Optimization of soy solid-state fermentation with selected lactic acid bacteria and the effect on the anti-nutritional components

In this study, a probiotic soy-derived food was developed by a novel solid-state fermentation approach using Lactobacillus plantarum B1-6. The fermentation parameters were optimized, and changes in anti-nutritional components in soy seeds during fermentation were investigated. Analysis using response surface methodology showed the following optimized parameters: addition of 2 g/100 g sucrose, boiling for 5 min, and fermentation duration of 17.61 hr; under the optimized condition, the resulting lactic acid bacteria (LAB) count was 8.12 log cfu/ml. Solid-state fermentation significantly reduced the total saponin content, phytic acid content, and typsin inhibitor activity in soy seeds. The total phenolic content significantly increased by the end of fermentation. In vitro protein digestibility improved significantly in soy seeds after fermentation. This study indicates that soy seeds can be a potential food carrier for probiotic LAB. Moreover, solid-state fermentation, a green technology, exhibits potential in producing probiotic soy-derived food with improved nutritional properties. Practical applicationsSolid-state fermentation is a novel approach to utilize the whole soy seeds to conduct lactic fermentation. Compared to the liquid-state fermentation (usually based on soymilk), it is a greener technology without generating of the by-product okara. Few study has investigated solid-state fermentation on soy seeds by lactic acid bacteria alone. Therefore, in the current study, solid-state fermentation on soy seeds was conducted by Lactobacillus plantarum. Parameters of the solid-state fermentation were optimized by response surface methodology and the influence of fermentation on anti-nutritional components, namely, phenolics, saponin, phytic acid, and typsin inhibitor activity in soy seeds were investigated. Results of the study will be helpful in future optimization and application of this emerging technology to produce healthy and environment-friendly soy-derived foods.