Preparation and in vitro Evaluation of High Performance Fermented Soybean Meal using a mixture of Lactobacillus plantarum, Bacillus subtilis and Saccharomyces cerevisiae

Abstract Background: Soybean meal is used in animal feeds as a protein supplement but contains significant amounts of anti-nutritional factors such as trypsin inhibitor that directly inhibit digestion, absorption and utilization of nutrients. Results: Herein, we used solid state batch fermentation of soybean meal using Lactobacillus plantarum, Bacillus subtilis and Saccharomyces cerevisiae alone and in combination to alter the content of anti-nutritional compounds in the meal. A systematic analysis identified a temperature of 40℃, water content of 40 % in a 48 h fermentation that optimized the fermentation according to our goals. The digestibility of the meal increased within 36 h and by 48 h, the free amino acid content increased while glycinin, β-conglycinin and trypsin inhibitor significantly decreased and the indigestible sugars stachyose and raffinose were reduced to undetectable levels. These processes correlated with high levels of lactic acid that were responsible for an overall pH decrease. Conclusions: Bacterial and mixed fermentations increased nutritional content while eliminating anti-nutritional factors and significantly improved the nutritional quality of the soybean meal.