Thermal Destruction of Cysteine and Cystine Residues of Soy Protein under Conditions of Gelation

摘要

ABSTRACTThermal destruction of cysteine and cystine residues of soy proteins was investigated under gelation conditions. Significant cysteine and cystine were lost as a function of heating time. The rate and extent of loss was affected by heating temperature, pH, salt concentration and viscosity of the protein solution. Greatest effects were from heating temperature, pH and viscosity. A significant amount was lost even at pH 7.0 at 100°C. Amino acid analysis revealed that thermal destruction of cysteine and cystine at high protein concentration and near neutral pH did not result in formation of lysinoalanine. The results can be useful to preserve nutritional quality in thermal processing of soy proteins