Availability of Lysine in Wholewheat Bread and in Selected Breakfast Cereal

Abstract

SUMMARYThe protein in wholewheat unbaked bread ingredients, microwave‐baked wholewheat bread, oven‐baked wholewheat bread, and two breakfast cereals was evaluated by gain in body weight of rats, protein efficiency ratio, increase in carcass nitrogen, and apparent availability of lysine as determined by fecal excretion.No significant differences were noted between the bread ingredients and microwave‐baked bread. Oven‐baked bread gave values significantly lower, 24–45%, than those of the ingredients. The apparent availability of lysine in bread ingredients and in microwave‐baked bread was 96% and 95%, respectively, whereas that for oven‐baked bread was 70%.The protein in one breakfast cereal barely maintained the weight of the animals, and gave low values for protein efficiency ratio and increase in carcass nitrogen. Seventy‐five percent of the lysine was available. The other cereal allowed good growth of the animals and gave values similar to those for nonfat milk. In this oat‐and‐wheat‐germ cereal, 88% of the lysine was available.A linear relation was obtained between either gain in body weight or increase in body nitrogen and the amount of available lysine ingested.