Lactiplantibacillus plantarum fermentation improves the flavor of Eucheuma cottonii and its transformation mechanism

The effect of Lactiplantibacillus plantarum on improving the flavor of Eucheuma cottonii and the biotransformation mechanism of fishy odor substances were investigated. The results showed that with Lactiplantibacillus plantarum fermentation at optimized conditions (inoculation amount of 2%, fermentation time of 8 hours, and solid-to-liquid ratio of 1:30 (g/mL) ), the content of aldehydes and 1-octen-3-one decreased by 47.8% and 60.56%, respectively ( p < 0.05), and 6-methyl-5-hepten-2-one was not detected in Eucheuma cottonii ; meanwhile, the contents of alcohols and esters increased by 35.88% and 83.29%, respectively ( p < 0.05), exerting a positive effect on improving the flavor of Eucheuma cottonii . Furthermore, the biotransformation pathway of fishy odor substances in Eucheuma cottonii regulated by Lactiplantibacillus plantarum was associated with the metabolic enzymes (e.g., aldehyde dehydrogenase, aldolase, and aldo-keto reductase) as well as ester synthesis reactions. This study offers a theoretical basis for developing high-value-added Eucheuma cottonii with favorable flavor via microbial fermentation. • The optimal conditions for removing the fishy odor of E. Cottonii via L. plantarum fermentation was obtained. • With L. plantarum fermentation , contents of aldehydes and ketones in E. cottonii decreased to eliminate the fishy odor. • Contents of alcohols and esters increased in fermented E. cottonii to improve odor characteristics. • Fishy odor transformation pathway was related with aldehyde dehydrogenase and enoate reductase, etc. produced in L. plantarum fermentation.