Cereal Chem 43:271 - 283.  |  VIEW ARTICLE

The Biological Availability of Essential Amino Acids in Wheat, Flour, Bread, and Gluten.

F. N. Hepburn, W. K. Calhoun, and W. B. Bradley. Copyright 1966 by the American Association of Cereal Chemists, Inc. 

Rat-feeding experiments were conducted to determine the extent to which the essential amino acids of wheat and wheat products are utilized. This study reports the availabilities of methionine, threonine, tryptophan, valine, phenylalanine, leucine, and isoleucine in wheat, flour, bread, and gluten. Availability values were measured both by determining the proportion of sample amino acid excreted in the feces and by equating the increase in carcass nitrogen to the ingestion of the amino acid. The latter is believed to be the more reliable method. The increase in total carcass nitrogen content was found to vary directly with the amount of available amino acid consumed when that amino acid was limiting in the diet. Nitrogen gains on sample diets were referred to standard response curves obtained by feeding pure amino acids, and the percent availability was calculated by comparing the derived values to those obtained by microbiological analyses of the samples. Results by both methods show the biological availability of these amino acids to be generally high in the products studied. Availabilities tended to be highest in gluten and lowest in the whole wheat, perhaps because of differences in digestibility.