Particle Size for Improvement of Peptide Production in Mixed-Culture Solid-State Fermentation of Soybean Meal and the Corresponding Kinetics

Abstract

Experiments were undertaken to study particle size and its distribution for improvement of peptide production by mixed-culture (Bacillus sublitis, Saccharomyces sp. and Lactococcus lactis) solid-state fermentation (SSF) of soybean meal and the corresponding kinetics. A particle size of 1-1.4mm of soybean meal gave the highest finial peptide yield, and as the proportion of 1-1.4mm/1-2mm in natural soybean meal up to 61.30%/58.58%, the distribution of particle size was also appropriate for peptide production. Logistic model fitted the data most accurately and could be used for growth kinetic profiles during the course of fermentation, and the higher growth rate was calculated for the substrate with optimal particle size distribution. Hence the mechanism could be inferred that appropriate particle size did improve the according rate of microbial growth, thus leading to the higher peptide yield in soybean meal SSF within a limited fermentation time.