Others, particularly sulfites, iron, and copper, are a part of the: oxidation system of wines, Small amounts of several metals in wines affect their clarity, and occasionally enough of a mineral component may be present to influence the flavor. Many, of course, are of significance in human nutrition. There are also legal limits for several. Legal limits for metals (as milligrams per liter) are reported in Table I. (Anonymous, 1955).

TABLE I Legal Limits for Metals (mg./l.) in Wines a

~~~ ~ ~ ~

Country Arsenic Copper Lead

France 0.4 Germany 2.0 Great Britain 1.4 Switzerland b

5

30 10

- 1.6 0.35 1.0 3.5

~~~

a Anonymous, 1955; Westhuyzen, 1955. b200 ml. should not show detectable arsenic.

In this review an attempt has been made to give a fairly complete summary of the methods employed at present for the analyses of the various inorganic constituents of wines. The use of the flame photometer greatly simplifies the determination of potassium, sodium, and calcium. The polarograph appears to be useful in a number of cases, particularly for oxygen. The colorimetric methods for copper and iron are now sufficiently accurate for. routine winery analyses. The procedures for total and free sulfur dioxide could be improved, both as to specificity and accuracy. Better methods for other constituents, especially for small amounts, need to be developed, but there does not appear to be any real lack of available procedures.

Data on the source and fate of inorganic constituents have not been conducted systematically enough, though Gartel's ( 1955) recent work on the effect of cellar operations is in the right direction. In order to be able to control the level of any constituent in the final product, it is highly desirable to know what may be the range in composition of the fruit of different varieties from various localities during ripening. We also need more information on the influence of equipment and fermenta-

136 MAYNARD A. AMERINE

tion conditions on the fate of the inorganic constituents. As more and more of the inorganic components of wine are found to be important to stability, and possibly quality, the greater will be our need of this type of data.

Finally, the biochemical aspects of the inorganic constituents have been too little studied. The obvious relationship of iron to the oxidation- reduction system has been investigated by several, but not completely clarified. Some of this delay is due to our ignorance of the condition of these constituents in wines. Using iron again as an example, we are almost completely in the dark as to the ionic species actually present in wine. The case with respect to carbon dioxide in sparkling wines is similar. It may very well be that we cannot fully explain the effect of iron on wine stability until we know the electronic structural formulas and amounts of each of the forms of iron present in wines.

There is, however, too little information on the interrelationships of the various constituents. Iron content has been studied apart from the effect of copper, phosphate, or other components. The same is true of tartrate stability; except for a few investigators, the influence of potassium, sodium, and other constituents has been neglected. In enology, as in food technology, we need accurate, rapid methods, quantitative data, and better biochemical interpretation of the data.

The present review, like its predecessor ( Amerine, 1954), is limited to pubIications since 1930. References to some 1957 papers are included. For general publications see Advances in Food Research 5, pp. 354 to 359. Admittedly, some of the compounds included in this review are not strictly inorganic, i.e., mercaptans, organic iron, and carbonate esters. However, they have been included here where they were not covered in the previous review.

II. GENERAL METHODS OF ANALYSIS

Several texts on general wine analyses have been published, Those of Amerine ( 1955), Jaulmes ( 1951 ), and RibBreau-Gayon and Peynaud ( 1947b) include procedures for the inorganic constituents. Details for wet ashing have been given by Gartel (1956), who used a 10:1:0.5 mixture of hydrochloric, perchloric, and sulfuric acids, using octyl alcohol to prevent foaming, and by Deibner and Bouzigues (1953b) who preferred hydrogen peroxide as the oxidizing agent.

Among the newer procedures, the flame photometer is particularly important. Stone et al. (1951) found it possible to use beer directly for caIcium, potassium, and sodium. However, a beer background solution was needed for preparing the calibration curves. Amerine and Kishaba (1952) and Amerine et al. (1953) ashed the wine or diluted it several


times. Pro and Mathers (1954) made a systematic study of the interference of organic and inorganic constituents in the determination of calcium, magnesium, potassium, and sodium. They reported alcohol and sucrose interference not to be of critical importance in normal wines. Cation effects on each other were likewise not significant. Phosphates and sulfates did interfere, but their interference was reduced by adding 5% dextrose. Compared with gravimetric procedures, good checks were obtained. They also got good recovery of added calcium, magnesium, potassium, and sodium. For a further discussion of the factors influencing the applicability of flame photometry see Bauserman and Cerney ( 1953). Bauserman and Olson ( 1955) used ethylenediaminotetraacetic acid (EDTA) to separate calcium so as to avoid ashing.

The polarograph has been employed for a variety of purposes by Almeida (1942), Rentschler and Tanner (1953), and Tanner and Rent- schler ( 1955). Methods for determining arsenic, phosphate, copper, zinc, iron, and manganese in musts and wines were outlined by Heide and Hennig (1933a). Dean (1951) used a spectrograph to determine 16 elements in the ash. In addition to those discussed herein he found barium, cobalt, lithium, and nickel, but in very small quantities. Bonastre and Pointeau (1957) used the polarograph for copper, lead, manganese and zinc determination.

1. EFFECT OF MINERALS

Frolov-Bagreev ( 1949) and Frolov-Bagreev and Andreevskaia ( 1950, 1955) believed their data indicated that high manganese, molybdenum, vanadium, titanium, and boron contents had a favorable effect on the organoleptic quality of wines. They suggested this might be due to their poisoning of enzyme systems. Deibner ( 1952) favorably reviewed this research, but inspection of the data shows such large variations in the amounts of the elements that it is difficult to evaluate the claim. Wines with high manganese and molybdenum did receive high organoleptic scores, but wines low in these elements had scores nearly as high. Lomkatsi (1956) added small amounts of copper, zirconium, nickel, cobalt, and thallium to fermenting musts. There was general stimulation and improvement in organoleptic quality, but again the effects are small and variable. Thallium (10 mg. per liter), copper (0.02 mg. ), and cobalt ( 10 mg.) seemed to be the most effective.

The effect of magnesium, sulfur, iron, copper, manganese, titanium, tungsten, and boron on vine growth was studied by Engles (1949), who considered these minerals favorable to growth. The sources of copper, iron, zinc, arsenic, and lead in musts and wines have been reviewed by Kieffer (1948).


Excessive or unusual mineral contents in the wine can arise from a variety of sources. The composition of the soil may lead to high mineral contents in the musts and in the resulting wines, In some cases, soil fungicides or insecticides on the grapes get into the crushed grapes and result in high metal content. Then there are the additions from equipment: metal crushers, filters, pumps, etc. Recently antiseptics and clarification agents have posed a problem, though some of these materials are of ancient origin (calcium sulfate, sodium chloride, various sulfites, fluorides, etc. ) , Even the metal content of quite dissimilar chemicals may pose a problem. The lead content of impure citric acid, for example, has been found to be high enough to create difficulties. The action of various metals on alcoholic beverages was studied by Walter (1951). The effect of metals on wines was also studied by Mrak et al. (1937), who reported a tolerance of 2 mg. per liter for aluminum, chromium, copper, and iron; 5 mg. for tin and zinc; and 50 mg. for nickel under the conditions of their experiment. The oxidation-reduction potential of the wine and other factors will influence this tolerance. Dougnac (1935) gives some data on minerals in wines in relation to their health values, mainly from pre-1930 papers.

2. BALANCE OF IONS

The principles of physical chemistry were applied by Genevois and Ribdreau-Gayon (1933) to the problems of the ions in wines and particularly to the dissociation of acids and the pH. Since the ion activities are not known, their calculations can be considered only as a first approximation. Genevois ( 1934) reported that the mineral composition of wines, particularly of potassium, calcium, and magnesium, is similar to that of muscle and liver. About one liter of wine per day would furnish '/3 to $4 of the body's needs of these elements. A complete balance of the cations and inorganic and organic anions found in six Portuguese wines by Correia and JBcome (1942b) showed that the usual analytical procedures are accurate enough to account for the total mineral content. Berner (1952) has made a balance of cations and anions for eight Swiss wines. A summary of much of the data on this subject may be found in Ribhreau-Gayon and Peynaud (1947a).

3. ASH

a. Methods

Eckert (1950) reported work by Bohringer showing that the ashing should be done at a temperature not exceeding 600OC. (1112OF.). While no new principles for the determination of the ash or of the alkalinity

WINES : INORGANIC CONSTITUENTS 139

of the ash are involved in the procedure of Sumuleanu and Ghimicescu (1935b), their titrating in the absence of carbon dioxide is worth noting.

b. Ammounts

De Soto (1951) analyzed the minerals in the ash spectrographically; his results are reported in Table I1 for seven samples (g . per 100 g. ash). These data are somewhat variable, e.g., the 10,000-fold range in aluminum and the 5,000-fold range in iron, suggesting that further work is desirable. Furthermore, the amount of ash per 100 ml. of wine is not given, so the results cannot be calculated in terms of volume of wine.

TABLE I1 Metal Content of Winen

( g . per 100 g. ash)

Metal No. of wines Mini 111 um Mnxirnum Average

Potassium Calcium Strontium Magnesium Copper Aluminum Iron Silicon Lead Sodium

4 7 3 5 7 7 7 7 3 4

20 1.0 0.01 0.01

Trace Trace Trace 0.001 0.001

Trace

20 70 0.3 5.0 0.10

10.00 3.00 5.00 0.001 1 .o

20 27 0.17 1.64 0.08 1.43 0.43 1.47 0.001 0.36

a DeSoto (1951).

The total ash content of wine varies with origin, type, and type of vinification, 1.5 to 10 g. per liter according to Berg (1943). Correia (1942b) reported little change in the alkalinity of the ash of sulfured wines, but a marked increase in the ash and sulfate contents. The ash content of a variety of types of wines are summarized in Table 111. It is difficult to reconcile these values with the 2.0 gram-per-liter limit for Swiss wines, noted by Paronetto and Dal Cin (1954).

4. ALKALINITY OF THE ASH

a. Methods

When a must or wine is ashed, the organic acids are converted, partially or wholly, to equivalent amounts of carbonates. It is customary to titrate this ash with acid and to report the value as “alkalinity of the ash.” Peynaud (1947b), Brkmond (1937b), Pato (1933), and Ribeiro


TABLE I11 Ash Content of Various Types of Winen

(Grains per liter)

Region No. of

samples Minimuin M axirnuni Average ~ ~~ ~~

California Sherry 4 2.36 3.74 3.02 Czech o s 1 ova k i a Table 708 1.60 2.30 2.00 France Table 64 1.20 3.90 1.84 Germany Table 434 1.31 3.97 2.05 Hungary Table 10 1.92 4.46 2.97 Italy Table 1168 1.10 4.80 2.06 Portugal Table 606 1.00 4.00 2.61 Rumania Table 33 1.33 4.74 2.24 Spain Sherry, etc. 81 2.06 7.08 4.29 Tunisia Table 25 1.90 3.40 2.65 Turkey Table 105 1.02 4.60 2.16 Yugoslavia Table 170 1.13 3.84 1.76

a Sources of data: California, Brajnikoff and Cruess ( 1948) ; Czechoslovakia, Kopal (1938); France, Lobstein and Schmidt (1931), Lebron and Radet (1933), Peynaud (1950a); Germany, Heiduschka and Pyriki ( 1930), Hennig ( 1944), Mader (1936), Remy (1932), Seiler (1935, 1944, 1952); Hungary, Torley (1942); Italy, Cerutti and Tamborini ( 1956), Cosmo ( 1950), Cusmano ( 1956), Dalmasso and Dell'Olio (1937), Dalmasso et al. ( 1939), Lucchetti (1941), Piano (1940), Sallusto (1936-1937, 1938-1939~1, b ) , Sallusto and Di Natale (1938-1939), Sallusto and Sculco (1937-1938); Portugal, Correia (1942a, 1942b), Correia and Vilas (1943), Guiinarles ( 1944); Rumania, Sumuleanu and Ghimicescu ( 1936) ; Spain, Brajnikoff and Cruess ( 1948), Bobadilla and Navarro (1952), Casares and Gonzalez ( 1953); Tunisia, Sallusto ( 1938-193913); Turkey, Biron ( 1950); Yugoslavia, Peretib ( 1950).

(1940) have emphasized the value of this figure in calculating the balance of anions and cations. The alkalinity of the ash should be corrected for ammonia, phosphate, and sulfurous acid. The methods for determining the alkalinity of the ash were reviewed by Ribeiro ( 1938). Schneyder (1957) employed a mixed indicator and a small excess of cerous chloride to avoid phosphate interference.

b. Amounts

In 50 port wines, Ribeiro (1938) found the alkalinity of the ash (methyl orange indicator) to range from 22 to 36 ml. 0.1 N base per 100 ml. in red port wines and from 17 to 24.5 ml. in whites. The alkalinity index

alkalinitv of the ash as ml. 0.1 N grams ash per liter of wine

was nearly constant a t 10, and Ribeiro proposed the alkalinity index as a criterion for the genuineness of these wines. One might question, how-


ever, how significant such an empirical index is, even though relatively constant, Ribeiro also discussed the various factors influencing the alkalinity of the ash (sulfurous acid, plastering, etc. ) .

The alkalinity of the ash of various types of wines is summarized in Table IV.

TABLE IV Alkalinity of the Ash of Various Types of Winesa

Minimum Maximum Average ''.of (ml.0.1 N / (ml.0.1 N / (ml.0.1 N /

samples 100 nil.) 100 ml.) 100 ml.) Region Type

Czechoslovakia White Table 572 10.9 25.9 18.4 France Table 97 12.4 35.6 21.7

Italy Table 975 5.0 30.2 12.9 Portugal Table 885 4.8 60.0 25.5 Rumania Table 33 6.9 30.5 12.8 Spain M ontilla 51 9.1 64.7 21.0 Tunisia Table 25 11.9 29.4 21.0 Yugoslavia Table 164 8.8 40.0 19.2

Germany Table 77 12.3 39.0 20.1

a Sources of data: Czechoslovakia, KopaI ( 1938); France, Peynaud ( 1947~1, b ) ; Germany, Heiduschka and Pyriki ( 1930), Hennig ( 1944), Mader ( 1936), Remy (1932); Italy, Cosmo (1950), Dalmasso and Dell'Olio (1937), Dalmasso et al. ( 1939), Piano ( 1940), Sallusto ( 1938-1939a, b ) , Sallusto and Di Natale ( 1938- 1939); Portugal, Babo (1951), Correia (1942a, b, 1956), Correia and ViIas (1943), Guimariies (1944), Salvador and FrazPo (1949, 1950); Rumania, Sumuleanu and Ghiniicescu (1936); Spain, Casares and Gonzalez (1953); Tunisia, Sallusto (1938- 193913); Yugoslavia, Peretii. (1950).

I l l . ANIONS

1. BORON

a. Methods A method for the microdetermination of small quantities of borate

in wines was developed by Sumuleanu and Ghimicescu (1933a, 1935~) . They converted borate into its methyl ester by treatment with methyl alcohol and sulfuric acid, distilled the ester, and titrated with barium hydroxide in the absence of carbon dioxide. As little as 5 mg. of boric acid (HsBOs) could be titrated with an accuracy of 28. Bionda (1952- 1953) and Gail (1932) developed colorimetric procedures for wines; the former used quinalizarin in sulfuric acid. Garters (1954) colorimetric procedure, using 1,l'-anthrimide ( 1,l'-dianthraquinoylamine) , was specifically developed for musts and wines and is probably the best now available. Alberti ( 1938) emphasized the analytical details, particularly the use of platinum or quartz equipment.


b. Significance

While the stimulating effect of minute quantities of elements such as copper and boron has been shown to be extremely important to plant growth, few studies have suggested a specific effect for yeast. Voicu and Niculescu ( 1931), for example, reported borates in concentrations of 1.7 to 88 mg. per liter to stimulate growth of a hlycoderrnu sp. (Kloeckeru?) film on wine. Niculescu (1937) indicates that about 37.5 mg. of boric acid (H,BO,) was required to give some resistance to acetification, Boron deficiency has recently been recognized in vineyard soils. Determination of the boron content of musts and wines has therefore become of some importance. The use of boron compounds as antiseptics is rare and illegal.

c. Amounts

Gad (1932) set 50 mg. per liter of boron as boric acid as the maximum for normal wines. In 104 authentic Rumanian table wines of vintages from 1887 to 1933 Sumuleanu and Ghimicescu (1935a) reported 17 to 94 mg. per liter (average 39.7). In 123 other Rumanian table wines they, (Sumuleanu and Ghimicescu 1933b), found 17 to 103 mg. per liter. In 26 Russian wines Frolov-Bagreev and Andreevskaia ( 1955) reported 0.61 to 2.8 mg. per liter (average 1.9). Grau and G6mez (1940) found 20 to 110 mg. per liter in Argentine wines. Wines with a high boric acid content were less resistant to attack by film yeasts. Alberti (1938) reported 3 to 16 mg. per liter in the wines of Pavia, Italy. In other Italian wines Bionda (1952-1953) found 14.7 to 14.8 mg. per liter. In six genuine port wines Almeida (1940) reported 22 to 55 mg. per liter, average 39. Herschler and Gartel (1954) analyzed 1,500 German musts and wines. The boric acid content fell between 11 and 28 mg. per liter. High nitrogen fertilization increased the boron content. Gartel (1955) also showed that the stems were high in boron and that destemming white grapes before pressing reduced the boron content of the must by two-thirds. In 18 German musts from destemmed grapes, the boron content ranged from 20 to 30 mg. per liter (average 22). Gartel (1954) found an average of 31 mg. per liter of boric acid in four German musts and 28 mg. in the resulting wines. In 39 Pavian wines Bionda (1957) reported 17.1 to 68.5 (average 36.7) mg. per liter of boron as boric acid.

2. BROMIDE

a. Methods

Guglielmi ( 1953) and Curli and Prati (1954) compared the standard methods, Florentin-Munsch and DenigBs-Chelee. Curli and Prati concluded that both gave low results but that the latter procedure was


the better. Jensen (1953) modified this method so as to detect amounts as low as 0.5 mg. per kg. Hansen (1954) gave a procedure specifically directed to the problem of detecting monobromacetic acid in musts and wines.

b. Amounts

Because of the possible (but now illegal) use of monobromacetic acid as an antiseptic in wines, the quantities of bromide normally present in wines is of interest. Florentin and Navellier (1951) showed that even wines from vineyards near the ocean never contained more than 1 mg. of bromide per liter. I n 11 wines the bromide content ranged from 0.1 to 1.0 mg., average 0.45. Potassium bromide was once employed on vineyards in France. Vitte (1937) found 6.7 to 7.5 mg. per liter of bromide in musts from treated vines as against 0.25 to 0.5 mg. per liter of bromide in musts of untreated grapes. Almeida (1945a) found traces to 2.5 mg. per liter (average 0.78) in musts and 0.125 to 3 mg. (average 0.55) in 12 ports. Venezia (1938-1939) reported 0.0 to 0.6 mg. per liter in 46 Italian musts and none in 38 wines. He suggested a limit of 1 mg. per liter. Cerutti and Tamborini ( 1956) reported only 0.0 to 1.0 (average 0.2) mg. per liter in 40 genuine Italian wines. They found no organic bromide in the same wines. The advantages and disadvantages of monobromacetic acid for wines are reviewed by Paronetto and Dal Cin (1954). Guglielmi (1953) reported 0.0 to 2.0 mg. per liter in 114 Italian wines from Lecce, no bromide being found in 93 of the samples. The presence of more than about 1 to 2 mg. per liter in wines would seem to indicate sophistication. In sparkling wines Oberto ( 1955) was unable to find organic bromide 12 weeks after monobromacetic acid had been added. This, of course, limits the effectiveness of monobromacetic acid and also reduces the diagnostic value of organic bromide as a means of detecting sophistication. She also reported that 40 mg. of organic bromide per liter was necessary to prevent fermentation. Ebach (1957) notes the danger of bromine-containing disinfectants, used for cleaning tanks or other winery equipment, getting into wines.

3. CARBON DIOXIDE

Carbon dioxide is present in all wines but only in small amounts in still wines, particularly in old wines. It interferes with the accurate determination of the volatile acidity, and its accurate measurement in sparkling wines is of some interest. Carbon dioxide is also undoubtedly organoleptically important in many wines.

a. Methods

A simple method for the determination of carbon dioxide in wines was given by Benvegnin and Capt (1938). They chilled the wine to


0°C. (32OF.) and quickly pipetted a sample under saturated barium hydroxide. Acid was then added, and the carbon dioxide measured in a weighed Geissler bulb containing potassium hydroxide. Merzhanian and Kozenko (1949), Vecher and Greshnov (1949), Schneyder and Epp (1955), Akiyama ( 1955), and Berntsson (1955) described procedures for determining dissolved carbon dioxide. Vartanian ( 1950) claimed that his vacuum procedure for determining carbon dioxide in wines is superior to that of Vetscher and Greshnov. The method most likely to be used in this country is that of the Laboratory of the Alcohol and Tobacco Tax Division (Internal Revenue Service, 1956). This absorption procedure is specifically designed for wines of low pressure. The apparatus is shown in a paper by Ettienne and Mathers (1956). Their table on the relation of pressure to the amount of dissolved carbon dioxide is based on experimentally determined values in wine at 15.5OC. (60°F.) (see Table V).

TABLE V Relationship of Pressure to Amount of CO, in Winea

Pounds ( per square inch ) Volume CO,

co, ( g . /I00 ml.)

0 0.95 0.1866 1 1.00 .1964 2 1.08 .2121 3 1.15 .2259 4 1.23 .2416 5 1.30 .2560 6 1.35 .2652 7 1.40 .2750 8 1.45 2848 9 1.52 .2986

10 1.65 0.3241

a Ettienne and Mathers ( 1956).

b. Amounts

In newly fermented wines, Mestre and Mestre (1939) reported 0.76 to 1.11 g. per liter of carbon dioxide. In finished wines only 0.19 to 0.55 g. was present. In Swiss wines, many of which are gassy, Benvegnin and Capt (1938) found 0.37 to 2.23 g. per liter. Capt and Hammel ( 1953) found 0.40 to 2.23 g. per liter (average 1.30) in 63 Swiss wines. They recommended adding 0.3 to 0.5 g. per liter to bring the average to about 1.0 (Capt and Hammel, 1956). Normal still wines contain small amounts (0.1 to 0.5 g. per liter) of carbon dioxide, particularly when young, according to Kielhofer (1951). Gassy wines contain about 1 g. per liter or over. At 1 atmosphere pressure at 10°C. (50OF.) about


1.430 ml., or 2.82 g., of carbon dioxide per liter is dissolved in a wine of 10% alcohol (1.670 ml. at 5OC. (41OF.). Kielhiifer has also called attention to the relation of dissolved carbon dioxide to wine handling: to the bottling of sparkling wine from tanks, to the pressure inside the bottles during corking, and to the pressure remaining when the bottles are left upright or placed on their sides. The pressure inside a bottle after corking, with a 10-ml. air space above the liquid, amounts to 0.2 to 0.8 atmospheres. For a 5-ml. space it amounts to 0.9 to 1.2 atmospheres, but with the best corks it may approach 1.2 to 1.8 atmospheres. Because of oxygen’s lower solubility (about 2% of that of carbon dioxide) the pressure when oxygen is present is different from that when only carbon dioxide is present.

Use of carbon dioxide in holding wines in casks which are not full has been indicated by many workers; this practice is still too uncommon. The important Swiss and German grape juice industry depends on the storage of relatively clear, high acid (B), and low pH (3.0) grape juice under high carbon dioxide (8 to 10 atmospheres) pressure. These musts may contain as much as 15 g. per liter of carbon dioxide according to Kielhofer (1951). He also recommends a counter pressure of carbon dioxide in filling bottles of sparkling wine from a tank.

Kozenko (1955) showed that all the wine was not saturated with carbon dioxide during the initial stages of fermentation, either with or without pressure. Later the saturation of the wine with respect to carbon dioxide increases rapidly, leading finally to supersaturation, especially in pressure fermentations. The data in Table VI demonstrate this phenomena (as mg. per 20 ml.), In the continuous process of

TABLE VI Effect of Stage of Fermentation on CO, Content of Winen

Theoretical CO, solubility at temp,

and % alcohol Days of co, co,

Fermentation produced dissolved

0 1 2 3 4 5 6 8

11 16 19

0.0 0.9 5.9

15.2 32.2 65.6 70.0 92.5 94.1 99.8

100.0

3.9 9.5

26.2 35.4 43.2 41.4 40.3 35.1 34.2 30.0 29.9

28.6 28.6 30.4 28.2 28.2 27.7 26.9 26.9 27.7 25.6 25.6

a Kozenko ( 1955).


producing sparkling wines the empty space in the fermentation vessel must be full of carbon dioxide from the start of the fermentation.

The perplexing question of determining when a wine with excess dissolved carbon dioxide is a sparkling wine and when it is not was considered by Hennig (195213). He recommended that wines not be considered sparkling if filled into ordinary bottles under less than 1.5

FIG. 1. Solubility of carbon dioxide at various alcoholic pcrcentages ( Filtrator, 1952 ) .

atmospheres pressure. This is considerably higher than permitted in this country.

A chart for predicting the carbon dioxide content is given in Fig. 1. Note that the level suggested for semisparkling (Pedwcin) German wines is about 6 g. per liter, equivalent to an equilibrium pressure of


about 1.25 atmospheres in a 12% alcohol wine. This chart should be compared with the data given by Paronetto (1953) for wines of 10% alcohol and extract contents of 2.0 and 7.0 g. per 100 ml.

