Optimization of fermentation conditions and physicochemical properties and structural feature of quinoa bran dietary fiber

Abstract

In order to improve the utilization of quinoa bran and improve its functional properties, using quinoa bran as raw materials, quinoa bran dietary fiber was modified by fermentation with Aspergillus niger. With the yield of soluble dietary fiber (SDF) as the response value, the fermentation process conditions were optimized by single factor and response surface tests, the physicochemical properties and structural feature of dietary fiber before and after modification were analyzed. The results showed that the optimal fermentation process conditions were solid and liquid ratio 1∶20 (g∶ml), inoculum 10% and fermentation time 96 h. Under the optimized conditions, the soluble dietary fiber yield reached 24.8%. Compared with the unmodified quinoa bran dietary fiber, the water holding capacity (WHC), oil holding capacity (OHC), water swelling capacity (WSC) and cation exchange capacity (CEC) of the modified quinoa bran soluble dietary fiber were increased by 74.29%, 47.35%, 32.73% and 115.8%, respectively. Fourier transform infrared spectrum (FT-IR) analysis results showed that the number of functional groups in soluble dietary fiber increased after modification, but no new functional groups were produced.

Keywords

• quinoa bran|soluble dietary fiber|aspergillus niger fermentation|modification|physicochemical property|structural feature