Enhanced functional properties and volatile profiles in Lactobacillus-fermented Hylocereus megalanthus juice: A strain-dependent analysis.

Hylocereus megalanthus is valued for its rich nutritional profile, including vitamins, minerals, bioactive compounds, and dietary fiber. Fermentation with Lactic acid bacteria offers a promising bioprocessing strategy, yet the strain-specific metabolic responses during H. megalanthus juice fermentation remains largely unexplored. This study investigated the metabolic differences between two Lactobacillus (Lactobacillus plantarum 082 and Lactobacillus fermentum 312) strains isolated from Hainan, as well as their co-culture in H. megalanthus juice. In this study, L. plantarum 082 primarily promoted the production of alcohols and organic acids, whereas L. fermentum 312 favored ketones, phenols, and amino acids. Notably, co-culture fermentation uniquely upregulated arginine-proline metabolism, the tyrosine pathway, and ABC transporter activity. Metabolomic correlation analysis identified 2,6-dihydroxybenzoic acid, oxoglutaric acid, and homovanillic acid as key contributors to the enhanced antioxidant activity. This comprehensive metabolomic characterization establishes a scientific framework for developing functional beverages with targeted health benefits by strategically selecting strains and optimizing fermentation.