Changes in the physicochemical properties and metabolites of Myeolchi-jeot (salted-fermented anchovy) based on fermentation time

Food fermentation enables long-term food storage; however, the safety and quality of fermented food varies according to the applied fermentation parameters. Despite advances in fishery product fermentation, few studies have addressed possible temperature-dependent changes in the quality and stability of Myeolchi-jeot(MJ), following long-term fermentation. Herein, physicochemical and microbiological changes in MJ were investi-gated following long-term fermentation at low(10 degrees C; LT-MJ) and high(30 degrees C; HT-MJ) temperatures and per-formed metabolic profiling to evaluate these alterations at the molecular level. Both fermentation temperatures showed continuous increases in amino nitrogen(AN) and total nitrogen(TN) from 15 to 480 days. The AN and TN levels were higher in HT-MJ than in LT-MJ, as fermentation time increased, suggesting higher activities of proteases or halophilic bacteria at higher fermentation temperatures. The amino acids detected in MJ were tryptophan, tyrosine, histidine, arginine, lysine, and ornithine, and their contents increased with fermentation time. Changes in volatile basic nitrogen and histamine contents were higher in HT-MJ relative to LT-MJ, and metabolomics analysis revealed a continuous increase in histamine during fermentation. The quality of HT-MJ was decreased compared to that of LT-MJ, suggesting that the quality and safety of fermented seafood prod-ucts from anchovy might be ensured by low-temperature fermentation for & LE;1 year.