The effect of the type of packaging on the physicochemical and microbial characteristics of rainbow salmon (Oncorhynchus mykiss) fillets stored at refrigerator temperature

Considering the sensitivity of fish meat to rapid spoilage, storage conditions and type of packaging are very effective factors in maintaining its quality and nutritional value after catching. In this research, rainbow trout fillets packed with aluminum and polystyrene as treatment and polyethylene bag as control were kept at 4°C for 12 days. Physical, chemical and microbial factors of fillets by recording changes in moisture, total protein, fat, total ash, free fatty acids, peroxide (PV), pH, Thiobarbituric acid (TBA), Total Volatile Basic Nitrogen (TVB-N) and also total microbial load It was measured. The results showed that with the passage of time, moisture and fat decreased significantly. Total protein, total ash, free fatty acids, PV, TBA, TVB-N and total microbial load increased significantly during storage. Also, pH had an increasing trend, but this increase was not significant. The highest amount of TVB-N on the twelfth day was related to the control package with a value of 24.52 mg/g. The lowest amount of total microbial load on the twelfth day was related to aluminum packaging with a log value of 6.86 cfu/g. According to the results, the priority of using packaging to increase shelf life and maintain the nutritional value of fillets was first with aluminum packaging and then with polystyrene. The polyethylene bag was declared unrecommended for consumption due to the lack of nutritional value and reduced product quality. Aluminum packaging worked significantly in maintaining the physicochemical and microbial properties of the product and according to the declared permissible limits of TVB-N and total microbial load, which are important indicators of spoilage, only fillets packed with aluminum containers could be consumed until the end of the storage period.