[Advances in Food Research] Advances in Food Research Volume 28 Volume 28 || Food Technological Evaluation of Xylitol

Download [Advances in Food Research] Advances in Food Research Volume 28 Volume 28 || Food Technological Evaluation of Xylitol

Post on 27-Jan-2017

219 views

Category:

Documents

1 download

Embed Size (px)

TRANSCRIPT

  • ADVANCES IN I-OOD KEStARCH, VOL.. 28

    FOOD TECHNOLOGICAL EVALUATION OF XYLITOL

    LEA HYVONEN, PEKKA KOIVISTOINEN,

    Department of Food Chemistty and Technology, Uriiversig of Helsinki, Helsinki. Finland

    FELIX VOIROL

    Xyrofn Ltd.. Baar, Switzerland

    I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 11. The Occurren

    A. Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Large-Scale Xylitol Production. . . . . . . . . . . . . . . . . . . . . . . . Physicochemical and Food Technological Properties of Xylitol. . A. Physicochemical Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . B. Food Technological Properties . . . . . . . . . . . . . . . . . . . . . . . .

    IV. Food Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Confectionery. . . . . . . . . . . . . . . . . . . . . . . . . B. Ice Cream . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    D. Jams, Jellies, and Marmalades.. . . . . . . . . . . . . . . . . . . . . . . E. Bakery Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. Drinks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    V. Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VI. Research Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    of Xylitol . . . . . . . . . . . . . . . .

    111.

    c. Yogurt . . . . . . . . . . . . . . . . . . . . . . . . . .

    . . .

    . . .

    . . .

    . . .

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

    . . . . . .

    . . . . . .

    . . . . . .

    . . . . . .

    . . . . . .

    . . . . . .

    . . . . . .

    . . . . . .

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

    313 314 374 375 378 382 382 389 392 392 396 396 396 398 398 399 399 400

    I. INTRODUCTION

    The sensation of sweetness and the concept of a sweetener have undoubtedly been meaningful and important to man throughout his entire existence. During much of the relatively recent culinary history, i.e., the last 15CL200 years, and indeed continuing to the present day sweetness and sweetener have for

    313 Copyright 0 1982 by Academic Press, Inc

    All rights of reproduction in any form reserved. ISBN 0-12-016428-0

  • 374 LEA HYVONEN ET AL

    most people meant the respective taste and functional use of sucrose, which in turn has simply been referred to as sugar.

    The world of food science, however, is not so simple. On the one hand, there are numerous substances which have the property of sweetness and hence have the potential to be used as sweeteners.

    On the other hand, the various potential sweeteners have many other proper- ties in addition to sweetness which have important and varying functional charac- teristics, both positive and negative in nature.

    As knowledge about the various kinds of sweet-tasting substances has in- creased, it has become generally recognized that there are valid roles which each of them can play. Sweetness and the enhancement of food palatability are, perhaps, the common denominators in the use of any sweetener in foods. The choice of sweetener for a particular food system, however, is based on other considerations as well. The food technologist may require bulking, preservative, or humectant functions, or other physical and chemical properties such as sta- bility to heat processing and storage. Most of these requirements are adequately fulfilled by the traditional sucrose or hydrolyzed starch sweeteners.

    From the nutritional and health point of view, however, there may also be objectives such as reducing the amount of energy which the sweetening compo- nent brings into the food system, avoidance of too rapidly absorbed carbohy- drates, or reducing the exposure to types of food which are known to cause dental decay, to note only a few of the more obvious considerations.

    In recognition of the validity of these other requirements there has been an intensive search in recent years for suitable alternative sweeteners. The search has not been in vain, because there are a number of sweeteners which hold promise in fulfilling some of the divergent special sweetening needs currently being developed and commercialized. One of the most promising of these from the standpoint of special dietary applications, is xylitol, particularly in the areas of noncariogenic confections and disturbances of carbohydrate metabolism, and from the standpoint of fulfilling many of the food technological requirements traditionally expected of the conventional sweeteners.

    The metabolic pathways of xylitol and the effects of xylitol on human metabo- lism as well as the tolerability and toxicity of xylitol have been discussed pre- viously in Advances in Food Research by Ylikahri (1979). The dental aspects of xylitol have also been reviewed in this series (Makinen, 1979). The manufacture, properties, and food applications of xylitol are discussed in this article.

    II. THE OCCURRENCE AND MANUFACTURE OF XYLITOL

    A. NATURAL OCCURRENCE

    Xylitol occurs widely in nature. Frerejacque (1943) showed the occurrence of xylitol in lichens, seaweed, and yeast. Kratzl and Silbernagel (1963) found

  • FOOD TECHNOLOGICAL EVALUATION OF XYLITOL 375

    xylitol in mushrooms (Psalliota campestris). Xylitol has been found in small quantities in many fruits, berries, and vegetables (Table I) (Washiittl et al., 1973; Makinen and Soderling, 1980), and is also a normal metabolic intermediate in mammalian carbohydrate metabolism, including that of man (Hollmann and Touster, 1956, 1957; Bassler, 1972). The normal xylitol concentration of blood is 0.03-0.06 mg/100 ml blood.