Swiss law considers a wine with over 4 grams per liter of carbon dioxide as sparkling. Paronetto ( 1953) has therefore calculated the gram per liter of carbon dioxide at various temperatures versus the volume per cent. The formula for gram per liter is ( P x D ) /lo0 [ (100 - E ) k x A x K ] , where P is the pressure (measured after holding 6 hours at 15OC. [59OF.], D the density of carbon dioxide at 15OC. (59OF.) (1.872), A the per cent alcohol (by volume), k the coefficient of solubility in wine at 15OC. (59OF.) (3.1993), and E the extract (grams per 100 ml.). The solubility at various temperatures is given in Fig. 2.

13

12 I1

5 I0 .- 0 % ._ 8 7

H 6 2 5

- 9 ; "

2

I

0 I 2 3 4 5 6

PRESSURE b ~ l m l 01 IS'C.

FIG. 2. Solubility of carbon dioxide at various temperatures and pressurcs (Paronetto, 1953).

The troublesome problem of distinguishing carbonated wines from those produced by fermentation has also been studied by Liotta (1956). He reports that if bottles are left open for seven days at 4.4OC. ( 40°F.), carbonated wines then contain less than 0.22 g. per 100 ml. of carbon dioxide (0.15 to 0.22 in 8 examples), while those naturally fermented in the bottle have over that amount (0.27 to 0.54 in 13 examples).

Gaudio (1942) found 5.0 to 5.8 atmospheres of pressure in good Italian sparkling wines. Should this amount not be present, he recommended adding carbon dioxide to the fermentation container. The review of Gilissen et al. (1952) on the use of carbon dioxide in carbonating beer is also of interest to producers of carbonated wine, Schmitthenner (1949) reviewed the antiseptic properties of carbonic acid and indicated that as much as 30 atmospheres was necessary to kill yeasts. Clarified musts require only 7.5 atmospheres to control yeast growth.


c. Factors Afecting Solzibility

The solubility of carbon dioxide in grape juice at various temperatures and pressures has been determined by Siegrist (1952). He recommends 8 g. per liter of carbon dioxide at O-lOC. (3232.8OF.) with an actual tank pressure of 1.5 atmospheres for holding grape juice in tanks. At 5-7OC. (4144.6OF.), 12 g. per liter is required and the pressure is 3.75, while at about 10OC. (50°F.), 15 g. per 1. is needed and the pressure is about 7 atmospheres.

A scientific study of the factors involved in the success of storing wines under carbon dioxide (Bohi process) was made by Jenny (1952), who fully discusses theoretical problems on the absorption of the carbon dioxide as a function of temperature, pressure, and nature of the media. Formulas for calculating the amount of carbon dioxide to add to maintain the 1.5% minimum are given, including data for tanks that are not full. The importance of periodically checking temperature and pressure is noted. To convert manometer readings to carbon dioxide in grams per liter a t 15OC. (59OF.), the following formula has been proposed (Anonymous, 1952); pP X 100 (100 - a ) w X na, where p is the manometer reading in atmosphere, p is a factor for the density of carbon dioxide in water a t 15OC. (59OF.) which equals 1.872 mg./cc., w the solubility of carbon dioxide in water at 15OC. (59OF.) which equals 1.0020 ml./ml., a the per cent by volume of alcohol, and (Y the solubility of carbon dioxide in alcohol at 15OC. (59"F.), which is 3.1993 cc./ml.

The extract content has been shown by Merzhanian (1950) to have little influence on the amount of carbon dioxide dissolved compared with the effect of the per cent alcohol and sugar. He made a simple calculation to obtain the amount of carbon dioxide in kilograms, a, adsorbed per hour over 1 square meter with a pressure difference of 1 atmosphere: a = bp/v, where b is a constant which depends on the alcohol and sugar content of the wine (determined graphically from experimental data given by Kocherga and Kashirin (1940), /.? is the ccefficient of absorption capacity of the wine, and 7 is the viscosity in centipoises a t the temperature used. Merzhanian and Kozenko ( 1952) studied the adsorption of carbon dioxide by the lees. Further theoretical studies of carbon dioxide absorption by wine have been made by Merzhanian (1955) and Agabal'iants et al. (1954). In the former the absorption in kilograms absorbed was calculated from the formula a FT ( p - P o ) , where a is the absorption index as above, F the size of the contact area in square meters, T the time in hours, p the pressure of carbon dioxide on the wine, and Po the pressure in atmospheres corresponding to the concentration of carbon dioxide in the wine. In the latter


study the index of absorption is calculated as follows: B, = at + btz where B, is the coefficient of absorption at OOC. (32OF.) and a and b are empirical factors depending on the sugar and alcohol contents. Tables are given for B,, a, and b for alcohol contents of 10 to 14% and from 0 to 11% sugar.

Merzhanian and Kozenko (1952) studied the carbon dioxide adsorption of powder-size yeasts and of large yeast particles. The carbon dioxide adsorbed per gram of dry yeasts was 0.10 to 0.11 g. for the former but only 0.006 for the latter. The adsorption of the powder-size particles followed the Freundlich equation a = 0.0197 where u is the amount of carbon dioxide adsorbed (in millimoles per gram), and p the pressure at equilibrium (in millimeters of mercury). At normal atmospheric pressure this gives :

a = 0.0197 x 760°.72g = 2.455 millimoles per gram (0.11 g. per g.) .

In wines containing powder-size yeasts the carbon dioxide adsorption is given by the equation: V = ,8 x 0.05 q, where V is the amount of carbon dioxide per liter, p the adsorption coefficient from the Kocherga and Kashirin (1940) tables, and q the amount of air-dried yeasts in grams per liter. ,8 is 1.04 at 10°C. (50°F.), 1.450 at O°C. (32”F.) , and 0.76 at 2OOC. (68OF.). The losses of carbon dioxide during filtration and bottling of tank-fermented sparkling wines were studied by Koval and Pazyrev (1952).

d. Forms of Carbon Dioxide Present

Frolov-Bagreev ( 1952) reviewed the Russian experiments on the forms of carbon dioxide present in sparkling wines. Baur and Namek (1940) believed that they had shown the reaction

C,H,OH + CO, + C,H,OCOOH

to occur in alcohol solutions under carbon dioxide pressure. Skotnikov (1950) reported other Russian work showing that the carbon dioxide in sparkling wine is primarily in solution or is combined with colloidal material. In the first case there is a rapid loss of gas when the cork is removed; in the second, there is a slow release. Since the colloids are important, he does not recommend filtration. The chemical combination of carbon dioxide he apparently considers less important. However, he does believe that better wines are produced at higher temperatures, and this would seem to indicate some sort of chemical combination, favored by high pressure ( u p to 10.5 atmospheres). Several possible ways in which carbon dioxide is temporarily “bound” in organic combinations i r sparkling wines were discussed by Parfent’ev and Kovalenko (1951).


They described the properties of diethylpyrocarbonate ( C,H,OOC) ?O - b.p. 73-74OC. ( 163.P165.2°F.), dZo2" 1.1300-which is colorless, has a sparkling taste and a fruity wine odor, is poorly soluble in water, and is readily soluble in ether, alcohol, and various organic solvents. Hydrol- ysis takes place very readily in distilled water at room temperature, yielding alcohol and carbon dioxide. The same reaction takes place in 0 .1N acid, or in a dry wine such as Riesling. Merzhanian (1951) also found that the diethyl ester of pyrocarbonic acid was 91% hydrolyzed to ethyl alcohol and carbon dioxide when added to a still wine. Rut when added to a wine with 1.25 atmospheres of pressure, addition of 76.6 to 102.4 mg./100 ml. of this acid raised the pressure to 2.26 atmospheres in three days. If the original pressure was over 3.5 atmospheres, no increase in pressure occurred. (See also Amerine (1954).)

4. CHLORIDE

a. Methods

Bohm (1944) proposed a simple procedure for determining chlorides in wines by direct titration of the chloride, using the Votocek-Tritilek technique with alcoholic diphenylcarbazone plus ether. To avoid ashing red wines, Grohmann (1939) treated the wine with barium hydroxide, neutralized with nitric acid, added potassium permanganate, and decolorized with hydrogen peroxide. The resulting solution was titrated by the Volhard technique. Sumuleanu and Ghimicescu ( 1937a ) decolorized the wine with animal char and added nitric acid and potassium ferrocyanide to the filtrate. Then 0.01 N mercuric nitrate was used for the titration with sodium nitroprusside as the indicator. Blanc et al. (1956) developed a nephelometric procedure.

b. Amounts

In German white wines from the Pfalz region, Grohmann (1939) found the chloride content to be much lower than that of Spanish red wines. Vitagliano (1949-1950) reviewed the earlier data on the chloride content of wines. He showed that wines made from grapes grown near the ocean or on high-salt soils, or from grapes irrigated with high-salt water, approached 0.17 g. per liter of chloride, whereas other wines usually had values below 0.10 g. He indicated that 0.5 g. per liter (as sodium chloride) was a more rational limit than the 1.0-gram limit of the 1926 Italian law. In Portuguese wines Correia and JBcome (1943) reported a normal limit of 0.15 g. per liter, expressed as chloride. How- ever, they reported values as high as 0.369 g. per liter in wines made from grapes grown near the sea; in such wines they suggest a limit of 1.0 gram. A sodium chloride content of over 0.5 g. per liter certainly


indicates added chloride, according to Mohler ( 1936). The Swiss legal limit is 0.607 g. per liter (as chloride). In normal French wines, Genevois and Ribkreau-Gayon (1933) reported an approximate range of 0.003 to 0.355 g. per liter as chloride, and Jaulmes (1951) considered the range to be 0.012 to 0.121, except near the sea where wines may approach the French limit of 0.607 (as chloride). Fransot and Geoffroy ( 1951) showed that champagnes were unusually low in chloride and calcium (Tables VII and XIV). The ratio of chloride to calcium (both expressed as

TABLE VII Chloride Content of Various Types of Wines=

No. of Minimum Maximum Average Type of wine samples ( ~ 1 in g./l. ) ( CI in g./1. ( CI in g./1.) Region

Algeria Table 8 0.042 0.108 0.083 France Various 72 0.003 0.212 0.057 Germany Table 140 0.011 0.138 0.043

Italy Table 22 0.024 0.085 0.055 Italy Table 52 11 0.030 0.170 0.079 Portugal Red tablec 12 0.260 0.380 0.320 Portugal Table 698 0.017 0.370 0.071 Rumania Table 9 0.009 0.065 0.021 Spain Red table 13 0.106 0.596 0.226 Switzerland Table 3 0.005 0.031 0.017

Israel Table, etc. 6 0.046 0.140 0.082

Q Sources of data: Algeria, BrAmond (1937a); France, Francot and Geoffroy ( 1951 ), Genevois et al. ( 1949), Lobstein and Schmidt ( 1931 ), Peynaud ( 1950a, b ) ; Germany, Grohmann (1939), Mader (1936); Israel, Lobstein et aE. (1935); Italy, Vitagliano ( 1949-1950); Portugal, Correia ( 1942a); Portugal, Correia ( 1942a, 1956), Correia and JBcome (1942a, 1943), Salvador and FrazPo (1949, 1950), Sini6es ( 1951 ); Rumania, Suinuleanu and Ghimicescu ( 1936); Spain, Grohmann (1939); Switzerland, Godet and Martin (1946).

b From salty soils or from exposed locations or irrigated with salty water. c From the Colares region where the vineyards face the Atlantic,

calcium chloride) varied from 0.025 to 0.275, average 0.070. For the relation of the chloride and sodium contents see Table XXIV.

The chloride content of various types of wines is summarized in Table VII.

5. FLUORIDE

a. Methods A method sensitive to as little as 0.01 mg. of fluoride in wines was

proposed by Rempel (1939). A procedure for determining fluoride in wines was outlined by Destrke (1939). No fixative to prevent loss of


fluoride from wines during ashing need be added, according to Rempel ( 1939). The fluoride is steam-distilled over perchloric acid and titrated with thorium nitrate. A special procedure was developed by Fellenberg ( 1937). A biochemical procedure for determining fluorides in wines was proposed by Mecca (1952). It depended on the specific inhibiting effect which fluorides have on glycerophosphatase. A standard curve was con- structed, using various amounts of sodium fluoride and determining the amount of hydrolysis of sodium glycerophosphate. The procedure requires 50 ml. of wine and 24 hours, but it is sensitive to 0.02 g. per liter of sodium flouride.

b. Amounts of Fluoride Present

Fluoride is of little interest except as an adulterant. However, small amounts are present normally in musts and wines. In eight musts, Almeida (1945b) found 1 to 6.2 mg. per liter, average 3. In 14 port wines, it varied from traces to 5 mg. per liter, average 3. The fluoride content of 98 German wines varied from 0.064 to 0.543 mg. per liter, average 0.27, according to Hennig and Villforth (1938) while Manrhofer (1938) reported 0.15 to 0.22. In 244 samples of Argentine wine, Cattaneo and Karman (1944) reported 0.04 to 1.75 mg. per liter of fluoride, but 228 samples had less than 0.5 mg.

Although Johnson and Fischer (1935) reported wines containing 3 to 28 mg. per liter of fluoride, Fabre and Brbmond (1934) considered 5 to be the maximum limit. Alcoholic fermentation was definitely inhibited at about 14. Amounts of over 5 mg. per liter are due to use of fluorides as an antiseptic or to very late application of fluosilicate as an insecticide in the vineyard. Fellenberg (1937) reported 0 to 0.3 mg. per liter of fluoride in normal Swiss wines, 0.41 to 0.54 mg. in wines produced near a plant discharging some fluoride into the atmosphere, and 4.7 to 6.3 mg. in wine produced from grapes sprayed with fluoride- containing compounds. Truhaut ( 1955) reviewed the previous studies, and although wines seldom contain more than 0.5 mg. per liter and musts more than 0.2, he recommended a tolerance of 5.0, compared to 2.0 for beers and ciders and 1.0 for fruit juices, This was based on Jaulmes’s (1951) limit which placed the tolerance high in cases where fluoride might come from vineyard insecticides. The subject is reviewed by Paronetto and Dal Cin (1954).

6. IODIDE

In Rhine musts and wines, Hennig and Villforth (1938) reported 0.25 to 0.30 mg. per liter of iodide in musts, 0.10 to 0.20 mg. in normal wines, but 0.40 to 0.60 mg. in an Auslese wine (made from late-picked


grapes). Manrhofer (1938) reported 0.027 and 0.012 mg. per liter of iodide in two German wines.

Airoldi (1942) used Hennig and Villforth's procedure for iodide and found 0.25 to 0.35 mg. per liter of must and 0.10 to 0.20 per liter of wine. Soil conditions did not seem to be correlated with iodide content. A Russian wine with 0.5 mg. of iodide per liter was reported by Grigoriev (1948).

7. OXYGEN Oxygen is of great significance in the handling of wines, but lack of

a simple, rapid, and accurate procedure for its determination has ham- pered research. Furthermore, the data may be difficult to interpret because of the rapid consumption of oxygen in wines. For a full discussion see Ribkreau-Gayon ( 1947). Potentiometric equipment specifically designed for measuring dissolved oxygen is now available.

a. Methods

Almeida (1951) and Rentschler and Tanner (1953) used a polarographic procedure for determining dissolved oxygen. The older method of using indigo carmine was studied by Kocherga (1940) and Kul'nevich (1954). In the latter method, the free oxygen is distinguished from the readily reduced peroxides and the difficultly reduced peroxides by removing the free oxygen. Neutral rcd was used for the difficultly reduced peroxides.

b. Amounts

According to Ribdreau-Gayon ( 1947) the maximum oxygen which table wines can absorb is 5.6 to 6 ml. per liter at 20°C. (68OF.). Almeida (1951) found little dissolved oxygen in sweet dessert wines stored in closed containers. In seven bottled grape juices, Rentschler and Tanner (1953) reported 0.0 to 0.6 mg. per liter (average 0.15). After filtration there was 0.2. No increase during pressing was noted, Frolov-Bagreev and Agabal'iants (1951) showed that wine stored in 250-liter casks absorbed 40 ml. of oxygen the first year, 20 by diffusion, 4 from around the bung, and 16 during the four racking. The second year about 30 ml. were absorbed.

8. PHOSPHATE The importance of phosphates in alcoholic fermentation accounts for

our interest in the amounts to be found in musts and wines. The ferric phosphate cloudiness of wines is also a troublesome problem. The former is stressed by Archer and Castor (1956) and both aspects by Gentilini ( 1954).


a. Methods

To determine inorganic phosphate, Reichard ( 1943b ) precipitated the phosphate in wine directly as molybdate and weighed or titrated. Total phosphate was determined on the ash, and the organic phosphate obtained by difference. Sumuleanu and Ghimicescu ( 1937c) precipitated phosphate as the uranyl salt and then determined the uranyl colorimetrically with ferrocyanide. Total phosphate was determined on an ashed sample and inorganic phosphate directly on a sample of wine decolorized with charcoal. A micromethod based on the phospho- molybdate color was developed by Salvarezza ( 1935-1937). In com- parisons with other procedures and in the recovery of added phosphate, good checks were obtained. Beck and Pro (1952) have compared the phosphate values obtained from nine wine samples by a colorimetric molybdate method with the values obtained by the A.O.A.C. titration method. The colorimetric method is more rapid and convenient than titration, and the values obtained by the two methods were in good agreement. Kourakou ( 1955) used a chromatometric procedure after separating the organic and inorganic phosphate by the differential solubility of their barium salts. The procedures for phosphate determination have been reviewed by Deibner and Bouzigues (1955), who also give their modification of the usual phosphomolybdic procedure, using a photoelectric colorimeter. Schneyder ( 1956a) employed the reaction H,PO,- + Ce+++ - CePO, + 2H'. By titrating the hydrogen released, the phosphate content was obtained. Solutions of the ash were required. Gartel ( 1957a) used a molybdate-vanadate reagent for the colorimetric determination, using an S42 filter, of phosphate in ashed wines. George- akopoulos and Kourakou ( 1955) compared various procedures obtaining very similar values and preferred p-monomethylaminophenol sulfate as an indicator. They found the ratio of organic to total phosphate averaged about 1 to 10 in Greek wines.

b. Amounts of Phosphate Present

In a study of the phosphorus content of grapes and wines, Garino- Canina (1941) showed that the percentage in grapes increases during maturation, and in musts it amounts to 150350 mg. per liter (average 210). Fermentation on the skins increases the phosphate content of the resulting wine, as does a longer fermentation. In the new wine there are 150 to 400 mg. per liter (as phosphate), and most of this is present as phosphate. Surprisingly, the small amount of organic phosphate (5 to 14% of the total) present in the new wine increased during aging. He suggested that although high-quality wines were frequently high in


phosphate, the ratio total phosphate/organic phosphorus might be of diagnostic value. In six table wines and one dessert wine, he reported 190 to 500 mg. per liter total phosphate (as phosphate), of which 9 to 18% was in the organic form. Almeida (1942) found in 27 ports 131 to 308 mg. per liter, with about 14% in the organic form. The values for phosphorus in the organic condition should be accepted with caution as they were obtained by difference (total less inorganic). Both total and organic phosphorus were determined by Reichard ( 194313). He found 170 to 686 mg. per liter (as phosphate) in 46 German wines of which 10 to 20% was in the organic form. Gartel (1955) found less phosphate in musts pressed from unstemmed grapes than from stemmed.

Little effect of phosphoric acid esters on alcoholic fermentation was shown by Pieri and De Rosa (1951), but their influence on the quality

TABLE VIII Phosphate Content of Various Types of Winesa

No. of Minimum Maximum Average Type samples ( g./1. ) (g.11.) (g.11.)

Region

Czechoslovakia France Germany Hungary Italy Italy Portugal Rumania Spain Switzerland Tunisia Yugoslavia

White table Table Table White table Table Table Various Table Sherry? Table Table Table

633 77 75 10

534

456 30 25 3

25 141

b

0.110 0.420 0.039 0.600 0.026 0.686 0.052 0.129 0.070 0.637 0.368 0.628 0.080 0.900 0.010? 0.624 0.073 0.527 0.276 0.468 0.122 0.364 0.130 0.820

0.260 0.262 0.276 0.084 0.236

0.360 0.303 0.216 0.383 0.284 0.420

-

Q Sources of data: Czechoslovakia, Kopal ( 1938); France, Genevois et al. ( 1949), Lebrun and Radet (1933), Lobstein and Schmidt (1931), Peynaud (1950a, b ) ; Germany, Mader (1936), Reichard ( 1943b), Remy (1932); Hungary, Torley (1942); Italy, Cosmo (1950), DaImasso and Dell'Olio (1937), Dalmasso et al. (1939), Sallusto (1936-1937, 1938-1939b), Sallusto and Di Natale ( 1938-1939), Sallusto and Sculco ( 1937-1938), Salvarezza ( 193S-1937); Italy, Casale ( 1935- 1937) ; Portugal, Babo ( 1951 ), Correia ( 1943 ), Correia and JBcome ( 1942a), Guiinarses (1944), Ribeiro (1938), SimBes ( 1951); Rumania, Sumuleanu and Chimicescu (1936); Spain, Bobadilla and Navarro (1952); Switzerland, Godet and Martin (1946); Tunisia, Sallusto (1938-1939b); Yugoslavia, Peretib ( 1950).

b200 wines, but range or average cannot be calculated as data are given as averages for seven varieties. Minimum and maximum reported are minimum and maximum average. Since these values are higher than those in musts of the same varieties, one wonders if ammonium phosphate may not have been used in their production.


of the wine was not adequately checked, and the possibility of public health hazards was noted. Gerasimov et al. (1931) showed that addition of phosphates did not influence the rate of fermentation of Crimean musts, but ammonium salts did. However, their addition was desirable only to high-sugar musts. Their results generally support those obtained elsewhere. Archer and Castor (1956) reported a phosphate uptake of 0.00128 to 0.00167 mg. per loG cells in fermentations of musts at 10OC. ( 5O0F.) and 22.2OC. (70OF.). Berg ( 1953) reported no relation between phosphate content and organoleptic quality in central Asiatic wines.

In normal French wines, Genevois and Ribdreau-Gayon (1933) reported an approximate range of 0.095 to 0.950 g. per liter (as phosphate). Jaulmes (1951) states that wines containing over 0.5 g. per liter of phosphate may be suspected of being sophisticated. No relation between the phosphate content of the wines and their quality was noted by Lebrun and Radet (1933) in the Champagne district of France. Casale (1935) reported clouding in iron-free wines. He called this phosphate casse. In dry Russian table wines, Berg (1953) found 0.068 to 0.340 g. per liter, while dessert wines, with their more restricted fermentation, had 0.111 to 0.616.

The amounts of phosphate reported in various types of wines are summarized in Table VIII.

9. SILICATE

Godet and Martin (1946) reported 20, 24, and 26 mg. of silica (as SiOz) per liter of three Swiss wines. Lasserre (1932-1933) reported 11 to 21 mg. per liter (average 17) of silica (as Si) in six Bordeaux red wines and 16 to 23 (average 19) in three whites.

10. SULFATE

a. Methods The usual procedure for the determination of sulfate is the classical

gravimetric precipitation with barium. It is still the standard method, but because it is slow and subject to interference by sulfur dioxide, etc., other procedures have been developed. The use of benzidine for sulfate determination in wines, developed by Lobstein and Ancel (1933), checked the gravimetric barium method within 1%. Several procedures for determining sulfate were reviewed by Sumuleanu and Ghimicescu (193713). They developed a micromethod based on precipitation as benzidine sulfate and titration of the precipitate with sodium hydroxide. They eliminated sulfurous acid, calcium, iron, and magnesium prior to ashing and determining the total sulfate content. A precise procedure was developed by Deibner and Bdnard (1954a, 1954b, 19554.


A method for determining sulfuric acid in wines, based on the variation in electrical conductivity between a natural wine and the same wins with added mineral acid was developed by Axenfeld (1938). Schneyder (195613) precipitated sulfate with lead in a strongly acid solution. The washed precipitate was dissolved in excess disodium ethylenediaminetetraacetic acid, and the excess titrated with zinc chloride, using “Erichromeblack T” as the indicator. The end point is excellent and duplicates check well with results obtained by the usual gravimetric procedure.

b. Sources of Sulfate

The primary source of sulfate in wine is the grape. The widespread use of sulfur dioxide in wine making has focused attention on its oxidation as another source. The ancient practice of plastering (addition of calcium sulfate to musts) is now very uncommon except in Spain but will, of course, markedly increase the sulfate content. Finally, elementary sulfur used as a vineyard fungicide may, by biochemical oxidation, end up as sulfate.

Schanderl (195213) showed that 40 to 60% of the sulfurous acid added to musts disappears in the first three weeks of the fermentation whether oxygen is present or not. The sulfurous acid is reduced to hydrogen sulfide, sulfides, and polysulfides. He found that about 100 p.p.m. of sulfurous acid was formed during fermentation with 1.5 g. of potassium sulfate per liter present. This throws a new light on the value of plastering in low-acid musts, but the experiments should be extended and verified. Amerine (1957), for example, was unable to obtain such clear- cut results.

