Optimization of bioprotein production from soybean residues by solid state fermentation

Abstract

Bioprotein is the total protein that extracted from the cultivated microbial biomass from various types of microorganisms. It is an alternative protein sources from the bioconversion of agricultural waste to satisfy the market needs in food and feed ingredients. In this study, the utilization of soybean residue as a potential substrate for bioprotein production was investigated. The objective of this study is to optimize the bioprotein production using Aspergillus niger in the solid state fermentation (SSF) by demonstrating the potential of soybean residues as raw material. The fermentation process was carried out aerobically with the working mass of 20 g each at 30°C for seven days. The protein concentration was analysed using Lowry’s method. The analysis of the effect of fermentation conditions of glucose concentration, substrate concentration and inoculum size were conducted using One-Factor-at-a-Time (OFAT) method. For the optimization, 3-factors 5-level Central Composite Design (CCD) was used to evaluate the optimum condition in each parameters in bioprotein production. Based on the growth profile analysis, the optimum fermentation period was at day 7 (168 hours), obtaining the highest protein concentration with highest weight of biomass. The maximum protein concentration was obtained at the condition of 20 g/L glucose concentration, 50 % (w/w) of substrate concentration and 8 % (v/w) of the inoculum size in the analysis studies. In optimization process, substrate concentration and inoculum size affected the bioprotein production most significantly among the parameters that being studied. Meanwhile, the validation for optimum conditions in bioprotein production were achieved at 20.130 g/L glucose concentration, 49.248 % (w/w) substrate concentration and 9.392 % (v/w) inoculum size with maximum protein concentration of 1857.17 mg/L.