Influence of green tea-enriched fermentation and cold storage on yogurt’s probiotic viability and metabolomic signatures

This study investigated the synergistic effects of varying green tea powder concentrations and storage conditions on total phenolic content, antioxidant activity, microbial viabilityand the metabolite profile of yogurt formulations. The total phenolic content and antioxidant activity increased proportionally to the concentration of green tea powder. Enhanced acidity, faster fermentation, and higher Lactobacillus spp. viability was observed.Multivariate analysis demonstrated distinct group clustering, indicating clear metabolic divergence driven by the incorporation of green tea and fermentation in cold storage. A total of 86 metabolites were identified, which predominantly comprise polyphenols derived from green tea powder. Pathway enrichment analysis revealed that the synergistic interaction between LAB (lactic acid bacteria) and tea polyphenols during cow’s milk fermentation significantly modulated multiple metabolic pathways, including central carbon metabolism, nucleotide metabolism, redox regulation, amino acid metabolism, and lipid metabolism, which are responsible for contributing enhanced nutritional and functional properties of yogurt.