Use of commercially available antimicrobial compounds for prevention of Listeria monocytogenes growth in ready-to-eat minced tuna and salmon roe during shelf life

Listeria monocytogenes found in minced tuna and fish roe can cause listeriosis. These products are classified in category B according to the Codex Alimentarius Commission, i.e., ready-to-eat foods in which L. monocytogenes growth can occur. We investigated the effectiveness of nisin and other commercially available antimicrobial compounds (lysozyme, ε-polylysine, and chitosan) for prevention of L. monocytogenes growth during the expected shelf life of raw minced tuna and salmon roe products. Food samples inoculated with L. monocytogenes were incubated with each antimicrobial at 10°C for 7 days or at 25°C for 12 h. Nisaplin (an antimicrobial containing nisin) effectively inhibited L. monocytogenes growth in minced tuna at 500 ppm and in salmon roe at 250 ppm within their standard shelf lives. The effective concentration of each antimicrobial was determined: 2,000 ppm for ART FRESH 50/50 (containing lysozyme) and SAN KEEPER No. 381 (containing ε-polylysine) and 10,000 ppm for SAN KEEPER K-3 (containing chitosan).