Effects of frozen storage on fatty acids profile, chemical quality indices and sensory properties of Red Tilapia (Oreochromis niloticus × Tilapia mosambicus) fillets

The aim of the investigation was to determine the changes in fatty acids profile and chemical quality indexes of Red Tilapia fillets during frozen storage at -۱۸°C. The fish were filleted by hand. The prepared fillets were then placed to the polyamide pouches and stored at -۱۸°C for ۱۵۰ days. Fatty acid profile, sensory properties and chemical quality indices were determined for a five month period. Results showed that ۲۹ fatty acids were identified in the fresh and frozen samples. Polyunsaturated fatty acids (PUFA) were found higher than saturated fatty acids (SFA) in fresh samples but after ۱۵۰ days of frozen storage this ratio became reverse. Oleic acid and Linoleic acid were the major MUFA (mono unsaturated fatty acids) and PUFA in fresh and frozen samples, respectively. The ratio of n۳/n۶ decreased from ۰.۵۹ to ۰.۴۹. The thiobarbituric acid value (TBA. Mg malondialdehyde/kg) increased significantly (p<۰.۰۵) throughout the storage time from ۰.۰۳ to ۱.۲۶ . Peroxide value (PV), Total volatile bases (TVB-N) and pH value also increased but were well within the limit of acceptability