The impact of Aspergillus Niger and Neurospora sitophila co-fermentation on the soluble dietary fiber of soybean residue

Abstract

Soybean residue, as a by-product of soybean, contains over 90% insoluble dietary fiber (IDF) and is underutilized. This study employed Aspergillus Niger and Neurospora sitophila (1:1) as mixed fermentation strains to ferment soybean residues insoluble dietary fiber. Through a single-factor study investigating fermentation time, temperature, and inoculum size, the optimal fermentation conditions for the mixed culture to increase the extraction rate of soluble dietary fiber from soybean residue were explored. After 8 days of fermentation at 22C with an inoculum size of 5%, the extraction rate of soluble dietary fiber reached 38.30%. The fermented soybean residue exhibited a threefold increase in swelling capacity, a 2.5-fold increase in water retention, a 1.56-fold increase in oil retention, and a 1.2-fold increase in oil absorption compared to the unfermented residue. This method provides a research basis for enhancing the extraction rate, obtaining nutritionally rich, and cost-effective soluble dietary fiber from soybean residue.