CONICET | Buscador de Institutos y Recursos Humanos

The use of solid fermentation substrate (SSF) has been appreciated by demand for natural and healthy products. Lactic acid bacteria and bifidobacteria play a leading role in the production of novel functional foods and their behavior is practically unknown in these systems. Soy is an excellent substrate for the production of functional foods for their low cost and nutritional value. The aim of this work was optimize different parameters involved in solid state fermentation (SSF) using selected lactic cultures to improve soybean substrate as possible strategy for elaboration of new soy food with enhanced functional and nutritional properties. Soy flour and selected lactic cultures were used under different conditions to optimize the soy SSF. The measured responses were bacterial growth, free aminoacids and beta-glucosidase activity, which were analyzed applying response surface methodology. Based on the proposed statistical model, different fermentation conditions were raised by varying the moisture content (50-80%) of soy substrate and the temperature of incubation (31-43ºC). The effect of inoculum amount was also investigated. These studies demonstrated the ability of selected strains (Lactobacillus paracasei subsp paracasei and Bifidobacterium longum) to grow with strain-dependent behavior on SSF system. beta-Glucosidase activity was evidenced for both strains and Lactobacillus paracasei subsp paracasei was able to increase the free aminoacids at the end of fermentation under assayed conditions. The used statistical model has allowed optimize fermentation parameters on soy SSF by selected lactic strains. Besides, the possibility to work with lower initial bacterial amounts to obtain results with significant technological impact was demonstrated.