Maturing and Bleaching Agents Used in Producing Flour U
C . G . HARREL Research and D e v e l o p m e n t D e p a r t m e n t , Pillsbury Mills, Inc., Minneupolis, M i n n .
F
and bleaching agent. It gives similar beneficial developmental and maturing results a t slightly lower levels of treatment (20,9526). It is approximately 80% as efficient for color removal as is nitrogen trichloride. Unlike nitrogen trichloride, flour treated with chlorine,dioxide shows no toxic effects on animals ( 3 , 3 4 , 3 6 ) .
OOD processing represents man’s age-old endeavor to increase the efficiency and enjoyment of food utilization and to extend the resources of raw materials available for supplying food nutrients. From earliest recorded times man has tried t o secure a white flour, because it symbolized t o him a pure and wholesome product. Many of the millers guarded their early application of bleaching agents to flour with secrecy, because they had discovered the desire of the consumer for an improved flour. The bleached flour of today represents the culmination of centuries of such efforts.
A
Figure 2.
Chopin Alveograph Tests on Clear Flour
It is possible to demonstrate the effects of these maturing agents in the laboratory by physical methods (10,24, .@). Figure 1 is a diagram of the rheological properties of a piece of dough made by the Extensograph. T h e Extensograph is a machine which provides a measure of the extensibility of the dough and the force required to obtain the maximum extension of which the dough is capable without breaking. The horizontal axis indicates extensibility and the vertical axis resistance t o extension. The effect of chlorine dioxide is clearly visible. T h e resistance to extension is increased and the extensibility decreased b y chlorine dioxide treatment of the flour. The surface area of the diagram indicating general strength of the dough, mainly based on protein quantity and quality, is the same in botH cases or slightly increased in the case of a treated flour. Figure 2 shows a typical chlorine dioxide effect a s measured by means of the Chopin Alveograph in t h e laboratory.
Figure 1. Extensograms of Hard Winter Wheat Flour
The earliest bleaching agent used extensively in America for aour was nitrogen peroxide (I, 3, 6) which was introduced at about the turn of the century. It produced a flour with slightly improved color characteristics, but did not otherwise affect baking quality. This treatment was largely abandoned in favor of other processes which have proved much more effective. One of these was chlorine, introduced in 1912 (46). This method improved color and also tended to improve baking quality. Later it was discovered t h a t chlorine was markedly useful in the improvement o f baking qualities of flour used in making cakes, especially cakes which carry a high proportion of sugar-namely, 120 to 140%. This “percentage” is obtained by dividing the weight of the sugar t)y the weight of the flour (20,33,43). Nitrogen trichloride was introduced in 1921 (la). This reagent, like chlorine, improved both color and baking quality, and was especially effective a s a treatment of flour used i n bread making (11, 29, 38). It was the advent of nitrogen trichloride which tended t o eliminate the price differential between southwestern and some northwestern wheats as compared with spring wheats by improving baking values. It aided the southwestern part of the United States in becoming the major flour-producing area. At about the same time nitrogen trichloride was introduced, benzoyl peroxide (44) began to be used as a bleaching agent. This powder differs from the two gas-type bleaches-namely, nitrogen trichloride and chlorine-in that it has no developmental or maturing effect, but is an efficient whitening agent (19,dS). Nitrogen trichloride was continuously used until August 1, 1949,when it was replaced with chlorine dioxide (18). Chlorine dioxide has completely replaced nitrogen trichloride as a maturing
Figure 3.
Extensograms of Soft Winter Wheat Flour
In Figure 3 are Extensograph curves showing the rheological properties of a low protein, low strength soft wheat flour before and after treatment with chlorine. The changes, clearly visible, are a n increased resistance to extension and a decreased resistance t o extensibility. Contrary t o the chlorine dioxide treatment in bread flours, the oxidizing action in t h e case of.this chlorine treatment is usually so great that the strength of the dough, as reflected b y a decrease in
95
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INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
the surface area of the extenssgram, is greatly impaired. Thip, of course, is a desirable factor in this case. For up-to-date official views and rulings on the treatments used for both bleaching and maturing of flour, the reader is referred t o Unless such addition con(16), which states in part: “15.00 , ceals damage or inferiority of the flour or makes it appear better or of greater value than it is, one or any combination of two or more of the following optional blerqching ingredients may be added in a quantity not more than sufficient for bleaching or, in case such ingredient has an artificial aging effect, in a quantity not more than sufficient for bleaching and such artificial aging effect. , . . .”
