Sugars in the Baking Industry - Advances in Chemistry (ACS

Sugars in the Baking Industry SYLVAN

EISEΝBERG

1

Downloaded by FUDAN UNIV on March 12, 2017 | http://pubs.acs.org Publication Date: June 1, 1955 | doi: 10.1021/ba-1955-0012.ch010

Chemistry Department, University of San Francisco, San Francisco, Calif.

Bakery products fall into two main groups—yeast-raised and nonyeast-raised. Yeast-raised goods account for roughly 3 5 % of the sugars used in the United States baking industry. The principal functions of sweeteners in yeast-raised products are to provide fermentability and sweetness; in nonyeast-raised products, sweetness. Sucrose and dextrose are the principal sugars purchased in highly refined form. Fructose, lactose, and maltose find their way into baked goods in the form of invert sirups or honey, milk, and malt sirups. These sugars differ in sweetness and in fermentability by yeast, as well as in physical properties such as hygroscopicity.

Bakery products may be classified into two main groups—those leavened by yeast and those by chemical or physical means. Yeast-raised goods include bread, rolls, sweet rolls, raised doughnuts, a n d crackers. Chemically leavened products include most cakes, cake doughnuts, pastries, and cookies. Foam-type cakes such as angel food and sponge cake are physically leavened by aeration. Pies represent a separate class. Of the total estimated bakery production i n 1947 (8) approximately 7 9 % was yeast-leavened. I n terms of sweetener consumption, however, yeast-raised goods accounted for only 3 5 % of total sweeteners purchased by the baking industry, as computed from known quantities of the individual types of merchandise produced (8) and estimates of added sweetener content f o r each type as required by their f o r m u lations. This disproportionate relationship between raised goods produced and sweeteners used i n their production merely reflects the fact that such goods are relatively unsweetened. Pertinent data are shown i n Table I . Table I. Estimated Amounts of Sweeteners Used for Baked Products in the United States in 1947 (Millions Products Yeast-raised goods, 79% Bread Rolls Sweet goods Crackers

Quantity

of

pounds) Sweetener,

(8)

3.7 5.0 9.0 0.0

10,500 942 612 928

Total Av. Nonyeast goods, 2 1 % Doughnuts Cakes and pastries Cookies Pies

12,982

Total Av. Grand total

3,403

6

1

a

Sweetener Used (Estimated) 890 47 55 0

492, 35% 3.8 20 33 25 20

400 1,291 1,111 601

80 430 280 120 910, 65%

27

16,385

Total sucrose used by U . S. baking industry, 1947 (8) Fraction of total sweetener represented by sucrose (5) Total sweetener used by U . S. baking industry, 1947 Estimated from trade formulas. Calculated (5, 8). &

a

%

1402 1139 76 % 1486

Present address, Anresco, 693 Minna St., San Francisco, Calif.

