Antioxidant activity and enzyme inhibition of phenolic acids from fermented rice bran with fungus Rizhopus oryzae

The solid-state fermentation (SSF) has been employed as a form making available a higher content of functional compounds from agroindustrial wastes. In this work, the effect of SSF with the Rhizopus oryzae fungus on the phenolic acid content of rice bran was studied. Phenolic extracts derived from rice bran and fermented rice bran were evaluated for their ability to reduce free radical 1,1-diphenyl-2-picrihidrazil (DPPH) and for the ability to inhibit the enzymes peroxidase and polyphenol oxidase. The phenolic compound content increased by more than two times with fermentation. A change in the content of phenolic acids was observed, with ferulic acid presenting the greatest increase with the fermentation, starting from 33 mg/g in rice bran and reaching 765 mg/g in the fermented bran. The phenolic extracts showed an inhibition potential for DPPH and for the peroxidase enzyme, however did not inhibit the polyphenol oxidase enzyme.