Addition of excessive amounts of sulfur dioxide to musts results in changes in the composition of the resulting wines. Pato and Sousa (1938) found that the sulfate content of the wine doubled when 100 p.p.m. of sulfur dioxide was added to the must and quadrupled with 312 p.p.m. of sulfur dioxide. They recommended adding sulfur dioxide in increasing amounts as the pH of the must increases: for example, at a pH of 3.0, 60 mg. per liter; at 3.2, 92; at 3.4, 148; at 3.6, 237; and at 3.5, 337.

Ribkreau-Gayon (1936) has also shown how the sulfate content increases as small amounts of sulfur dioxide are added successively to white wines during storage. He also noted that the increase in sulfate during the aging of wines in the barrel was noted as long ago as 1889 by Gayon. In 26 months the potassium sulfate content of a wine in barrels increased from 0.37 to 0.87 g. per liter, all presumably from oxidation of sulfur dioxide. He noted that white Bordeaux wines with their higher sulfur dioxide content have higher sulfate contents: 2.15 g.


per liter in an 1874 wine, 2.4’0 in wines of 1880 and 1884, and 2.85 in a wine of 1879. Excessive sulfate may be prevented by using lesser amounts of sulfur dioxide according to Muth ( 1940).

Widmer et al. (1931) found that 1840 p.p.m. of sulfurous acid added. to musts resulted in formation of 1.10 g. per liter of potassium sulfate, while addition of 460 p.p.m. resulted in formation of only 0.14 g. per liter, The sulfate content of highly sulfured Portuguese white wines is much above normal, according to Correia (1942b). Amerine and Joslyn (1951) also reported excessively high sulfate contents in some white California table wines which had obviously been heavily sulfited. Vitagliano (1956b) also stated that high sulfates in modern Italian wines are not the result of plastering but of the repeated use of sulfur dioxide. Jaulmes (1951) also believes high sulfate content in French wines can be traced to excessive use of sulfur dioxide, The influence of calcium sulfate added to musts (plastering) on the composition of the resulting wines was reviewed and studied by Borntraeger ( 1931). Schanderl ( 1952a ) believed the sulfurous acid formation accounted for most of the beneficial effects of plastering. Saenko and Solov’eva (1948) recommended gypsum only for wines with a pH of over 3.5. They recommended use of pH meters to control the amount of gypsum to be added, enough to keep the must in the pH range 3.2-3.4. Morani and Marimpietri (1930) did not find much variation in the pH decrease resulting from addition of 1.2 or 3 g. per liter of calcium sulfate ( A pH, -0.02 to -0.09).

Plastering is still common in southern Spain. Casares and Gonzalez (1953) analyzed 51 samples of Montilla and reported uniformly high sulfate. Since the sulfur dioxide content was low, this admittedly arose primarily from plastering. However, the solera system of aging does permit long periods in the cask, and if the volume decreases, as it does in the dry climate of southern Spain, this, too, would be a factor in the high sulfate content. Bobadilla et al. (1954) made a full study of the use of plastering in the sherry region of Spain. They found the wines of plastered musts to be superior, probably because of the lower pH and cleaner fermentations. Various countries limit the sulfate content ( as potassium sulfate) to 1 to 2 g. per liter according to Paronetto and Dal Cin (1954).

A tentative defense of the use of calcium sulfate (plastering) in wine making in hot countries was made by Hickinbotham (1952). However, he points out that since plastering really results in the formation of sulfuric acid, it would be more logical to use this acid directly since a given reduction in pH will be obtained with only half as much acid. While the increased sulfate content is probably of little danger to


health, it may be organoleptically objectionable, The most important objection to the use of sulfuric acid is probably the difficulty of controlling its use and the resulting danger that unscrupulous producers will use excessive amounts in low-quality musts. Tanteri (1948) showed that even if the grapes were grown on soils containing gypsum, the resulting wines seldom contained over 0.1% potassium sulfate. The legal limit of 0.2 should, therefore, not be exceeded. Higher values were due to addition of gypsum, as Castiglioni (1933) had pointed out. Serra (1928-1933) reported that wines made in 1924 after a heavy frost a t harvest time had sulfate contents (as potassium sulfate) of 2.90 g. per liter.

c. Amounts of Sulfate Present

Sulfate contents (as potassium sulfate) ranged from 0.05 to 0.126 g. per 100 ml. in 1258 Argentinean wines in Rumi’s (1936) study. He recommended lowering the liimt from 0.2 to 0.12%. According to Sumuleanu and Ghimicescu (193713); the sulfate content of wines treated with large amounts of sulfurous acid should not exceed 0.6 g. per liter (calculated as potassium sulfate). The legal limit in most countries, including the United States, is 2 g. per liter (also as potassium sulfate). The limit is intended to prevent excessive use of plastering (addition of calcium sulfate) and to detect addition of sulfuric acid. The sulfate content also figures in some enological ratios.

Genevois and Ribkreau-Gayon (1933) reported a range of 0.270 to 0.676 g. per liter (as potassium sulfate) in normal French wines. Correia and Jhcome (1942a) reported 0.233 to 0.617 g. per liter in the usual Portuguese table wines, but wines to which mutkl had been added contain 0.95 to 2.34 g. These wines were also appreciably higher in ash and very variable in alkalinity of the ash. Correia and JBcome (1943) considered 0.7 g. per liter of sulfate, calculated as potassium sulfate, to be the normal limit in Portuguese wines. Kramer and Schwarz (1931) studied the removal of excess sulfate with calcium carbonate but found it impractical as the acidity was unduly low in treated wines.

The sulfate content of various types of wines is summarized in Table IX.

11. SULFIDE AND MERCAPTANS

Both hydrogen sulfide and ethyl mercaptan are occasionally found in young wines. The former usually arises from reduction of elemental sulfur, while the latter results from the reaction of the sulfide and ethyl alcohol. The sources of hydrogen sulfide in fermentation gases have been

1 Mute is highly sulfited grape juice.


TABLE IX Sulfate Content of Various Types of Wines=

Region Minimum Maximum Average

No. Of ( g . K,SO,/ ( g. K2S0,/ (g . K,SO,/ 1. ) 1.1 1.) Type samples

~ ~~

Algeria California Czechoslovakia France Germany Israel Italy Portugal Rumania Spain

~

Sweet table Various Table Various White table Table, etc. Table Various Table Sherry, etc.

8 177 92 71 10 6

106 794

24 81

0.45 0.07

0.31 0.16 0.90 0.12 0.11 0.07? 1.05

0.33

0.70 3.03 0.44 2.31 0.52 1.72 2.92 2.34 1.48 4.39

0.58 1.10 0.39 0.93 0.33 1.47 0.75 0.38 0.65 2.03

a Sources of data: Algeria, BrCmond (1937a); California, Amerine and Joslyn ( 1951), Brajnikoff and Cruess ( 1948); Czechoslovakia, Kopal ( 1938); France, Lob- stein and Ancel ( 1933), Lobstein and Schmidt ( 1931), Peynaud ( 1950a, b ) ; Ger- many, Remy (1932); Israel, Lobstein et al. (1935); Italy, Sallusto (193%1939a), Vitagliano (1956b); Portugal, Andrade (1941), Correia (1942b, 1956), Correia and Jicome ( 1943 ), Salvador and Frazzo ( 1949, 1950 ), SimBes ( 1951 ) ; Rumania, Sumuleanu and Ghimicescu (1936); Spain, Bobadilla and Navarro (1952), Brajni- koff and Cruess (1948), Casares and Gonzalez (1953).

reviewed by Ricketts and Coutts ( 1951). According to Rentschler (1951b), hydrogen sulfide is easily removed by aeration, and if removed promptly, formation of the mercaptans will be reduced or prevented. Mercaptans in beer have been reviewed by Brenner et al. (1955a), who find sulfhydryl compounds to be partially responsible for the character- istic odor of beer. Figure 3 summaries some of the biochemical reactions.

,CH,.CH,OH

;H3'CH0

HOOC .CH.NH,.CH,.S.

FIG. 3. Interrelationships of sulfur compounds (Brenner et al., 1955a).


a. Methods

Woll ( 1955) gave a quantitative procedure for determining hydrogen sulfide. To determine sulfide and rnercaptans in beer Brenner et al. (1953, 1954a, b, 1955a) have developed methods which appear to be usable for wines also. The basis of the latter’s sulfide procedure is the formation of methylene blue with p-aminodimethylaniline and ferric sulfide. The mercaptan method depends on formation of hydrogen sulfide by the reduction of added sulfur. Their “odor filter” for distinguishing sulfide and mercaptan is particularly interesting for wine. Copper sulfate added to beer completely screens out hydrogen sulfide and mercaptans. Cadmium sulfate, however, screens out only the sulfide. The simple test, then, is to place 2 or 3 ounces of beer in each of three glasses, adding to glass 1, 5 ml. of water, to glass 2, 5 ml. of 5% cadmium sulfate, and to glass 3, 5 ml. of 5% copper sulfate. The differences in odor between the glasses establish the presence of hydrogen sulfide or mercaptans or both. The test has been successfully applied to wine in this laboratory. Ricketts and Coutts (1951) used moistened lead acetate paper for detecting sulfide.

b. Source of Sulfide

Martraire (1941) considers reduction of sulfur dioxide to be an important source of hydrogen sulfide during fermentation. The mechanism for the formation of ethyl mercaptan appears more complex. To detect ethyl mercaptan he suggested drawing air through a solution of mercuric oxide. A white crystalline percipitate of ethyl mercaptide forms immediately if ethyl mercaptan is present. He also suggested a 1% solution of isatin in sulfuric acid. This turns green in the presence of mercaptans.

Ricketts and Coutts (1951) studied the formation of hydrogen sulfide by yeasts. They reported that it is a normal component of the gas liberated during fermentation of the eight yeasts tested. Two races of top yeast produced no hydrogen sulfide in normal fermentation, but one did after storing. A number of inhibitors of enzymes in fermentation reactions, such as arsenites (but not arsenates ) , fluorides, cyanide, sodium azide, o-phenanthroline, 2,2’-bipyridine, nitrites, and salts of copper, cadmium, bismuth, mercury, silver, lead, antimony, cobalt, zinc, and nickel were effective in checking or even stopping hydrogen sulfide production. Copper ( at low concentrations ) , tin, aluminum, manganese, chromium, iron, strontium, uranium, borates, vanadates, molybdates, and tungstates had no effect. The oxidizing agents tested, bromate, thiosulfate, and hydrogen peroxide, did not affect the production of hydrogen sulfide, and chromate, permanganate, iodate, ferricyanide, and nitrates inhibited it. Ascorbic acid, cysteine, and glutathione had no influence, but sulfites and sulfates stimulated its production. They believed that the action of


yeast enzymes containing sulfhydryl groups, such as triose phosphate dehydrogenase and alcohol dehydrogenase, on the thioproteins of malt and yeast was responsible for the hydrogen sulfide production during fermentation of bottom yeast. Respiratory enzymes capable of oxidizing sulfhydryl groups to disulfide groups in top yeast may account for the absence of sulfide during top fermentation.

It is known, of course, that direct reduction of sulfate is possible, but only a few organisms are capable of carrying on this reaction. Actually the objectionable odor may be due more to methyl mercaptan than to sulfide. Methyl mercaptan could be produced by yeast reduction of cysteine. Cysteine is formed from cystine by reduction with sulfites. Macher (1952) noted that different yeasts produced varying amounts of hydrogen sulfide, some only at higher temperatures or not a t all. Addition of sulfuric acid to cereal mashes increased sulfide production. Where the fermentation liquid has a relatively high rH and no reduc- tases, little sulfide is formed,

12. SULFUROUS ACID This acid, usually as the gas, sulfur dioxide (SO,) or as the potas-

sium metabisulfite (K,S,O, ), is commonly used in the fermentation and storage of wines, and its accurate determination is of considerable importance. Reviews as to its importance in wines are given by Amerine and Joslyn (1951) and Paronetto and Dal Cin (1954). Reviews of the sources of sulfur dioxide in wines and its determination may be found in Franco ( 1937-1952), Joslyn and Braverman (1954), Paronetto and Dal Cin (1954), and Joslyn (1955).

a. Methods

The deficiencies of the direct procedure for determining sulfur dioxide have long been recognized, However, the Ripper procedure con- tinues to be used, largely because of its convenience, Ribkreau-Gayon (1932) reported that the amount of free sulfur dioxide increases with the temperature, and this makes it difficult to duplicate analytical results. Joslyn (1955) in particular has standardized the conditions for its use. Andrade (1941) with the sweet wines of northern Portugal found the Ripper results high, sometimes by several hundred per cent, compared to the Haas distillation procedure. A simple apparatus and direct procedure for determining free and total sulfur dioxide in red wines was described by Benvegnin and Capt (1931). They titrated in a dark room and lighted the solution from below through opalescent glass and a solution of saturated potassium chromate. This procedure has been used satisfactorily for moderately colored wines in our laboratory ( Amerine, 1955).

Various distillation procedures have been recommended. Ionesp


(1936) used $umuleanu and Ghimicescu’s (1935c, d ) procedure for free sulfurous acid which was found to give not only the free but a large portion of the bound sulfurous acid. The procedures for determining the free sulfurous acid content of wines were reviewed by Sumuleanu et al. ( 1937). They criticized the earlier procedure of Sumuleanu and Ghimi- cescu (1935d) and developed a method based on entraining the free sulfurous acid with carbon dioxide and oxidizing to sulfate with hydrogen peroxide. They obtained good checks with the Ripper procedure. Photiadis ( 1932) also distilled under carbon dioxide using phosphoric acid. The sulfur dioxide distilled was oxidized with peroxide to sulfate and precipitated as the barium salt. The excess barium was precipitated as the chromate and determined by adding potassium iodide and titrating with thiosulfate. Gimel ( 1951) has shown that the distillate from the volatile acid determination cannot be used in determining free sulfur dioxide, as it gives high results owing to decomposition of the aldehyde-bisulfite complex during distillation. For the rapid determination of free sulfur dioxide Hennig (1952a) has proposed the use of an N/128 iodate-iodine solution and a phosphoric acid-starch solution in a calibrated mixing tube,

Jose (1947) studied the distillation and direct procedures for determining the sulfurous acid content of wines, preferring the iodine procedure. If the titration is made rapidly, the positive error should not exceed 3%. The errors in the distillation procedure seem to be due to recombination of the sulfur dioxide with aldehyde and loss on acidifying the wine. Marcille (1935, 1937) investigated the various methods proposed for the determination of sulfur dioxide. Introduction of phenol- phthalein will give erroneous results in the iodimetric procedures, he reported. In order to prevent oxidation of sulfurous acid during distillation, Weinmann and Walther (1914) allowed the liquid being tested to drop into the distillation flask. Their results were 10% higher by this procedure than by the Fischler and Kretzdorn (1939) method. Use of pumice stones to prevent bumping in the distillation of sulfur dioxide led to low results, and glass beads were recommended by Schatzlein ( 1940). Further improvements in the Monier-Williams method applied to the determination of sulfur dioxide in wines were indicated by Taylor (1942). However, a gravimetric procedure was preferred to the volumetric. Care is needed to prevent loss of sulfur dioxide between the time of taking the sample and carrying out the analysis, according to Taylor (1939, 1941). Steam distillation gave low and variable results unless a large distilling flask and a Xjeldahl-nitrogen trap were used (Taylor, 1940). Deibner and B6nard ( 1953, 1955a) critically reviewed the various procedures for the precise determination of total sulfur dioxide by distillation. They recommended a special distillation apparatus with gradual introduction of the wine and ample condenser cool-


ing. Deibner (1953) has given details for the determination of free sulfur dioxide and he stresses the necessity of controlling the concentration of potassium iodide.

To determine sulfite and sulfate in wines, Flanzy and Deibner (1948) distilled off the former and determined the latter in the residue. TO check the results, in another sample the sulfite was oxidized to sulfate with peroxide and the total sulfate determined. In the distillation, care was taken to prevent oxidation by air. A special steam distillation apparatus was designed by Woidich (1930) for the microdetermination of sulfur dioxide in wine. One advantage of this procedure is its speed (about 12 minutes), the small sample (5 ml.), and the all-glass apparatus. Removal of volatile acids from wines prior to distillation under carbon dioxide for the sulfur dioxide determination was considered necessary by Petronici (1950). Direct iodine titration of grape juices or iodine titration of the distillate gives high results, according to Rent- schler ( 1951b). He recommended distillation under carbon dioxide and precipitation as barium sulfate.

A microcolorimetric procedure was proposed by Dupaigne (1951), who used fuchsin in the presence of formaldehyde and an acid. Joslyn (1955) preferred the Ripper titration procedure to the colorimetric acid- bleached fuchsin method, Mathers (1949) proposed a rapid lead sulfite photometric or iodimetric procedure for the determination of total sulfur dioxide in wine. Brenner et al. (195513) used reduction of stannous chloride by sulfur dioxide as the basis for their sensitive and precise method for determining the small quantities present in beers. A simpli- fied technique applicable to red and white wines was proposed by Procopio ( 1949). Klantschnigg ( 1955) used chromic oxidation of the sulfite and determined the sulfate content with barium. The original sulfate content must also be determined, and the procedure takes at least 7 hours.

A polarographic method of determining sulfurous acid in musts and wines was developed by Salvarezza ( 1939). He recommended electrometric titration for determining the active (free?) sulfur dioxide. The electromotive force ( e.m.f. ) changes rapidly when the reduction potential of the sulfur dioxide is reached. The “dead stop” or null-point electrometric method has been applied to the determination of total sulfur dioxide in colored liquids, particularly wine, by Tanner and Rentschler (1951). No comparative data were given. Joslyn (1955) obtained variable results with electrometric titration.

b. Sulfurous Acid in Musts and Wines

The forms in which sulfur dioxide is added are reviewed by Amerine and Joslyn (1951) and Paronetto and Dal Cin (1954). The use of sodium metabisulfite was reviewed by Gentilini ( 1952a). While cheaper and


higher in available sulfur dioxide, the sodium metabisulfite is more hygroscopic than the potassium salt and it increases the sodium content, though up to 400 mg. per liter this does not appear to affect the taste. However, Bohringer ( 194813 ) found potassium metabisulfited wines better organoleptically than those treated with the sodium salt (see also Section IV, 16, a ) . Sodium tartrate is very soluble and it is uncertain whether high tartrate increases iron solubility. Recommendations for using sulfur dioxide in Australia were outlined by Quinn (1940) and for Italy by Capris (1948). The various methods of applying sulfur dioxide to wines, including a description of a new device for adding liquid sulfur dioxide, were described by Vogt (1939). Yang and Wie- gand’s (1951) suggestion that the sulfur dioxide content be maintained by suspending polyethylene bags containing potassium metabisulfite in the wine is interesting, but the level of free sulfur dioxide suggested is too high for quality wines.

The binding of sulfur dioxide in musts probably takes place in stages, according to Voskoboinikov ( 1930a). In the first stage it is bound mainly by the aldehyde group of the sugars, in the second, primarily by the yeast cells. During fermentation the sulfur dioxide is mainly bound by the aldehyde produced during fermentation. In fresh grape juice the composition of the must is the chief factor influencing the fixation of sulfur dioxide. The varieties show considerable variation in rate of binding sulfur dioxide. The reactions between sulfur dioxide and aldehydes and aldehydic or ketonic sugars were studied by Bianconi and Bianchi (1932). They showed that 73% of the sulfur dioxide would com- bine with dextrose in 40 hours, but only 27% with levulose. Voskoboini- kov (1930b) also showed that the less yeast present in the must, the longer it will be before rapid fermentation begins. To keep musts without adding too much sulfur dioxide, filtering was recommended.

On the basis of experiments with and without sulfur dioxide Rib& reau-Gayon and Charpentie (1949) recommend using as little sulfur dioxide as possible in white Bordeaux musts or wines until the malolactic fermentation has reduced the acidity sufficiently to produce a balanced wine. About 50 mg. per liter before fermentation seemed best when the wines were sampled immediately after fermentation, but wines prepared with no sulfur dioxide were of better quality in the spring following the vintage. The advantages of sulfur dioxide in increasing the extraction of color and extractives from grapes were shown by Astruc and Caste1 (1934). They used up to 400 mg. per liter of sulfur dioxide! This is certainly too high. Addition of up to 75 mg. per liter (40 to 50 recommended) of sulfur dioxide before fermentation increased the color of red wines, according to Rentschler (1945). The influence of the addition of sulfurous acid to musts on the pH, total acidity, delay in start of fermentation, and quality of the resulting wines was studied


by Pato and Sousa (1938). They recommended using liquid sulfur dioxide on low-acid musts and sulfites (such as potassium metabisulfite) for high-acid musts. The effect of sulfur dioxide on the extraction of color during fermentation is still not completely clarified. Amerine and Joslyn (1951) found approximately 50 per cent greater color in the juice of more heavily sulfited musts whereas Berg and Akiyoshi (1957), while they found an increase in color in sulfited musts compared with nonsulfited musts, reported a decrease in color in the more highly sulfited musts.

Many specific studies on the changes in free and total sulfur dioxide in musts and wines have been made. Porchet (1931), for example, measured these changes for various amounts of original sulfur dioxide periodically for four days. She noted that repeated fermentations in the presence of sulfur dioxide acclimated the yeasts so that fermentation started with less and less delay. Overly sulfured musts may still ferment. Osterwalder ( 1934), for example, isolated a yeast, Saccharomyces oviforniis var. sulfuroresistens, which readiIy fermented such musts. Verona (1947) reported that continued use of sulfur dioxide induced a change from a normal “S” type yeast too the “R” type. Somewhat slower fermentations are reported with “R” type yeast. Various strains of S. ellipsoideus were classified by Burgvits (1933) as to their resistance to sulfur dioxide. His results are summarized in Table X: Scardovi

TABLE X Classification of Various Strains of Sacchorornyces ellipsoideus as to Their

Resistance to Sulfur Dioxide a

Amounts of sulfur dioxide (in mg. per liter) at which

Strain Fernientation ceases Multiplication ceases

Bordeaux B 142-209 186290

Steinberg, 1892 361-418 480

a Burgvits ( 1933).

Riesling A 310-360 289-480

(1951) found variants of S. cerevisiae which were not inhibited by 10 to 12 times the usual inhibitory concentrations of sulfur dioxide. He studied various factors which influence the toxicity of sulfur dioxide to these yeasts. Schanderl ( 1 9 5 2 ~ ) reported that 40 to 60% of the sulfur dioxide present during the most active period of fermentation is reduced to sulfide.

New evidence of the value of sulfur dioxide and pure cultures of Saccharomyces in increasing the alcohol yield, particularly with musts


from sound grapes, has been presented by Castelli (1948). He used 12 species or varieties of yeast with no sulfur dioxide and 14, 56, and 112 mg. per liter of sulfur dioxide. Increased alcohol yields were obtained in most cases, but 56 or 112 mg. per liter were better in 11 of the 12 fermentations. With sound grapes, 139 and 208 mg. per liter gave greater yields than 69 mg. per liter in four fermentations, but in only six of eight with damaged grapes. The net increase was much greater with damaged than with sound grapes.

The influence of the time of addition and the amount of sulfur dioxide added on the production of glycerin was studied by Schumakov (1930). More glycerol was produced when the daily addition of sulfur dioxide was increased from 21 to 63 mg. per liter during the first seven days. In other studies, sulfur dioxide added at the beginning of the fermentation was found to have a greater effect on glycerin production than that added later. To increase glycerol production he recommends adding the maximum amount of sulfur dioxide (but below that which would cause sticking) a t the beginning of the fermentation and lesser amounts twice daily1

The determination of the correct amounts of sulfur dioxide to add to wines has been studied by a number of workers. The influence of pH on the relative dissociation of sulfurous acid is shown in Table XI, according to Schelhorn ( 1951).

TABLE XI The Influence of pH on Relative Dissociation of Sulfurous Acid a

~

0 0.000 0.000 1 0.855 0.145 2 0.370 0.630 3 0,055 0.939 4 0.005 0.948 5 0.0004 0.667 6 10-5 0.167 7 0.0000 0.019

a According to Schelhorn (1951 ).

0.000 0.000 0.000 0.005 0.047 0.332+ 0.833 0.981

In winery operation, a small free sulfur dioxide content is desirable. Because of the varying percentages of tannin, sugars, aldehydes, and other sulfur-dioxide-fixing substances present in wines, the amount of free sulfur dioxide resulting from a given addition is very variable. However, Moreau and Vinet (1937a, b ) have shown that for a given wine or must, all of the sulfur dioxide up to a certain amount (called T )


will be fixed in four days, Also, for a given wine, for each 100 mg. per liter of sulfur dioxide added, a certain amount will remain uncombined after four days (called R ) . In the wines of the Anjou region, Moreau and Vinet found R to be generally 70 to 80, but T was very variable. Cultrera (1937) also used the Moreau and Vinet procedure for determining the amount of sulfur dioxide to apply to fermentable sweet wines. The graphic procedure of Moreau and Vinet (1933) for determining the “useful” amount of dissociated sulfur dioxide in wine was used by Testa and Paso (1941) and Paronetto and Dal Cin (1954). This can be calculated from the formula [ ( I - a ) (100 - R ) ] / R , where I is the free sulfur dioxide in the wine, a the amount of sulfur dioxide which must remain free to maintain antisepsis, and R the index of partial combination as determined graphically. In 20 red port wines, Andrade (1941) reported an average T of 153 and an R of 19. In 14 white ports, the T was 168 and R 21.

