Enhancing Antioxidant Activity and Modulating Gut Microbiota Through Lactiplantibacillus plantarum-Fermented Processing Wastewater of Yuba (FPWY)

Processing wastewater of yuba (PWY), a by-product of yuba production, contains valuable bioactive compounds such as soy isoflavones. However, its utilization remains limited. This study investigated the effects of Lactiplantibacillus plantarum fermentation on the bioactivity of PWY, focusing on its antioxidant properties and gut microbiota modulation. The fermentation resulted in a significantly increased amount of free flavonoids from 63.62 μg/mL to 145.91 μg/mL, and transformed glycosylated isoflavones into their more bioavailable aglycone forms. FPWY exhibited stronger antioxidant activity than non-fermented PWY (NFPWY) as indicated by DPPH, ABTS, and FRAP assays. Furthermore, FPWY promoted the growth of beneficial gut bacteria, including Bifidobacterium, Akkermansia, Ruminococcus, and butyrate bacteria, while inhibiting Escherichia coli. FPWY also enhanced the production of short-chain fatty acids (SCFAs), with propionic acid increasing from 5.01 to 9.30 mmol/L and butyric acid increasing from 0.11 to 2.54 mmol/L. These findings suggest that FPWY has a beneficial effect in relation to gut health and oxidative stress.