The study of Freezing Effect on Amino Acid Profile and Shelf Life of Rainbow Trout (Oncorhynchus mykiss) Fillet During 9 Months at -18°C

Rainbow trout (Oncorhynchus mykiss) is a species with high commercial value and much appreciated by consumers. This study was carried out to determine proximate analysis, amino acids composition and their changes in rainbow trout fillets during 9 months storage at -18°C. The results revealed that 17 amino acids were obtained in rainbow trout fillet,10 essential and 7non essential amino acids. In this research, Aspartic acid, Glutamic acid, Arginine, Leucine and Lysine were the main amino acids of rainbow trout fillets. The results of proximate analysis and its changes shown that moisture content of fillet s gradually reduced, protein content was decreased significantly, and fat and ash content were continually increased during frozen storage time (p<0.05). Primary and secondary lipid oxidation compounds measure by PV and TBA. PV was raised from 0.84±0.005 to 5±0.05meq O2/Kg and TBA from 0.65±0.03 to 1.92±0.05mg ma/Kg. In this research the increase was observed in FFA from 0.46±0.008 to 1.3±0.05g of Oleic acid/Kg. The TVB-N value raising from 10±0.1 to 40.5±0.02mg/Kg after 9 months (p<0.05). The results shown that the reduction of protein content related to breakdown of protein and all of essential and nonessential amino acids were changes. This changes, specially, shown after3 months and affected to the quality and nutrition value of fish fillets.