Synergistic effects of pH, temperature and glycosylation on the functional properties of rice protein

Abstract This study investigated the effects of pH treatment, heat treatment, pH‐synergistic heat treatment and glycosylation on the functional properties of rice protein (RP). The results showed that all treatment methods could improve the functional properties of RP. Heat treatment improved functional properties by generating aggregates after RP unfolds, and pH treatment improved those by causing RP to hydrolyse and aggregate. Compared to RP, the solubility, emulsification activity (EA), emulsification stability (ES), foaming activity (FA), surface hydrophobicity and in vitro digestibility of pH‐synergistic heat treatment of RP (S‐RP) were increased by 11.47, 3.12, 3.45, 2.27, 3.36 and 2.12 times, respectively. Glycosylation mainly improved the functional properties of RP by introducing hydrophilic groups. Compared to those of S‐RP, solubility, EA, ES, FA, surface hydrophobicity and in vitro digestibility of RP–dextran conjugates (RPDCs) were increased by 2.03, 1.25, 1.97, 1.05, 1.64 and 1.48 times, respectively. Therefore, compared to glycosylated chemical modification, heat treatment and pH treatment had a weak improvement in the functional properties of RP. The comparison of pH‐treated RP (pH‐RP) and RP–dextran mixtures (RPDMs) showed that in the absence of heat treatment, carbonyl ammonia condensation almost did not occur.