Application of Lactiplantibacillus plantarum LP95 as a Functional Starter Culture in Fermented Tofu Production

Several studies have shown that lactic acid bacteria (LAB) fermentation plays an important role in the development and application of soy-based products and could increase their nutritional values and content of bioactive substances. Lactiplantibacillus plantarum LP95 has shown in previous studies to be a promising candidate as a probiotic and microbial culture in fermented soymilk production. In this study, the suitability of Lp. plantarum LP95 as a functional starter culture in tofu production was verified, with a focus on evaluating the isoflavone and amino acid content in the final product after 21 days of storage at 4 °C. Lp. plantarum LP95 was found able to ferment monosaccharides and disaccharides naturally present in soymilk (D-glucose, D-fructose, D-galactose and D-sucrose) after 24 h while leaving the content of galacto-oligosaccharides (stachyose and raffinose) unaffected. The rich amino acid profile of tofu has undergone some quantitative but not qualitative variations compared to the soy milk used, highlighting the high nutritional value of the product obtained. The enzymatic activity of Lp. plantarum LP95 allowed the release of isoflavone aglycones (daidzein, glycitein and genistein) that were not further metabolized during the fermentation phase of soymilk and during storage at 4 °C. In addition, Lp. plantarum LP95 showed a good viability after 21 days of tofu storage at 4 °C. The results obtained highlighted the suitability of this LAB strain to be used as a microbial culture capable of playing a pro-technological role in the production of fermented tofu, which has good nutritional and functional properties.