Untargeted metabolomics revealed the metabolites profile and conjugated linoleic acid formation mechanisms of fermented milk produced by novel Limosilactobacillus fermentum L1

Effect of Limosilactobacillus fermentum L1 on formation mechanism of conjugated linoleic acid (CLA) and metabolite fingerprint for CLA-rich fermented milk was investigated in this study. Our results showed that adding L1 improved the fermented milk physicochemical properties, texture and flavor. The highest level of CLA formed in fermented milk after adding L1 was 814.26 μg/g. Metabolomics analyses revealed that a total of 4241 significant differential metabolites were identified, including fatty acids, amino acids and their derivatives, organic acids. KEGG pathway enrichment analysis indicated that linoleic acid (LA) was in the core position of fatty acid metabolism and the conversion function of L1. Thus, LA was transferred to CLA. L1 fermented milk characteristic fingerprints including fatty acids, amino acids, organic acids, alkaloids and lignans, with the account of 42.86%, 34.13%, 9.52%, 8.73% and 4.76%, respectively. This study provides a theoretical basis for the research of fermented foods rich in functional nutrition. • L. fermentum L1 improved fermented-milk physicochemical properties, texture and flavor. • A high conjugated linoleic acid (CLA) content is achieved via L. fermentum L1. • Linoleic acid and CLA are identified as the key factors for fatty acid change. • The metabolite fingerprint of CLA-enriched fermented milk is revealed. • This study provides a theoretical basis for developing functional fermented foods.