Particle size of insoluble dietary fiber from rice bran affects its phenolic profile, bioaccessibility and functional properties

•Particle size of rice bran IDF powders affected their functional properties.•Superfine rice bran IDF powder exhibited a higher phenolic extractability and antioxidant properties.•Superfine rice bran IDF powder exhibited a higher phenolic bioaccessibility.

Despite its various health benefits, rice bran insoluble dietary fiber (IDF) is not favored by people because of its rough texture and bad flavor. Therefore, many efforts have been made to modify IDF, including reducing its particle size. In the present study, the effects of superfine processing on the functional properties of rice bran IDF and its phenolic profiles and bioaccessibility were investigated. Superfine rice bran IDF powder exhibited a higher water holding capacity, swelling capacity and nitrite ion adsorption capacity, and a lower oil holding capacity than the other IDF powders. Moreover, the superfine rice bran IDF powder exhibited a higher extractability in both free and bound phenolics, higher phenolic bioaccessibility and antioxidant properties than its coarse counterpart. The extractable phenolic profile in superfine rice bran IDF was also different from those of other IDFs. These results suggest that superfine grinding can improve the functional properties of rice bran IDF and may benefit its application in functional foods.