..
Figure 4. Yield of Flour and Feeds O b t a i n e d from Wheat
From this it is seen that two effects are definitely recognized by the administrator of the Food, Drug, and Cosmetic Act of the Federal Security Agency-namely, bleaching and artificial aging effects, which have been referred to previously as developmental or maturing effects (37). The following substances are permitted in the United States: oxides of nitrogen, chlorine, nitrosyl chloride, chlorine dioxide, and benzoyl peroxide. Under the definitions and standards of identity of flour, potassium bromate i~ a permitted constituent. Potassium bromate has a maturing action in a dough made from bromated flour. As its action occurs almost completely in dough stage, it will not be discussed in detail in this paper (17). Jorgensen (d6), Shen and Geddes (QI), and Freilich and Frey (21)have discussed the bromate effect a t considerable length. DEFINITION OF BLEACHING
Since bleaching and artificial aging (maturing or developmental action) are clearly recognized, these terms should be defined. In the milling trade the term “bleaching” has been all-inclusive and in many instances this terminology remains. Actually, bleaching action should be differentiated from maturing effects. Bleaching of flour is obtained by an oxidation reaction on its yellow pigment so that the finished flour is whiter than untreated flour. Kent-Jones, English cereal chemist, stored unbleached flour in air, in vacuum, and in hydrogen (27), and he found, to quote his concluding paragraph: “After the two months, the flours were compared again. The one exposed to the air had acquired the usual bleach. The one kept in the vacuum had not bleached a t all. The hydrogen-bottled flour was also scarcely changed. The oxidizing action of the air in causing the bleach in aged flours was thus proved conclusively.” The usual pigmentation of patent flour will vary from l 1 / 2 to 4 p.p.m. expressed as carotene (9). Commercial bleaching may reduce this pigmentation by 90 to 97y0. There appears t o be some confusion in the literature regarding the term “carotenoid” pigments. Formerly it was supposed that the pigmentation was due to carotene, but recent work by Bailey, Zechmeister, and others (30,31 ,46) using chromatography and advance techniques of separation and isolation have shown the yellow pigment of wheat to be xanthophyll, usually in esterified form. The term “carotene” remains because it has been used a t times for standardization pur-
VO~,.44, NO. 1
poseR, and actually the absorption spectra of carotene and xanthophyll esters are very similar. Bleaching is thus a means of control of flour color, allowing relatively high pigmented but good baking wheats to be used withoub penalty. Benzoyl peroxide and, to a leseer extent, nitrogen peroxide produce these whitening results and have practically no effect on baking characteristics. Table I shows the effect of various levels and types of treatment on flour pigment. As the level of treatment is increased the carotenoid pigment expressed in parts per million decreases. DEFINITIOBN OF MATWRING
Maturing of bread flour by careful chemical treatment has :I similar objective t o natural aging in that each is characterized i)) the application of an oxidation process to flour which changes it. properties, so that when made into dough, a livelier, drier, more machinable, better baking, and also whiter product results Chlorine dioxide produces these typical effects much mole spc,edily and uniformly than does natural long-time storage aging. Maturing of cake flour enables the baker and the housewife to obtain products with greatly improved grain and texture, and larger volume. I n performance cakc batters made from chlorinetreated flour are more tolerant, less likely to fall, and will carry a higher percentage of shortening and sugar, and thus they product a sweeter and more tender cake than untreated flours ( I S , SS,Qi?), Use of these maturing agents in treatment of flour for bread and cake are of major importance. Additional whiteness in both bread and cake may be obtained because of the finer texture and grain resulting lrom the use of such maturing agents. Thrv cause a greater number of gas cells in the bread or sake, thereh\, producing this whiter coloi by a simple but sigaificant change i n physical structure. By way of recapitulation, maturing agents cause the follov ing. 1. Developmental maturing or artificial aging which direct11 improves the baking quality. 2. A chemical bleaching action .rzhich results in a chaiige i n the yellow pigment of flour. These pigments are not only prebeiil in extremely small amounts but they also consist primarily of xanthophyll and xanthophyll esters which are not convertible i n t o vitamin A i n animals. 3. A better color because of a physical change in the halictl bread which is caused by finer texture and grain.
TABL~E I. EFFECT OF TEE~ T ~ I E NON T COLOR Treatment Patent flour Untrca-ted 0 . 2 gram chlorine dioxidea 0 . 4 gram chlorine dioxide 0 . 7 gram nitrogen trichloride Clear flour Untreated 1 .O gram chlorine dioxide 1 .B grams chlorine dioxide 2.85 grams nitrogen trichloride a Per 100 pounds of flour.