TABLE XI1 Distribution of SO, in Wine

SO, bound SO2 bound

Free Total Bound dehyde a substances

Acetal- Sulfur dioxide Type of wine dehyde to aCetd- to other

RibLreau-Gayon and Peynaud (1947b) Sauternes, 1914 22 244 222 109 160 62 Bnrsac, 1933 68 404 336 123 179 157 Haut-Barsac, 1936 82 516 434 222 322 112 Sauternes, 1937 108 376 268 54 79 189 Graves, 1938 68 272 204 43 63 14 1 Medoc, 1929 0 58 58 29 42 16 Medoc, 1936 0 36 36 24 35 1

Pinot blanc 97 308 211 75 109 102 Amerim b

Pinot blanc 35 151 116 69 100 16 Chardonnay 38 232 194 115 167 27 Sauterne 39 205 166 89 129 37 Sauterne 23 202 179 109 159 20 Sauterne 54 590 536 292 425 111 White Pinot c 20 232 202 140 204 0 Chardonnay c 6 94 88 121 176 0 Pinot blanc c 16 182 166 148 211 0

a Calculated on assumption that all acetalydehyde is present as acetaldehyde-

b Unpublished data 1947 California State Fair wines. CIndicates wines in which some of the aldehyde is bound to substances other

sulfite complex.

than sulfurous acid or is “free.”


Ribhreau-Gayon and Peynaud (1947a) point out that it is unnecessary to calculate these empirical constants since one can calculate from the bound sulfur dioxide and acetaldehyde contents how much of the sulfur dioxide is combined with the acetaldehyde in a given wine on the assumptions that the aldehyde-sulfite complex is formed completely and is stable a t the pH of the wine. Typical data (mg. per liter) on the distribution of sulfur dioxide are shown in Table XII.

Ribhreau-Gayon (1937) noted that the free sulfur dioxide content could be reduced by using smaller amounts, by holding the low-alcohol wines separately instead of blending, and by sterile filtration, pasteuriza- tion, and handling without excessive aeration. Picking the grapes as late as possible was also recommended to reduce the high total acidity. Leaving the wine in the wood too long is undesirable. The study of Mills and Wiegand (1942) also indicated that the ratio of free sulfur dioxide to total varies for each type of wine and for different samples of the same type, The percentage of sulfur dioxide lost during storage was directly related to the original concentration in the wine and varied inversely with the sugar concentration.

Benvegnin and Michod (1952) noted that the percentage of total sulfur dioxide in the free state increased as the total increased. To determine how much to add to obtain a given free sulfur dioxide content, they recommend determining the percentage of free sulfur dioxide in two samples of a wine to which different amounts of total sulfur dioxide have been added and making a graph. Values a t other percentages can than be calculated, They obtained good results in six samples. Wid- mer et al. (1931) studied the behavior of sulfur dioxide added to six grape juices. They found some bound, some free, and the remainder either oxidized to sulfate or carried off with the carbon dioxide during fermentation.

A review of the various factors which influence the percentage of fixation of sulfur dioxide in wines was given by Procopio (1953). These include the minerals and organic constituents, such as acetaldehyde, acetylmethylcarbinol, sugar, polyphenols, pectins, etc., as well as the amount of sulfur dioxide and the pH, temperature, and time following its addition. Curves showing the relationship between total and free sulfur dioxide when various concentrations of the various substances were present were given. Wanner (1938b) and Geiss (1947-1948) noted that the sulfur dioxide content of the wine in a cask varies with the depth, being highest near the top. Since sulfur dioxide is found in the pores of the wood, it was suggested that there might be less “breathing” through the pores than is usually thought. The distribution of sulfur dioxide in the wine in fuders (1000 liters) 30 minutes and 3 weeks


after adding liquid sulfur dioxide was studied by Kielhofer (1944). He reported a very unequal distribution in various parts of the containers, and this was not equalized after 3 weeks. He surmised that in larger containers the inequality would be greater. The variation was very random, Very slight differences in the alcohol content of wines in the upper and lower parts of wooden casks were reported by Kielhofer ( 1947-1948). In a sealed cask, however, no differences in sulfur dioxide developed after 15 months’ storage. Bohringer (1948a) did not find layering of sulfur dioxide in his study. Kielhofer admits, however, that differences in some constituents might arise owing to the different rates of transfer of water and alcohol through wood, In wines drawn from a concrete tank after fermentation, he found differences in alcohol, extract, and ash. These differences might arise from iron cloudiness and other temperature or aeration effects which cause clouding.

Rib6reau-Gayon (1935a) reported that when a sulfur wick was burned in a cask to secure sulfur dioxide, only about two-thirds of the theoretical sulfur dioxide was absorbed when the container was filled from the top. A common, and frequently overlooked, source of excessive sulfur dioxide in wines is the wooden containers. In normal cellar practice, they are filled with this gas by burning a sulfur wick in them when they are empty. Wanner (1938a) has shown that much of this gas is adsorbed by the wood. Filling with water as many as eight times did not remove all of the adsorbed sulfur dioxide. Soda ash solutions were recommended for rinsing. Wine was no better a remover of the adsorbed gas than water. Wanner (1938b) also demonstrated that more sulfur dioxide is adsorbed by the wood in the lower portion of the cask. For this reason some bottles may contain more sulfur dioxide than others when wine is bottled directly from the casks. The difficulty in removing the sulfurous acid from bottles rinsed with a 1, 2, 3, or 4% solution is emphasized by Geiss (1955). He found increases of 30, 60, 68, and 120 mg. per liter with 1, 2, 3, and 4% solutions with 2 minutes’ draining. With 5 minutes’ draining 23, 26, 36, and 46 mg. per liter were picked up by the wine. After 20 minutes the increases were 16, 17, 24, and 22, and after 30 minutes 14, 15, 20, and 21 mg. per liter. He recommends using sterile water for rinsing sulfited bottles.

The more rational use of sulfur dioxide has received much attention recently. Joslyn (1954) has reviewed much of this data. Schanderl (1953) notes the dangers of high sulfur dioxide both to the quality of the wine and to the health of the consumer. He estimates that 50% of the German white table wines contain more sulfur dioxide than is necessary. In his recent review of the toxicology of sulfur dioxide Schanderl (1956) gives the present legal limits of free and total sulfur dioxide in


wines in various countries (see also Amerine, 1955). He demonstrated that much of the combined sulfur dioxide is converted and hydrolized in the stomach and that this free sulfur dioxide can be irritating. Koch (1953, 1955) reported that sulfur dioxide could not be replaced completely by ascorbic acid in the handling of white table wines, where a relatively low rH is desired. Bound sulfur dioxide, he considers important to the proper development of the bouquet, He recommended pas- teurization of musts to produce wines requiring less sulfur dioxide, especially wines to be used for sparkling-wine production.

Kielhofer ( 1954) recommended heating to 20-25OC. (68-77OF.) for three weeks to reduce the total and free sulfur dioxide of over-sulfited wines. For removing excess sulfurous acid prior to distillation Capt and Michod ( 1951a) recommended commercial liquid ferrous chloride ( 3 8 O B.). Rakcslnyi (1935) used peroxide, peroxide plus urea, hexa- methylenetetramine, and formaldehyde to remove excessive amounts of sulfur dioxide, The first two were preferred, since the third reduced only the free, and the last is illegal. The special problem of desulfiting highly sulfited musts was studied by Gentilini (1949) and Mareca (1951). Distillation under vacuum seems to give the best results of the procedures tested.

Frolov-Bagreev et al. (1951) used LIP to 20 mg. per liter of sulfur dioxide in addition to the 50 already present in preparing bottle- or tank- fermented sparkling wines, but he employed a special sulfite-tolerant yeast. The treated wines were reported better than the untreated, being lower in p H and rH. The bacteria causing spoilage of dessert wines in Australia were found by Fornachon (1943) to be very sensitive to sulfur dioxide, less than 100 mg. per liter holding them in check.

In 1000 sweet white Bordeaux table wines Peynaud and Lafourcade (1952) reported 403 to have less than 350 mg. per liter of sulfur dioxide, 262 to contain 350 to 400, 264 to have from 400 to 450, and 71 to be above the legal limit of France. In 79 California white table wines, Amerine (1947) reported from 13 to 520 mg. per liter of total sulfur dioxide (average 187); in 282 red table wines, 0 to 259 (average 54); and in 266 dessert wines, 0 to 354 (average 46).

13. SULFUR: ELEMENTAL AND ORGANIC

In addition to sulfates, sulfites, mercaptans, and the various forms of sulfite, sulfur may occur as the element and in other organic forms. Elemental sulfur may occur in wines, according to Schanderl (1955), from sulfur applied to the vines, from sulfur wicks or sublimed sulfur from burning wicks, by action of sulfur dioxide on hydrogen sulfide, and by action of microorganisms on sulfur dioxide during aging. It is not


entirely clear how microorganisms first reduce sulfite to hydrogen sulfide and later oxidize the sulfide to free sulfur. Schanderl (1955) reported that the free sulfur is responsible for the failure of some German sparkling wines to referment. Growth of yeasts is decreased by the addition of 5 mg. per liter of sulfur and they do not grow with over 40 mg. The size of sulfur particles and their number is a factor.

Organic sulfur has seldom been determined in wines. Vitagliano (1956b) determined inorganic and total sulfur and calculated the difference as organic sulfur. Very little of this was amine (methionine). In musts, the inorganic sulfur equaled or exceeded the organic (by about threefold in one case). Red musts had slightly more than whites. In wines the inorganic exceeded the organic up to 15-fold. In 25 musts, the organic sulfur varied from 14 to 30 mg. per liter (average 22). In 49 wines the variation was from 15 to 31 with an average of 22.

IV. CATIONS

The hydrogen ion has been previously discussed in connection with the titratable acidity, pH, and buffer capacity (Amerine, 1954). The remaining normal cation constituents are considered in the following section.

1. ALUMINUM

The resistance of blocks of aluminum (99.5%) and of three Italian aluminum alloys to corrosion by wines was studied by Gentilini and Missier ( 1952). Since the corrosion was fairly rapid, particularly with high-acid red wines, and undesirable changes in the taste of the wines occurred, experiments with protective coatings were made. Special liter bottles of one of the aluminum alloys were used. Two types of coating were tried: one a patented oxidizing treatment and the other a resin. Both were successful in preventing changes in the wines stored in the bottles. Hochstrasser ( 1951 ) also demonstrated that aluminum could not be used in wineries without a protective coating. He noted particularly the reduction of sulfur dioxide to hydrogen sulfide and discussed the limitations of the use of aluminum in wineries.

According to Jaulmes (1951), no more than 50 mg. per liter of aluminum should be permitted in wines. In 11 ports, Almeida (1846a) reported 5 to 13 mg. per liter of aluminnm, average 10. When these wines were exposed to aluminum for one month, they gained an average of nearly 5 mg. per liter. Aluminum containers were therefore not approved for use with port wines. In three Swiss white table wines, Godet and Martin (1946) reported 1 to 2 mg. per liter of aluminum. Berner (1952) found 0.9 to 3.0 mg. per liter in eight Swiss table wines


(average 1.5). SimBes (1951) fomd 2.8 to 15.7 mg. per liter in eight Portuguese wines (average 7.5). Gelatin and isinglass, which are used in the fining of wines, may be a source of aluminum according to Salvador ( 1953 ) .

Thaler and Muhlberger (1956) found turbid German musts with as much as 3.2 mg. per liter, whereas no more than 1.5 was found in clear musts. As expected, therefore, red wines which are fermented in contact with the skins were higher in aluminum than whites. Their results are summarized in Table XIII.

TABLE XI11

(mg. per liter) Aluminum Content of Musts and Winesa

Type No. of samples Minimum Maximum Average

Red must 32 0.37 0.88 0.58 White must 48 0.40 1.52 0.73 Red wine 5 0.38 1.15 0.75 White wine 18 0.30 1.17 0.63

a Thaler and Miihlberger ( 1956 < 2. ARSENIC

The use of arsenic-containing insecticides in wine grape production may lead to public health problems. Butzengeiger (1949) studied several hundred vineyardists with mild symptoms of arsenic toxicity. Procedures for determining arsenic in wine were developed by Bleyer and Thies ( 1939), Fischler and Kretzdorn (1939), and Burkard and Wullhorst (1935). The latter found 3.9, 4.1, and 4.2 mg. per liter in three musts and 3.8 to 6.4 in eight wines (average 5.2). A review of the arsenic contents of German musts was given by Heide and Hennig (1933b). They reported traces to 4.4 mg. per liter in 112 musts examined by others. Their own results with 30 musts showed 0.41 to 3.93 mg. per liter; the resulting wines, however, had only 0.23 to 2.33 mg. per liter. In 63 Italian wines Gentilini (1944-1945) found 0.0 to 30.0 mg. per liter (average 5.56) . Konlechner et al. (1941) reported that settling of the musts reduced the arsenic content of the wine. Bleyer and Thies (1939) reported losses during fermentation but showed that in musts, arsenate inhibited fermentation at all concentrations tried. In cell-free fermentations, however, arsenate in small concentrations stimulates fermentation. While arsenate does not appear to be combined with proteins or colloids (as shown by dialysis experiments), it is combined differently in musts than in water solutions (as shown by the difference in silver nitrate effect). If lead arsenate is the insecticide employed, very little will be


found in the clarified wine. because it is nearly insoluble in wine; however, Piguet (1936) did report some arsenic pickup. Arsenic can be removed by use of iron oxide or sodium sulfide.

Although arsenical insecticides have been illegal in Germany since 1942 Roth (1956) reports 24 cases of Moselle grape growers who still suffer from symptoms of arsenic poisoning. Bureau et al. (1956) also report three new cases in France.

3. CADMIUM Monnet et al. (1946) found cadmium so soluble in wine ( 3 0 4 0 mg.

per liter dissolved in one hour) that they recommended it be prohibited for winery use. Monnet and Sabon (1946) reported 300 cases of cadmium poisoning from a wine stored in cadmium-lined containers. The cadmium content of the wines ranged from 100 to 180 mg. per liter.

4. CALCIUM Reichard (1942) and De Soto (1951) have reviewed the methods

for determining calcium in wines. Botelho (1938) observed that addition of ammonium oxalate caused a precipitate in port. Reichard (1942) found little difference in calcium by direct precipitation in wines compared to using ashed samples. Two rapid volumetric procedures were developed by Schreffler and Witzke (1952). Amerine and Kishaba (1952) used the flame photometer.

Calcium tartrate formation in California dessert wines were studied by Crawford (1951). He found that wines with as little as 50 mg. per liter of calcium form a precipitate, usually in four to seven months, after bottling. Other wines with a much higher calcium content showed no precipitate. Approximately 30% of the precipitate was calcium oxalate. In this connection it is interesting to note that Marsh and Kean (1951) also suspected oxalic acid in chromatographic tests with berry wines. Florentin (1956) has also called attention to the dangers of calcium in French wines. He recommended that calcium carbonate not be used for deacidification, preferring ion exchange procedures or magnesium carbonate.

The calcium in California wines is not derived from plastering (use of calcium sulfate). Some is present in the grapes. A small amount is dissolved from the concrete tanks used for fermentation and storage, particularly from improperly conditioned new tanks, from poor asbestos pads, from bentonite, from diatomaceous filter-aids, and possibly from careless use of calcium hypochlorite. Crawford ( 1951) found one asbestos pad with as much as 15% calcium. De Soto (1951) in 10 different asbestos filter pads found 0.83 to 7.28% calcium, average 4.15. In 10

WINES: INORGANIC CONSTITUi. NTS 175

wines, he reported 123 to 415 mg. per liter of calcium, average 181. In Swiss wines, Michod (1952) reported that the majority of tartrate pre- cipitates in bottles were of calcium, not potassium tartrate, The wines were not only saturated with calcium tartrate, but picked up additional calcium from filter pads. He recommended that filtration be avoided or done through calcium-free filter pads. Later (Michod, 1954) found 222 to 906 mg. of calcium in 40 x 40 cm. filter pads. Citric acid (1%) should be used to remove the calcium. Nestle (1949) reported small amounts of calcium being dissolved from wine bottles by dilute tartaric acid solutions.

Crawford (1951) found poor removal of calcium with potassium racemate. De Soto and Warkentin (1955) reported that calcium stability was a function of pH, little or no deposit being found if the p H was below about 3.70. The influence of various factors on the solubility of calcium tartrate in wines was considered by Kramer and Bohringer (1940) in order to develop more rational methods for deacidifying wines. Up to a titratable acidity of L4%, they preferred calcium carbonate.

Very little data on the calcium content of wines have been published. Genevois ( 1934) considered that white wines are essentially saturated as to calcium tartrate. Lasserre (1932-1933) showed that red wines contain less calcium than white. The solubility of calcium is greater, at low concentration, with higher sulfate. The range of calcium in normal French wines was reported to be from 0.100 to 0.200 g. per liter by

TABLE XIV Calcium Content of Various Types of Musts and Wines Q

No. of Minimum Maximum Average Type samples ( g./I. (g.11.) (g./1.) Region

~~ ~~ ~~

Algeria California France Germany Germany

Portugal Rumania Switzerland

Portugal

Table Various Table Table Must Various Must Table Table

8 101 70 23 4

22 8

96 11

0.044 0.006 0.036 0.054 0.164 0.036 0.078 0.037 0.065

0.103 0.117 0.112 0.115 0.181 0.101 0.214 0.175 0.138

~~

0.071 0.052 0.091 0.092 0.171 0.055 0.134 0.091 0.102

a Sources of data: Algeria, Br6mond ( 1937a); California, Amerine and Kishaba (1952), De Soto and Warkentin (1955), Schreffler and Witzke (1952); France, Francot and Geoffroy ( 1951), Genevois et al. (1949), Lasserre ( 1932-1933), Pey- naud ( 1950a, b) , Rib6reau-Gayon et al. ( 1956); Germany, Reichard ( 1942), Remy ( 1932 ) ; Germany, Reichard ( 1942 ) ; Portugal, Correia ( 1956 ), Correia and Jicoma ( 1942a); Portugal, Simdes ( 1951); Rumania, Ghimicescu ( 1935b), $umuleanu and Ghimicescu (1936); Switzerland, Berner ( 1952), Godet and Martin ( 1946).


Genevois and Ribhreau-Gayon ( 1933). Jaulmes ( 1951) gave a range of 0.05 to 0.20 g. per liter, average 0.06. Genevois (1934) found that the solubility of calcium tartrate in alcoholic solutions should limit the calcium content of wines to 0.08 to 0.18 g. per liter. In central Asiatic wines, Berg (1953) reported 0.118 to 0.176 g. per liter in musts but only 0.043 to 0.090 in their wines. The calcium content of several types of wines is summarized in Table XIV.

5. COPPER

Copper occupies an increasingly important position among the cations, because of its influence on the cIouding of wines.

a. Methods

A volumetric and colorimetric ( thiocyanate ) procedure for copper determination was given by Golse (1933). Golovatyi (1950, 1953) used a cation resin exchanger for securing the copper for iodimetric titration. Unfortunately, 2 to 3 liters were necessary, and the method is accurate only if the wines contain more than 0.9 mg. per liter. Bernasconi (1951) separated copper from the wine by electrolysis, dissolved the copper from the electrode, adjusted the acidity to slightly acid, developed the color with thiocyanate, pyridine, and chloroform, and compared with standards. Fellenberg ( 1932) points out that electrolytic methods are not sensitive enough for the small quantity of copper in normal wines unless large quantities of wine are used. He gives a simple volumetric procedure. Astruc and Caste1 ( 1935) used Fellenberg’s method (slightly modified). They ashed and converted the copper to the sulfate, Sugar was then added and the precipitated cuprous oxide determined. Three methods for determining copper in musts and wines were studied by Pato and Costa ( 1943). These included an electrolytic procedure directly on the wine and two electrolytic procedures following ashing. They recommended one of the latter. The necessity of ashing is an objectionable feature, and the amounts of copper reported are very high. Deter- mination of copper in the ashed solution as colloidal copper sulfide, using a nepholometer, was proposed by Malvezin (1942).

Most American enologists now employ the methods of Coulson and Drabkin as modified by Marsh (see Amerine and Joslyn, 1951). These are applicable to wines or to the ash, depending on the degree of accuracy required. The color is developed with diethyldithiocarbamate. Ant-Wuorinen ( 1936) used dithizone to determine copper, extracting the color with carbon tetrachloride. The color was measured in a photometer with an S50 filter. His results showed variations of 2 0.3 mg. in wines. The amounts reported in seven European wines, 0.6 to 2.8 mg.


per liter, are higher than obtained by other studies. Peynaud (1954), using 2,2-diquinoline, reported a sensitivity of 0.2-0.3 mg., in only 5 ml. of wine. Ashing was not necessary for white wines. Schapiro and Lapina (195313) ashed and used a colorimetric curve with guaiacol. Dukhovnyi (1955) determined the copper in brandy with a colorimetric ferricyanide procedure.

Almeida (1949a) ashed port wines and determined the copper polarographically under hydrogen with good results. Francesco and Falchi ( 1955) successfully used oscillographic polarography to determine copper in wines. Hennig and Burkhardt (1954) used a polarographic procedure for determining copper in the ash. They report that it took about two hours per determination. Mareca (1953) also used a polarograph but did not ash, separating a copper-ammonia complex. No comparative data were presented. Tanner and Rentschler (1955) ashed and employed ethylenediamine as the base electrolyte in their polarographic procedure. They obtained good recovery of added copper. See Section IV, 6, a for Banick and Smith's (1957) highly specific procedure.

b. Sources and Effects

The source of the copper content of port wines has been studied by Vasconcellos ( 1947). While small amounts are naturally present, some being derived from the copper sulfate used in spraying, new wines contain little copper. Amerine and Joslyn (1951) also found this to be true in California (Table XV).

TABLE XV Copper Content of New Winesa

Minimum Maximum Average ( mg. /I. ) (mg./l. ) (mg./l. ) Source of wine No. of samples

Commercial 46 0.16 0.39 0.25 Experimental white 39 0.04 0.43 0.12 Experimental red 33 0.04 0.28 0.09

Q Amerine and Joslyn ( 1951).

Copper in wine, then, must come primarily from contact of the wine with copper. In Swiss work quoted by Vasconcellos (1947), 62.9% was lost with the pomace, 34.0% in the lees, and only 3.1% remained in the new wine three or four months after the vintage; 8 months after the vintage, only 0.5% of the original copper was in the wine. In Portuguese wines, he reported data listed in Table XVI. Gartel (1955) showed that


TABLE XVI Copper Content of Portuguese Wines a

Minimum Maximum Average Type No. of samples (mg./l.) (mg./l.) (mg./l.)

Table Port Brandy

32 0.00 2.27 0.37 64 0.00 2.24 0.43 5 0.09 0.67 0.26

a Reported by Vasconcellos ( 1947)

the copper content of the musts of 12 copper-sprayed German vineyards ranged from 11.1 to 44.5 mg. per liter (average 18.9), while in 11 non- sprayed vineyards it ranged from 6.3 to 17.0, averaging 9.5. Musts from a metal Wilmes press contained more copper than those from a wooden basket press, During pressing, with either press, the copper content of the must decreased, possibly indicating that most of the copper is on the surface of the fruit. With boron, iron, phosphate, and potassium the opposite was true,

The detailed study of Benvegnin and Capt (1934) on copper in Swiss white musts and wines showed that settling eliminated little copper, but of the original copper of the grapes 90% or more was removed with the pomace and the lees, In general, the copper content of completely fermented wine did not depend on the copper content of the must. Six-months-old wine usually had 0.5 mg. per liter or less of copper. Abnormal amounts were due to contact with copper equipment. The copper content of commercial grape juices, however, may be high, up to 10 mg. per liter, and grape concentrates were even higher. It must be remembered, however, that most Swiss vineyards are sprayed with copper sulfate. Musts from unsprayed vineyards had little copper. Similar results were obtained by Heide and Hennig (1933b), who found 2.46 to 10.91 mg. per liter in 30 musts and only 0.30 to 3.68 mg. per liter in the resulting wines. Thoukis and Amerine (1956) reported 40.9 to 89.0 per cent of the copper was lost during fermentation, and they showed that most of the copper was incorporated in, or very tightly fixed to, the yeast cells. Franyot (1954b) found 10 to 30 times as much copper in the musts and 3 to 7 times as much in the wines of heavily copper- sprayed vines. From 25 to 82.5% of the copper in the must was lost during fermentation. Franyot and Geoffroy ( 1956) reported that Cham- pagne grapes sprayed 4 to 5 times with copper sulfate yielded musts with as much as 7 mg. per liter of copper. More copper was present in the first juice from the press and also in its wine, but 80 to 95% of the must copper was lost during fermentation.


c. Effects of Copper

Rentschler and Tanner (1951), after centrifuging cloudy wines suspected of copper cloudiness, reported copper sulfite in the sediment. High sulfur dioxide, over 250 mg. per liter total and 50-100 free, was required for copper cloud formation. Flamand (1935) has reviewed the clouding of white wines in the presence of copper and sulfur dioxide. Ribkreau-Gayon ( 1930) proposed a comprehensive theory to explain the difference in cloudiness due to iron and copper in bottled wines. While his theory that the ferric iron causes iron c a s e seems well established, there has been less acceptance of his concept that cuprous sulfide is responsible for copper casse. He has shown that the presence of copper increases the tendency of iron to precipitate and proposed (Ribkreau- Gayon, 1935b) using sodium sulfide for removal of copper. Doubt as to his theory is found in the work of Kean and Marsh (1956a). The clouds they investigated ( denatured proteins ) contained little sulfur but were high in nitrogen. Chromatographic analyses of the cloud material showed it to be proteinaceous. In synthetic systems, the necessity of copper for cloud formation was demonstrated. If both copper and sulfur dioxide were present an initially reversible cloud formed, but with time it became less reversible. They concluded that copper clouds were probably a mixture of various clouds : protein-tannin, copper-protein, and copper-sulfur (probably as copper sulfide). Kean and Marsh (195613) suggested bentonite fining of wines as the best means of reducing the protein content and thus preventing copper clouds. Storage in the dark or in brown or red bottles or maintaining low sulfur dioxide contents were other means of reducing susceptibility to copper clouding. Joslyn and Lukton ( 1953) also believed proteins and polypeptides, particularly those rich in sulfur-containing amino acids, to be involved in copper clouding.

