Digestibility of Proteins and Racemization of Amino Acid Residues in Roasted Foods

Abstract

Beef, bacon, almond and bread were heated in an electric roaster at 150-250°Cfor twenty minutes. The amino acid residues of protein, especially serine, threonine and arginine, in the foods were easily decomposed above 180°C. The racemization in the amino acid residues also occurred, and aspartic acid and glutamic acid were markedly racemized. The order of the racemization of food was generally as follows: bacon>beef>almond>bread. The promotion of the racemization of amino acid residues by lipid were speculated on four foods. In vitro digestibility of the roasted food protein extremely decreased above 210°C, and it decreased to 8-20% at 250°C.