Enrichment of White Bread with Vitamin B Complex Through the Addition of Debitterized Brewers’ Yeast ROBERT SCHWARZ, STEPHEN LAUFER LOUIS LAUFER, AND MORTIMER W. BRENNER Schwarz Laboratories, Inc., New York, N. Y.
In view of the trend toward fortification of white bread with vitamins, consideration was given to utilization of brewers’ yeast for this purpose. Millions of pounds of surplus brewers’ yeast are being produced yearly in American breweries, but only a small fraction is used for preparations of vitamins and food products; the major portion is wasted. Brewers’ yeast is rich in the whole vitamin B complex. Consequently the addition of a moderate amount of yeast to white flour would enrich the bread, not with a few vitamins, but with the whole B complex, and the nutritional value of the bread would be increased. Addition of brewers’ yeast to white flour would not affect the eating habits of the public with regard to white bread.
Laboratory baking tests with addition of 2.5, 5 , and 7.5 per cent dried debitterized brewers’ yeast on bread solids basis indicated that, while the bread with 2.5 per cent yeast was equal in quality to the control, addition of increasing amounts of brewers’ yeast exerts some unfavorable influences on the quality of the bread. The 2.5 per cent yeast bread, which was as good in quality as the control, showed a considerable increase in thiamin, riboflavin, nicotinic acid, and pantothenic acid over the control bread. These tests, although preliminary in nature, demonstrate that earnest consideration should be given to addition of dried, debitterized brewers’ yeast to flour for the purpose of fortifying baked goods with vitamin B complex.
riboflavin, i t has been suggested that milk solids be used as a source of this vitamin. Another possibility for enriching white bread with the vitamins of the B complex lies in the utilization of brewers’ yeast for this purpose. At present such yeast is largely a waste product, although its nutritive value and high vitamin content have long been recognized. There are available in this country about 150 million pounds of liquid yeast annually, corresponding to 25 million pounds of dried yeast. Only a small fraction of this yeast is used for pharmaceutical, nutritive, or animal feed purposes, while the major portion is discarded. An obstacle to employing brewers’ yeast for human consumption has been its bitter taste. Methods are available, however, for completely debitterizing brewers’ yeast without affecting its nutritive properties. The idea of incorporating brewers’ yeast into bread is not new. During the first World War the Germans did considerable experimenting along these lines. The results were not entirely satisfactory, owing to the fact that relatively large quantities of liquid yeast (the equivalent of 10 per cent dry yeast) were used to replace part of the flour and gave the bread an unpalatable yeasty taste. In recent years, however, more success has been obtained by reducing the percentage of brewers’ yeast added to the dough. I n 1930 Koschkin (13) ran experiments on the introduction of 10 to 50 per cent of incompletely debitterized pressed yeast into the dough (3 to 15 per cent dried yeast). He found that additions up to 40 per cent did not affect the color, odor, or taste of the bread as compared to controls run without brewers’ yeast. The nutritive value of the treated bread was reported to be improved as the result of an increase in assimilable protein. Wohl and Woosley (28) showed that the addition of as little as 0.5 per cent of brewers’ yeast to American white-
H I T E bread is perhaps the most widely consumed food in the American dietary. Much publicity has been given recently to the well-established facts concerning the losses of vitamins and minerals during the milling of white flour. Furthermore, governmental agencies and scientific institutions have been working on a program for promoting the enrichment of flour. The goal of enrichment is the restoration of the nutritive factors (especially the vitamins of the B complex, calcium and iron) which are removed from whole wheat by processing (3). This program offers far greater promise of raising the level of the diet of the American people than any attempt a t changing the eating habits of the people. Over 95 per cent of the bread eaten in this country is white bread, in spite of educational campaigns aimed a t converting people to consumption of whole-wheat bread. The cooperative efforts toward establishment of standards of enrichment of white bread have been stimulated and aided by the demands of the present national defense program upon American workmen and the interest of the Government in the improvement of our national diet (17). The last published report of the Food and Drug Administration (8) set tentative requirements for enriched white bread. These are aubject to revisions which may appear desirable in the light of future advances in the science of nutrition. For the present, however, the recommendations cover minimum and maximum levels for the following nutritive factors: thiamin, 1-4 mg. per pound of bread; riboflavin, 0.8-3.2 mg.; nicotinic acid, 4-16 mg.; and iron, 4-16 mg. The present methods for enriching white bread with vitamins depend upon adding to the flour or dough either crystalline vitamins and/or special bakers’ yeast high in thiamin content. Because of the scarcity of commercial quantities of 480
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wheat flour ensured constant growth in white rats and prevented polyneuritis in pigeons. Simultaneous control experiments on the same animals and birds, fed the same basal vitamin-B-free ration plus white-wheat flour, resulted in a loss in weight, followed by death after about 18 weeks, for the rats and the development of polyneuritis by the pigeons. Schulein (19) reported in 1935 that the addition of 3 per cent dry irradiated brewers’ yeast to bread (in Germany) prevented vitamin B1,Bs, and D deficiencies in pigeons and rats, whereas the ordinary bread consumed by the general public permitted the appearance of these deficiencies in the test animals.
