Enhancement of Okara Functionality via Fermentation With Single and Cocultures of Lactic Acid Bacteria

Okara, a byproduct of tofu or soy milk production, remains underutilized in the food industry due to its rancid aroma and high perishability. Fermentation with lactic acid bacteria (LAB) provides a sustainable and cost-effective approach for its valorization. Herein, we used Lactiplantibacillus plantarum C11 and Weizmannia coagulans C8 and their cocultures to explore the feasibility of fermenting okara for enhancing its functionality and shelf life after initial screening in soy milk. Results indicated that okara is a suitable substrate for bacterial strain growth based on their high viable counts. Fermentation of okara with Lpb. plantarum C11 and the coculture effectively reduced pH, suggesting improved preservability. Furthermore, both fermentations enhanced the permeability of isoflavones in Caco-2 cells through bioconversion into isoflavone aglycones. Moreover, the increased interleukin-8 (Il-8) expression and interleukin-1β (IL-1β) production in inflamed Caco-2 and J774.1 cells, respectively, were markedly reduced by administration of Lpb. plantarum C11-fermented okara. This finding suggests that fermentation of okara, especially with Lpb. plantarum C11, enhances the conversion of isoflavone glucosides into their aglycones, such as genistein, thus exerting anti-inflammatory effects. Hence, this study demonstrated the potential of okara bioactivation using LAB that exerts anti-inflammatory effects and improves its quality and shelf life, which may substantiate and increase its inclusion in functional food development.