Fermentation of Chaenomeles sinensis (Thouin) Koehne with lactic acid bacteria: dynamic changes in metabolites and enhancement of antioxidant activity

This study investigated the effects of lactic acid bacteria fermentation on the bioactive components and functional properties of Chaenomeles sinensis (Thouin) Koehne ( C. sinensis ). Fermentation conditions were optimized as follows: ratio of Lactiplantibacillus plantarum and Lactobacillus acidophilus 2:1, inoculum size 0.46% ( w / v ), fermentation time 6 days and sugar addition 7.6 g, resulting in an 80% increase in proanthocyanidin content (1.84 mg/mL). Furthermore, significant increases in total phenolics, total flavonoids, and superoxide dismutase activity were observed under the optimized conditions. Untargeted metabolomics revealed the differential metabolites with antioxidant activity were significantly enriched in citrate cycle, propanoate metabolism, inositol phosphate metabolism, pentose and glucuronate interconversions and starch and sucrose metabolism. C. sinensis fermentation broth demonstrated strengthened free radical scavenging ability and effectively attenuated oxidative stress in HepG2 cells by reducing reactive oxygen species and malondialdehyde levels while enhancing antioxidant enzyme activities, supporting its potential application as functional food ingredients with antioxidant activity.