Effects of Solid-state Fermentation on the Phytochemical Composition and Antioxidant Activities of Cereal/Pulse/Oilseed Processing By-products
In this study, the effects of solid-state fermentation (SSF) using food-grade microbes (Aspergillus spp., Rhizopus spp., Bacillus subtilis, Saccharomyces cerevisiae) on the phenolic compositions and antioxidant activities of low-value brans/hulls, including wheat bran, pea hull and mustard bran, were investigated. Brans/hulls were fermented over a 7-day period at optimal incubation temperatures per treatment group. SSF led to significant enhancement (p<0.05) of total phenolic (TPC) and total flavonoid contents of all brans/hulls, which depended on the fermentation duration and treatment group. Antioxidant activities (FRAP, DPPH, ORAC) of fermented brans/hulls were significantly correlated with TPC. The phenolic acid profile of wheat bran was altered throughout SSF, while changes in the composition of phenolic acids and flavonoids, mainly flavonol glycosides, were observed in pea hulls and mustard bran. These findings demonstrate that SSF can effectively enhance the phenolic contents and antioxidant properties of low-value brans/hulls, which may lead to their development into value-added products.