Copper may also act as a yeast poison, although the amounts in California grapes are too small (since copper sprays are not used in California vineyards). (See Schanderl ( 1950) for further details.) Guil- lement (1936) found that when yeasts fix 2.3 to 2.5 mg. of copper per gram of dry matter, fermentation rapidly slows down. Very high concentrations of copper in the must (500 mg. per liter) were necessary to slow down fermentation. The possible beneficial effects of copper have been much studied by Russian investigators. Sapondzhian and Gevorkian (1953), for example, examined the effect of added copper (10 rig. per liter of copper sulfate) on the amount of sherry flavor developed by film yeasts. Acetal and neutral ester content were higher than in the controls and quality was better.


The removal of copper is a subject of great interest. Joslyn et nl. (1953) and Joslyn and Lukton (1953) investigated a wide range of compounds of which rubeanic acid was the best. Potassium ferrocyanide ( the classic agent) and a mixture of i t and Prussian blue also gave excellent removal. For further information see Section IV, 6, c.

d. Amounts of Copper

The copper content of musts produced from 1887 to 1933 has been summarized by Heide and Hennig (1933b). They reported 0.4 to 80 mg. per liter, amounts far higher than those encountered in California. The limit a t which copper affects the taste of wines seems not to have been fixed, and it may vary for different types of wines. The taste of water is affected by about 2 mg. per liter, and in cider 3 or 4. With wines it takes as much as 5 mg. per liter. According to Jaulmes (1951), no more than 1 mg. per liter should be permitted in French wines. Kock and Breker (1955) recommended a maximum of 5 mg. per liter for category “a” quality French grape juices and 10 for category “b.”

Pato and Costa (1943) reported extraordinarily high amounts of copper in 23 Portuguese table wines, varying from 0.0 to 22.8 mg. per liter, average 5.1 (3.9 not counting the two highest vaIues) . These values are about 10 times greater than those reported in California wines. In Russian wines, Bolotov (1939) found 0.22 to 3.0 mg. per liter. Prado (1937) reported an average of 1.05 mg. per liter in various Argentinean

TABLE XVII Copper Content of Various Types of Musts and Winesa

No. of Minimum h4axinium Average Region Type samples (mg./l.) (mg./l.) (mg. / l , )

California Various 72 0.04 0.43 0.11 France Table 7 0.54 1.78 1.28 France Must 49 0.01 12.06 2.20 Germany Table 52 0.0 3.68 1.24 Germany Must 61 2.46 34.2 8.27 Italy Table 13 0.12 1.12 0.36 Portugal Port 30 0.0 14.0 4.1 Switzerland Table 12 0.0 2.15 0.95 Switzerland hlnst 5 1.26 3.4 2.5 Switzerland Grape juice 26 1.7 10.6 4.9

a Sources of data: California, Amerine and Joslyn ( 1951 ) ; France, Golse (1933); France, Kock and Breker (1955); Germany, Heide and Hennig (1933b), Hennig and Biirkhardt ( 1954), Rcmy ( 1932); Germany, GLrteI ( 1955), Heide and Hennig ( 1933b); Italy, Chierego ( 1954); Portugal, Alnieida ( 1949a); Switzerland, Tanner and Rentschler (1955); Switzerland, Tanner and Rentschler (1955); Swit- zerland, Tanner and Rentschler (1955).


wines. Lherme (1931-1932) reported 0 to 2.6 mg. per liter of copper in 32 new Bordeaux wines from vines which had been sprayed 5 to 10 times. Only 7 of the 32 contained as much as or more than 0.5 mg. per liter. Fabre (1942) gives the following permissible lirnits for copper in concentrates: half-concentrated must ( 2 6 O Be.), 40 mg. per kg.; fully concentrated must (36" B6. ), 70.0; fully concentrated must (37-57O Be.), 73.0; fully concentrated must ( 4 9 O Be.), 100.0. In brandy Lafon and Couillaud (1953) found the copper content of cognac rarely to exceed 3 mg. per liter. The copper content of various types of wines is summarized in Table XVII.

6. IRON Like copper, iron is of interest because of the possible cloudiness

induced by excessive amounts. It may also be important in oxidation- reduction reactions and to the organoleptic quality.

a. Methods

For a general review of the colorimetric procedures for iron see Deibner and Bouzigues (1953a). Capt (1938) ashed 50 ml. of wine, reduced the iron to the ferrous state, and titrated with chromate. A simple procedure for iron determination in musts or wines is that of Mousseron (see Astruc and Castel, 1935), who simply add freshly prepared cuprous oxide and titrate the ferrous iron with permanganate. A rather involved colorimetric-dilution procedure, applicable only to white wines, was proposed by Hanak (1930). The method could also be used for determining ferrous iron.

The thiocyanate and ferrocyanide procedures for iron in wines have been employed by many enologists (see Malvezin, 1930 and Genevois, 1933) because they permit determining both the total iron and the iron present in complexes; no color is produced by the iron complexed with tartaric acid. Ribkreau-Gayon ( 1934a-1933a) studied the determination of iron in wine by the thiocyanate and ferrocyanide procedures. For the latter he recommended hydrosulfite to hydrolyze iron complexes in wine, addition of hydrogen peroxide to keep all the iron in the ferric state, and a solution of gum arabic to prevent precipitation of the Prussian blue formed. Ferr6 and Michel (1933) recommended adding hydrogen peroxide after the ferrocyanide, and their best results were obtained at a pH of 2.7 to 3.0. They preferred the thiocyanate procedure. Ribdreau- Gayon (1933b; 1936) responded by defending his procedure, claiming that the results of Ferre and Michel were due to their failure to consider that some iron is present neither as ferric nor ferrous ions, but in a complexed form. Dubaqui6 ( 1933) continued his polemic with Ribkreau-

182 MAYNARD A. AMEFUNE

Gayon as to the priority of details of the ferrocyanide procedure. Rib& reau-Gayon’s (1933b) final rebuttal seems to have prevailed. Methods similar to Ribkreau-Gayon’s for determining ferrous and ferric ions and the iron in complexes were given by Fantini (1940). The ferrocyanide procedure was employed directly on wines by Barini-Banchi ( 1951 ), using a spectrophotometer and determining the change in color after adding the ferrocyanide. His procedure gives values that averaged 15.5 mg. per liter on 17 Italian wines compared to 14.2 in ashed samples. Gentilini (1952b) used a modification of Barini-Banchi’s (1951) procedure for determining ferrous and ferric ions.

Ant-Wuorinen (1936) wet-ashed the wine and then used potassium thiocyanate to develop the color. He employed a Zeiss photometer and an S50 filter. Marsh and Nobusada (1938) determined total ferric ion plus ferric complexes and total iron with thiocyanate. The procedure of Romano (1952) is a modification of the usual thiocyanate methods. He showed that the amount of color also depends on the acidity and thiocyanate concentration and does not strictly follow Beer’s law so that a curve must be prepared for exact work. Prillinger (1951) recommended determination of the total iron content of the wine with ammonium thiocyanate and blue-fining the wine on the basis of 9 mg. of potassium ferrocyanide for each milligram of iron present. No new principles are indicated in Ghimicescu’s (1937) microprocedure for iron in wines. Barium hydroxide was used for clarification and potassium thiocyanate for development of the color. In 30 Rumanian wines he reported 7 to 60 mg. per liter of total iron and 5.9 to 25 mg. of ferric iron. Nobile ( 1954 ) also employed potassium thiocyanate. Procedures for determining ferric and ferrous ions and for combined ferrous and ferric iron were developed, Deibner and Bouzigues (1953a) showed the inherent difficulties of all thiocyanate procedures: effect of chloride, effect of excess reagent, etc.

The colorimetric orthophenanthroline method as modified by Saywell and Cunningham (1937; see also Saywell, 1937) is now commonly used in California. Vecher and Petrov ( 1954) also employed orthophenanthroline, but they present modifications to determine ferric and ferrous ions as well as total iron in white wines, which are the wines for which this determination is most often employed. Colagrande (1956) also used orthophenanthroline directly in white wines and obtained good checks with 16 wet-ashed checks. Deibner and Bouzigues (1952) give a precise orthophenanthroline method using ashed samples. They found phosphate to interfere unless the pH is controlled. To facilitate the determination they have developed (Deibner and Bouzigues, 1953b) a rapid wet- ashing procedure based on the use of hydrogen peroxide.


Banick and Smith ( 1957) used “Bathophenanthroline” (4,l-diphenyl- 1,lO-phenanthroline ) for determination of iron in the presence of copper and “Bathocuproine” ( 4,7-dephenyl-2,9-dimethyl-l, 10-phenanthroline ) for the determination of copper in the presence of iron. Both reagents are highly specific, of high sensitivity, extractable using immiscible organic solvents, and do not require close pH control for color stability. The main attraction of their procedure is that ashing is not necessary.

Other colorimetric procedures include the use of protocatechol by Schapiro and Lapina ( 1953a ), ammonium thioglycolate by Iozzi ( 1956 ) , ferron ( 8-hydroxyquinoline-7-iodo-5-sulfonic acid) by Roupert ( 1956 ) , and dithizone by Kretzdorn and Miiller ( 1954a). Golovatyi ( 1950) proposed using a sulforesorcinol resin cationite for securing the iron for determination, The titration is made with dichromate, using diphenyl- amine as the indicator. As much as 300 ml. is necessary, Dukhovnyi (1955) determined iron in brandy using a salicylic acid reagent.

A polarographic procedure for determining iron in wines was developed by Almeida (1950a). No comparison with ashing procedures was given. Deibner (1949, 1950) proposed the reduction of ferric chloride by potassium iodide under carefully controlled conditions of pH. Ashed samples were used. The iron was separated from copper and cobalt as a tetramine. The procedure proposed, although accurate, is time-consum- ing and useful mainly for standardization. Bettignies (1956) used ethylenediaminetetraacetic acid for the determination of metals in wines with ‘feron” as the indicator.

b. Source

The sources of iron in musts have been extensively studied as a means of reducing the amount present in the wines. Flanzy and Deibner (1956) found surface iron on the grapes to be an important source. Reduction to soluble ferrous ion by microorganisms or yeasts or both was postulated. Thaler and Muhlberger (1956) found 10 to 25 (average 17) mg. per liter in seven cloudy German musts but only 0.5 to 12

TABLE XVIII Iron Content for Various Parts of the Grapea

(mg. per 100 g . )

Low iron soil Medium iron soil High iron soil

Sterns 1.46 3.44 4.30 17.20 Skins 1.14 1.11 2.01 4.20 Seeds 0.65 0.74 1.30 G.60 Pulp 0.16 0.22 0.12 0.37 Whole fruit 0.34 0.48 0.55 1.68

a NL.gre and Cordonnier ( 1953).


(average 2.3) mg. in the clarified musts. Giirtel (1955) found more iron in two musts of stemmed grapes than in one from unstemmed. Cordon- nier (1953) separated the various parts of the cluster and fruit and determined the iron in each. He reported 21 to 51% in the stems, 23 to 32% in the skins, 7 to 7.7% in the seeds, and 18 to 39% in the flesh. The must will contain 4 to 7 mg. of iron if no contamination occurs. The amount of iron in the grapes is limited, even when grown on high-iron soils. The analyses for the various parts of the grape (mg. per 100 g.) as given by NBgre and Cordonnier (1953) are included in Table XVIII. They calculate that of the iron present in new wine 5 mg. per liter is about the maximum which is derived from the fruit.

Dupuy et al. (1955) also studied the sources of iron in new wines. They found no relationship between the variety and the iron content although wines of different varieties grown on the same soil did vary considerably in iron content. They did not find any direct relationship between the total iron content of the soil and that of the new wine. When the phosphorous content of the soil was compared with that of the wine, they found wines of less than 6 mg. per liter of iron came from soils with 4.5 to 7.0 mg. per liter of phosphorus (as P,O,) in the extract solution (Morgan’s procedure) while wines with over 6 mg. per liter of iron came from soils with 10 to 19 mg. per liter of phosphorus. However, further study showed no direct relationship between the mineral phosphorus content of the soil and the iron content of the soil. The method by which high extractable phosphorus leads to high plant iron is thus not clear. Iron pickup from equipment was also studied and was especially important in the crusher. However, some of this contamination, perhaps much of it, appears to be due to dissolution from soil under the reducing conditions of fermentation. While Dupuy et al. favor the idea that soil iron plays the more important role, the Cali- fornia winery evidence and that of Cordonnier and NAgre and Cordon- nier would indicate that the equipment is equally or more important. However, Sim6es (1951) reported that the region of production influ- enced the total iron content of the must and the ratio of ferrous to ferric ions. In the Braga district of northern Portugal, the total iron varied from 2.7 to 9.9 mg. per liter with ferrous:ferric ratios of 0.32 to 3.00. In the Santo Tirso region, total iron was 15.6 to 26.0 and the ratio 0.06 to 4.17.

In southern Italy, Vitagliano (1956a) showed that the iron content of musts did not exceed 10 to 12 mg. per liter unless continuous presses were used, in which case the iron content may amount to 20 to 22 mg. per liter. In wines it amounted to 10 to 100 mg. per liter! However, the iron content of the wine was closely correlated with that of the must if normal equipment was used. The iron content of wines stored in cement containers was six times that of wines stored in wood. For


ordinary wines, cement-lined tanks and stainless steel containers were satisfactory, but for wines to be bottled, wooden containers were pre- ferable. In 17 washed and unwashed grapes, Pozzi-Escot (1938) fomd 7.3 and 8.8 mg. of iron per kilogram respectively. Byrne et al. (1937) found the iron content of 57 California musts to vary from 1.5 to 23 mg. per liter (average 8.6). During fermentation of 16 musts they showed the iron content to decrease from an average of 9 to 1.8. Winery contact with metals seems to be the primary source of iron.

Capt (1957) also concluded, on the basis of analyses of 608 Swiss wines, that equipment contamination was the main cause of excessive iron but, in nearly all cases, citric acid would protect the wines against cloudiness.

The order of corrosion resistance of various metals to wine, given by Ash (1935), was chromium steel (18-8), Duriron, corrosion (and other silicon-iron) alloys, bronzes (such as Amberac and Tobin), copper, Monel metal, brass, nickel, aluminum, aluminum alloys, wrought iron, steel, lead, tin, cast iron, and zinc. This order would certainly not be considered correct today. The most satisfactory metal tested by Filipello (1947) was Inconel No. 8. However, very high volatile acidity developed during the test and was possibly a factor in the unsatisfactory results obtained with Monel and Dural. While Mrak and Fessler (1938) found 2.3 to 25.5 mg. per liter of iron in 14 fresh California musts and 9.5 to 52.8 in nine of the musts after crushing, they found that much of this was lost during fermentation. Schanderl (1938) found the loss to be due to absorption by yeast.

Iron, in small amounts, favors a decrease in rH during aging, according to Schanderl and Schulle (1936). In larger amounts, about 26 mg. per liter, it may reduce the rate of fermentation, according to Schanderl (1938, 1950). The decrease in iron content during fermentation is well known. The data of Schanderl (1950) show that at this stage iron is removed by the yeast (Table XIX).

Further data on the removal of iron during fermentation are given

TABLE XIX Effect of Yeast on Iron Content during Fermentation a

Iron Content (mg. per liter)

Before fermentation After fermentation Loss Found in yeast ash

103.6 97.0 6.6 7.1 24.0 13.0 11.0 9.9 27.5 11.0 16.5 14.7 16.6 9.0 7.6 7.5 16.6 8.5 8.1 8.0 9.4 6.4 3.0 3.0

Schanderl (1950).


by Thoukis and Amerine (1956). They reported that 47.5 to 70.0% was removed during fermentation and that it was mainly incorporated in the yeast or tightly bound to it.

The presence of significant amounts of iron in filter pads was reported by Capt and Michod (1951b). In 19 samples they reported 6.6 to 59.7 mg. per 100 g. of pad. The usual recommendation of washing with 1% citric acid was made. Capt (1951) found 8 mg. per liter to be the critical content of iron. He reported certain activated charcoals to be useful in removing excessive iron, Fining agents are another possible source of iron. Salvador (1953) found traces to 10 mg. per 100 g. (average 4) in 23 samples of Portuguese gelatin and isinglass. A limit of 10 mg. per 100 g. was suggested for commercial samples.

c. Effects

Wines usually contain 5 to 20 mg. per liter of iron. These amounts are imperceptible to the taste [alterations of taste usually occur in wines when the iron content exceeds 10 mg. per liter, according to Balavoine (1950)], but they do participate in the oxidation-reduction systems in the wine, and the higher amounts may influence the appearance of the wine. Hanak (1930) was one of the first to call attention to the importance of the oxidation state of iron ions to the clouding of wines. However, Ribbreau-Gayon has contributed much to our knowledge of the mechanisms by which iron and copper cloud a wine, participate in fining procedures, and operate in oxidation-reduction systems. These studies are reviewed in two books ( Ribbreau-Gayon, 1933a, 1947) and in both, a bibliography of the original papers is given. A general theory for the iron in wine has been proposed by RibBreau-Gayon (1930). Wines stored out of contact with the air have nearly all of their iron present in the ferrous condition. Some iron is present in an organic complex. Iron and copper act as catalysts in the oxidation of sulfurous ion in wines, copper more than iron. Oxidation of tannin is also catalyzed by iron. Tannin appears to act as a antioxidant only in the presence of metallic ions. Later Ribkreau-Gayon ( 193413) showed that organic acids form complexes with iron, and this explains their advantage in winery practice. A review of the work of the Bordeaux school of enologists on complexes of iron in wine was made by Genevois ( 1933). They have shown that some of the iron complexes with the tartaric acid at a pH of about 2.5. However, phosphoric acid has a greater affinity for iron than tartaric, and citric more than phosphoric. It is this complex formation with citric acid that makes this acid a good protection against ferric phosphate casse.

The claim of Chelle et uZ. (1935) that organic acid-iron complexes


do not exist in wine was challenged by Genevois (1935). He reports iron at the anode in electrophoresis experiments. Also, oxidation-reduction potentials of ferrous-ferric solutions in the presence of organic acids show very low potentials.

Rodopulo (1953) isolated a complex iron salt of tartaric acid (of a canary-yellow color) whose catalytic activity was five times that of ferrous iron. The exact structure of these complexes is not known. Deib- ner (1956) has reviewed the theories. Using 3 ml. of wine in a Warburg apparatus, Rodopulo (1951) showed the effect of ferrous salts and complexes on the uptake of oxygen (see Table XX).

TABLE XX The Effect of Ferrous Salts and Complexes on Uptake of Oxygen by Winea

Uptake of oxygen ( y ) by 3 ml. wine in Warburg apparatus

12 hr. 36 hr. 72 hr.

Demetalized wine 3.5 4.6 5.5 Wine + 0.025 mg. FeSO, 10.7 20.5 57.8 Wine + 10 mg. FeSO, 20.6 55.7 121.7 Wine + 10 mg. iron complex 46.3 90.5 165.9

a Rodopoulo ( 1951 ).

Demetalized white wine absorbs little oxygen. The mechanism of oxygen transfer in iron-catalyzed reactions has not been determined, but it is not direct. The formation of complex unstable peroxides has been postulated. Rodopulo has made a practical application of his studies by adding iron complexes to wines (corresponding to 5-6 mg. per liter, calculated on the basis that the complex is 30% iron) stored in large containers where oxygen penetration is restricted. Aging was believed to be accelerated, With film-yeast sherries, however, Sapondzhian and Gevorkian (1953) found ferrous and ferric ions harmful to flavor development.

In several articles, Casale (1934) has reported on the solubility of iron in organic acids at various p H values and made electrometric titration curves, colorirnetrically determined the iron, made spectro- graphic determinations in the ultraviolet, and determined the oxidation- reduction potentials. He concluded that most of the iron present in wine cannot, at the pH of the wine, be present in an ionized form but must be in a colloidal condition. To prevent iron cloudiness he recommended clarifying with casein, adjusting the pH, or reducing the concentration of organic salts. Or the ferric ion can be kept in solution by increasing


the content of organic salts or by removing constituents which induce the precipitation of ferric phosphate.

Ferric and ferrous phosphates were shown by Seifert (1932) to be less soluble in lactic and tartaric acids than in malic. Hence, during the malolactic fermentation, precipitation of ferric phosphate may occur as the malic acid is destroyed. The problem of clouding due to iron has been reviewed by Heide (1933) and Ferr6 and Michel (1934). They reported the organic acids to have a dissohing action on ferric phosphate, citric acid being 30 times as effective as tartaric and about 7 times as effective as malic. They note that aeration, fining (casein preferred), and filtering the wine sometimes reduce the iron content below the danger point. TBodorescu (1943) used wheat meal and casein to remove 39.3 to 81% and 14.3 to 51%, respectively, of iron. However, even clay-fining reduced the iron 8.6 to 32%. The phytate content of the wheat meal undoubtedly was responsible. The general problem of iron removal will not be discussed here because the literature is so extensive. For reviews see Joslyn and Lukton (1953) and Deibner and Bouzigues ( 1954).

d. Amounts

A range of 5 to 30 or more mg. per liter of iron may be expected in normal French wines, according to Jaulmes (1951), but he states that 20 is considered the maximum naturally present. Mihnea (1941) determined the iron content of 87 Rumanian wines. In the Odobesti region

TABLE XXI Iron Content of Various Types of Musts and Wineso

Region No. of Minimum Maximum Average-

Type samples (mg./I.) (mg./l.) (mg./l.) ~~

~~

California Various 720 0.0 35.0 4.89 France Table 38 3.5 26.0 8.81 Germany White table 10 2.24 9.89 5.82 Germany Must 152 0.5 84.0 7.67 Italy Table 123 1.5 90.0 16.00 Portugal Various 304 1 .o 58.0 13.42 Rumania Table 33 4.0 350.0 22.0 Russia Table? 13 6.9 16.1 12.0 Switzerland Table 630 2.1 26.0 5.5

a Sources of data: California, Amerine (1947), Byrne et al. (1937); France, Deibner and Bouzigues ( 1952 ), FranGot and Geoffroy ( 1951 ) ; Germany, Remy (1932); Germany, Koch and Breker (1955), Thaler and Miihlberger ( 1956); Italy, Barini-Banchi ( 1951 ), Cerutti and Tamborini ( 1956 ), Colagrande ( 1956 ), Cusmano (1956), Vitagliano ( 1956a); Portugal, Almeida ( 1950a); Correia ( 1943); Rumania, Sumuleanu and Ghimicescu ( 1936 ) ; Russia, Schapiro and Lapina ( 1953a) ; Swit- zerland, Bemer (1952), Capt (1938, 1957).


the iron content was highest, up to 19 mg. per liter, and was associated with 50 to 70% of clouding and brawning. Blue-fining was recommended. Peynaud (1950b) reports very high iron contents in eight French dessert wines, from 15 to 45 mg. per liter, and slightly less in six Bordeaux red table wines (195oa), 15 to 24, and 10 to 18 in six Bordeaux sweet white table wines. The iron content of 73 South African wines varied from 7 to 23 mg. per liter, with turbidity occurring only above 8, according to Waal (1932). The iron constituted 90% of the total heavy metal content. Since their grapes contained only 1 to 3 mg. per liter, equipment is seen to be the primary source. Prado (1937) reported an average of 10.5 mg. per liter of iron in various Argentinean wines. Bretthauer (1956) recommended a limit of 4 mg. per liter for commercial grape juice in order to prevent cloudiness or off-flavor. The iron content of other types of wines is summarized in Table XXI.