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Kinds of Sweetener Used

The three principal sweeteners purchased as such are sucrose, dextrose monohydrate, and corn s i r u p ; sucrose represents about 7 5 % of the total. Relatively small quantities of malt sirup, honey, invert sirup, and molasses find special use. Two other sugars occur i n bakery products i n significant quantities, though often overlooked. Lactose is introduced through nonfat dry milk, and must approach at least 10% of the total sucrose used. Maltose, other than that directly added as malt sirup, is i n v a r i a b l y introduced by the influence of diastatic enzymes on flour starch. Quantities so introduced are difficult of estimate, but there are some data for yeast-raised goods. Rice (7) reports maltose content of bread on a dry basis, from which a value of 2.8% maltose can be calculated on a fresh bread basis. This figure is certainly of the r i g h t order as judged by the known diastatic activity of commercial bread flours, and i t may be reasonably applied to yeast-raised goods i n general. On this basis, maltose is believed to occur i n baked goods to the extent of 3 2 % of the total sucrose used by the United States baking i n d u s t r y — t h a t is, i n bread at least maltose is a principal sugar. Sucrose. Sucrose is the sweetener purchased i n largest amount, and, as might be expected, i t is produced i n many forms. Besides the several grades of brown or so-called soft sugars which have limited use i n some icings and i n dark variety goods, highly refined sucrose can be classified into three main groups—granulated, powdered, and liquid. The grades of granulated sugar differ from each other i n crystal size, which is controlled by processing and not by g r i n d i n g of coarser material. The finer products find particular application i n dry mixes and i n cakes, the coarser for general use and for m a k i n g cooked fondants. Powdered sugar is produced by g r i n d i n g granulated stock, and is available i n several grades of different mesh. U n i f o r m i t y of particle size w i t h i n grade is important, p a r t i c u l a r l y i f the sugar is to be used i n cream fillings or coatings, where coarse grains may produce grittiness. Of the several grades made, the finer are used i n making cream fillings and coatings and i n preparing uncooked fondants, the coarser for dusting fried goods such as doughnuts. L i q u i d sugar, pure sucrose sirup, is relatively new to the baking industry, and use at present is confined to the larger bread manufacturing plants. Such plants, when they are located not too f a r f r o m the source of supply, can take advantage of a price differential which more than offsets the cost of shipping contained water. Dextrose Monohydrate. Second i n importance only to sucrose, this sugar finds considerable use i n the manufacture of raised goods, p a r t i c u l a r l y bread, and i n many plants it has displaced sucrose entirely. Other grades of dextrose, powdered and pulverized, are used i n cakes, cookies, and icings. I n such products up to 2 5 % of the sucrose has been replaced w i t h dextrose, p a r t i c u l a r l y i n chocolate cake (5, page 107). This provokes thought, inasmuch as chocolate cake and chocolate goods i n general differ from others by being alkaline, and i n them sucrose would undergo a minimum of inversion. De Boer (2) contends that interconversion between dextrose and lévulose occurs i n cakes i n the presence of bicarbonate or carbonate leavening. The combined solubility of two sugars is greater than that of either alone, though less than the sum of the two (5, page 56). This would apply possibly to the combined use of dextrose and sucrose i n high sugar formulas, p a r t i c u l a r l y as only p a r t of the water i n baked goods is available as solvent (6). Other sugar products. Corn sirup and invert sirup find use i n cakes, cookies, icings, and fillings, where their hygroscopic properties are useful i n increasing the amounts of moisture retained. I n icings these sirups also serve as stabilizers, i n the sense that they retard crystal growth of other sugars. Honey and molasses are also used i n the same w a y when their characteristic flavors are required. Nondiastatic malt sirup is used i n raised goods and i n some cookies, to supply fermentable sugars for the one, or to i m p a r t characteristic flavor, color, and moisture-retaining ability to the other. USE OF SUGARS AND OTHER CARBOHYDRATES IN THE FOOD INDUSTRY Advances in Chemistry; American Chemical Society: Washington, DC, 1955.

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Functions of Sweeteners

Nonyeast Goods. Here the most important function is to impart sweetness. T h i s practically eliminates maltose and lactose f r o m consideration. Sucrose and dextrose are the two most important sweeteners purchased. Possibly next i n importance is the ability of the sweetener to caramelize, i m p a r t i n g crust color. T h i s is important i n yeast-raised goods as well, and certainly i n such products caramelization is a complex process affected by components other than sugars. I n nonyeast goods sweetness controls, and discussion of crust color as a function of kind of sugar is academic, except f o r one application. I n the m a k i n g of piecrust nonfat d r y m i l k is often used to i m p a r t color. Sucrose and dextrose allegedly encourage sogginess. Possibly lactose w i t h its low solubility could be used to advantage, price permitting. Sweeteners have other functions as well. They i m p a r t tenderness to cakes, thus enhancing their practical keeping quality. They increase the mobility of batters and the spread of cookies. The sirups increase moisture-retaining ability and retard crystallization of other sugars. Yeast-Raised Goods. F i r s t i n importance, but possibly second i n some instances, is the ability of the sweetener to support fermentation, for only by this means is leavening achieved i n this k i n d of merchandise. Second i n importance, but possibly first i n some instances, is the requirement of sweetness. I n sweet goods at least, and also i n bread as judged by present trends, sweetness is becoming more important. These functions must be served. Besides these, sweeteners contribute crust color and toasting quality. Here differences among various sweeteners, though important, have not been established w i t h sufficient objectivity to w a r r a n t discussion. W i t h regard to dextrose and sucrose, however, B a r h a m and Johnson (1) report no pract i c a l difference. Sweeteners are also said to influence keeping quality, some sugars being more effective than others. Such differences again are not considered clearcut; so-called bread softeners are more effective. Sweetness