Experimental Procedures
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made on this series of breads. In general, the score test indicates that the addition of 2.5 per cent of yeast on bread solids basis yields a white bread whose qualities are practically the same as those obtained with the control containing no yeast. The only appreciable difference is a slight decrease in bread volume. Five per cent of brewers’ yeast, on the other hand, markedly affects bread quality. The vitamin values for the ingredients used in the experimental breads are presented in Table 11. The results obtained for the skim-milk powder mixture are useful only for the purpose of calculating balances. Those secured for flour, bakers’ yeast, and brewers’ yeast are of interest beyond their use in calculations of vitamin balances. The thiamin value for the sample of white flour tested (0.183 mg. per pound) is low as compared to values ranging from 0.318 to 1.22 mg. per pound reported in the literature (10,80). When employed to calculate the amount of thiamin contributed to the bread by the ingredients, however, this value checks closely with that found in the bread* Hence, O*lg3 mg- per pound appears to be the correct value for this white flour.
The possibility of utilizing debitterized brewers’ yeast for enriching white bread nrith the vitamins of the B complex was investigated. Experiments were conducted in which 0, 2.5, 5.0, and 7.5 per cent of a commercial dry brewers’ yeast, bou ht on the open market, were added to the dough. The Yeast adfitions are expressed as a percentage of the amount of the usual solids employed in baking white bread. The breads were prepared and scored by an experienced bakin laboratory. Four loaves were made for each level of yeast acfdition, one loaf being used for scoring purposes and the other three for analysis. Determinations were carried out on each of the three loaves at least once for each of the vitamins listed TABLE11. VITAMINB COMPLEX CONTENT OF BREAD INQREDIENTS below. In many instances more than one assay was Mg. per Pound, Dry Basis made for one vitamin on a particular loaf. Hence the Nicotinia Pantovalues on the ex erimental breads presented in the acIngredient Moisture, % Thiamin Riboflavin acid thenio acid companying tabks are averages of triplicate results, 12.7 0.183 0.234 3.61 2.15 at least. In addition, three commercial. breads bought :pdmmi1k powder, salts, on the open market were tested to obtain comparative sugar, yeast food mixt. 3.32 0.807 2.94 1.33 5.78 70.8 6.15 28.5 146 69.8 values. These were an ordinary white bread, an en6.61 97.8 35.0 285 34.0 riched white bread, and a bread made o! specjally processed flour. Furthermore, all of the ingredients possibly contributing vitamins to the experimental breads were assayed. These ingredients were: white flour: a mixture of skim-milk powder, salt, sugar, and yeast food; No data could be found in the literature for the riboflavin bakers’ yeast; and the supplement of brewers’ yeast. content of white flour, for comparison with the result given The breads as received were weighed, air-dried for 24 hours in Table 11. The nicotinic acid content of white flour has weighed again, and finally ground through a Straub electric mii been reported to vary from 3 to 5 mg. per pound ( I @ , and the to pass through a 20-mesh sieve. The samples were then stored in the dark in moistureproof containers. Moisture and vitamin pantothenic acid content is about 2.7 mg. per pound (16). determinations were made on the ground, air-dried Sam les and These values agree with those presented here. on the ingredients employed to bake the experimentaf loaves. To the authors’ knowledge, no comparative values on the All values were calculated to terms of milli rams per pound, and vitamin B complex content of brewers’ and bakers’ yeasts the results for the breads are expressed on.tke ?s-reqeived basis. The vitamin assays were made by microbiological methods. have been reported previously. Published data on the vitaThe sulfite cleavage modification of the yeast fermentation min content of bakers’ yeast is sparse although much informethod of Schultz, Atkin, and Frey (d, $1 28) was employed for mation is available on brewers’ yeast. The vitamin B1 convitamin B1 (thiamin) determinations. fitamin BS (riboflavin) tent of the sample of brewers’ yeast used is somewhat high was assayed by the microbi?logical method of