Changes in the antioxidant properties of rice bran protein isolate upon simulated gastrointestinal digestion

초록

This study aimed to evaluate changes in the antioxidant properties of rice bran protein isolate (RBPI) upon simulated gastrointestinal digestion. A two-stage in vitro digestion system (pepsin treatment followed by pancreatin treatment) was used to generate GI-digested RBPI. Antioxidant activities were evaluated using various oxidative systems: measurement of oxygen radical antioxidant capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS(+) ) assay, and reducing power assay. After gastrointestinal digestion, the protein solubility and free phenolic compounds increased from 24.6% to 94.5% and from 2.1 to 17.6 mg/g, respectively. The ORAC value of the GI-digested RBPI was significantly higher (p < 0.05) than that of the intact RBPI (473.5 vs. 44.2 mu mol Trolox equivalents/g); furthermore, the GI-digested RBPI also showed significantly higher DPPH & ABTS radical-scavenging activities and reducing power than intact RBPI (p < 0.05). This study provides novel quantitative insights into the antioxidant properties of GI-digested RBPI in various oxidation systems and indicates that simulated gastrointestinal digestion is potentially applicable for producing bioactive components with higher antioxidant potentials than those of RBPI.

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