Sweetness cannot yet be determined by chemical or instrumental means. E s t i mates of the relative sweetness of different substances remain dependent upon s t a tistical treatment of data obtained subjectively by means of taste panels. Reduction of such results to practical application appears simple, but may indeed become illegitimate. Cameron (3) and others (5, page 48) have found that sweetness i s not a linear function of concentration, and that the relative sweetness of different sugars varies w i t h the concentrations at which they are compared. Sweetness is influenced by temperature, p H , and the presence of other substances which need not themselves be sweeteners. F o r example, a 5% sucrose solution containing 2 % urea was found to be equal i n sweetness to a 3.1% sucrose solution. Thus, sweetness had been reduced 3 8 % by the presence of urea. Though these difficulties must be kept i n m i n d , the quality of bakery products must be controlled, and bakers are prone to flirt w i t h a single numerical "score" of quality. Doing this, they are also impressed w i t h s i m i l a r scores of the sweetness of different sugars. Such scores of relative sweetness, w i t h sucrose a r b i t r a r i l y assigned the value 100, are shown i n Table I I . There is evidence that at high concentrations the less sweet sugars become relatively sweeter compared to sucrose and that synergistic effects among sugars act i n the same direction. Thus, Cameron reports that invert sugar is sweeter t h a n sucrose at concentrations above 1 0 % , but not so sweet as sucrose at lower concentrations. Fermentability

Of the monosaccharides involved i n raised-goods manufacture, dextrose and lévulose are fermentable. Of the disaccharides, sucrose and maltose are fermentable whereas lactose is not. T h i s much is clear. Difficulties arise, however, when relative fermentability of different sugars is considered. Answers to this question have been sought by two methods, measurement of USE OF SUGARS AND OTHER CARBOHYDRATES IN THE FOOD INDUSTRY Advances in Chemistry; American Chemical Society: Washington, DC, 1955.

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carbon dioxide produced or determination of residual sugars. E a c h of these techniques has been applied either to fermenting doughs or to other fermenting media. If concern with fermentability is limited to leavening—and this is certainly justified—then only those methods that measure gas production i n fermenting doughs are pertinent. A n d even w i t h this limitation we have at least two possible c r i t e r i a : efficiency of conversion to carbon dioxide and rate of conversion. Both factors may well v a r y and v a r y differently for different sugars, w i t h modification of fermentation conditions and materials.


Table II.

Relative Sweetness of Sugars and Sugar Products

Lévulose Invert sugar Sucrose Dextrose, anhydrous Dextrose monohydrate Enzyme-converted corn sirup Corn sirup, unmixed Maltose Lactose Galactose (estimated f r o m d a t a of

Cameron)

140-175 100-130 100 70-75 60-75 60 30 80 15 58

A promising attack on this problem has been made. In plotting instantaneous rates of gas production against fermentation time (4), a region of exponential decline of rate is found as sugar exhaustion approaches. In this region the f e r mentation functions as a first-order reaction, and one may w r i t e : Rt =

