Lactobacillus strains inhibit biogenic amine formation in salted mackerel (Scomberomorus niphonius)

Biogenic amines (BAs), deriving from the microbial decarboxylation of free amino acids (FAAs) in fish products, have toxicological effects on human health. This study selected two Lactobacillus plantarum strains to reduce BAs accumulation in salted mackerel (Scomberomorus niphonius). Compared with BAs in spontaneously fermented salted S. niphonius, the concentration of BAs in samples inoculated with L. plantarum YC-5 and YC-6 strains decreased by 17.9% and 53.8%, while the histamine contents decreased by 96.9% and 86.5%, respectively. The histamine contents in samples inoculated with L. plantarum YC-5 were lower than the safety level during the entire process, although the precursor (histidine) was available at this stage. Then, the antibacterial activity of the L. plantarum strains was analyzed. The cell-free supernatant (CFS) of the L. plantarum reduced the biomass of the histamine-producing Morganella morganii and displayed stability at different pH and temperatures. Resequencing and bioinformatic analysis demonstrated that the L. plantarum strains contained plantaricin EF and JK encoding gene clusters. This study provided two promising LAB starters to reduce BAs accumulation in salted S. niphonius and elucidated their possible elimination mechanism of BAs, contributing to the safe production of salted fish.