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The utilization of the calcium in white bread has been found to be very good1" '*. Most of the calcium in American bread is derived from the added milk used in mak- ing bread, the calcium saltsâusually phos- phates and sulphates of dough conditioners âand antimycotics such as calcium pro- pionate. Mollsgaard et oi20, Denmark, car- ried out some extensive experiments on phytates in brown bread. By extending the time of fermentation, the phytates were broken down, thus preventing some of the deleterious effects of whole wheat bread on calcium utilization. MILK IN BREAD Non-fat dry milk has long been an im- portant constituent of bread. It is generally used in amounts of approximately 4 per cent in standardized enriched white bread. In 1950 the Committee on Cereals spon- sored a study to determine the value of various methods in use for evaluating the quality of non-fat dry milk for baking pur- poses. Much of the skim milk powder pro- duced is unsuitable for bakery use and no accepted test of quality from this standpoint exists. In the manufacture of non-fat dry milk, it should be heated at 165° F. for 30 minutes or the equivalent before drying; otherwise it has a strong softening action on doughs which makes them difficult to handle with modern machinery. The Harland-Ashworth Test for unde- natured whey proteins remaining in the non-fat dry milk has been widely used to determine baking quality. In the collabo- rative study conducted by Bradley et al21, twelve laboratories ranked six samples of non-fat dry milk rather consistently on the basis of this test. However, the absolute differences of the results among laboratories precluded its use as a basis for specifica- tions. Subsequently the Harland-Ashworth Test was standardized by workers at the University of Minnesota and rechecked in a collaborative study conducted by the American Dry Milk Institute22. It now appears suitable for specification purposes. PROTEINS IN BREAD Wheat proteins have been extensively studied, but there is very little information on the nutritive value of protein in bread made from 72 per cent extraction flour. The chief source of protein in bread is the wheat protein. Second in importance is the protein of non-fat dry milk solids added in breadmaking, and third, the protein of the yeast used in breadmaking. It has been possible to improve the pro- tein supply of the American people by addi- tions of non-fat dry milk solids to bread. The amounts added generally range from 3 to 5 per cent. This addition supplies a number of important amino acids, such as lysine, valine, and methionine, which with the amino acids supplied by yeast greatly improve the flour proteins. Comparison of the pattern of man's amino acid require- ments according to Rose with the pattern of the amino acid content of average en- riched bread, using tryptophan as unity, reveals that bread protein is only slightly deficient in lysine and even less deficient in methionine to meet man's require- ments23. " C. Hoffman. Reproduction of animals on an exclusive diet of bread. Ind. Eng. Chem. 15: 1225 (1923). u W. Hale. The role of bread in nutrition. Ind. Eng. Chem. 15: 1221 (1923). "H. Mollsgaard, K. Lorenzen, I. G. Hansen, and P. E. Christensen. Biochem J. 40: 589 (1946). 11 W. B. Bradley, C. N. Frey. W. F. Geddes, and R. Jenness. A collaborative study of methods for eval- uating the quality of non-fat milk solids for use in breadmaking. Transactions, American Association of Cereal Chemists 11 (3): 217 (1953). " S. Kuramoto, R. P. Choi, S. T. Coulter, and R. Jenness. Standardization of Harland-Ashworth Test for whey protein nitrogen (in preparation). " F. N. Hepburn, E. W. Lewis, and C. A. Elvehjem. Amino acid content of wheat flour and bread. Cereal Chemistry 24: 312 (1957). 6
Until the niacin requirement was officially stated, the only information regarding nia- cin that the label could carry was the num- ber of milligrams provided, a practice in effect for many years. OPTIONAL INGREDIENTS Calcium and vitamin D are optional ingredients but, if added, must be declared on the label. If used, the levels prescribed per pound of enriched bread are as follows: Calcium Vitamin D Minimum 300 mg. 150 USP units Maximum 800 mj 750 U! :P units In general, the optional ingredients have been little used in enriched flour or bread. In enriched self-rising flour, calcium is a required ingredient. It appears as mono- basic calcium phosphate which, together with sodium bicarbonate, constitutes the leavening agent in lieu of added baking powder. This form of flour is very popular in the South and is generally enriched, but Vitamin D is not included as an optional ingredient. In 1951-52 a number of large bread- manufacturing companies began adding vitamin D to bread at levels which supplied 92 per cent of the daily requirements in 8 ounces of bread. This amount was designed to insure the proper utilization of the cal- cium supplied by the bread. Perhaps this move by bakers was dictated in some de- gree by a desire for a new advertising point. The position of the Food and Nutrition Board has been not to encourage the addi- tion of vitamin D to bread. Actually, approval of the optional ingre- dients in enriched flour and bread in 1941 by the Committee on Food and Nutrition, predecessor of the present Board, was predi- cated on some legal complications concern- ing the use of the term "enriched" which had already risen at that time. Prior to inauguration of the systematic cereal en- richment program, farina "enriched" with vitamin D had been sold by the Quaker Oats Co., which later took exception to the cereal enrichment formula proposed by the Food and Drug Administration and took the matter to court. The company won in the lower court but the decision was even- tually reversed by the Supreme Court as recounted in "Enrichment of Flour and Bread. A History of the Movement."15 In the hope that it would be of assistance in resolving these issues then in contest, the Food and Drug Administration then favored the inclusion of vitamin D as an optional ingredient. Calcium was added as a second optional ingredient on the ground that vitamin D plays a large role in the utilization of calcium. Further evidence bearing on the scien- tific merit of these inclusions has since ac- cumulated. A review of data indicates that the average calcium content of enriched bread in the United States is approximately 400 milligrams per pound16. Inasmuch as the recommended daily allowance of the Food and Nutrition Board calls for 800 milligrams for the average man, the amount supplied by bread can make a substantial contribution to the body's requirements. Bread and other grain products were sec- ond only to dairy products as a source of calcium in the average diet of families in 1955. Grain products accounted for 16 per cent of the calcium, compared with 64 per cent from dairy products17. u National Research Council Bulletin 110, (1944). p. 17. " U. S. Dept. of Agriculture. The calcium content of commercial white bread. Tech. Bull. 1055 (1952). p. 5. K. Kulp, O. C. Golosinec, C. W. Shank, and W. B. Bradley. J. Am. Dietet. Assoc. 32: 331 (1956). " U. S. Dept. of Agriculture. Dietary Levels of Households in the U. S. Household Food Consumption Survey 1955, Kept. No. 6. p. 24.