K(VT

- Vt)

i n which Rt is the instantaneous rate at time t, Κ is the velocity constant, VT is the total amount of gas to be expected from the sugars existent up to and included i n the first-order range, and Vt is the total volume of gas produced up to time t. N o w i f Rt is plotted against Vt, a linear region corresponding to the first-order range should be found, and this is done w i t h v a r y i n g degrees of success, depending upon the fermentation conditions and materials. The slope of this line is K. The V intercept is VT* This intercept can be determined w i t h almost analytical ac curacy; the slope, w i t h sufficient accuracy to j u s t i f y statistical study. W i t h VT determinable, i t becomes possible to measure increments i n volume of gas produced as a function of k i n d and quantity of sugar; hence the efficiency of conversion to carbon dioxide. K, other conditions the same, measures the rate at which the sugar is converted to carbon dioxide. Table I I I reports data for sucrose, dextrose, and maltose, where these sugars were added to the dough stage of an 8 0 % sponge fermentation. Sponge times were 5.5 hours i n one case and 24 hours i n another. A l l figures are averages of two independent determinations. Volumes of carbon dioxide per gram of sugar have been adjusted to 30° C. and 760 mm. of mer cury pressure, and to the anhydrous basis. Table III.

Fermentability of Sucrose, Dextrose, and Maltose V = volume of CO„ per g r a m of s u g a r Κ — specific reaction rate V

Κ

Sugar

5V hr.

24 hr.

Av.

5V2 hr.

2 A hr.

Sucrose

219

220

220+1

0.34

0.53

Dextrose

216

218

217+1

0.55

0.63

0.59+0.04

Maltose

200

208

204+4

0.55

0.63

0.59+0.04

2

Av. 0.44+0.10

These results establish that sucrose and dextrose i n chemically equivalent quantities are converted to carbon dioxide w i t h practically identical efficiencies, whereas maltose is some 10% less effective. Maltose and dextrose under the con ditions investigated fermented w i t h practically identical specific reaction rates. The induction period usually observed for maltose under sponge conditions of fermentation was not observed here. Sucrose appears to have a smaller Κ value. This indicates that the rate of conversion is somewhat lower than for the other USE OF SUGARS AND OTHER CARBOHYDRATES IN THE FOOD INDUSTRY Advances in Chemistry; American Chemical Society: Washington, DC, 1955.

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sugars under the specified conditions, but the difference is too small to have practical significance. I t is possible that sugars other than those discussed may become important to the baking industry. Interest i n the production of pure lévulose continues. Lactose has dropped f r o m about 60 to 14 cents per pound over the past 15 years, whereas the cost of nonfat d r y milk has increased about 300%. If lactose were hydrolyzed, perhaps even i n the dough, its fermentability would be increased f r o m n i l to 5 0 % that of dextrose and i t would become as sweet. Literature Cited


(1) (2) (3) (4) (5)

B a r h a m , H. N., Jr., and Johnson, J. A., Cereal Chem., 28, 463 (1951). Boer, H. W . de, Chem. Weekblad, 47, 269-74 (1951). Cameron, A. T., Sugar Research Foundation, Sci. Rept. Ser. 9 (1947). Eisenberg, S., Cereal Chem., 17, 430-47 (1940). Jones, P . E . , and Thomason, F . G., Production & M a r k e t i n g A d m i n i s t r a t i o n , U . S. Dept. A g r . , Agr. Inform. Bull. 48 (1951). (6) K u h l m a n n , A. G., and Golossowa, Ο. N., Cereal Chem., 13, 202 (1936). (7) Rice, W . , Ibid., 15, 672 (1938). (8) U . S. B u r . Census, Northwestern Miller, Section 2, 245, 113-15 (1951). RECEIVED September 2,

1953.

USE OF SUGARS AND OTHER CARBOHYDRATES IN THE FOOD INDUSTRY Advances in Chemistry; American Chemical Society: Washington, DC, 1955.

Sugars in the Baking Industry - Advances in Chemistry (ACS

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