Stability of the antioxidant peptide SeMet-Pro-Ser identified from selenized brown rice protein hydrolysates

SeMet-Pro-Ser (Se-MPS) is an antioxidant selenopeptide derived from selenized brown rice protein hydrolysates. In this study, the stability of glutathione (GSH), Met-Pro-Ser (MPS), and Se-MPS under different processing conditions, namely, temperature, pH, NaCl, citric acid, light, and gastrointestinal proteases, were evaluated by measuring ABTS⁺ scavenging and Cr(VI) reduction capacities. The ABTS⁺ scavenging capacity of GSH under thermal treatment, high salt density, and long-term storage was significantly decreased, while its Cr(VI) reduction activity was relatively stable. No significant change of Se-MPS antioxidant activity was observed under different conditions, except under citric acid. Meanwhile, its Cr(VI) reduction activity was partially or mostly retained under different treatment conditions. However, it displayed negligible ABTS⁺ scavenging capacity. Se-MPS was superior to GSH and MPS in terms of stability and antioxidant activity and could be a candidate for development of nutraceuticals or functional food.