Carotenoid Pigment, P.P. M
.
2.52 2.34
1.94 1.95 3.15 2.15 1.74 1 84
Before continuing further, it is well that the person riot informed in milling technology understand the separations made in wheat with particular reference t o the grades of flour produced. Figure 4 presents these separations. Here 2.3 bushels, or 138.9 pounds, of wheat have been separated into two major divisionsfeed and flour. From this 138.9 pounds of wheat approximately 100 pounds of straight-grade flour can be produced. If, instead of making a straight-grade flour, it is desired to divide this into two grades, an Soyopatent and a 20y0 clear flour can be compounded. I n pounds this would correspond to 80 pounds of patent and 20 pounds of clear. The patent streams come from the
INDUSTRIAL AND ENGINEERING CHEMISTRY
January 1952
H
Fip.ure 6 . Effect or Maturing on
FIour
A.
Ma~uml
R. Ne1 matured
il
Long Extraction
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INDUSTRIAL AND ENGINEERING CHEMISTRY
98
The maturing eKect is mwe rnnrked on the clear Hourc tliaii on the patent floum. This type o f flour is used in admixture of rye snd whole wheat Hours for those types of bread, as well 8s B flour constituent of longer extraction flours, such 8 9 strxights and etuKod atrsights (a stieight being the total flour from the wheal nnd the stuffed straight heing the straight, Hour p l u ~added clear),
Vol. 44, No. 1
perieuceii trouble in their bake shups because of the use of URmatured cake flour. Figure 10 shows lion cooky Hours oan be treated and the spread and thiekuevs o w t r o l l e d fur more uniform production and elimination of packaging difficulties. ADVANTAGESOFBLEACIIING AND MATURING F O B T H E WIlE*T GROWER
B
A
Fi(rure 8 . Effect of Maturing
OD
Southwest Patent
Flour A. 8.
Top.
Over 2M) recognized viLriet,irts of wheat RE grown eomnrercially i n the Uiriled States under all kinds of environmental oonditions. These two factors-wheat, variety and environmental conditions--largely determinc the quwlity uf the wheel and the qmlity tof the flour produced from tlie wiieilt. I t follows that thc quality of the many kinds of flour produced is distinctly variable ($8) Not only is this true for any one seirson, hut it is equally true for wheats grown in any given %rea fmm m a o n to sesmn. Thiw ir due to the variation of the euvimnmental conditions of growth and development of the w h a t plant. Maturing 8nd bleaching of flour make it possible four the miller to produce a standard and more uniform pmduct regardlese of the variations encountered in wheat production. The differences referred to B I ~twofold i n n s t u r e - h t , in baking quality and maturing, and second, in color or pigmentation. Bath must bc adjusted. Flour from southwestern and from =me northwestern whests,in particular, require more trestment than fmm wheats gmwn in other areas. Before the advent of artificial maturing, the average price of Kiln9 ~ hard s winter wheat in Chicago was lower than spring wheat in all but 2 of the 15 yeara bet,ween 1900 and 1914. In wmtmat, after the introduction of maturing agents, the Kansas hard winter wheat price was higher in 6 years, equal in 1 year and lower in 7 years for tho period from 1919 tr, 1933, thus indicating that the
1934cmp 1935crop Impnrssd. marurod losras
The matured tioun are
Cake Flour 1.
P.
Chlorioctrrarsd Untreptsd
formerly poorer bakiirg wheat WM tbus enabled to compete 011 "e. equal baais. It'is apparent that the agricultural eoanomy of the Southwest and of mme northwestern ltrwa would have suffered disadvantages if suitable wnd acceptable maturity methods had not t,een available for modifying the properties and improving the utilityof these wheat,p. ADVANTAGE OF BLEACHING *TI> MAI'UHINO TO 'THE FLOUR MILLER ANI) T H E BAKER
Flour kept in atorage improves in haking value until an optimum is reached ($8). Months may he required for this change. Further tora age may be damaging. In addition, there is a serious and very red dilngef of insect infeatation. Flour stored to secure natural aging will not be uniform in perfwmance. Uniformity depend8 upon temperature conditione and the ability of air to gain R C C ~ S Sto the flour. The increaaea use of multiwall paper sacks to minimize insect infestation undoubtedly has 8ome effect
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
January 1952
98
TABLE IT. FLOURBLEACWINQ RSQULATIONS IN FOREIQN Cormns Bleaching Agenta Permittad and Prohibited country AusLrdia.
