Abstract: In this research, changes in polyphenols content and antioxidant capacity during in vitro digestion of brown rice were studied. The total phenolic content in brown Japonica rice was significantly higher than that in brown Indica rice (about 1.5 times). During simulated in vitro gastrointestinal digestion, the release of polyphenols (calculated as gallic acid equivalent) was increased significantly for both rice varieties (P < 0.05), with the maximum value (460.9 mg/100 g) of Japonica rice being significantly higher than that (401.1 mg/100 g) of Indica rice. The release of polyphenols versus digestion time was fitted to a power function. The results of ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) showed that the polyphenols released during in vitro digestion of brown Japonica and Indica rice possessed potent antioxidant activity. Both FRAP and ORAC were calculated as trolox equivalent. The maximum FRAP values of digested Japonica and Indica rice were 10.76 and 8.44 μmol/g, and the maximum ORAC values were 6.82 and 6.23 μmol/g, respectively.

Key words: brown rice, in vitro digestion, polyphenols content, antioxidant activity