Selected lactobacilli and bifidobacteria development in solid state fermentation using soybean paste.

At present, consumers are looking for more natural foods so as to improve health through their active compounds. Within this context, soybean is an excellent substrate due to its beneficial effects on consumers' health. Moreover, lactic cultures are widely used in the food industry to improve the technological, nutritional and functional characteristics of fermented foods. It is interesting to find new matrices in which to transport these starter cultures (potentially probiotic microorganisms). The aim of this research was to obtain a solid state fermentation system from soybean to analyze the behavior of selected lactobacilli and bifidobacteria, with the potential to develop a functional vegetarian food to serve as carrier for the microorganisms. A soybean solid substrate system was optimized by selecting the relationship of the main processing parameters. Homogeneous soybean pastes with different moisture content (60-80%) were obtained and used as substrate and support for solid substrate fermentation. Moisture, inoculum size and temperature were optimized: 80%, 4%, 37°C, respectively. L. rhamnosus CRL 981 was chosen as the best starter to use in this kind of fermentation, showing high acidification and cell counts at 24h of fermentation and increased specific growth rate in tested soybean pastes. It was demonstrated that the selected soybean paste could be used as a carrier of these microorganisms having probiotic potential for the production of vegetarian foods. Moreover, these microorganisms are able to modify the substrate to enhance their nutritional and functional characteristics, which would change the soybean into a more attractive product for consumers.