Cereal Enrichment in Perspective, 1958 (1958)

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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 salts—usually phos- phates and sulphates of dough conditioners —and 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