%%a
AW
Wholeeome Agent
Nitrogen Peroxide
Chlorine
Nitrogen
Triahloride
S.
Austraiia, New South Wale-
Belgium Belgian Congo Breaii R algaiia Canada CEO* Colombia( Costa Rica
Cuba
Denrnsrk Ecuador Eire Franoe Frenah W . Indiea Germany Greece Guatemela fiong Ken* cnaia z::xLd.nda
New Zedand Pskiatan
Phiiippinca
Spain Sweden Switzerland
union of S. Afrioe Turkey VWJe."ela 0 - signifies rxohibited. signi6es permitted. e N o regulation.
*+
+++ +++ 2
+t ++
i
+-
++-
+ t
i
+
t
t
t
+
+
+
-
++a
++ -
++ ++-
_.
+
+
-
ff
*
Adulteretion of Uour pmhibited. Except by irradiation. bromatna. peradfatas. and braad impmvera prohibited
I Uep of
ivn the natural aging of unmaturwf Hours. There is uneveu maturing in any aack due to the vsrioue conditions. The core will be the greonest.--deficierit in oxidation-and flour nearest the outside of the sack will he the most mature. Under present conditions there is not enough atorage space in the country to pennit using the storage method for aging Hour. The estimated coRt is 20 oente per month per hundredweight, which would undouhtrrily be reHected in the cost of Hour to the consumer. This estimate is made up of the idlowing extra costa retlected in flour storage: return on invstment on the storage space and theatored flour; deterioration and 5hrinkege in storage; extra labor rout; extra inaurmee coat; the inability for quick turnover under best market eonditionw; and last but not lehst, avoidance of the gamble of large inventory. Entimating the time for natural zging to be from 4 to 5 months, the east of natural aging varies from 16 to 20% of the selling price of the product. The cost of maturing and bleaching is appmxinietely half of 1% OT lesa uf the selling price of the product. Thus, the enOrmOU8 economic advantage iii evident. D ~ ~ r ~ofu the r e economies involved, the difficulties enwuntemd in shop production and the nonuniform baked pmducts, natural sging ia almost extinct. With maturing and bleaching available the millers CRD avoid wasteiul carryover of tremendoua stocks o i d d emp wheat for blending purposcr. With rapid maturing agent8 the bxker is able to use flour from new crop wheat BE Roo11 RS it ir available. The modem bake shop ia B highly developed food faotory for the mechsnienl production o i B delicate pmdunt. When the baker must use Rourv of varying maturity, he must contitantly adjust hin production methods and schedules. lnvolved in thia are high labor costs and wastage due to nonunifarmity in haking red t 8 . Modern bakery machinery makes mandatory II uniformly matured flour. lmmsture Hour c a u m costly delay8 or stick-ups. When the miller properly uses bleaching and maturing procernes, the baker H i assured of a uniform ingredient and can adjust hia production metliod~[or the product he wants. Before the advent of maturing methods, bread baking was B ylow and lengthy upccrtion. The traveling oven and other modern automatic eqnipment iisv resulted in an increase in daily output. Maturing and blwohing are major factors in securing uniform flour for scheduled porformnnee with modern equipment. It is
evident that the UYB uf uniformly awtured flour h a permitted the baker to make B aonsistently better product snd that upta-dste technology improves upon storage by asauring a given flour the very be& treat,ment requirtxi for opt,imulp haking performance nt a ~ 2 O # l z b lGO& e AbVANTAGE O F BLEACHING ANV MATURING FOR THE CONSUMER
Modern, rapid trebtnients are helpful in household baking 1 1 6 use of standard recipes with maximum certainty of fine baked foods. The svailability of %our of uniiornr maturity BIBOavoids waste in the household. The longer ext.nietion flnum can he made tnore suitable for bresd chime they permit the succensful
Figure 10. Effect of Maturing OD Cooky Flour rnwkiog by wat.uring, thus incmaaiag the potential quality ofHour for tho production of baked pmducte of improved loaf xppeac mce, and hence, the increased appetite appeal. Both the 50ur and baked products are lesa C o d y to the comumer hecause of the saving in the milling and haking process when modem ",&hods are used in place of uncertain natural nging. NOTRITIONAL ASPEC1'9 OF ARTIFICIAL BLEACHING &ND MATURING Ay far its data now aveilahle are concerned, there is very little evidence of a decreare in the vitamin content of flour through bleaching or maturing metbodfi now in use. Bailey (9) refers to work done in Germany, showing that flour blesched with benzoyl penrxirle or nitmgon trichloride contained less t,oropherol than
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INDUSTRIAL AND ENGINEERING CHEMISTRY
unbleached flour. The loss of tocopherol became greater as the concentration of bleaching agents increased. Doty and Sherwood (16) found that the use of ammonium persulfate as a flour maturing agent did not affect thiamine and riboflavin contents of enriched flour. Information given a t the flour hearings in 1948 (14) indicated that chlorine dioxide had no deleterious effect upon t h e contents of thiamine and riboflavin in enriched flour. The elfeet of other commonly used bleaching agents is probably similar.
