Effect of lactic acid bacteria fermentation on biotransformation of phenolic compounds and bioactivities of hawthorn pulp based on metabolomics

Abstract

Lactic acid bacteria (LAB) fermentation can offer an improvement in the nutritional quality and biological activity of foods. This study aimed to explain the impacts of LAB fermentation on bioactivities and biotransformation of polyphenols in hawthorn pulp. Firstly, a strain with better polyphenol transformation capacity was selected from four LAB strains; then, microbial characteristics, polyphenols content, antioxidant capacity, and digestive enzymes inhibitory capacity of fermented hawthorn pulp were evaluated and their correlation was established; finally, metabolomics was used for analyzing the biotransformation of polyphenols. The results showed that Lactobacillus rhamnosus FN518 exhibited the best efficiency, which reached viable counts of 8.28 ± 0.03 log CFU/mL after 48 h of fermentation and exhibited strong malolactic-conversion ability. The total phenolic content significantly increased to 11.25 ± 0.12 mg GAE/g and DPPH radical scavenging capacity, FRAP, and α-amylase inhibitory capacity significantly increased by 30.80 %, 13.21 %, and 16.82 %, respectively (p < 0.05), which were significantly and positively correlated with phenolic compounds. Metabolomics revealed that flavonoid biosynthesis and enzymatic degradation of macromolecular phenolic compounds were primary biotransformation pathways of polyphenols in fermented hawthorn pulp. This study contributes precious insights into biotransformation of hawthorn polyphenols via LAB fermentation and development of fermented hawthorn products.