Effect of free and nanoencapsulated extract of Foeniculum vulgare on behavior of Staphylococcus aureus and microbial and chemical changes of rainbow trout (Oncorhynchus mykiss) fillet during storage in 4˚C

 Microbial growth and lipid oxidation, as a major source of meat and meat products spoilage, results in undesirable changes and thus leads to food poisoning, human mortality and also considerable economic losses. In order to evaluate the behavior of Staphylococcus aureus (cusative agents of food poisoning) in the polyphenols presence of natural preservative (free extract and nano-encapsulation of Foeniculum vulgare) in the concentration of (0.1 and 0.3 %) the rainbow trout (Oncorhynchus mykiss) fillets were preserved for 15 days at refrigerator temperature. and some chemical parameters such as Peroxide Value and microbial parameters such as Total count, Psychrotrophic Count and Staph aureus bacteria count was stemated. Results showed that there was significant differences between free extract and nano-encapsulated treatments (Pnano-encapsulation of F.vulgare, especially at high concentrations was more effective than conventional form that leading to a slower rate of growth of S.aureus number in rainbow trou fillets. So, using of the nano-encapsulated form of F.vulgare, especially, in concentration of %0.3, as natural preservative, was recommended in rainbow trou fillet.