7. LEAD

Only in recent years has the lead content of wines been determined. However, stricter enforcement of the laws establishing maximum lead content of foods has drawn attention to lead determination and possible methods for reducing lead content.

a. Methods

Fischler and Kretzdorn (1939) and Kretzdorn and Miiller (195413, 1955) used the dithizone procedure. They emphasized the necessity of using lead-free reagents, particularly nitric acid. They ash at not over 5OOOC. (932OF.), dissolve in hydrochloric acid, and rinse into glass- stoppered flasks. The color is measured in a photoelectric colorimeter, using a J61.5 filter and a 2-cm. cuvette. A standard curve is prepared, using lead nitrate solutions, and a blank must be run. Kock and Breker (1955) also employed dithizone, preferring it to the lead sulfide method for grape juices containing iron and copper. Ashing of high-sugar wines is always a difficult problem (see Section 11). Greenblau and Westhuyzen ( 1956) suggest adding iodine pentoxide followed by concentrated nitric acid. The final ashing is done in a muffle furnace at 48OOC. (896°F. ). They estimate the lead colorimetrically after extraction with dithizone in chloroform. They reported 0.25 mg. per liter in a South African red dessert wine. Applying a nitric-sulfuric acid method to the same wine, they found 0.27 mg. per liter.

b. Amounts

Lead sprays are used in European vineyards, and the question of the lead content of musts and wines has been studied by Kielhofer ( 1930). He reviewed previous work, which generally indicated contents


of 0.38 to 8.0 mg. per liter of must and 0.13 to 2.2 mg. per liter of wine although as much as 11 mg. have been reported in wine. He found 1.4 mg. in wine, 1.1 after the first racking and 0.5 after the second racking. (Lead tartrate is very insoluble. ) Potassium ferrocyanide (blue-fining) removed only a small amount of the lead. Fransot (1954a) showed that lead sprays do increase the lead content of musts. Up to 50% of the lead was lost during fermentation when small amounts were present, more with large amounts. Gentilini ( 1944-1945), however, approved of the use of lead sprays. Konlechner et al. (1941) reported that settling the must reduced the lead content 33 to 81%. According to Kock and Breker (1955), French grape juice should not contain over 1.6 mg. per liter. Of 55 grape juices of the 1954 vintage imported into Germany, only one-third fell below 0.3 and two-thirds below 1.6 (0.0 to 13.0, average 2.3). The others should have been condemned if 1.6 mg. per liter is the limit. Larkin et al. (1954) reported under 0.5 mg. per liter in an American grape jelly but only 0.02 in a grape concentrate.

In Russia, Bolotov (1939) found 0.10 mg. per liter of lead in five grape juices and 0.12 to 0.14 in nine wines. In four laboratory-fermented samples, the average lead content was 0.06 mg. per liter. The lead originated from lead-containing metals and paints as well as from the fruit. He suggested that a tolerance of 0.2 mg. per liter of lead be established, The lead content should not exceed 0.35 mg. per liter in German wines, but 0.2 is the limit in water. Few German wines exceed this limit. The source is believed to be lead sprays, lead in filter pads, lead in silver as an impurity, and lead capsules. Querberitz (1954) also mentions that glass may contain lead. Westhuyzen (1955) reports the British limit as being set at 0.5 mg. per liter for spirits and 1.0 for wine. To reduce lead contamination he recommended that all paints, buckets, solders, pipes, packings, washers, and hoses used in any aspect of wine-making be as nearly lead-free as possible. Hickinbotham (1954) refers to the generally accepted limit of 0.2 mg. per liter as being too high for many wines. Cerutti and Tamborini (1956) found 0.0 to 0.9 (average 0.2) mg. per liter in 40 Italian wines. Rankine (1955) found 0.04 to 0.86 (average 0.23) mg. per liter in 55 Australian wines. A good review of the literature may be found in this work.

Kretzdorn and Muller ( 1954b) reported 0.01 to 0.33 (average 0.11) mg. per liter in 50 Baden wines. The sources of lead have been under extensive study because of the limits that have been established. FranGot (1954a) found 0.14 and 0.15 mg. per liter in musts of grapes sprayed with DDT. The wines contained 0.105 and 0.075. In blocks sprayed with lead arsenate, the musts contained 3.2 and 4 mg. per liter and the resulting wines 0.19 and 0.45. Almeida (1946b, 1947) reported small, but in some cases abnormal, amounts of lead in bottled wines. In 54 samples


of port wine 32% had only traces, 32.5% had less than 1 mg. per liter, 20.5% from 1 to 2 mg. per liter, and 15% between 2 and 2.6 mg. per liter. In seven non-Portuguese wines the range was 1.8 to 3.5. A whisky and a brandy had 3.2 and 0.8. Almeida (1947) than systematically investigated the possible sources of the lead in port wines. Since fresh grape juice from unsprayed vines had little or no lead, the suspicion fell first on lead impurities in the commercial copper sulfate used for spraying. The lead content was as high as 25 mg. per liter in one sample. Since considerable alcohol is added to port wine during and after fermentation, 15 Portuguese brandies were checked. These contained traces to 0.6 mg. per liter (average 0.28). This much, he believed, might be dissolved from the solder in the serpentine of the still. Some lead was detected in solutions in contact with vulcanized red-rubber hoses. But the primary source of the lead was found to be the lead capsules. Just how the lead migrates into the wine through the cork is not clear. Ferr6 and Jaulmes (1948) and Querberitz (1954) also found the lead capsules to be the primary source of the lead in wines.

Greenblau and Westhuyzen (1957) found the chief sources of excessive lead in South African wines to be lead-containing paints, lead solders, rubber hoses, gasoline engines, and possibly animal charcoal. Rankine (1957) noted that only about 30% of the small must lead is lost in fermentation. In Australia rubber hoses and lead-containing brass (in pipes) were the main sources.

Gajdos et nl. (1953) reported a case of 41 men on a French ship who suffered from acute lead poisoning after drinking a wine containing 4.5 mg. per liter of lead. The clinical details were given.

8. MAGNESIUM

Reichard ( 1942) proposed two methods for determining magnesium in wines, Lasserre (1932-1933) found the magnesium:calcium ratio to vary from 0.4 to 1.1 in grapes, from 1 to 2 in pressed musts, from 2 to 2.6 in white wines, and from 3 to 4 in red wines. The approximate range of magnesium in French wines was given as 0.05 to 0.136 g. per liter by Brkmond (193713). Gartel (1955) reported 0.11 to 0.14 in unstemmed and stemmed Moselle musts. Correia (1956) found 0.050 t o 0.073 (average 0.058) g. per liter in 16 Portuguese dessert wines. The magnesium content of some other types of wine is summarized in Table XXII.

9. MANGANESE

MCric (1940) reviewed the procedures proposed for the determination of manganese in wine. Ghirnicescu and Kotcis (1938) procedure for manganese is hardly a micromethod, as indicated, since 50 ml. of sample


TABLE XXII Magnesium Content of Various Types of Winesa

-~ ~

Region No. of Minimum

Type samples ( g. 11.

Algeria Table 8 0.072 France Various 42 0.074 Germany White table 8 0.073 Portugal Various 14 0.045 Switzerland Table 3 0.072

Maximum Average (g.11.) (€511.)

0.136 0.098 0.165 0.123 0.091 0.084 0.120 0.072 0.091 0.080

a Sources of data: Algeria, Br6mond ( 1937a); France, Genevois et al. ( 1949), Lasserre ( 1932-1933), Peynaud ( 1950a, b ) , Ribkreau-Gayon et al. ( 1956); Ger- many, Reichard (1942); Portugal, Correia and Jicome (1942a), Sim6es (1951); Switzerland, Godet and Martin ( 1946).

is used. Moreover, it is based on the same principle as Heide and Hen- nig’s ( 1933a) procedure, oxidation to permanganate and colorimetric determination, Recently Bouzigues and Bouzigues ( 1956 ) have given a colorimetric procedure with an error of only 2% for concentrations above 0.5 mg. per liter.

Following Flanzy and Thkrond’s (1939) report of higher manganese in hybrids, MBric (1940) studied the manganese content of a large number of wines and found it very variable. He confirmed in a general way the higher manganese content of hybrids; however, because of the variability, he saw little interest in the determination. Motoc and. Popesdu (1941-1942) studied the physical and chemical properties of the wines of “direct producers” in Rumania. The manganese content again appears to be higher in the hybrids. Wurziger (1954) reported 0.40 to 2.48 (average 1.33) mg. per liter in six German hybrid wines. The data of Bouzigues and Bouzigues (1956) showed hybrids with about twice the manganese of nonhybrids. A definitive study needs to be made, but it appears that soil differences, etc., may also be important, and this factor would reduce the diagnostic value of the determination as far as identifying hybrids is concerned.

Ghimicescu and Kotcis (1938) reported 1.0 and 1.5 mg. per liter of manganese in two Rumanian wines. Using a polarographic procedure, Almeida (1949b) found traces to 4.7 mg. per liter of manganese in 29 ports (average 1.7). He noted, without giving any figures, that the manganese content of 10 unfermented musts was in the same range. Flanzy ( 1938) reported small amounts of manganese to stimulate development of Mycodermu h i (Kloeckera sp.) and of acetification. About 5 to 7% of the original manganese of the must is lost during fermentation. In four wines he reports 0.57 to 0.85 mg. per liter (average 0.76).


Berner (1952) reported 1 to 15 mg. per liter in eight Swiss wines (average 5.6). Kretzdorn ( 1944) found 0.22 to 1.88 mg. per liter of manganese in genuine German wines, Wines containing over 2.5 mg. per liter are considered sophisticated, either from treatment with potassium permanganate or with manganese-containing charcoal. Thaler and Muhlberger (1956) found 0.0 to not over 6.0 mg. per liter in five Pfalz white wines. Frolov-Bagreev and Andreevskaia (1955) found 0.47 to 5.32 mg. per liter (average 1.92) in 26 Russian wines. In six Bordeaux red wines, Peynaud (1950a) reported 0.8 to 1.8 mg. per liter (average 1.2) and in six whites, 1.2 to 3.3 (average 2.1). Ribkreau-Gayon et al. (1956) found 0.8 and 1.4 mg. per liter in one red and one white Bor- deaux wine. Wurziger (1954) reported 0.0 to 3.20 (average 0.97) mg.. per liter in 70 wines of various European countries. In four French wines in which he found 38 to 72 mg. per liter, treatment with permanganate was indicated (apparently to reduce high sulfur dioxide contents). Deibner and BCnard (1956) reported that additions of manganese ranging from 5 to 15 mg. per liter to sweet wines plus heating improved their organoleptic quality.

10. MERCURY A procedure for determining mercury in wines was studied by Mar-

tini and Berisso (1945). This involved displacement with copper and conversion of the iodide to a mercury cobalt thiocyanate.

11. MOLYBDENUM Frolov-Bagreev and Andreevskaia (1955) reported only 0.001 to 0.1

mg. per liter (average 0.02) of molybdenum in 26 Russian wines. Deib- ner and BBnard (1956) reported that adding 1 to 5 mg. per liter of molybdenum, with or without manganese, followed by heating, improved the organoleptic quality of sweet wines.

12. POTASSIUM Although potassium constitutes about three-fourths of the cation

content of wines, it has not been studied as extensively as it should be, probably because of the difficulty in its accurate determination. Flame photometry, however, now offers a method giving accurate results, and further analysis may be expected. One interesting aspect of potassium is its extreme variability in grapes and wines.

a. Methods

SBmichon et al. (1930) reviewed the methods used to determine potassium in musts and wines. They preferred precipitation as calcium

194 MAYNARD A. AMEFUNE

racemate. Tartrate precipitation procedures were also employed by Debordes ( 1931-1932), Dubaquid (1932), Brkmond ( 1937b), and Aus- terweil (1955). Reviews of a number of methods for the determination of potassium were given by Ghimicescu ( 1 9 3 5 ~ ) and Jaulmes (1951). Both favored cobaltinitrite as the reagent. A comparison of old and new methods is given by Bonastre (1955), who preferred flame photometry or tetraphenylborate to the tartrate and cobaltinitrite procedures. Never- theless, Deibner and Bknard (1955b) used wet-ashing of the wine and precipitation of the acid tartrate, using aniline tartrate in the presence of methyl alcohol at 0°C. (32OF.). Good recovery was obtained for added potassium but the procedure takes 7 to 8 hours, Wiseman (1955) has also recently employed the tartrate method. The tetraphenylborate procedure was favored by Reichard ( 1954). Satisfactory results were obtained both on ashed samples and on charcoaled wines. Austerweil ( 1955) employed the magnesium salt of hexanitrodiphenylamine. Ashing was unnecessary and the potassium precipitate could be determined colorimetrically or dried and weighed. Sodium tetraphenylborate was employed by Garino-Canina ( 1955) for the volumetric determination of potassium in grape leaf material, musts, and wines. The procedure was similar to that of Reichard and was adapted to semimicro quantities ( 1 ml. of wine).

b. Amounts

Potassium fertilization was believed by Hugues and Bouffard (1935) to increase yield as well as to improve the composition and quality of the wines. Where a very high level of potassium fertilization was maintained for several years, there was a lower fixed acidity and higher potassium content in the wines, particularly in a cool season. Most French workers believe more potassium is translocated to the fruit during rainy weather. Flanzy (1948), for example, gives this as a cause of the high potassium content of the 1943 wines. More data are needed. Giirtel (1955) found no difference in the potassium content of musts prepared from stemmed and unstemmed grapes.

In view of its importance in connection with tartrate precipitation, potassium should aIso be determined, according to Dubaquid ( 1932). The potassium content as a factor in tartrate precipitation has also been stressed by Nkgre (1954). He expresses the solubility as a function of bitartrate and tartrate ions and gives an equation for calculating the potassium acid tartrate content of a wine. Examples of high-potassium and high-tartrate wines are given. A similar study was made by Wise- man ( 1955). He found solubility-product determinations to be useful in predicting whether tartrate precipitation would occur or not. The true


solubility-products varied from 1.40 to 2.85 X compared with 8.2 to 21.8 x for calculated values. However, he found that a simple test of the wine's stability to cold was best. The potassium content was higher than expected from the acid-tartrate content. The potassium content of various types of wines is given in Table XXIII.

TABLE XXIII Potassirin Content of Various Types of Wines Q

~~

Region

~~

No. of Minimum Maximum Average Type samples (g . / l . ) (g./l.) (g./l.)

Algeria Table 8 0.850 1.180 1.120 California Table and dessert 71 0.50 1.53 0.92 California b Table 155 0.281 1.580 0.940 California b Dessert 104 0.109 1.420 0.897 France Table 13 0.094 1.760 0.654

Portugal Various 65 0.115 0.924 0.356 Rumania Table 90 0.190 0.950 0.554 Switzerland Table 11 0.505 1.170 0.950

Germany Table 21 0.627 1.293 0.903

a Sources of data: Algeria, BrCmond (1937a); California, Anierine and Kishnba ( 1952); France, Genevois et al. ( 1949), RibCreau-Gayon et al. ( 1956); Germany, Reichard (1954), Remy (1932); Portugal, Almeida (1950b), Babo (1951), Correia and Jicome ( 1942a), Simdes ( 1951 ); Rumania, Ghimicescu (1935a), Sumuleanu and Ghimicescu (1936); Switzerland, Berner ( 1952), Godet and Martin ( 1946).

b Lucia and Hunt ( 1957).

13. RADIUM Frolov-Bagreev and Andreevskaia (1950) showed that the radium in

26 Russian wines varied from 0.7 to 2.7 x lo-'" mg. per liter (average 1.27).

14. RUBIDIUM Bertrand and Bertrand (1949a) reported 0.22 to 1 mg. per liter

(average 0.46) of rubidium in ten French white wines and 0.22 to 4.16 (average 1.15) in ten French red wines, The higher rubidium in the reds is due to the higher rubidium content of the skins and stems. A wine fermented from the free-run contained 0.36 mg. per liter, while it had 0.60 when fermented on the skins, Bertrand and Bertrand (1949b) found the skins and stems to be richer in rubidium than the pulp. Hence, wines prepared from the juice only should be lower in rubidium. This proved correct as white wines showed less than 1 mg. per liter, pinks 0.54 to 1.97, and reds 23 mg. per liter.


15. SILVER To determine small amounts of silver in wines, Jendassik and Papp

(1936) wet-ashed a liter of wine, made the residue slightly alkaline, filtered, and made the filtrate acid. The silver was determined colorimetrically on an aliquot with p-dimethylaminobenzylidene rhodanine. Use of minute amounts of silver as an aid to wine stability and quality has been reviewed by Dubsky and Gero (1937) and Dal Cin (1950).

16. SODIUM

Wines differ from many biological materials in having very little sodium in comparison with potassium. Sodium content of wines has recently become of interest in relation to low-sodium diets. It is also of interest in connection with the use of cation exchange resins.

a. Methods

Grohmann (1941) criticized Reichard's (1936) high results as due to technique. On the other hand, although he reported a sodium content of below 20 mg. per liter for 1934 and 1935, in 1936-1939 higher sodium contents were found. These he attributed to sodium in the sugar-water solutions used for treating low-sugar high-acid musts, to the sodium in cleaning compounds or in cask cleaners, to sodium nitrate fertilization (his own results showed no such increase), or to added sodium salts (such as sodium phosphate or bisulfite). Reichard (1943a) used the gravimetric magnesium uranyl acetate procedure for sodium. Previous results by Grohmann and Reichard were criticized as being too high. When more than 30 mg. per liter was present in Pfalz wines, it was believed that sodium had been added. Almeida (1950b) determined sodium and potassium using a polarographic procedure, while Amerine and Kishaba (1952) and Amerine et al. (1953) employed a flame photometer as did Lucia and Hunt (1957).

b. Amounts of Sodium

In normal French wines Genevois and Ribdreau-Gayon ( 1933) reported a range in sodium of 0.023 to 0.230 mg. per liter. In about 98 Rhine wines Hennig and Villforth (1938) reported 14.9 to 37.9 mg. per liter of sodium. Herrmann (1952) reported 1 to 25 mg. per liter of sodium in Baden wines, with an average value of 10 mg. per liter. The sodium content of German (Baden) wines is low according to Reichard (1943a) as he found less than 26 mg. per liter in them, and in most less than 20. German wines should have below 30 mg. per liter, he concluded, but genuine imported wines may contain up to 300 mg. per liter, particularly when the grapes are grown near the ocean. In 39 American and 12 foreign beers, Stone et al. (1941) reported the sodium


content to range from 9 to 170 mg. per liter (average 68). The explana- tion of the high chloride content of some Mediterranean wines was believed by Merz (1934) to be due to addition of sea water, particularly along the Dalmatian coast.

Grohmann (1939) investigated the claim that the value for the sodium chloride content calculated from the sodium determination is similar to the value calculated from the chloride content. H e found very little relation between the two as the selected date in Table XXIV indicate.

The sodium content of various types of wines is summarized in Table XXV.

TABLE XXIV Comparison of Values of Sodium Chloride Content Calculated from Chloride

and Sodium Determinations a

Type of wine

White table White table White table Red table Red table Red table Dessert

Chloride (mg./ l . )

43 28 53

596 213 138 184

NaCl Cnlc. Sodium (nig./l.) ( mg. /l. )

70 16 47 17 87 30

892 131 351 80 228 343 304 443

NaCl Cnlc. (mg./l.)

40 44 77

332 203 871

1126

a Grohmann ( 1939 ).

TABLE XXV Sodium Content of Various Types of Wines a

Region No. of

s a m p 1 e s Type Minimum (mg./I. )

hlaximuni Average (ing./l.) (mg./l .)

Algeria California California b California b

France Germany Miscellaneous Portugal Spain Switzerland

Table 8 Table and dessert 146 Table 155 Dessert 104 Various 28 Table 187 Dessert 24 Various 33 Table 4 Table 11