Snell Fnd Strong (24) using Lactobacillus casm e. Sunilarl antothenic acid was but well within the wide range of 11 to 220 mg. per pound determined with the same organism a n c t f e procedure of Penreported by other workers (9, 14). The same holds true for nington, Snell, and Wilhms (18). Finall nicotinic acid was a& the riboflavin content of brewers’ yeast, which has been sayed by the microbiological procedure oTknell and Wright ( N ) , in which the organism Lactobaczllus arabinosus 17-6is used. found to vary from 15 to 35 mg. per pound (4, 23, 24). Furthermore, the published values for the nicotinic acid content Discussion of Results of brewers’ yeasts vary from 150 to 420 mg. per pound (6, 6, I,%’), and those for bakers’ yeasts from 110 to 230 mg. Table 1 gives the results of score tests on the experimental per pound (4, 6, la). The values tabulated fall within these loaves. The bread containing 7.5 per cent yeast is poor limits. Strong et al. (27) reported the pantothenic acid concompared to the control; therefore no vitamin assays were tent of yeast, without specifying the type, as ranging from 7 to 39 mg. Der Dound. T G simile of bakers’ yeast tested was found to have about OF EXPERIMENTAL BREADS TABLE 1. SCORE one twentieth the thiamin content and about one half the 1 2 3 4 Series No. 2.6 6 7.6 Brewers’ yeast, %a None nicotinic acid of the brewers’ yeast. The riboflavin content (aontrol) of the bakers’ yeast is also less than that of the brewers’ 4.07 3.76 4.37 4.37 Symmetry yeast, but the pantothenic acid content of the former is, 4.68 4.69 4.37 4.47 Bloom 4.37 4.37 4.37 Color of crust 4.37 surprisingly, twice that of the latter. The pantothenic acid 3.62 3.13 4.37 3.91 Volume 4.46 4.64 4.64 Conaistenoy of must 4.37 figures obtained for the brewers’ yeast were carefully checked, 8.12 6.25 6.00 8.75 Color of crumb 6.25 8.75 8.12 and three other samples of bakers’ yeast bought on the open 6.00 Grain 13.36 9.37 7.60 13.13 Texture market were assayed for pantothenic acid content. In all 8.44 7.60 6.26 8.75 Aroma 10.26 18.00 17.62 18.12 Flavor instances the values obtained for the bakers’ yeasts were 8.76 8.12 7.60 8.76 Eating quality higher than that found for the sample of brewers’ yeast. Total score 87.60 86.48 74.82 68.75 Shortly after our assays for pantothenic acid were completed, a Added on bread solids baaia. Strong et al, (27) pointed out that ordinary extraction of
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B complex tested occurred under the baking conditions used in these exCODE I 15 periments. It is known, however, 0 N O B R E W E R S ’ Y E A S T ADDED 14 that in practical baking operations 2.9%8REWERS’ YEAST ADDED there are vitamin losses which may 13 vary for thiamin from 5 to 29 per S.O%BREWERS’Y E A S T ADDED I2 12 cent, depending on the conditions of O R D I N A R Y COMMERCIAL EREA baking ( 2 1 , 26). Little information is available regarding the baking losses of the other constituents of the B complex. The results obtained on the three commercial breads are presented in Table IV. Ordinary white bread is low in all the B vitamins. Enriched white bread shows addition of thiamin and nicotinic acid above the minimum requirements. The values for riboflavin and pantothenic acid for the enriched bread are practically the same as for ordinary white bread and for breads of series 1 ; no significant enrichment with regard to the latter factors is indicated. The FIGURE 1. THIAMIN, RIBOFLAYIN, NICOTINIC ACID, AXD PANTOTHENIC ACID CONTENTS snecial-orocess bread. which is beO F EXPERIDIENT.4L AKD COMRIERCIAL BREADS likved t o be baked from flour prepared by a new flotation process, yeast by autoclaving with a large volume of water near neugives values for thiamin, riboflavin, and pantothenic acid trality (the method employed by the authors) gives values similar to those found in the loaves in series 2 (containing for free, and not total, pantothenic acid. They recommend 2.5 per cent of dried debitterized brewers’ yeast). The either a preliminary autolysis of the yeast or an enzyme nicotinic acid content of this commercial bread ia the digestion followed by autoclaving for 20 minutes a t 15 pounds highest in any of the loaves assayed (15 mg. per pound). per square inch pressure. It may be that a large proportion of the pantothenic: acid in brewers’ yeast is in a combined form so that low values, as compared to bakers’ yeast, are TABLE IV. CONTENTOF VITAMINB COMPLEX IN COMMERCIAL obtained. This point requires further investigation. BREADS Table I11 shows the vitamin contents of the three series of Mg./Lb.