The Availability of Lysine in Wheat, Flour, Bread and Gluten

Abstract

The availability of lysine in wheat, flour, bread and gluten was determined by rat growth studies. Two basal diets, one containing 20% of wheat gluten and the other containing an amino acid mixture (omitting lysine) patterned after this amount of gluten were compared. Performance was measured by gain in weight, gain in empty weight and gain in carcass nitrogen over a three-week period. Response to samples was referred to standard curves and the results were compared with those obtained by microbiological assay. Values of lysine availability were calculated by performance versus percentage of added lysine, performance per 100 grams of food consumed versus percentage of added lysine, and performance versus intake of available lysine. Closest agreement between basal diets resulted when carcass nitrogen gain was related to total available lysine consumed. By this method the availability of lysine in wheat, flour and bread was 75, 72 and 76%, respectively, with the gluten basal diet. With the amino acid basal diet, 78, 80, 83 and 80% availabilities were found, respectively, for wheat, flour, bread and gluten.