51 26 10 15 30 5

19 30 80 23

~~~

162 118 400 85 172 55 253 71 125 62 43 15

443 167 87 58

343 22 1 65 41

a Sources of data: Algeria, BrPmond ( 1937a); California, Anierine and Kishabn ( 1952); France, Peynaud ( 195Oa, b ) , Ribkreau-Gayon et al. ( 1956); Germany, Alfa (1932), Grohmann (1939), Reichard (1936, 1943a); Misc., Reichard (1943a); Portugal, Almeida (1950b), Correia (1956), Correia and Jhcome (1942a), Sim6es (1951); Spain, Grohmann ( 1939); Switzerland, Berner (1952), Godet and Martin (1946).

b Lucia and Hunt ( 1957).


17. TIN, TITANIUM, AND VANADIUM Kielhijfer and Aumann (1955) found wines to cloud when in contact

with metallic tin. The reaction of tin and sulfite leads to the formation of hydrogen sulfide and free sulfur, Protein precipitation also occurs when wines containing tin are heated. Neither tin nor tinned containers should be employed in wineries. The normal tin content of wines is below 1 mg. per liter.

Frolov-Bagreev and Andreevskaia ( 1955) determined the titanium content of Russian wines. In eight of them they found a trace to 0.58 mg. per liter (average 0.107). Traces were also found in the ash of Spanish wines by Dean (1951). The Russian workers also reported a trace to 0.58 mg. per liter (average 0.046) of vanadium in their wines.

18. ZINC The use of zinc-containing insecticides and fungicides has stimulated

interest in the determination of zinc in musts and wines (see Section 11).

a. Methods The earlier work was reviewed by Villforth (1940). The purple color

of zinc with dithizone has been the basis of several procedures. Villforth ( 1940) has emphasized the possible errors of earlier direct procedures (see Heide and Hennig, 1933a) and proposed precipitation with ferrocyanide, tannin, and gelatin; ashing; and development of the color with dithizone in a buffered solution, The color is compared with standards using a Pulfrich photometer. Yields of 96.6 to 98.8% were obtained. Kiel- hofer and Giinther (1941) also used the dithizone procedure. A rapid oxyquinoline procedure for zinc was proposed by Ney (1948). Hennig and Burkhardt (1954) used a polarographic procedure for zinc in the ash as did Francesco (1954a).

b. Amounts

Ney (1948) stated the normal zinc content of French wines to be 0.3 to 0.8 mg. per liter. A wine containing 100 mg. per liter had a metallic taste, and at higher concentrations a styptic taste. A metallic taste was conisdered to be the main danger of excess zinc. Villforth (1940) reported 5 mg. per Iiter of zinc as the maximum, above which blue-fining should be practiced to prevent a metallic taste. In three German musts and wines, which may have been sprayed with sprays containing zinc, Villforth found 2.7 mg. per liter in the must and 1.25 and 6.45 mg. per liter in the wine. He noted that undissolved zinc oxide may precipitate out on clarification. Querberitz (1951) found 17 mg. per liter in five Moselle wines, whereas Giirtel (1955) reported 1.5


to 3.4 mg. per liter in Moselle musts. In two Chilean wines Micheli (1951) found 0.96 mg. per liter. In a German must, Villforth (1940) reported 2.7 mg. of zinc per liter. In two wines he found 1.3 and 6.5 mg. per liter. Kielhofer and Giinther (1941) found 1 to 3 mg. per liter in 33 normal German wines, although slightly higher amounts were found in a few wines, and particularly in two from a small producer. Hennig and Burkhardt (1954) found 0.0 to 5.4 mg. per liter (average 2.4) in 10 German wines. Querbertiz (1951) reported 17 mg. per liter of zinc in four German white wines by the dithizone procedure. Heide and Hennig (1933b) reported 0 to 18.5 mg. per liter of zinc in 38 German musts (average 5.0). Tarantola and Bianco-Crista ( 1957) found 0.57 to 5.60 (average 2.35) mg. per liter in 14 Italian red wines, 0.93 to 2.86 (average 1.91) in 3 pink wines, and 0.45 to 4.80 (average 1.40) in 8 white wines. From 36 to 56 per cent was eliminated during fermentation. This was slightly less in the presence of sulfur dioxide and slightly more if sulfur was added before fermentation. Giirtel (1957b) reported 0.5 to 2 mg. per liter (average 1.0) of zinc in 14 German musts. Up to 3.5 was found in musts from heavily pressed pomace.

The accidental occurrence of zinc in wines due to contact with zinc was emphasized by Seiler (1932), who found 104 to 167 mg. per liter in two wines, The solubility of zinc in organic acids would naturally favor this. The observation of Seifert and Ulbrich (1933) that copper and iron are removed by ferrocyanide before zinc was an unfortunate one as it led to procedures, still used in Greece and elsewhere, whereby zinc sulfate is added before the ferrocyanide in order to insure removal of all the heavy metals. Francesco (1954b) also found residual zinc in blue-fined wines.

V. RESEARCH NEEDS

The importance of the inorganic components of wines to their stability and quality obviously means that more data are needed on the sources and amounts present in wines. What is particularly required are studies in which the total biochemical status of the wine as well as the amount of a particular metal is known, Admittedly it is difficult to obtain such data now that routine analyses are so expensive. However, the interrelationship of metal content with changes in organic constituents, physical measurements (such as redox potential ), and sensory quality cannot be detected by piecemeal analyses.

Analytical procedures suitable for such a program are not always suitable, Methods that are rapid yet accurate are needed. In some cases the flame photometer would represent a notable advance. In others the polarograph appears useful. More specific colorimetric procedures need to be developed for certain metals.


The ionic forms in which the metals are present in wines is still largely unknown. Application of the more recent knowledge of inorganic chemistry should aid in a solution of this problem. This would also be an aid in interpreting the part which the various metals play in the aging of wines. It might also suggest better methods of controlling the pickup of metals or in their removal.

The role of many of the minor elements is still obscure. Data on amounts, stability, and sensory quality are needed. The biochemistry of these elements also requires further studies. Some, at least, may play a role in fermentation, wine stability, and quality.

The addition of metals needs to be systematically studied. If small amounts improve wine stability or sensory quality methods for adding them should be investigated. However, addition of metals as antiseptic agents where not now authorized obviously should not be made unless specific approval from Public Health authorities is obtained.

ACKNOWLEDGMENTS

I am indebted to Professors J. G. B. Castor, M. A. Joslyn, and A. D. Webb and Mr. Harold Berg for reading the manuscript, and for their suggestions. I wish also to thank Mr. John Sekerak of the University Library for his patience in checking many of the references. I am particularly grateful to Mrs. Angela Arnold for so carefully typing the manuscript. The errors that remain, however, are the author’s.

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Chelle, M., Dubaquik, J., and Turbet. 1935. Btude toxicologique sur le collage bleu. Bull. SOC. chim. France 2, 845-864; see also Bull. ofice intern. uin 8( 86) , 49-67 ( 1935 ) .

Chierego, N. 1954. Contenuto in rame nel vino. Riv. uiticolt. e enol. (Conegliuno) 7, 387-388.

Colagrande, 0. 1956. Deterniinazione colorinietrica, con ortofenantrolina, del contenuto di ferro nei vini. Riv. viticolt. e enol. (Conegliano) 9. 167-172.

Cordonnier, R. 1953. Le fer et ses origines dans le vin. Ann. technol. agr. (Paris) 2,

Correia, E. M. 1942a. As caracterisicas Qcidas dos vinhos da regiHo vinicola de Colares. Junta Naciorral do Vinho, PBrto. p. 11. (Paper read at Congresso Luso- Espanhol para o progresso das ciCncias.)

Correia, E. M. 194213. Riqueza em sulfatos dos vinhos brancos adamados. Junta Nacional do Vinho, PBrto. p. 8. (Paper read at Congresso Luso-Espanhol para o progresso das ciCncias.)

Correia, E. M. 1943. Riqueza em Acido fosf6rico e ferro de alguns vinhos de pasto portugueses. Anuis inst. super, agron. Uniu. te'c. Lisboa 14, 327434.

Correia, E. M. 1956. Le vin de liqueur "Muscat de Setubal" et son identification analytique. Bull. ofice intern. uin 29( 299), 383-395.

Correia, E. M., and Jicome, J. C. 1942a. Riqueza em sulfatos dos vinhos brancos adamados. Anais inst. super agron. Univ. te'c. Lisboa 13, 143-147.

Correia, E. M., and JQcome, J. C. 194213. VerificaG.50 da exactidzo e rigor da anilise quimica em enologia. Amis inst. super. agron. Univ. te'c. Lisboa 13, 149-153.

Correia, E. M., and Jicome, J. C. 1943. Riqueza em sulfatos e cloretos de alguns vinhos portugueses. Anais inst. super. agron. Univ. te'c. Lisboa 14, 343350.

Correia, E. M., and Vilas, M. A. 1943. Subsidio para o estudo das caracteristicas fisicas, quimicas e fisico-quimicas dos vinhos da regiCo deinarcada de Colares. Anius inst. super agron. Uniu. te'c. Lisboa 14, 359-360.

Cosmo, I. 1950. Ulteriori indagini sui vini rosati e cerasuoli delle Venezie. Ann. spec. agrar. (Rome) [N.S.] 4, 803-817; see also Annuar. staz. sper. viticolt. e eml. (Conegliano) 14{ 9), 1-15 (1950-51).

Crawford, C. 1951. Calcium in dessert wine. Proc. Am. SOC. Emlogists 1951, 76-79. Cultrera, R. 1937. Sulla valutazione del potere antifermentativo reale dell' acido

solforoso aggiunto ai mosti d'uva, ai vini dolci ed ai succhi di frutta in genere. Ann. chim. appl. 27, 499-504.

Curli, G., and Prati, V. 1954. Ricerche dell'acido monobromoacetico e dei suovi esteri nelle bevande. Chim. e ind. (Milan) 36, 704-705.

Cusmano, I. 1956. I vini e i terreni vitati delle marche. Ria uiticolt. e eml. (Cone- gliano) 9, 279-288.

Dal Cin, G. 1950. I derivati alogenati dell'acido aeetico in enotecnia. Riu. uiticolt. e enol. (Conegliuno) 3, 357-361, 387393, 419-428.

solforoso. Ann. fac. agrar. univ. studi, Perugia 5, 27-40.

165-175.

1-13.


Dalmasso, G., and Dell'Olio, G. 1937. I vini bianchi tipici dei colli Trevigiani. Annuar. staz. sper. utticolt. e erwl. (Conegliano) 7, 3-115; see also Ann. sper. agrar. (Rome) 25, 4-93 (1937).

Dalmasso, G., Cosmo, I., and Dell'Olio, G. 1939. I vini pregiati della provincia di Verona, Annuar. staz. sper. viticolt. e enol. (Conegliarw) 9 ( 2 ) , 1-197.

Dean Guelbenzu, M. 1951. Nota sobre el contenido en oligoelementos de la cenizas de vino y vinagre. Anules bromutol. (Madrid) 3, 319-322.

Debordes, G. 1931-33. Dosage de la potasse et de l'acide tartrique dans les mofits et dans les vins. Proc. verb. sban. SOC. sci. phys. nut. Bordeaux 1931-32, 14-16.

Deibner, L. 1949, Microdosage iodomktrique du fer et son application au dosage du fer dans les vins et les jus de raisin, Paris, Dunod. p. 92. These Facultk des Sciences de l'universitk du Montpellier.

Deibner, L. 1950. Un nouveau prockd6 de submicrodosage iodomktrique du fer, son application aux substances minerales ou organiques et, en particulier aux vins, aux moGts de raisin et aux jus de fruits. Mikrochemie ver. Mikrochim. Actu 25, 488-514; see also Bull. SOC. chim. France 15, 1125-1142 (1948); Ann. agron. [N.S.] 19, 843-924 (1949); Chim. anal. 31, 228-253 (1949).

Deibner, L. 1952. Les recherches effectukes en U.S.S.R. sur le rBle des microdkments dans la biochimie du raisin et du vin. Ann. technol. agr. (Paris) 1, 177-180.

Deibner, L. 1953. Sur les particularitks du dosage iodomktrique de petites quantitks d'anhydride sulfureux libre et combink a l'acktaldbhyde en solution diluke et, en particulier, dans les distillats des vins. Ann. technol. agr. (Paris) 2, 207-242.

Deibner, L. 1956. Donnbes actuelles sur les processus de l'oxydation de l'acide tartrique et sur la skparation chromatographique des acides organiques du vin. Ann. technol. agr. (Paris) 5 , 141-157.

Deibner, L., and Bknard, P. 1953. Recherches sur la sbparation quantitative, B Iiide d'un nouvel appareil distillatoire, de l'anhydride sulfureux contenu dans les liquides organiques, et sur les conditions de sa stabilitk dam les distillats. Inds. agr. et aliment. (Paris) 70, 11-15, 187-195.

Deibner, L., and Bknard, P. 1954a. h d e du dosage de l'ion sulfurique dans les vins a p r h la separation de l'anhydride sulfureux. Inds. agr. et ailment. (Paris) 71, 23-30.

Deibner, L., and BBnard, P. 1954b. Valeur analytique du dosage de l'ion sulfurique dans les vins sous forme de sulfate de baryum. Inds. agr. et aliment. (Paris) 71, 427-436.

Deibner, L., and Bknard, P. 1955a. Dosage de l'anhydride sulfureux total et de l'ion sulfurique dans les liquides organiques. Application a m vins, aux jus de raisin et a m solutions de sucre cristallis6. I d s . agr. et aliment. (Paris) 72, 565473, 673-676.

Deibner, L., and Bknard, P. 1955b. Nouvelle technique de dosage du potassium dans les vins par prkcipitation Q l'ktat de tartrate acide. Ann. fals. et fraudes

Deibner, L., and Bknard, P. 1956. Recherches sur la maturation des vins doux naturels. 11. Essai de catalyseurs mktalliques. Ann. technol. agr. (Paris) 5 , 377-397.

Deibner, L., and Bouzigues, H. 1952. Dosage klectrophotocolorimetrique de traces de fer total dans les vins ?i l'acide de l'orthophknanthroline. Ann. technol. agr. (Paris) 1, 283309.

Deibner, L., and Bouzigues, H. 1953a. Les mkthodes de dosage colorimetrique des traces de fer dans les vins. Ann. technol. agr. (Paris) 2, 65-74; see also Mikro- chim. Actu 1954, 501-508 ( 1954).

48, 165-180, 217-222.


Deibner, L., and Bouzigues, H. 1953b. ProcCdk rapide de traitement oxydatif des vins secs ou sucr6s par voie humide i I'aide du peroxyde d'hydrogcine; son application au dosage 6lectrophotomCtrique de traces de fer B I'aide de I'orthoph6n- anthroline. Ann. technol. agr. (Paris) 2, 301321.

Deibner, L., and Bouzigues, H. 1954. Sur l'action de quelques agents de fenisants employes en oenologie. Inds. agr. et aliment. {Paris) 71, 833-837.

Deibner, L., and Bouzigues, H. 1955. Dosage de l'anion orthophosphorique dam les vins par le procCdB Blectrophotonktrique au bleu phosphomolybdique. Ann. technol. agr. {Paris) 4, 309-334.

De Soto, R. 1951. Survey of the methods for calcium determination. Proc. Am. SOC. Enobgists 1951, 80-89.

De Soto, R., and Warkentin, H. 1955. Influence of pH and total acidity on calcium tolerance of sherry wine. Food Research 20, 301309.

DestrCe, G, 1939. La recherche des fluorures dans les vins, bicires, confitures et gelCes de fruits, et dans les beurres et margarines. I. pharm. Belg. 21, 501504,

Dougnac, F. 1935. Le Vin aux Points de Vue Physico-chimique, Physiologique, HygiCnique, ThCrapeutique, 2 ed., p. 354. Editions Delmas, Bordeaux.

DubaquiC, J. 1932. Potasse et compos6s tartriques dans les vins. Ann. f a k . et fraudes 25, 280-285; see also Proc. uerb. SOC. sci. phys. nut. Bordeaux 1931-32, 8-14 (1932).

Dubaquik, J. 1933. A propos du dosage colorim6trique du fer dans Ies vins rouges. Ann. fals. et fraudes 26, 418420.

Dubsky, S., and Gero, F., 1937. Der Einfluss des Silbers auf Wein und Spirituosen. Winzer (Prague) 3, 91-92, 105-106, 110-112.

Dukhovnyi, A. I. 1955. Determination of copper and iron in cognac (transl.). Vino- delie i Vinogradarstuo S . S . S . R . 15( 6 ) :2%29.

Dupaigne, P. 1951. Contribution h l'6tude d'un microdosage de I'anhydride sulfureux dans les moGts de raisin. Ann. fals. et fraudes 44, 111-121.

Dupuy, P., Nortz, M., and Puissais, J. 1955. Le vin et quelques causes de son en- richissement en fer. Ann. technol. agr. (Paris) 4, 101-112.

Ebach, K. 1957. Bromhaltige Konservierungsmittel in Wein und deren Nachweis. Deut. Wein-2 tg. 93, 630, 632.

Eckert, A. 1950. Sitzung des Ausschusses fur Weinforschung in Rudesheim. Z . Lebensm.-Untersuch. u. -Forsch. 90, 445-448.

Engels, 0. 1949. Die Bedeutung der Spurenelemente fur das Wachstum der Reben und die Qualitat des Wienes. Weinblutt 43, 368-387, 408-409.

Ettienne, A. D,, and Mathers, A. P. 1956. Laboratory carbonation of wine. J . Assoc. Ofic. Agr. Chemists 39, 844-848.

Fabre, J. -H., and BrBmond, E. 1934. Les fluosilicates et les vins. Ann. fals. et fruudes 27, 453466.

Fabre, R. 1942. Sur Ies teneurs maxima en cuivre et en arsenic des moilts de raisin. Aim. hyg. publ. ind. et sociule 20, 171-173.

Fantini, C. 1940. Existencia normal y anormal del hierro en 10s vinos argentinos. Metodos fisicos y quimicos para su evaluacibn. Reu. fac. cienc. quim. Uniu. nacl. La Plata 15, 271-278.

Fellenberg, Th. von. 1932. Kupferbestimmung in Wein. Mitt. Gebiete Lebensm. U. H y g . 23, 70-71.

Fellenberg, Th. von. 1937. Die Bestimmung kleinster Fluormengen in Lebensmitteln. Mitt. Gebiete Lebensm. u. H y g . 28, 150-169.

F e d , L., and Jaulmes, P. 1948. Les capsules en Btain plombifhre, cause de la pres-

527-530.


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Traubenwein und Traubensiissmost nach verschiedenen Methoden. VorratspjZege u. Lebenmittelforsch. 2 , 223-229.

Flamand, J. 1935. Biochimie oenologique. Bull. assoc. anciens 918ues inst. sup&. fermentations G a d 36, 128-143, 148-159, 209-216.

Flanzy, M. 1938. Observations sur le manganese en oenologie. Compt. rend. acad. agr. France 24, 319-325.

Flanzy, M. 1948. Les acides organiques dans les raisins et les vins. Ann. agron. 18,

Flanzy, M., and Deibner, L. 1948. Sur les dosages simultanes de SO, et H,SO, dans les jus de raisin et les vins. In&. agr. et aliment. (Paris) 65 , 25-37.

Flanzy, M., and Deibner, L. 1956. Sur la variation des teneurs en fer dans les vins obtenus en presence ou en absence dune terre ferrugineuse. Ann. technol. agr. (Paris) 5, 69-73.

Flanzy, M., and Therond, L. 1939. Le manganese dans les vins de Vitis vinifera et les vins dhybrides. Rev. uiticult. 90, 433-454; see also Ann. technol. agr. (Paris) 1, 67-76 (1938).

Florentin, D. 1956. Sur le danger de l'addition dions calcium aux mollts et aux vins. Revue vinicole 57( 6 ) , 27-28.

Florentin, D., and Navellier, P. 1951. Sur la teneur en brome normal des vins naturels francais. Ann. fals. et fraudes 44, 297-298.

Fornachon, J. C. M. 1943. Bacterial Spoilage of Fortified Wines, p. ix, 126. Australian Wine Board, Adelaide.

Francesco, F. de. 1954a. Ricerca e determinazione microchimica dello zinco ione per mezzo del polarografo oscillografica. Applicazione all'analisi del vino. Boll. lob. chim. provinciaZi (Bolognu) 5(4 ) , 111-115.

Francesco, F. de. 1954b. Sulla reazione fra zinco-ione e ferrocianuro potassico in presenza di ferr-ione. Boll. lab. chim. provinciali (Bologna) 5( M ) , 56-58.

Francesco, F. de, and Falchi, G. 1955. Riconoscimento e dosagio di tracce di rame negli alimenti per mezza della polarografia oscillografica. Boll. lab. chim. provinciali (Bologna) 6( 3 ) , 83-84.

Franco, G. 1937-52. L'anidride solforosa in enologia dal punto di vista teorico e pratico. Annuar. staz. enol. sper. Asti 113, 28.

Fransot, P. 1954a. Compte rendu des premiers resultats des essais entrepris, relatifs oux teneurs en plomb des mollts et des vim. Le Vigneron Champenois 75,

FranCot, P. 1954b. Expos6 sur les 6tudes relatives au methanol e t au cuivre dans les moiits et dans les vins. Le Vigneron Chumpends 7 5 , 198-200.

FranCot, P., and Geoffroy, P. 1951. Le chlore, Ie calcium et le fer dans les vins de Champagne et les sous-produits de la champagnisation. Bull. ofice intern. uin 24( 242), 97-125.

Francot, P., and Geoffroy, P. 1956. Repartition du cuivre dans les m o b et vins au cours du pressurage Champenois. Le Vigneron Champenois 77, 451459.

60-64.

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Frolov-Bagreev, A. M. 1949. Minor elements in the biochemistry of grapes and wines (transl.). Vinodelie i Vinogradurstvo S.S.S.R. 9( 6 ) , 22.

Frolov-Bagreev, A. M. 1952. Forms of carbon dioxide in champagne (transl.). Vino- delie i Vinogradarstvo S . S . S . R . 12( 6 ) , 20-21.

Frolov-Bagreev, A. M., and Agabal’iants, G. G. 1951. Chemistry of Wine (transl.), p. 391. Pishchepromizdat, Moscow.

Frolov-Bagreev, A. M., and Andreevskaia, E. G. 1950. On the role of micro-elements in enology (transl.). Vinodelie i Vinogradarstoo S.S.S.R. 10( 6 ) , 38-40.

Frolov-Bagreev, A. M., and Andreevskaia, E. G. 1955. On the role of trace elements in wines (transl.). Viwdelie i Vinogradarstvo S.S .S .R. 15( 5) , 12-13.

Frolov-Bagreev, A. M., Agopov, V. V., and Kalinina, N. I. 1951. UtiIization of sulfurous acid in champagnizing wine ( transl. ), Vinodelie i Vinogradurstvo S.S.S.R. 11( 7 ) , 22-24.

Gail, L. 1932. Le contenu en acid borique des vins. MCthode expkditive pour la determination de ce contenu Rumania. Anulele inst. cercetciri agron. Roumdniei 4, 188-202.

Gajdos, H. B. A,, Gajdos-Torok, M., and Rambert, P. 1953. Une intoxication aigue collective par le plomb. Semaine hdp. 29, 785-788.

Garino-Canina, E. 1941. I1 fosforo organic0 nei vini. Ann. chim. appl . 31, 342-349. Garino-Canina, E. 1955. Metodo rapido per la determinazione del potassio col

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Cartel, W. 1954. Kolorimetrische Borbestimmung in Rebteilen, Most und Wein mit 1,l’-Anthrimid. Weinberg u . Keller 1. 437-445.

Cartel, W. 1955. Untersuchungen iiber des Einfluss des Kelterns auf die Zusam- mensetzung von Traubenmost. Weinberg u. Keller 2, 450-454.

Gartel, W. 1956. Die Bestimmung mineralischen Bestandteile in Most und Wein. Weinberg u. Keller 3, 393395.

Cartel, W. 1957a. Die Bestimmung mineralischen Bestandteile in Most und Wein. Kolorimetrische Phosphorsaurebestimmung nach der Molybdat-Vanadat-Methde. Weinberg u. Keller 4. 69-72.

Cartel, W. 195%. Untersuchungen iiber den Zinkgehalt von Rebteilen und Most. Weinberg u. Keller 4, 419-424.

Gaudio, A. 1942. Caratteri dei vini spumanti i methodi lor0 preparazione. Coltiuatore 88, 39.

Geiss, W. 1947-1948. Beitrage zur Frage der Verwendung von schwefliger Saure in des Kellerwirtschaft. Wein-Wiss. Beih. Fuchz. deut. Weinbau 1, 115-119; 2, 3-10,

Geiss, W. 1955. Das Entschwefeln der mit wasseriger SO,-Lasung sterilisierten Flaschen. Deut. Wein-Ztg. 91, 578, 580, 582.

Genevois, L. 1933. Recherches rkcentes sur les complexes du fer. Application B 1’8tude des vins. Ann. brass. et dist. 31, 188-192, 205-208.

Genevois, L. 1934. RBle physiologique des BlCments ionisables du vin. Ann. brass.

Genevois, L. 1935. A propos des compIexes du fer dam les vins. Bull. sue. chim.

Genevois, L., and Ribkreau-Gayon, J. 1933. Les kquilibres ioniques dans les modts

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Gentilini, L. 1949. Valutazione dei mezzi fisici nella desolforazione dei mosti muti. Ann. sper. agrar. (Rome) [N.S.] 3, 351-381; see also Annuar. staz. sper. uiticolt. e enol. (Conegliam) 13( 12) , 1-31 ( 1949) and Riu. uiticolt. e enol. (Conegliuno)

Gentilini, L. 1952a. A proposito del metabisolfito di sodio. Riu. uiticolt. e enol. (Conegliano) 5 , 29-30.

Gentilini, L. 1952b. Di un metodo elettrocolorimetrico per la determinazione diretta del ferro nei vini rossi. Riu. viticolt. e e m l . (Conegliam) 5, 251-252.

Gentilini, L. 1954. I1 fosforo nella vite nel mosto e nel vino. Riu. uiticolt. e enol. (Conegliano) 7, 385-386.

Gentilini, L., and Missier, G. 1952. L'alluniinio e alcune sue leghe in enologia. Ann. sper. agrar. (Rome) [N.S.] 6 , 391-399; see also Annuar. staz. sper. uiticolt. e enol. (Conegliano) 14( 19) , 1-8 (1950).

Georgeakopoulos, G., and Kourakou, B. 1955. Dosage colorimetrique du phosphore total et du phosphore mineral dans les vins. M i n i s t h agr. lnst. du Vin, Athens,

Gerasimov, M. A,, Saenko, N. F., and Chalenko, D. K. 1931. Use of phosphate and ammonium salts in fermentation of wine (transl.). Trudy Krymskoi Zonal'noi Opytnoi Stantii PO Vinogradarstuu i Vinoldeliiu 1, 1-43.

Ghimicescu, G. 1935a. Le dosage du potassium dans les vins naturels de Roumanie. Ann. sci. uniu. Jassy 21, 339-342.

Ghimicescu, G. 1935b. Le microdosage du calcium dans les vins et ses proportions dans les vins naturels de Roumanie. Ann. sci. uniu. Jassy 21, 352-355.