    Commercially produced xylitol is a nature-identical product similar in struc- ture and properties to the natural substance.

    B. HISTORY

    Xylitol is by no means a new substance, having been first prepared as a syrup 90 years ago almost simultaneously in the laboratories of Bertrand (1891) and Fischer and Stahel (1891). Wolfrom and Kohn (1942) succeeded in obtaining crystalline xylitol upon hydrogenation of highly purified xylose. Carson et al. (1943) demonstrated the existence of two crystalline forms: the stable rhombic and the unstable monoclinic forms.

    Chiang et al. (1958) reduced xylose to xylitol by Penicillium chrysogenum and Onishi and Suzuki (1966) by yeasts. Later Onishi and Suzuki (1969) produced xylitol from glucose via D-arabitol and D-xylulose by certain yeasts.

    Since the time when xylitol was found to be a normal intermediate in carbohy- drate metabolism (Touster, 1960) there has been an ever-increasing volume of knowledge about its metabolic behavior in parenteral nutrition (e.g., Horecker et al., 1969; Brian and Miller, 1974; Thomas et al., 1974; Ritzel and Brubacher, 1976; Ylikahri, 1979) as well as its use as a sweetener in diabetic diets, which was first considered by Mellinghoff (1961).

    By the end of the 1960s xylitol had drawn the attention of dental scientists as being possibly less cariogenic than other known nutritive sweeteners. Miihlemann and his colleagues (1970) confirmed this in the rat model. Scheinin and Makinen and their colleagues (1 974, 1975a) found in the Turku sugar studies that when xylitol was substituted for sucrose in the human diet the result was a 90% reduction in the incidence of new carious lesions, as well as indications of a remineralizing effect on existing caries. Later Scheinin et al. (1975b) made a 1- year chewing gum study, the findings of which indicated a therapeutic, caries- inhibiting effect of xylitol even for a partial sucrose replacement in the diet.

    Before 1975 the production of xylitol was centered in Italy, Germany, the Soviet Union, Japan, and China, with the largest quantity being produced in the Soviet Union, where xylitol is the principal nutritive sweetener used in special dietary foods for diabetics. Total world production was estimated to be under 2000 tonslyr. In 1975 the first truly large-scale production of xylitol was begun in Kotka, Finland, at the sucro-chemical plant of the Finnish Sugar Co. Ltd., Helsinki, with a capacity for producing xylitol of over 3000 tons/yr. In 1976 ownership of the Kotka plant was transferred to Xyrofin Ltd., a joint venture

  • TABLE I OCCURRENCE OF XYLITOL IN FRUITS"

    Relative ripenessh

    Fruit A B XylitoP

    Raspberryd (Rubus idaeus)

    Strawberryd (Fragaria vesca)

    Red whortleberryd (lingonberry) (Vaccinium vitis idaeu)

    Cranberryd (Vaccinium oxycoccus, Oxycoccus quadripetalus)

    B il berryd (Vaccinium myrtillus)

    Sea buckthornd (Hippophae rhamnoides)

    Rowan berryd (Sorbus aucuparia)

    1 2 3 1 2 1 2 3 4 5 6 1 2 3 4 1 2 3 1 2 3 4 I 2 3 4

    0.030e 0.300 0.420 0.196f 0.740 0.0308 0.040 0.120 0.600 0.740 1.100 0.0128 0.030 0. I28 0.600 0.124e 0.353 2.0 0.310" 0.380 0.400 0.412 0.030h 0.050 0.242 0.410

    Unripe, green, hard Half ripe, reddish, hard Ripe, red Half ripe, reddish, hard Ripe, red Unripe, green, hard Unripe, green, hard Unripe, reddish, hard Half ripe, reddish, hard Half ripe, reddish, hard Ripe, red Unripe, reddish, hard Unripe, reddish, hard Half ripe, reddish, hard Ripe Unripe, green, hard Half ripe, reddish, hard Ripe Unripe, slightly orange. hard Unripe, orange, hard Half ripe, orange Ripe, orange Unripe, green, hard Unripe, reddish, hard Half ripe, reddish Ripe, red

    7.5 405

    26 150 280 58 I 1 36 9

    64 17

    37 18 21 38 28 21 91 15 26 25

    160 I30 1 I9 81

    -

  • 1 2 3

    0.050e 0.413 1.460 0.250'

    1 . o o o e

    0.450g

    Unripe, green, hard Half ripe, bluish Ripe, blue Ripe, yellow

    Ripe, black

    Ripe, red

    Unripe, green, hard Ripe Ripe

    Bog whortlebenyd 77 (bog bilbeny) 100 (Vaccinium uliginosum) 34

    Cloudberryd 85

    Black curranv 70 (Rubus chamaemorus)

    (Ribes nigrum)

    (Ribes rubrum)