@. As-Received Basis Nicotinic Pantothenio breads analyzed, together with a balance calculated from the Bread Moisture. % Thiamin Riboflavin acid acid ingredients employed to bake the loaves. I n general, the Ordinarywhite 35.4 0.361 0.386 3.31 1.66 results found for series 1 (control loaves) conform with values Enriched white 34.8 1.05 0.406 6.23 1.81 36.0 Special-processed 1 .47 0.820 15.1 2.40 reported by others for the thiamin, riboflavin, and nicotinic T o convert mg. per pound t o micrograms per gram, multiply by 2.204. acid content of ordinary white bread (16,20). No values, as far as the authors are aware, have been published previously on the pantothenic acid content of bread. It is clearly evident that the addition of brewers’ yeast to The special-process bread is much darker in color than a white white bread appreciably increases the vitamin B complex conbread and apparently similar to whole-wheat bread. The tent of the bread. As little as 2.5 per cent of the brewers’ nicotinic acid content of whole-wheat bread has been reported yeast raises the thiamin, riboflavin, and nicotinic acid content ( I ) as 16 mg. per pound. of the bread above the tentative minimum requirements set A summary of the results obtained in Tables I11 and IV is given in a graphical form in Figure 1. up by the Food and Drug Administration for enriched white bread. Results calculated from ingredient assays agree with the Conclusions values found in all three experimental series, within the While these tests have been carried out on a laboratory experimental error of the methods employed for analysis. scale, the results warrant earnest consideration by governThis indicates that no losses in the components of the vitamin ment agencies and the milling and baking industries of addingdried debitterized brewers’ yeastto white flour prior to baking for the purpose of restoring the vitamin TABLE 111. CONTENT O F VITAMIN B COMPLEX IN EXPERIMENTAL BREAD B complex to white bread, Nutritional tests have Mg./Lb.. As-Received Basis definitely established that addition of the whole B comBrewers’ east (Bread hfoisture, Nicotinic PantoBreads Solids Basis) % Thiamin Riboflavin mid thenio acid Plex to the diet gives better results than equal supplements of all the known vitamins of the B complex in Series 1 Found 0 35.7 0.168 0.451 2.76 1.64 synthetic form (7,26). Furthermore, addition of the Ca1cd.o ... .. 0.184 0.475 2.55 1.88 B complex to white flour in form of debitterized Series 2 Found 2.5 37.3 1.50 0.879 6.92 2.10 brewers’ yeast would not interfere in any way with Ca1cd.a ... .. 1.57 0.954 6.51 2.28 Geriea 3 2.58 the long-established habits of the consuming public Found 5.0 38.1 2.71 1.15 10.6 Calcd. ... .. 2.82 1.38 10.1 2.66 with regard to white bread. The addition of irradiated brewers’ yeast to white bread also merits From ingredients. consideration. Besides providing the vitamins of the
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B complex, irradiated brewers’ yeast would add vitamin D, supplements of which are now optional in bread.
Acknowledgment The authors are indebted to Charles A. Glabau, of Bakers’ Weekly, who carried out the baking and scoring tests. The assistance of Leonard Saletan, Jesse Charney, and Henry Vogel, members of the staff of Schwarz Laboratories, Inc., in preparing the data presented in this paper is also acknowledged. Literature Cited (1) Ackroyd, W. R., and Swaminathan, M., Indian J . Med. Research, 27, 667 (Jan., 1940). (2) Am. Assoc. of Cereal Chem., Comm. on Methods of Analysis, Release of Methods for Analysis of Vitamin Bi, May, 1941. (3) Am. Chem. Soo., Symposium on Nutritional Restoration and Fortification of Foods, IND. ENQ.CHIM., 33,707 (1941). (4) Arnold, Aaron, Lipsius, S. T., and Greene, D. J., Food Research, 6,39 (1941). (5) Arnold, Aaron, Schreffler, C. B., and Lipsius, S. T., IND.ENQ. CHEM.,ANAL.ED., 13,62 (1941). (6) Bandier, E.,and Hald, J., Biochem. J., 33,264 (1939). (7) Bean, W. B., and Spies, T. D., J . Am. Med. Assoc., 115, 1078 (1940). (8) Food and Drug Administration, Federal Register, June 7, 1941. (9) Hennessy, D.J., and Cerecedo, L. R., 1.Am. Chem. SOC.,61, 179 (1939). (10) Hoffmann, C., Schweitzer, T. R., and Dalby, G., Cereal C h m . , 17,733 (1940).
