Improvement of protein quality and degradation of allergen in soybean meal fermented by Neurospora crassa

The nutrition quality and bioactivity of soybean meal was investigated via solid-state fermentation using Neurospora crassa (NC) alone or Neurospora crassa and saccharomyces cerevisiae (NCSC) together. The optimized fermentation conditions of NC or NCSC were obtained as follow: fermentation temperature (30 degrees C both), fermentation time (72 h vs 74.7 h), solid-liquid ratio [1:3.5 vs 1:3.0 (g/mL)], inoculation amount (the inoculation amount of fungi/soybean meal (dry weight)) of Neurospora crassa + Saccharomyces [1% (m/m) + 0 vs 1% (m/m) +20% (v/m)], initial pH (7.0 both). The protein hydrolysis of fermented soybean meal (FSM) could reach to 10.05% and 8.05% by NC and NCSC, respectively. In fermented soybean meal by NC, the level of total free amino acids (TFAA) increased 13 times (p < 0.05), in vitro digestion rate of protein reached to 95.96%, increased by 37.97% (p < 0.05) compared to soybean meal (SM). In fermented soybean meal by NCSC, the level of TFAA increased 6.76 times than that in SM (p < 0.05). SDS-PAGE results showed that macromolecular proteins were degraded to micromolecular proteins (< 14.4 kDa/mw). No stripe of antibody response was observed and IC50 values of allergic reaction were significantly increased. It indicated fermentation improved nutritional quality and antioxidant activity of SM, and may be applied to food materials.