Solid-state fermentation by Rhizopus oryzae improves flavor of wheat bran for application in food

Abstract

This study aimed to evaluate the effect of solid-state fermentation of Rhizopus oryzae on the flavor of wheat bran and the sensory properties of bran-containing cake. The results of comprehensive sensory evaluation and electronic nose analysis showed that the optimal time for solid-state fermentation was 36 h. GC-MS analysis showed that the relative levels of unpleasant flavor substances such as n-hexanal, heptanal, and benzaldehyde were decreased, while the relative contents of various aromatic components such as alcohols and esters were increased in fermented wheat bran compared to unfermented wheat bran. Moreover, the addition of fermented wheat bran significantly improved the sensory and nutritional properties of the bran-containing cake. The contents of protein and dietary fiber were significantly increased in the cake, while the carbohydrate content was obviously decreased. Fermented wheat bran not only improved the flavor and texture properties, but also reduced the in vitro starch digestibility. Compared to traditional cakes, the fast digestible starch decreased by 37.03 ± 1.54% and the hydrolysis rate of starch reduced approximately 23.89% in bran-containing cake. Results showed solid-state fermentation of wheat bran by Rhizopus oryzae is a feasible approach to expand the utilization of wheat bran in food processing.