Effect of chitosan and cinnamon essential oil on a food-borne pathogen and antioxidant activity in frozen rainbow trout (Oncorhynchus mykiss)

Food industries use synthetic preservatives to improve the quality and enhance the shelf life of food products during storage. However, the most common industrial strategies for preservation may not always bring the desired protection for curbing corruption. Furthermore, consumer demands for safer foods encourage researchers to find natural and effective preservatives. In this study, the antioxidant and antibacterial activity of chitosan in combination with cinnamon were investigated in frozen condition. Rainbow trout were combined with 2% chitosan in combination with different concentration of cinnamon essential oils (0.125, 0.25 and 0.5 ml). The samples were kept at -18 ºC. Oxidative stability of samples was assessed by measuring lipid peroxidation level using thiobarbituric acid reactive substances (TBARS) method. The bacterial test was assayed by counting colony forming unit. The evaluation of statistical differences between groups was analyzed using the student's T-test by SPSS software according to the statistical facts, the difference of more than 95% (P ≤0.05) was considered significant. Combination of chitosan with 0.25 and 0.5 ml cinnamon significantly decreased lipid peroxidation level compared to control group and chitosan combination with 0.5 ml cinnamon showed the synergistic effect. The antimicrobial activity of chitosan in combination with 0.5 ml cinnamon was higher than other concentrations and control groups. Chitosan in combination with cinnamon oil could considerably increase the oxidative stability and decrease the total count of bacteria in frozen fish. These results may suggest that these edible coatings can be used instead of artificial preservatives and non-edible coatings.