Effects of two preservatives nisin and sodium acetate on changes the growth of Clostridium botulinum in rainbow trout (Onchorhynchus mykiss)

Nisin is a natural antimicrobial and has inhibitory effect on the pathogens and spoilage organisms. The efficiency of nisin was reduced after reaction with food compounds. There is the hypothesis that combination of nisin with organic salt increases the shelf life of fish. The aim of this study was evaluation of the effect of nisin (0.15%) and sodium acetate (1%), individually and in combination together, to increase the shelf life of fillet and gutted whole rainbow trout. In next examination, behavior of Clostridium botulinum was also surveyed in different treatments. The results showed that the greatest growth of C. botulinum was observed in control treatment (without any preservatives) (log 8). However, in single preservative treatments, bacterial growth was slower than control treatment (log 5 on day 16). The lowest of bacterial changes was seen in combination of nisin and sodium acetate treatments. Different parameters such as kind and the method used of preservatives, pH, proteolytic enzymes, and resistance stains of bacteria influence on action of preservatives.