Abstract

Purpose: Not many studies have been done on amino acids changes during freezing storage. So, the purpose of this study was to investigate the changes of amino acids (Arg, Asp, Ala, Glu, His, Ilu, Leu, Lys, Met, Phe, Gly, Pro, Ser, Thr, Tyr, Val, Cys) in Rutilus frisii kutum (Caspian Kutum), Liza aurata (Golden Grey Mullet), Cyprinus carpio (Common Carp), Sander lucioperca (Pick perch) and Clupeonella cultriventris caspia (Common Kilka or Sprat) during frozen storage (-24 °C) in time intervals of 0, 1, 2, 3, 4, 5 and 6 months.

Design/Methodology/Approach: To study the effects of frozen storage (-24 °C) on changes of fish amino acids, 5 species of fish (Caspian kutum, golden grey mullet, common carp, pick perch and common kilka) were used and the amount of amino acids were evaluated during frozen storage at - 24 °C in time intervals of 0, 1, 2, 3, 4, 5 and 6 months.

Findings: Glutamic acid was the dominant amino acid in all species. The procedure of amino acids alteration was not similar but the amount of most of them decreased gradually. In all spices, His, Phe and Gly increased during frozen storage. The content of Lys enhanced significantly (P≤0.01) at sixth month compared with first day in common carp, pike perch and common kilka. Amino acids resistance to freezing in pike perch and common Kilka was higher than the other species because they had insignificant change during storage at -24 °C.

Practical Implications: Determination amount of amino acids by derivatization with PITC and measurement with Reversed-Phase High Performance Liquid Chromatography (RP-HPLC) showed that alterations were not similar in different amino acids and different species.

Originality/Value: Comparison content of amino acids in Caspian kutum, golden grey mullet, common carp, pick perch and common kilka in during storage period (6 months) at -24 °C showed that the frozen storage can alter the amount of amino acids in these fishes.

Keywords: Amino acids, chemical composition, fish species, Caspian Sea, Frozen storage, glutamic acid.

Graphical Abstract