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(11) Ibid., 17, 737 (1940). (12) Kodioek, E.,Biochem. J . , 34, 712 (1940). (13) Koschkin, M. L., Z.untersuch. Lebensm., 60, 489 (1930). (14) Laufer, Louis, Brenner, M. W., and Laufer, Stephen, Proc. f s t Food Conf. Inst. Food Tech., 1, 77-87 (1940). (16) Marx, V. E.,Bakers’ Helper, 76,370 (Aug., 1941). (16) Millers Natl. Federation Tech. Comm., Northwestern Miller, 207, 20 (Aug., 1941). (17) Natl. 8esearch Council, Rept. of Comm. on Foods and Nutrition, Jan., 1940. (18) Pennington, D., Snell, E. E., and Williams, R. J., J . Biol. Chem., 135,213 (1940). (19) Schiilein, J., “Die Bierhefe als Heil-, Nahr-, und Futtermittel”, Leipzig, Theodor Steinkopf, 1935. (20) . , Schultz. A. S..Atkin, L., and Frev, C. N., Cereal Chem., 16. 643 (1939). (21) Schdtz, A. S., Atkin, L., and Frey, C. N., J . Am.. Chem. SOC., 59,2457 (1937). (22) Schdtz, A. S.,Atkin, L., Frey, C. N., and Williams, Ibid., 63, 632 (1941). (23) Schumaoher, A. E.,and Heuser, G. F., IND. ENQ.CHEM.,ANAL, ED., 12, 203 (1940). (24) Snell, E. E.,and Strong, F. M., Ibid., 11, 346 (1939). (25) Snell, E. E., and Wright, L. D., J . Biol. Chem., 139,675 (1941). (26) Spies, T.D.,Swain, A. P., and Grant, J. M., Am. J . Med. Sci., 4m. -zoo. - - , AX --- m \ - - - - I
(27) Strong, F. M.,Feeney, R. E., and Earle, A., IND.ENQ.CHEM., ANAL.ED.,13, 566 (1941). (28) Wohl, G. M., and Woosley, F., Arch. Path., 7, 761 (1929) PRESENTED before a joint program of the Diviaions of Biologioal Chemistry, of Agricultural and Food Chemistry, and of Medicinal Chemistry at the 102nd Meeting of the AMERICAN CHEMICAL SOCIETY, Atlantio City, N. J.
Recovery of Butanol in
Butanol Pulping The recovery of butanol from butanol pulping liquors was effected quantitatively by azeotropic distillation and by extraction with isopropyl ether to demonstrate the recovery commercial operation could expect. Neither lignin nor alkali interfered in the separation, and both methods are suitable for industrial use.
0 SEPARATE the components of a binary liquid system, distillation and extraction are usually easier, cheaper, and more practical than other methods. Both may be used in the recovery of butanol from butanol-water-lignin solutions resulting from the pulping of wood by butanolysis. While by no means complete, sufficient laboratory experiments have been completed (9, 3) to justify consideration of industrial butanol pulping. Few data have been published on the recovery of butanol for re-use (3). There is a real need of quantitative information on the efficiency of recovery to permit an estimate of chemical losses on a commercial scale.
T
Extractive Recovery of Butanol Theoretically any solvent which could meet the requirements of low solubility in water, effective solvent action on
A. J. BAILEY, University of Washington, Seattle, Wash. butanol, a boiling point not too near that of butanol, low cost, ready availability, and absence of complicating factors such as toxicity, formation of azeotropes, etc., should be suitable for solvent extraction. Hence, a large number of solvents might be used. Diisopropyl ether, (CH&CHOCH(CH&, was selected for this study. It dissolves butanol in all proportions, is soluble in water at room temperature to the extent of 0.2 per cent, boils a t 67.5” C., and under normal conditions costs about 30 cents per gallon. The apparatus employed consisted of a unit for continuous ether extraction similar to that shown in Figure 1. Extractor charges of about one liter were generally used, containing butanol-water solutions consisting of the pure compounds alone, as well as the aqueous layer of waste pulping liquors which contained lignin, carbohydrates, and alkali as well. Pulping liquors without alkali were also used. I n general, the test solutions consisted of water or the water layer of a cook with all alcohol driven off by distillation, with known quantities of anhydrous butanol added. Complete removal of alcohol from these pulping liquors was achieved by distillation in efficient columns (I), usually in cascade-that is, a thirty-plate roughing column, a thirty-plate concentrating column, and a sixty-plate final column. All were run simultaneously and allowed to come to equilibrium and maximum