TOXICOLOGICAL ASPECTS OF ARTIFICIAL BLEACHING AND MATURING
The Food and Drug Administration exercises constant vigilance over the treatment of flour by the miller. Only those methods which are approved in the Federal Standards of Identity may be used. The methods which are used today were approved only after extensive public hearings conducted by the Food and Drug Administration. I n December 1946 Mellanby, an eminent scientist in England, reported that when dogs were fed a diet including as its main constituent flour heavily treated with nitrogen trichloride, they developed running fits or canine hysteria (3%'). The news of this discovery led the milling industry and the Food and Drug Administration into an extensive program of scientific investigations. Dogs, cats, rats, rabbits, monkeys, chickens, ferrets, guinea pigs, and, finally, humans were involved in experiments in at least ten laboratories under the direction of leaders in the fields of biochemistry, pharmacology, toxicology, neurology, xtc. (7, 8, 34, 40). It was concluded that when certain animals, notably dogs, were fed a diet consisting of a high percentage of flour treated with extraordinarily large amounts of nitrogen trichloride, the animals developed a nervous disorder. Tests on humans (35), hovever, proved that no deleterious effect occurs regardless of the quantity of nitrogen trichloride-treated flour present in the diet. Despite this conclusion, the milling industry petitioned for a hearing at which the Food and Drug Administration eliminated from the Standards of Identity on August 1, 1949, the use of nitrogen trichloride in the treatment of flour, and substituted therefore chlorine dioxide, which in the same investigations had been found harmless to all animals studied, as well as to humans. This is a fine example, not only of vigilance on the part of the Food and Drug Administration, but also of the cooperation the Adrninistration had from industry. Other nations followed closely the facts developed a t the flour hearings and the final conclusions reached therein which appeared in the Federal Register (18). Table I1 contains a summary of flour bleaching regulations in foreign countries adapted from material given in the Northwestern Millers Almanac (37). CONCLUSION
Continued research is being carried on by the milling and baking industries and by suppliers for the protection of the consumer from both economic and nutritional standpoints. The achievement of these goals is an outstanding contribution to the amount and quality of the food supply of the world today and, consequently, to the welfare of mankind. ACKNOWLEDGiMENT
The author wishes to extend his very grateful thanks to the following persons for their counsel and guidance in the preparation of this paper, so that it might be a paper that would be truly representative of the practices followed in the milling and baking industries: C . C. Thomas, Betty Sullivan, John Andrews, Guy C. Robinson, W. L. Rainey, H. K. Parker, John C. Baker, Paige Lehman, Frank L. Cunderson, R. K. Durham, and C. W. Brabender.
s.
