Microbial, chemical, textural and sensory properties of coated rainbow trout by chitosan combined with pomegranate peel extract during frozen storage

The current study was aimed to investigate the combined effects of chitosan (Ch) and pomegranate peel extract (PPE) on the overall quality of rainbow trout (Oncorhynchus mykiss) during the frozen storage. Fresh gutted fishes were dipped for 60 s either in sterile distilled water (Control) or in chitosan combined with 0 (Ch), 1% (Ch + PPE1), 2% (Ch + PPE2), or 4% (Ch + PPE4) (w/v) PPE. Microbial, chemical, textural and sensory properties of the samples were intermittently checked during six months. At the end of storage, the highest and lowest values of psychrophilic, lactic acid bacteria and mold counts in the control and Ch + PPE4 groups were respectively, 5.14 +/- 0.19, 2.91 +/- 0.00; 3.11 +/- 0.03, 0.33 +/- 0.57 and 2.86 +/- 0.19, 2.24 +/- 0.13. Our results showed the best performance to prevent the oxidation of fats and protein was in the chitosan combined with 4% PPE, however, due to its undesirable color, the chitosan combined with 2% PPE was preferred. A considerable improvement in the chemical, microbial, sensory and textural properties was shown in the Ch + PPE2 groups. Therefore, this active coverage was suggested as safe to store rainbow trout up to 6 months frozen storage. (C) 2017 Elsevier B.V. All rights reserved.