Ultrafiltration fractionation of rice protein hydrolysates: Physicochemical properties and potential biological activities of different rice protein hydrolysate fractions

In this study, rice protein hydrolysate (RPH) was separated by membrane ultrafiltration, and three ultrafiltration fractions (UFs) with distinct molecular weights (RPP-1, RPP-2 and RPP-3) were yielded. The physicochemical properties and in vitro bioactivities of these fractions were characterized. Among RPH and its UFs, RPP-1 exhibited highest DPPH radical scavenging activity (IC50 = 4.42 ± 0.08 mg/mL) and ferric reducing antioxidant power (84.21 mg GSH/g). RPP-3 exhibited the highest ABTS radical scavenging activity (IC50 = 0.97 ± 0.01 mg/mL). All the samples exhibited angiotensin converting enzyme inhibitory activity (5.38% ± 0.76%–54.14% ± 3.04%) and α-glucosidase inhibitory activity (−38.90% ± 3.20%–99.99% ± 0.01%). In addition, the activation of alcohol dehydrogenase by RPH and its UFs was observed in this study, with an activation percentage of 46.20% ± 4.96%–199.77% ± 7.71%. However, no inhibitory activity towards acetylcholinesterase was detected. In present study, the potential antialcohol and hepatoprotective activity of RPH was observed. Overall, this study would provide a new idea for the high-value utilization of RPH and a theoretical foundation for the development of bioactivity peptides derived from rice protein.