Improvement of the Nutritional Quality and Fibrinolytic Enzyme Activity of Soybean Meal by Fermentation of B acillus subtilis

Abstract

Solid-state fermentation condition of soybean meal (SBM) by Bacillus subtilis XZI125 for producing fibrinolytic enzyme and soybean peptides was optimized, and the effect of microbe fermentation on decreasing anti-nutritional factors was studied. The optimum fermentation conditions were obtained by one-factor-at-a-time and orthogonal array design as follows: fermentation temperature 30C, fermentation time 48 h, grinding particle size of soybean meal 40 mesh, pH 7.0, soybean meal loading 10 g in a 250-mL flask, 1.5% glucose, initial moisture content and inoculum sizes were 1.0 mL/g and 3%, respectively. Under the optimum fermentation condition, fibrinolytic activity and soybean peptides reached 1347.35 IU/g and 171.32 mg/g, respectively. Furthermore, the trypsin inhibitor, phytic acid and urease content were reduced by 33.57, 42.65 and 67.31%, respectively. In our knowledge, it was first reported that the nutritional quality of SBMs was improved and fibrinolytic enzyme in fermented soybean meal (FSBM) was produced by fermentation. Practical Applications Soybean meal (SBM) has traditionally been used as an important dietary protein in the feed industry. However, SBM may be used as food for human consumption if anti-nutritional factors are reduced by fermentation with food-grade microbes. Solid-state fermentation condition of SBM by Bacillus subtilis XZI125 to produce fibrinolytic enzyme and soybean peptides was optimized. The FSBM complemented the fibrinolytic enzyme and peptides, and simultaneously reduced anti-nutritional factors, such as trypsin inhibitor, phytic acid and urease, indicating that the nutritional and health function of FSBM was upgraded through fermentation, and it could become a potential health food.