    Red curranv 100

    Apple (Malusp 128 Apple, Yellow Cinnamon, 48 Apple, Astrakan' 67

    53 20 Pruned

    Grapd 105 White wine (Bordeaux

    Dubonnet (-77) 135

    Plums (a Romanian variety)' 0 Plums (a South African variety)'

    Bananai 93

    Blanc-77) 35

    UReprinted from Makinen and Soderling (1980). Copyright 0 by the Institute of Food Technologists. bRelative ripeness is given as extinctions (A) determined from sample homogenates, and by estimating the ripeness visually and observing the collection time (B). cThe values are in micrograms per 1 g of edible portion (fresh weight). dCrown in the wild state. eAt 540 nm. fAt 520 nm. gAt 500 nm. hAt 410 nm. 'At 370 nm. Kultured.

  • 378 LEA HYVONEN ET AL.

    established between the Finnish Sugar Co. and F. Hoffmann-La Roche & Co. Ltd., Basel, Switzerland.

    The annual world production of sugar alcohols was about 345,000 tons in 1978, and of that amount 330,000 tons were sorbitol. The amount of xylitol and mannitol produced was 6000 tons. The production amounts of maltitol, iso- maltitol, galactitol, and lactitol amounted to less than 1000 tons/yr (Albert et al., 1980).

    C. LARGE-SCALE XYLITOL PRODUCTION

    Production of xylitol by means of extraction from its natural sources is imprac- tical and uneconomical because of the relatively small amounts in which it occurs. Xylose, a pentose which can be hydrogenated to xylitol, is known to be widely distributed in plant material. It does not occur in the free state in plants, but is usually in the form of xylan, a polysaccharide composed of D-xylose units, which occur in association with cellulose. Xylose is also found as part of glyco- sides (Spalt et al . , 1973).

    Despite its wide occurrence in nature, xylose is difficult to produce commer- cially because of the problems encountered in separating it, particularly from other carbohydrates such as glucose. However, the fact that xylan is more easily hydrolyzed than cellulose provides the technical possibility for xylose extraction and xylitol production. Accordingly, the recovery of xylose from plant materials and its subsequent hydrogenation is the basic principle of xylitol production (Fig. 1).

    Plant materials which contain a suitable amount of xylans to be used in this process include hardwoods such as birch and beech, oat and cottonseed hulls, corn (maize) cobs, sugar cane bagasse, straw, and various nut shells. The xylan or xylose content of such materials is 2&30% of the dry substance.

    The choice of raw materials for the manufacture of pure xylitol is important. Most of the alternatives are bulky and of low density. Optimally, therefore, the raw material for large-scale production should be one which is centrally available in large quantities and of relatively high xylan content. In some of the existing processes agricultural by-products are being utilized, e.g., almond shells in Italy and apparently rice and cotton seed hulls, respectively, in China and the Soviet Union. The large Finnish production is based on birchwood chips, whereas other hardwood chips have been utilized in Germany. Xylan-containing sulfite waste from the paper and pulp industries has been proposed as a more economical alternative to hardwoods. Production in the United States will probably be based on corn cobs. All of these raw materials contain relatively small amounts of polymers of other sugars such as glucose, mannose, arabinose, and galactose in their hemicelluloses. The hydrolyzates require extensive purifications and sepa- rations to remove these sugars from xylose and xylitol. Nevertheless, it is possi- ble to recover about 50-60% of the xylans as xylitol.

  • Hydro l ys i s

    H 2 0

    t acid

    CHO I

    H-C-OH I

    I

    I

    HO-C-H

    H-C-OH

    CH20H

    D - Xylose

    C5H1005

    Hydrogenation

    H2

    + c a t a l y s t

    FIG. 1. Principle of xylitol production.

    Hydro lys is o f pentasan- containinq r a w mate r ia l s

    pen tose sugar mater ia l

    Ion exclusion

    r - - - - - - - - I

    Fina l pu r i f i ca t i on and co lor removal

    I I I I

    I I puri f ied pentase solution

    CH20H I

    I

    I

    I

    H - C - O H

    HO-C-H

    H-C-OH

    CH20H

    Xyl i to l

    125

    Hydrogenation

    I polyol so lu t ion

    Fractionation and molasses crystallization crystal l izat ion molasses

    I 1 _ _ _ _ _ _ _ J +

    XYLOSE 4

    XYLlTOL FIG. 2. Production of xylitol aild xylose

  • 380 LEA HYVONEN ET AL.

    The main steps in the xylitol production process are illustrated in Fig. 2 and described in detail below.

    I . Hydrolysis

    In mass production plant material is treated with a dilute acidic solution under heat and pressure to hydrolyze the hemicelluloses and to precipitate the lignins. The monomeric sugars dissolve in the reaction media together with other soluble products. Fortunately, the cellulose is not attacked, otherwise the xylose would be contaminated with large amounts of glucose which would be troublesome and costly to separate. The simultaneous occurrence of undesired side react...

Recommended

View more >