Effects of Rhizopus oryzae and Aspergillus oryzae on prebiotic potentials of rice bran pretreated with superheated steam in an in vitro fermentation system

Abstract

Rice bran was first treated by superheated steam to inactivate the enzyme and then fermented with single Rhizopus oryzae, Aspergillus oryzae, or their mixture, respectively. The prebiotic potentials of fungi fermented rice bran were investigated by in vitro human fecal microbiota fermentation. Compared with the fermented rice bran, the fungi fermented rice bran significantly increased soluble sugar, soluble protein, and total phenol content (P < 0.05). Additionally, the fungi fermented rice bran showed better prebiotic capability in promoting the production of short-chain fatty acids and the populations of beneficial bacteria. Especially, the rice bran fermented by a mixture of Rhizopus oryzae and Aspergillus oryzae showed the highest levels of Bifidobacterium and Bacteroidaceae in the fermentation slurries compared with single Rhizopus oryzae and Aspergillus oryzae fermented samples. These findings revealed that fungi fermented rice bran showed better prebiotic potentials. Therefore, rice bran processed by superheated steam and fungi fermentation can be used as potential functional ingredients in food and nutraceuticals.