Effects of chitosan coating combined with sumac on the quality of rainbow trout (Oncorhynchus mykiss) fillets stored in refrigerated condition (4°C) for 12 days were evaluated. The treatments in this study were—T1, control; T2, chitosan: 2% w/v; T3, chitosan: 2% w/v and sumac: 1% w/v; and T4, chitosan: 2% w/v and sumac: 2% w/v. The shelf life of the samples were determined periodically using physicochemical (pH, peroxide value [PV], thiobarbituric acid [TBA], and total volatile basic nitrogen [TVB‐N]), microbiological (total viable counts [TVCs] and psychrotrophic bacteria), and sensory analyzes. During the storage period, T3 and T4 groups showed lower pH, PV, TBA, and TVB‐N values than T1 and T2 groups. The sensory results are in line with chemical and microbiological results. Treatment with 2% chitosan + 1% sumac and 2% chitosan + 2% sumac increased the shelf life of rainbow trout fillets by 6 days as compared to the control samples. Practical applications To avoid the adverse effects of chemical preservatives and to answer natural and reliable product demands of the consumers, plant extracts and edible coatings are applied to increase the shelf life and to prevent the spoilage of fresh fish. The results of this study reported the efficacy of chitosan edible coating combined with sumac as a new natural preservative for improving the shelf life of rainbow trout fillets. The findings revealed that sumac extract combined with chitosan coating can be an alternative method to extend the shelf life, to preserve the quality and safety of fish, as a result of their good antioxidant and antimicrobial activity.

This study aims to investigate the effect of glazing with sumac (Rhus Coriaria, L.) extract on the quality of rainbow trout (Oncorhynchus mykiss) fillets during frozen storage. Fish fillets were glazed with 5% and 10% sumac extracts and were stored at-18°C for 6 months. Results showed that glazing with sumac treatment prevented lipid oxidation when compared to non-glazed and water-glazed treatments. Sumac extract decreased the free fatty acid production during 6 months of storage. PV, TVB-N and TBA values of S5 and S10 groups were lower than NG and G groups. Samples glazed with sumac extract showed the best results compared to non-glazed and water-glazed samples. Glazing with 10% sumac extract treatment significantly decreased the total aerobic mesophilic bacteria. Our results showed that sumac can be used as natural antioxidant, antibacterial agent and glazing material for delaying lipid oxidation and to inhibit the quality loss in frozen fish.

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In this study, some quality attributes of smoked Cyprinus carpio sausages supplemented wıth %1 Propolis Extract, stored under cold condition (2°C) for 9 weeks were investigated. Quality of sausages were determined using physicochemical (Thiobarbituric acid (TBA), microbiological (Coagulase-positive Staphylococci, Sulphite-reducing Clostridium, E. coli and Salmonella) and sensory analyzes. During the storage period, propolis added group was measured lower TBA than control (Without propolis) group. E. coli and Salmonella were not detected in the all sausage samples. In addition, significant differences were found each two groups as sensorial quality (p<0.05). Consequently, %1 propolis treatment increased the shelf life of sausages by 3 weeks as compared to the control samples. Therefore, propolis extract as natural preservative can be used on other studies to enhance seafood product quality.