Production and antibacterial activity of fish sauce from mature chum salmon (Oncorhynchus keta)

The meat color fades and the taste deteriorates as the chum salmon matures (hereafter referred to as “buna salmon”), which lowers its commercial value. To expand the use of buna salmon, fish sauce was produced and its general and functional food components as well as antibacterial properties were investigated. The total nitrogen and amino nitrogen contents of the produced fish sauce were 2.10g/100g and 0.66g/100g, respectively, both of which were higher than those of soy sauce. The volatile basic nitrogen content of the fish sauce was low at 16.4 mg/100 g. This confirmed the good quality of the fish sauce. The free amino acids in the fish sauce were particularly high in isoleucine, serine, arginine, lysine, leucine, and glutamic acid. The antioxidant activity and the γ-aminobutyric acid content of the fish sauce were 127 μmol Trolox/100g and 1.8mg/100g, respectively, making it a highly functional fish sauce. Fish soy sauce demonstrated antibacterial properties against Escherichia coli, and fish soy sauce is presumed to contain factors that inhibit E. coli growth, demonstrating sufficient antibacterial properties. Using buna salmon as an ingredient in fish soy sauce, a highly functional fish soy sauce with antibacterial properties can be produced, and buna salmon has been confirmed to be used effectively. Results of this study indicate that fish sauce can be effectively produced from aged chum salmon, and that using this fish sauce in processed foods and cooking can not only impart a salty and umami taste but also produce functional foods that are less likely to spoil.