Effect of Heating on the Molecular Structure of Soy Protein

Studies on Gelation of Soy Protein during Cold Storage Part II

Abstract

Effect of heating on the molecular structure of soy protein was investigated. In ultracentrifugal analysis, 7S and 11S components retained after heating at below 100°C, while they disappeared after heating at 140°C. In DSC analysis, after heating at above 100°C endothermic peaks of 7S and 11S components disappeared. In solubilization tests with urea and 2-mercaptoethanol, the maximum solubility was observed after heating at 100°C, indicating that binding capacities of hydrogen bond, hydrophobic interaction and disulfide bond, as well as the SH contents in the protein decreased as the heating temperature increased. In amylography soy protein heated at above 100°C showed a typical viscosity pattern in a swelling state. Fluorescent intensity and the intrinsic viscosity increased in accordance with an increase in heating temperature and showed maxima at 100°C heating. These observations suggest that the soy protein molecular structure after heating at 100°C would be in a highly unfolded state and become susceptible to intermolecular interaction.