Vol. 44, No. I
LITERATURE CITED
(1) Alexander, G. L., Cereal Chem., IO, 623-6 (November 1933). (2) Allison, J. B., White, J. I., Ajemean, E. B., and Roth, J. S.,
Ibid., 27,495-500 (1950). (3) -4lsop, J. N., U. S. Patents 758,883, 758,884 (May 3, 1904), 759,651 (May 10,1904). (4) Am. Assoc. Cel'eal Chemists, St. Paul 1, Minn.. "Cereal Lab Methods," 5th ed., pp. 22-50,1943. (5) Ibid., pp. 40-7, 1943. (6) Andrews, John, and Andrews, Sidney, U. S. Patent 693,207 (Feb. 11,1902). (7) Arnold, Aaron, Cereal Chem., 26,46-51 (1949). (8) Arnold, Aaron, and Goble, F. C., Ibid., 27,375-82 (1950). (9) Bailey, C. H., "Constituents of Wheat and Wheat Products," ACS Monograph 96, pp. 261-79,316-17, New York, Reinhold Publishing Corp., 1944. (10) Bailey, C. H., and Le Vesconte, A . M., Cereal Chem., 1, 59 (January 1924). (11) Baker, J. C., J . A.m. Assoc. Cera2 Chemists, 7, 108-11 (1922). (12) Baker, J. C., U. S. Patent 1,367,530(Feb. 8, 1921). (13) Bohn, L. J., Cereal Chem., 11,598-614 (1934). (14) Docket No. FDC-21 (C), exhibit No. 22, proposed to amend the Definition and Standard of Identity for Flour, Oct. 8, 1948. (15) Doty, J. M., and Sherwood, R. C., Cereal Chem., 22, 409-14 (1950). (16) Federal Food, Drug, and Cosmetic BUZZ. No. 2, revision 1, p. 13, Washington, D. C., F a d and Drug Administration, Federal Security Agency (January 1949). (17) Federal Register, 13, 6382 (Oct. 30, 1948). (18) Ibid.,pp. 6969-70 (Nov. 27, 1948). (19) Ferrari, C. G., and Bailey, C. H., Cereal Chem., 6, 457-81 (September 1929). (20) Ferrari, C. G., Hutchinson, 1%'. S.,Croye, A. B., and Mecham, D. K., Ibid., 18,699-704 (1941). (21) Freilich, J., and Frey, C. N., Ibid., 16, 485-94 (1939): (22) Gortner, R. A., "Colloid Chemistry," Vol. 111, pp. 597-625, New York, The Chemistry Catalog Co., Inc., 1931. (23) Hanson, W. H., Cereal Chem., 9 , 358-77 (July 1932). (24) Hill, G., Spots, E. X., and Dalby, G., paper presented at the American Association of Cereal Chemists Convention, Minneapolis, Minn., 1951. (25) Hutchison, W-.S., and Derby, R. I., CereaE Chem., 24, 372-6 (1947). (26) Jorgensen, Holger, "Studies in the Nature of the Bromate Effect," London, Oxford University Press, 1945. (27) Kent-Jones, D. W., "Modern Cereal Chemistry," 1st ed., pp. 175-6. Liverpool, England, The Northern Publishing Co., Ltd., 1924. (28) Kent-Jones, D. W., and Amos, A. J., Ihid., 4th ed., p. 251, Liverpool, England, The Northern Publishing Co., Ltd., 1947. Lawellin, S. J., Nail. Miller, 52 (February 1924). Markley, M. C., and Bailey, C. H., Cereal Chem., 12, 33-40 (1935). Ibid.,pp. 40-9. Mellanby, E., Brit.Med. J . , 2, 885-7 (1946). Montyheimer, J . W., Cereal Chem., 8 , 510-18 (1931). Nakamura, F. I., and Morris, hl. L., Ibid., 26,501-7 (1949). Newell, G. W., Erickson, T. C., Gilson, W. E., Gershoff, S.N., and Elvehjem, C. A., J . A m . Med. Assoc.. 135,760-3 (1947). Xewell. G. W., Gershoff, S. N., Suckle, H. M., Gilson, W. E., Erickaon, T. C., and Elvehjem, C. A., Cereal Chem., 2 6 , 160-6 (1949). iVorthwestern Millers Almanac, p. 42 (April 24, 1951). Parker, H. K., "An Industrial Application of Nitrogen Trichloride," Proc. First Internatl. Conf. Flour and Bread Manuf., pp. 147-52, abstracted in Chem. Abstracts, 24, 3506 (1930). Parker, H. K., Baker'sBigest, 25,30-1 (February 1951). Radomski, J. L., Woodard G., and Lehman, A. J., J . Nutrition, 36, 15-25 (1948). Shen, Ling, and Geddes, W. F., Cereal Chem., 19, 609-31 (1942). Smith, D. E., and Andrews, J. S., paper presented at the American Association of Cereal Chemists Convention, Minneapolis, Minn., 1951. Smith, E. E., CereaE Chem., 9, 424-8 (July 1932). Sutherland, E. C., U. 8.Patent 1,539,701 (May 26, 1925). Wesener, J. A,, Ibid., 1,096,480 (May 12, 1914). Zechmeister, L., and Cholnoky, L., J . Biol. Chem., 135, 31-6 (1940). RECEIVED Beptember 8, 1950. Presented before the Division of Agricultural and Food Chemistry at the 118th Meeting of the AMERICANCHEMICAL
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SOCIETY, Chicago, 1U.
