Liquid smoke inhibits growth of pathogenic and histamine forming bacteria on skipjack fillets

Pathogenic bacteria were analyzed using the most probable (MPN) method, and histamine level was analyzed using spectrofluorometer. The best liquid smoke concentration was determined using a sensory hedonic test including smell, taste and texture. In addition, water content and pH were also analysed. Concentration of liquid smoke varied between 0, 0.4, 0.8, 1.0 and 1.2%. The best concentration of liquid smoke was 1%. Fresh fillet dipped in 1% liquid smoke showed significantly decreased total plate count (TPC), from 4.1 x 10³ CFU/g in fresh fillet to 7.4 x 10² CFU/g in fillet dipped for 20 minutes. Analysis of pathogenic bacteria showed a positive result in fresh fillet, and a negative result in fillets dipped in 1% liquid smoke, after 2 days of incubation at 30°C. Analysis of anti-pathogenic bacteria showed the positive results in fresh fillet, and negative result fillets dipped in 1% liquid smoke. Further analysis of histamine content also supports our finding, in which the level of histamine goes down from 19.55 to 18.56 when dipped in 1% liquid smoke solution for 20 minutes. The results indicated that dipping fillet in liquid smoke is a very effective treatment to prevent pathogenic bacteria and histamine forming bacteria.