Effect of particle size and ammonium sulfate concentration on rice bran fermentation with the fungus Rhizopus oryzae

► Rice bran was used as substrate for solid-state fermentation. ► The increase in particle size of rice bran favored the Rhizopus oryzae biomass. ► Particles of a smaller size provided the highest protein and phenolic contents. ► A higher concentration of ammonium sulfate favored the phenolic content gain.