Improving nutritional and sensory properties of rice bran by germination and solid-state fermentation with fungi

Rice bran, a by-product of the rice milling industry, is rich in protein, fiber, and other nutrients. However, its utilization in food has been limited due to the presence of unpleasant flavors and anti-nutritional components. The present study investigated the impact of germination and solid-state fermentation with various fungi starters on the nutritional and sensory features of rice bran. The results showed germination can significantly decrease phytic acid content and increase the contents of protein and fibers but had a negligible influence on the sensory characteristics of rice bran. Fungal fermentation demonstrated a notable increase in protein content and effective degradation of insoluble fiber and phytic acid in rice bran. Meanwhile, the sensory characteristics of rice bran after fermentation with different fungal cultures varied according to the instrumental analysis (electronic nose/tongue and GC-IMS) and sensory panelists evaluations. Rice bran fermented with Aspergillus niger, Actinomucor elegans and liquor koji exhibited similar GC-IMS spectra and characteristics of odor. However, A. niger imparted bran a musty smell and A. elegans contributed tastes of bitter and astringency. Mucor racemosus fermentation resulted in the highest score of fruity odor. Additionally, rice bran fermented with soy sauce koji stood out with the highest richness score, distinguishing it from other fermented brans. This research can provide insights into improving nutritional and sensory attributes of rice bran.