Metabolomic and bioactivity analysis of plum pulp fermented with Lactiplantibacillus, Lacticaseibacillus, and Bifidobacterium strains

Probiotic fermentation is a promising method for enhancing fruit functionality. This study investigated the effects of Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, and Bifidobacterium infantis fermentation on plum pulp quality and bioactive properties. Mixed probiotics maintained viable counts above 7 log CFU/mL during fermentation. Compared to unfermented samples, total sugar content decreased by 24 % on day 5, while phenolic and flavonoid contents increased by 17.5 % and 31.4 %, respectively, on day 3. Non-targeted metabolomics detected 2113 metabolites, revealing pathways related to flavonoid biosynthesis and organic acid metabolism. Quercetin and proanthocyanidin B2 were key metabolites significantly upregulated by fermentation. These biochemical changes resulted in optimal antioxidant capacity observed in day 3 fermentation samples across both chemical and cellular antioxidant assays. Correlation analysis identified 30 metabolites, including 4-hydroxybenzoic acid, niacinamide, and resolvin D1, that were strongly associated with antioxidant capacity. This study demonstrates that mixed probiotic fermentation transforms plum pulp into a functional product with enhanced bioactive properties, providing valuable insights for developing health-focused fermented fruit products.