Potential of Three Probiotic Lactobacilli in Pueraria thomsonii Juice into Functional Beverages

The functional effects of Pueraria thomsonii fermented with single and mixed (1:1) cultures of Lactiplantibacillus plantarum (Lp), Lacticaseibacillus rhamnosus (Lr) and Lacticaseibacillus paracasei (Lpc) were investigated to identify the superior strain. The effects of different lactic acid bacteria (LAB) starter cultures on the nutritional and functional components (pH, total soluble solids, titratable acidity, reducing sugar, puerarin, daidzin and daidzein) and sensory characteristics of juices were examined and compared. Total phenolic and flavonoid contents, antioxidant activity (DPPH, ABTS, FRAP, and SOD), and α-glucosidase and tyrosinase enzyme inhibitory activity during the fermentation process were analyzed. The ideal fermentation strain was selected using principal component analysis (PCA). The results indicated that juices fermented with single and mixed strains underwent similar changes during 72 h fermentation period. After fermentation, the pH of the juices decreased from 5.22~5.23 to 3.17~3.48, and the total acid content increased from 0.11~0.12 g/L to 1.29~3.11 g/L. After fermentation, Lp and Lp combined with Lr significantly increased the puerarin content in the fermentation solution by 120% (P<0.05). Lpc fermentation significantly increased daidzein content to up to 253.3%. Notably, daidzein content decreased significantly in all fermentation groups after fermentation with LAB (P<0.05). The sensory evaluation results showed that LAB fermentation improved the aroma and taste of P. thomsonii juice. Except for L. rhamnosus, no significant differences in sensory scores were observed in the other fermentation groups (P>0.05). Spearman's correlation analysis showed that phenolic metabolism likely contributed to enhancing the α-glucosidase and tyrosinase enzyme inhibitory activities. Additionally, the antioxidant activities of fermented P. thomsonii juice were significantly improved (P<0.05). The comprehensive score ranking showed that the antioxidant activities and functional components content of juices with Lp were superior, and the α-glucosidase enzyme inhibitory activities and SOD-like activities of juices with Lp+Lpc and Lp+Lr were better. Therefore, the selection of appropriate probiotics is a promising alternative method to develop novel functional beverages with specific aromatic notes using P. thomsonii juice.