Ghimicescu, G. 1935c. Une micromhthode colorimhtrique pour le dosage du potassium dans les vins. Ann. sci. uniu. Jassy 21, 333-338.

Ghimicescu, G. 1937. Microdosage colorim6trique du fer dans le vin, et ses proportions dans quelques vins naturels de Roumanie. Mikrochaie 22, 208-215.

Ghimicescu, G., and Kotcis, G. 1938. Microdosage du manganese dans le vin. Mikrochemie 25, 183-186.

Gilissen, M., Van Gheluwe, J., and Fraeyes, P. 1952. L'acide carbonique. Bcho Brass. 8, 271-273, 275, 277, 297-301, 303-305, 307-308.

Gimel, R. 1951. Rkflexions chimiques et biochimiques sur les dosages courants d'acide sulfureux dans les moDts et les vins et conclusions pratiques ti en tirer. Bull. SOC. phurm. Nancy No. 9, 15-21.

Godet, C., and Martin, L. 1946. Contribution ?i la connaissance des vins suisses. Mitt. Gebiete Lebenm. u. Hyg. 37, 327-342.

Golovatyi, R. N. 1950. Determination of copper and iron in wines by cationites (transl.). Vinodelie i Vinogradarstuo S.S.S.R. 10(5), 27-28.

Golovatyi, R. N. 1953. Determination of copper in wine (transl.). Vinodelie i Vinogradarstuo S.S.S.R. 13( 4 ) , 14-16.

Golse, J. 1933. Dosage du cuivre dnas les vins. Bull, trau. SOC. pharm. Bordeaux 71, 24-30.

Grau, C. A,, and Gbmez, R. E. 1940. El acido borico natural contenido en algunos vinos argentinos. Rev. farm. (Buenos Aires) 83, 89-98; see also Reu. brasil. farm. 22, 245-253 (1941).

Greenblau, N., and Westhuyzen, J. P. van der. 1956. An improved preliminary treatment for the routine estimation of lead in wines and related products. 3. Sci. Food Agr. 7, 186-189.

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Greenblau, N., and Westhuyzen, J. P. van der. 1957. Lead contamination of wines, spirits and foods. S. African lnd. Chemist 11, 150-153.

Grigoriev, I. N. 1948. Iodine in the wines of Halbsinel Apscheron (transl.). Vino- delie i Vinogradarstvo S.S.S.R. 8( 2 ) , 24.

Grohmann, H. 1939. Direkte Bestimmung von Chlor im Wein und sein Gehalt bei Pfalzer und auslandischen Weinen. Z . Untersuch. Lebensm. 77. 482-488.

Grohmann, H. 1941. Beitrag zurn Natriumgehalt des Weines. 2. Untersuch. Lebensnz. 81, 27-34.

Guglielnii, L. 1953. Bromo naturale e hronio aggiunti degli alirnenti: metodi di dosaggio. Alimentazione 3, 2f?-30.

Guillement, R. 1936. L'action defaibles doses de cuivre sur la fermentation alcoolique par la levure. Bull. soc. chim. biol. 18, 1125-1131.

Guimarzes, A. F. 1944. Alguns indices oenolbgicos de Vinhos Verdes. Tip. Alves and Novais, Pbrto, p. 15. (Paper read at I Congress0 Nacional de Cihncias Agrarias).

Hanak, A. 1930. Zur Kenntnis der Rolle des Eisen in Wein und anderen Obster- zeugnissen. Z . Untersuch. Lebensm. 60, 291-297.

IIansen, A. 1954. Chernische Bestiminung von Monobromessigsaure in Most, Obstsaft, Bier und Wein. 2. anal. Chem. 143, 17-21.

Heide, C. von der. 1933. Die Blauschonung. Wein u. Rebe 14, 325-335, 348-359, 400408; 15, 5-19, 35-44.

Heide, C. von der, and Hennig, K. 1933a. Bestiinmung des Arsens und der Phos- phorsaure, des Kupfers, Zinks, Eisens, Mangans in Most und Wein. Z . Unter- such. Lebensm. 66, 341-348.

Heide, C. von der, and Hennig, K. 193313. Zusammensetzung von Trauben- und Pipfelsussmosten und ihr Gehalt an Arsen, Kupfer und Zink. 2. Untersuch. Lebensm. 66, 321-338.

Ileiduschka, A,, and Pyriki, C. 1930. Untersuchung von 1929er Traubenmosten des Weinbaugebietes Pillnitz-Lossnitz-Meissen-Seusslitb. Z . Untersuch. Lebensm. 59, 613-615.

Hennig, K. 1944. Einige Fragen zur Bilanz der Stickstoffverbindungen im Most und Wein. Z . Lebensm.-Untersuch, u. -Forsch. 87, 40-48; see also Bull. ofice intern.

Hennig, K. 195%. Die Bedeutung der freien schwefligen Saure und ihre Bestim- mung. Deut. Wein-Ztg. 88, 515-516.

Hennig, K. 1952b. Der Deutsche Schaumwein. Deut. Wein-Ztg. 88, 341-342, 345- 346.

Hennig, K., and Burkhardt, R. 1954. Die quantitative, polarographische Bestim- mung von Kupfer und Zink in der Weinasche. 2. Lebensm.-Untersuch. u. -Forsch. 98, 25-29.

Hennig, K., and Villforth, F. 1938. Spurenelemente im Most und Wein. Vorrat- spflege u. Lebensmittelforsch. 1, 563592.

Herrmann. 1952. Wber die Zitronensaure- und Natriunigehalte badischer Weine. Land- und Haus- wirtschaftlicher Auswertungs- und Informationsdienst. Bericht iiber die Gartenbau-Forschung 1930-1945 16, 91.

Herschler, A., and Gartel, W. 1954. Untersuchungen iiber den Borgehalt von Mosten und Weinen. Weinberg u. Keller 1, 256-263.

Hickinbotham, A. R. 1952. What does plaster do? Australian Brewing Wine J. 70(8 ) , 4, 6, 8, 10.

Hickinbotham, A. R. 1954. The lead content of beverages. Australinn Brewing Wine J . 72(8) , 20.

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Hochstrasser, R. 1951. Ober die Venvendung von Aluminum in der Getranke-

Hugues, E., and Bouffard, E. 1935. Influence des engrais potassiques sur la com-

Internal Revenue Service. 1956. The Determination of Carbon Dioxide in Wine,

Ionesqu, M. V. 1936. Beitrage zur Bestimmung der schwefligen Saure im Wein.

Iozzi, C. 1956. Determinazione del ferro totale nei vini per via colorimetricn, con

Jaulmes, P. 1951. Analyse des vins, 2nd ed., p. 574. Libraire Poulain, Montpellier. Jendassik, A., and Papp, S. 1936. Determination of silver in wine or other fluids

treated by the katadin process (transl. ), Kishletiigyi Kiizlemknyek 39, 207-213; see also Z. Untersuch. Lebensm. 69, 369-374 ( 1935).

Jenny, J. 1952. Les bases scientifiques de la conservation des jus sans alcool de raisin et de fruits B pCpins sous pression d'acide carbonique. Absorption, pression, concentration. Inds. agr. et aliment. (Paris) 69, 687-700.

Jensen, F. B. 1953. Om phvisning af monobromeddikesyre eller dennes estere i levnedsmidler. Kemisk Muanedsblad 34, 94.

Johnson, F. F., and Fischer, L. 1935. A report on fluorides in wine. Am. J . Phmm. 107, 512-514.

Jose Isola, J. 1947. Deterininacih de anhidrido sulfuroso total en vinos. Ind. y quim. (Buenos Aires) 9, 80-93.

Joslyn, M. A. 1954. How to cut down on SO, content. Wines G Vines 35( 12),

Joslyn, M. A. 1955. Determination of free and total sulfur dioxide in white table wines, J . Agr. Food Chem. 3, 68-95.

Joslyn, M. A., and Braverman, J. B. S. 1954. The chemistry and technology of the pretreatment and preservation of fruit and vegetable products with sulfur dioxide and sulfites. Advances in Food Research 5, 97-160,

Joslyn, M. A., and Lukton, A. 1953. Prevention of copper and iron turbidities in wine. Hilgardia 22, 451-533.

Joslyn, M. A., Lukton, A., and Cane, A. 1953. The removal of excess copper and iron from wine. Food Techwl. 7, 20-29.

Kean, C. E., and Marsh, G. L. 1956a. Investigation of copper complexes causing cloudiness in wines. I. Chemical composition. Food Research 21, 441-447.

Kean, C. E., and Marsh, G. L. 195613. Investigation of copper complexes causing cloudiness in wines. 11. Bentonite treatment of wines. Food Technol. 10, 355- 359.

Kieffer, N. 1948. e tude du r6le des mktaux introduits accidentellement dans les vin. 7th Congr. intern. inds. agr., Paris 1(Q5), C 1-4.

Kielhofer, E. 1930. Der Bleigehalt von Most und Wein aus Trauben, die niit blei- haltigen Schiidlingsbekampfungsmitteln behandelt wurden. W e i n u. Rebe 11, 543-548.

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Kielhofer, E. 1947-1948. Kann bei langerer ungestorter Lagerung eine Entmischung des Weines stattfinden? Deut. Wein-Ztg. 83, 23-24; 17-18, 230-231,

Kielhofer, E. 1951. Die Kohlensaure im Wein. Deut. Wein-Ztg. 87, 313-315.

Industrie. Schweiz. 2. Obst- u. Weinbau 60, 249-251, 267-269.

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31-34.


Kielhofer, E. 1954. Die Verniinderung der schweHigen Saure im Wein. Deut. Weinbau 9, 259-262.

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Kielhofer, E., and Giinther, P. 1941. Zur Zinkbestimmung in Most und Wein. Wein u. Rebe 23, 169-173.

Klantschnigg, P. 1955. Dosaggio dell’anidride solforosa totale nel vini come solvato di bario in seguito ad assidazione chromica. Ann. sper. agr. {Rome) [N.S.] 9 ( 3 ) , I-IX.

Koch, J. 1953. Kann die schweHige Saure in der Kellertechnik der Weinbereitung durch “andere Stoffe” ersetzt werden? Deut. Wein-Ztg. 89, 344, 356, 358, 360.

Koch, J. 1955. Der Schwefelbedarf der Weissweine. Deut. Weinbau 10, 343, 345- 348.

Koch, J., and Breker, E. 1955. Uber die Bestimmung von Schwermetallen in Traubenslften ( Traubensiissmost ) . Ind. Obst-u. Gemiiseverwert. 40, 252-256.

Kocherga, P. V. 1940. An indigometric method for determining the oxidizing powers of wine (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 1( 9-10), 9-12.

Kocherga, P. V., and S. M. Kashirin. 1940. Determination of the absorption coefficient of CO, in champagne (transl. ). Vinodelie i Vinogradarstvo S.S.S.R. 1( 11-12), 12-15.

Konlechner, H., Ulbrich, M., and Bauer, W. 1941. Uber den EinHuss des Absetzen- lassens von Traubenmost auf den Arsengehalt der Weine. Weinland 13, 57-60.

Kopal, S. 1938. Die slowakische Weinfabrikation und die chemische Zusammen- setzung der Weine. Chem. Listy Vedu Prumysl 32,, 366-375.

Koval, I. G., and Pazyrev, P. IA. 1952. Loss of carbonic acid during filtration and bottling of champagne in bulk (transl.). Vinodelie i Vinogrudurstvo S . S . S . R .

Kourakou, 8. 1955. Chromatometric method for determining inorganic phosphorus in wine. (transl.). Chim. Chroniku {Athens, Greece) 20, 7-10.

Kozenko, E. M. 1955. Dynamics of saturation of wine with carbon dioxide during fermentation (transl.). Vinodelie i Vimgradurstvo S.S.S.R. 15( 8 ) , 17-19.

Kramer, O., and Bohringer, W. 1940. Untersuchungen und Versuche iiber die Saureverhaltnisse bei wiirttembergischen Weinen und Mosten. Wein u. Rebe

Kramer, O., and Schwarz, R. 1931. Die Entfernung von Schwefelsaure aus dem Wein mit Hilfe von kohlensaurem Kalk. Wein u. Rebe 13, 224-231.

Kretzdorn, H. 1944. Uber die Manganbestimmung in Weinen und iiber den Man- gangehalt badischer Weine. Wein u. Rebe 26, 23-28.

Kretzdorn, H., and Miiller, F. W. 1954a. Die Bestimmung des Eisens im Wein mit ad-Dipyridyl. Deut. Wein-Ztg. 90, 302, 304.

Kretzdorn, H., and Miiller, F. W. 1954b. Die Methodik der Bleibestimmung im Wein und der Bleigehalt nordbadischer Weine. Deut. Wein-Ztg. 90, 484.

Kretzdorn, H., and Muller, F. W. 1955. Erfahrungen bei der Bleibestimmung in Weinen und Siissmosten. Deut. Wein-Ztg. 91, 582, 584, 586.

Kul’nevich, V. G. 1954. Determination of different forms of oxygen in wines (transl.). Vinodelie i Vinogradurstuo S.S.S.R. la( 6 ) , 12-18.

Lafon, J., and Couillaud, P .1953. Sur la presence du cuivre dans les eaux-de-vie de Cognac. Ann, technol. ugr. (Paris) 2, 41-50; see also Vignes et Vins 6(27) , 29-30 (1953).

12 ( 7 ) , 27-29.

22, 97-110, 123-142, 230-245, 252-269.


Larkin, O., Page, M., Bartlet, J. C., and Chapman, R. A. 1954. The lead, zinc and copper content of foods. Food Research 19, 211-218.

Lasserre, A. 1932-33. Sur les quantitks de silicium, de calcium et de magnksium contenus dans les vins et leurs mob. Proc. uerb. se'an. SOC. sci. phys. nut. Bordeaux 1932-33, 66-72.

Lebrun, and Radet. 1953. Quelques observations sur la composition des vins de la rkcolte 1932, en Champagne. Ann. fals. et fraudes 26, 475480.

Lherme, G. 1931-32. La teneur en cuivre des vins de la Gironde (rkcolte 1931). Proc. verb. sban, SOC. sci. phys. nut. Bordeaux 1931-32, 119-121.

Liotta, C. 1956. Interim Report Concerning Experiments on NaturalIy Fermented and Artificially Carbonated Wines, Internal Revenue Service-21174, p. 4. Washington, D. C.

Lobstein, E., and Ancel, M. 1933. Dosage des sulfates dans les vins par la mkthode benzidinique. Ann. chim. anal. et chim. appl. [3] 15, 389-397.

Lobstein, E., and Schmidt. 1931. Le vignoble Alsacih et ses vins. Ann. fals. et fraudes 24, 220-229.

Lobstein, E., Flatter, Mme. and Raffeld, M. 1935. Le vignoble de Palestine et ses vins. Ann. fuls. et fraudes 28, 411-418.

Lomkatsi, T. S. 1956. Effect of certain microelements on wine fermentation (transl.). Sadovodstuo Vinogradurstuo i Vinodelie Moldavii 11 ( 1 ), 4647.

Lucchetti, E. 1941. Un'inchiesta sui vini de Montecarlo (Lucca). Ann. ~ a c . agrar. uniu. Pisa [N.S.] 4, 216-230.

Lucia, S. P., and Hunt, M. L. 1957. Dietary sodium and potassium in California wines. Am. 1. Digest. Diseases 2, 26-30.

Macher, L. 1952. HefegLning und Schwefelwasserstofiildung. Deut. Lebensm.- Rundschau 48, 183-189.

Mader. 1936. Der Einfluss der Veredlung auf die chemische Zusammensetzung des Mostes und des Weines. Wein u. Rebe 17, 250-258.

Malvezin, P. 1930, Dosage des sels ferreux dans les vins blancs. Ann. fnls. et fraudes 23, 412-414.

Malvezin, P. 1942. Dosage de mininies quantitks de cuivre dans les vins et liquides organiques. Bull. assoc. chinaistes 59, 721-722.

Malysheva, R. I. 1956. Determination of arsenic in grape wines (transl. ) Vinodelie i Vinogradurstvo S.S.S.R. 16( 5) :17-19.

Manrhofer, A. 1938. Biochemische Studien iiber das Vorkommen kleiner Mengen von Jod und Fluor im Organismus. 111. Biochem. Z. 295, 302-314.

Marcille, R. 1935. Le dosage de I'anhydride sulfureux dans les vins. Ann. fals. et fraudes 28, 93-96, 360-362; see also Bull. ofice intern. uin 8( 84) , 49-52 ( 1935).

Marcille, R. 1937. Btude des prockdhs de dosage de l'anhydride sulfureux dans les moQts et les vins. Bull. inst. oenol. Alge'rie 10, 225-232.

Mareca CortBs, I. 1951. Un procedimiento para desulfitar mostos. Rev. cienc. apl. (Madrid) 5, 235-238.

Mareca Cortks, I. 1953. Contenido en cobre de un vino: su determinacih polar- ogrbfica. Spain. Secc. de Ferment. Indus. Cuaderno 5, 13-16; see also Inform. quim. anal. (Madrid) 7, 67-70 (1953).

Marsh, G., and Kean, C. 1951. Applications of chromatographic methods to organic acids in wine. Proc. Am. SOC. Emlogists 1951, 157-159; see also Wines G Vines 33(3) , 19-20 (1952).


Marsh, G. L., and Nobusada, K. 1938. Iron determination methods. Wine Rev. 6 ( 6 ) , 20-21.

Martini, A., and Berisso, B. 1945. Sobre la aplicacibn del reconocimiento micro- quimico del niercurio en analisis bromotolbgico. Publs. inst. inuest. microquirn., Uniu. nrrcl. litoral (Rosurio, Argentina) 9, 53-58.

Martraire, M. 1941. Composes sulfur& des alcools. Bull. assoc. chimistes 58, 293- 300.

Mathers, A. P. 1949. Rapid determination of sulfur dioxide in wine. 1. Assoc. Of@. Agr. Chemists 32, 745-751.

Mecca, F. 1952. Un metodo di determinazione biochimico dei fluori nei vini. Chirn. e ind. (Milan) 34, 345-346, 568-570.

M&ric, P. 1940. Le manganese en oenologie. Bull. assoc. chimistes 57, 33-38. Merz, J. L. 1934. Ueber das Vorkommen von Chlornatrium im Wein. Wein u. Rebe

14, 144-145. Merzhanian, A. A. 1950. Carbon dioxide absorption coefficient of wine ( transl. ).

Vinodelie i Vinogradarstuo S.S.S.R. 10( 5 ) , 34-37. Merzhanian, A. A. 1951. On the behavior of diethyl esters of pyrocarbonic acid in

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Merzhanian, A. A. 1955. Kinetics of absorption of carbon dioxide by wine (transl.). Vinodelie i Vinogradarstuo S.S.S.R. 15( 6 ) , 41-42; see also 15( 3), 55-57.

Merzhanian, A., and Kozenko, E. M. 1949. Determination of the dissolved carbon dioxide in wines (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 9( l o ) , 30-33.

Merzhanian, A. A., and Kozenko, E. M. 1952. Absorption of carbon dioxide by yeast dregs of wine (transl.). Vinodelie i Vinogradarstvo S.S.S.R. 12( 8 ) , 20-23.

Mestre Artigas, C., and Mestre Jand, A. 1939. Estudio comparativo de fermenta- ciones de mostos a moderadas y bajas teniperaturas. Bol. inst. mcl. invest. agron. (Mudrid) 2( 3), 31-43.

Micheli, R. P. de. 1951. Deterniinacibn de zinc en algunos alimentos. Tesis quim. Uniu. Chile 3, 1-11.

Michod, J. 1952. Rdsultats de rechcrchcs rdcentes sur la gravelle. Rev. roinande ugr. uiticult. et arboricult. 8, 46-47.

Michod, J. 1954. Les depots de tartre en bouteilles. Ann. agr. Suisse [N.S.] 3,

Mihnea, A. 1941. Die Eisenbestimniung in den Weinen des Weinbergs Odobesti und die Notwendigkeit der Anwendung von Kaliuniferrocyanid fur ihre Sclionung. Anulele inst. cercetciii agron. Romhiei 13, 169-179.

Mills, R. R., and Wiegand, E. €1. 1942. Effect of storage on sulfur dioxide in wine. Fruit Prods. J. 22, 5-9.

Molder, H. 1936. Ueber den Zitronensiiuregehalt des Weines. Mitt. Gebiete Lebensm. u. Hyg. 27, 27-40.

Monnet, R., and Sabon, F. 1946. Du danger de I’emploi de recipients cadmies pur la conservation des aliments et des boissons. Presse n&d. 54, 677-678.

Monnet, R., Sabon, F., and Grignon, H. 1946. Recipients cadniies et hygiene alimentaire. I. Dosage du cadmium ddns lCi vin et dans la bikre. Ann. pharm. franc 4, 242-251.

Morani, V., and Marimpietri, L. 1930. Ulteriore studi snl potere tampone dei vini:conservazione e gessatura. Ann. chim. upp l . 20, 313-335; see also Ann. Staz. chim.-agrar. sper. Roma 121 Publ. 274, 1-23 (1930).

1023-1028.


Moreau, L., and Vinet, E. 1933. Sur la dissociation de l'anhydride sulfureux combini! dans les moiits de raisin et dans les vins. Ann. fals. et fraudes 26, 454463.

Moreau, L., and Vinet, E. 1937a. Sur la determination du pouvoir antiseptique rCel de l'acide sulfureux dans les molits et les vins par la niethode de l'index iod& Compt. rend. acad. ugr. France 23, 570-576.

Moreau, L., and Vinet, E. 1937b. Variations du pouvoir antiseFtique rirel de l'acide sulfureux dans le mofits et les vins suivant I'aciditC du milieu. Compt. rend. mad. agr. France 23, 599-607.

Motoc, D. D., and Popesdu, D. M. 1941-1942. Beitrag zuin Studium der Hybriden- weine. Bul. chim. SOC. Romdne chim. [2]3, 186-205.

Mrak, E. M., Cash, L., and Caudron, D. C. 1937. Effects of certain metals and alloys on claret- and sauterne-type wines made from vinifera grapes. Food Research 2, 539-547.

Mrak, E. M., and Fessler, J. F. 1938. Changes in iron content of musts and wines during vinification. Food Research 3, 307-309.

Muth, F. 1940. Die Schwefelsaure im Wein und die durch das Schwefeln der Weine entstehenden Mengen dieser Saure. Weinland 11, 277-279; 12, 13-14, 24-25, 4 4 4 6 .

NBgre, E. 1954. Le facteurs de solubilite de l'acide tartrique en prksence de potassium. Application au cas du vin. Compt. rend. mad. agr. France 40, 705-709.

NBgre, E., and Cordonnier, R. 1953. Les origines du fer des vins. Compt. rend. acad. agr. France 39, 52-56; see also Progr. agr. et vit. 139, 160-164 (1953).

NestIe, K. T. 1949. Der Angriff von Flaschenglas durch Weinsaure. Deut. Wein-Ztg. 85, 20-21 (Chem. Zentrl. 1950 11, 953).

Ney, M. 1948. Dosage rapide du zinc dans les vins. Ann. fals. et fraudes 41, 533- 537.

Niculescu, M. 1937. RCsistance des vins boriques B la maladie de la piqfire. Chirn. d? ind. (Paris) 31, 646648.

Nobile, C. 0. 1954. Su una tecnica semplificata per la determinazione del ferro libero combinato e totale nei vini bianchi e rossi a mezzo del solfocianato potassico. Riv. viticolt. e enol. (Coneglicmo) 7 , 348-352.

Oberto, M. C. 1955. Sull'efficacia antifennentativa dell'acido monobromoacetico nei vini spumanti. Ann. sper. agrar. (Rome) [N.S.] 9, 927-934.

Ostenvalder, A. 1934. Die Vergarung iiberschwefelter Traubenmoste. Landwirtsch. Jahrb. Schweiz 48, 1101-1131.

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 (trans].). Vinodelie i Vinogradarstvo S.S.S.R. 11( 3 ) , 16-19.

Paronetto, L. 1953. Dosaggio delIa CO, in peso nei vini spumanti. Riu. vitimZt, e enol. (Conegliano) 6 , 143-147.

Paronetto, L., and Dal Cin, G. 1954. I prodotti chimici nella tecnica enologica, p. 458. Scuola d'Arte Tipofrafica "Bosco," Verona.

Pato, M. d. S. 1933. Quimica-fisica aplicada aos mostos e aos vinhos. Reu. agron. Lisboa 21, 129-182; see also Estgcio Viti-oinicokz da Beira Litoral, Sdr. A, Bol. 1, 1-49 (1932).

Pato, M. d. S., and Costa, A. V. R. da. 1943. 0 doseamento do cobre nos vinhos e nas solupoes diluidas dos sais deste catizo, por volumetria condutim6trica. Anadia. p. 19. (Communicaclo apresentado ao Congress0 Nacional de Cikncias Agririas. )

Pato, M. d. S., and Sousa, T. T. de. 1938. Da influencia do anidrido sulfuroso na


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Peretii., M. 1950. Les vins de la Croatie Nord, vendange 1948. Reprinted froin Biline proizvodnje, p. 26.

Petronici, C. 1950. Sulla deterniinazione dell anidridc solforosa a debole concen- trazione nei prodotti vegetali. Ann. fuc. sci. agrar. univ. Palermo 1, 7-11.

Peynaud, E. 1947a. Contribution B I'Ctude biochimique de la maturation du raisin et de la composition des vins. Inds. ugr. et ulirnent. (Paris) 64, 87-95, 167-188, 301-317, 399-414; also printed by Imprimerie G. Sautiii et Fils, Lille (1948), and summarized in Rev. uiticult. 92, 177-180, 271-272 (1946).

Peynaud, E. 194713. h i d e sur les acides organiques du raisins et du vin. Bull. ofice intern. uin 20( 191), 34-51.

Peynaud, E. 1950a. Analyses compl6tes de donze vins de Bordeaux. Ann. inst. iiutl. recherche agron. Se'r A 1, 252-266.

Peynaud, E. 1950b. Analyses complCtes de huit vins doux naturels. Ann. inst. natl. recherche agron. S8r. A 1, 383-388.

Peynaud, E. 1954. MBthode colorinvitrique de dosage clu cuivre dims les vins h l'aide du 2,Z-diquinolyle. Chim. anal. 36, 187-190; see also Bull. soc. chini. France [5] 1954, 166 (1954).

Peynaud, E., and Lafourcade, S. 1952. Sur les conditions d'eniploi de l'anhydride sulfureux dans les vins liquoreux. Bull. ofice intern. sin 25( 252), 110-120; see also Bull. inst. natl. app l . orig. vim et eaux-de-uie No. 42, 2 0 3 1 (1952).

Photiadis, P. 1932. Uber die Bestimmung der schwefligen Saure in Mosten, Rot- und Siissweinen. Z. anal. Chem. 91, 181-182.

Piano, G. 1940. I mosti ed i vini nella provincia di Aosta (Cuneo, Novara, Torino, Vercelli) nel triennio 1937-1939 ) . Annuur. regia stnz. chim. ugrur. Torino 14A. 333-440.

Pieri, G., and De Rosa, T. 1951. Studio dell'eventuale azione degli esteri fosforici sdla fermentazione alcoolica. Ann. sper. ngrur. (Rome) [ N.S.] 6, 197-206.

Piguet, G. A. 1936. La Tenenr en Arsenic des Produits de Vignes TraitCes aux Sels Arsenicaux, Imprimerie Federative S.A., Berne; see also AnnwLire ugr. Suisse 50, 908-950 { 1936).

Porchet, B. 1931. Contribution B 1'Ctude de l'adapt:ition des levures B I'acide sulfureux. Annuuire agr. Suisse 32, 135-154.

Pozzi-Escot, E. 1938. Prinieras investigaciones sobre la presencia del hierro en 10s uvas peruanas. Rev. cienc. (Lima) 40, 293-298.

Prado, L. de. 1937. Valoraci6n del cobre y del hierro en algunos mostos y vinos argentinos. Ind. y quim. (Buenos Aires) 2, 67-71.

Prillinger, F. 1951. Kolorinietrische Methode zur Bestimmung des Ferrocyankalium- bedarfes bei der Blauschonung. Mitt. hoher. Bundeslehr- u. Versuchsanstult Wein- u. Obstbau, Klosterneuberg 1, 55-59.

Pro, M. J., and A. P. Mathers. 1954. Metallic elements in wine by flame photometry. J. Assoc. Ofic. Agr. Chemists 37, 945-960.

Procopio, M. 1949. Valutazione pratica delle anidride solforosa nei vini. Progr. vinicole, olea. Ital. 25, 5-8.

Procopio, M. 1953. Snl potere fissatore solforoso dei vini. Riu. uiticolt. e enol. (Conegliano) 6, 9-19.

Querberitz, F. 1951. Tiefkuhlversuche an Moselweinen. Deut. Wein-Ztg. 87, 182- 186.


Querberitz, F. 1954. Blei in Flaschenkapseln. Deut. Wein-Ztg. 90, 284, 286, 288. Quinn, D. C. 1940. Sulfur dioxide, Its use in the wine industry. J. Agr. (Victoria)

Rakcsinyi, L. 1935. Diminishing the sulfur dioxide content of oversulfured wines and musts (transl.). Magyar Ampelol. Evkonyi 9, 442-447. (Chem. Abstr. 30: 1508.)

Rankine, B. C. 1955. Lead content of some Australian wines. J . Sci. Food Agr. 6, 576-579.

Rankine, B. C. 1957. Factors influencing the lead content of wine. J. Sci. Food Agr. 8 , 458-466.

Reichard, 0. 1936. Nachweis und Bestimmung von Natrium in Wein und sein Gehalt bei Pfdzer Weinen. Z . Untersuch. Leben~m. 71, 501515.

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[advances in food research] advances in food research volume 8 volume 8 || composition of wines. ii....

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