Effects of a chitosan edible coating containing pomegranate peel extract, nisin, and citric acid on the microbiological, chemical, and sensory characteristics of vacuum-packed rainbow trout fillets

Natural coatings incorporating antimicrobial and antioxidant active components can be utilized to inhibit undesirable alterations in food products. In this investigation, nisin (500 IU/g) and citric acid (0.5 %) and pomegranate peel extract (PPE) (1 % w/v) were incorporated into the chitosan coating. Chemical analyses (including pH, volatile basic nitrogen, and thiobarbituric acid tests), microbial analyses and sensory evaluations were conducted on days 0, 3, 6, 9, and 12. The results indicated that the pH, TVB-N, and TBA values of the samples increased gradually over the storage period; however, the increase in the combined treatment was slower than that in other treatments (p ≤ 0.05). The results of microbial analyses demonstrated that nisin-containing treatments had the greatest inhibitory effect on the growth of all microorganisms in this study. The sensory evaluation data, which aligned with the microbial and chemical results, indicated that the addition of active compounds not only preserved but also prolonged the sensory properties of the treated samples. In conclusion, the combination of citric acid, nisin, and PPE in a chitosan coating effectively extended the shelf life of refrigerated trout and demonstrated its potential as a natural preservative.