Comprehensive metabolomics based exploration of digestive characteristics of biotransformed apple polyphenols.

Apple () polyphenols possess functional properties; however, their human body absorption is impeded. To enhance their absorption, apple polyphenols were fermented using zrx01. Gastrointestinal digestion and metabolomics analyses were conducted. The results showed that the polyphenol content decreased significantly to 1.12 mg/mL ( < 0.05) in fermentation group and increased to 2.01 mg/mL in non-fermentation group; 6 differential metabolites such as ferulic acid (log₂ FC = -3.28) and p-hydroxybenzoic acid (log FC = -2.80) were identified by metabolomics, among which epicatechin (VIP = 2.54) and chlorogenic acid (VIP = 2.40) were significantly increased. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that differential metabolites were significantly enriched in 10 metabolic pathways, including phosphatidylinositol 3 kinase-protein kinase signaling pathway ( = 0.00029), fluid shear stress, and atherosclerosis pathway ( = 0.00327). The research shows fermentation converts macromolecular polyphenols into small molecules deglycosylation, altering postdigestive metabolite profiles and providing evidence for bioavailability mechanisms and functional development of apple polyphenols.