Co-fermentation of papaya juice with Lactiplantibacillus plantarum and Saccharomyces cerevisiae enhances the physicochemical properties, antioxidant activity, and bioaccessibility

Fermentation can extend fruit shelf life and enhance fruit products’ quality. This study investigated the effects of co-fermenting with Saccharomyces cerevisiae (SC) and Lactiplantibacillus plantarum (LP) at different ratios (1:0 to 1:10) on the physicochemical, antioxidant, and digestive properties of papaya juice. Co-fermentation reduced pH by 1.12 units and increased titratable acidity by 72.30%. Spectroscopic and HPLC analyses showed that the 1:8 group exhibited 46.33% higher antioxidant power and 20.66% greater polyphenol. These enhancements likely result from synergistic interactions, where LP’s hydrolases mediate polyphenol release, while SC provides nitrogen for LP growth. Following in vitro digestion, the 1:8 group also showed >100% carotenoid bioaccessibility and a 2.68% increase in α-glucosidase inhibitory activity. Molecular docking results further revealed procyanidin B1 and β-carotene exhibited strong binding scores to α-glucosidase, contributing to competitive inhibition. Overall, a 1:8 SC–LP ratio was optimal for papaya juice fermentation, highlighting its potential for functional plant-based beverages.