Heat-induced changes in the physicochemical properties and in vitro digestibility of rice protein fractions

The effects of heat treatment on protein interaction, surface hydrophobicity, protein profile, amino acid composition, and in vitro digestibility of individual rice protein fractions were investigated. Heat treatment at 100 °C for 20 min had no negative effect on essential amino acids in rice protein. Surface hydrophobicity increased significantly with the increased heat treatment temperature. Moreover, free-thiol content decreased significantly with increased temperature and time extension. Hydrophobic interactions contributed to the heat-induced interaction of glutelin and prolamin. Intramolecular disulfide linkages participated in the heat-induced interaction of all rice-protein fractions. Heat treatment had no effects on the in vitro digestibility of glutelin, globulin, and albumin. Thus, the heat-induced interactions of glutelin, globulin, and albumin were not related to their digestibility. By contrast, the formation of intramolecular disulfide bonds and hydrophobic interactions in prolamin may reduce its digestibility by strengthening protein bodies-Is.