Preparation and improvement of physicochemical and functional properties of dietary fiber from corn cob fermented by Aspergillus Niger

Abstract

Abstract Corn cobs were fermented with Aspergillus niger to produce the high-quality soluble dietary fiber (SDF) with excellent food safety. In this work, the fermentation process was optimized by single-factor test and response surface methodology (RSM) to determine the fermentation conditions (material-liquid ratio 1:30, inoculum concentration 11%, temperature 32 ℃, time 6 d, shaking speed 200 r/min), the SDF yield of corn cob increased from 2.34–11.92% and SDF/TDF reached 19.08%, achieving the requirements of high-quality dietary fiber (SDF/TDF was more than 10%). SEM and FTIR analysis revealed that the fermentation effectively degraded part of cellulose and hemicellulose, resulting in the formation of a loose and porous structure. After fermentation the water swelling capacity, water-holding capacity, and oil-holding capacity of the corn cob SDF were obviously improved and the adsorption capacity of glucose, cholesterol, and nitrite ions all increased by more than 20%. Moreover, the total phenolic content increased by 20.96%, which correlated with the higher antioxidant activity of SDF. Overall, the fermentation of corn cobs by Aspergillus niger improved the yield and functional properties of its DF.