Abstract

Fish and fishery products can undergo undesirable changes during frozen storage and deterioration may limit the storage time. These changes result from lipid oxidation and enzymatic hydrolysis of lipid and protein. Approach: The quality changes (total lipids, primary and secondary lipid oxidation products as well as lipid and protein hydrolysis) in Caspian kutum, golden grey mullet, common carp, pike perch, and common kilka during frozen storage (-24 ^°C and a 6 month period) were examined. The statistical result showed that among all of fish species the highest lipid content belonged to the fresh samples and the least value was recorded for those stored for 6 months. The damage indices tested such as peroxide value (PV), thiobarbituric acid (TBA), free fatty acid (FFA) and total volatile nitrogen (TVN) during frozen storage revealed significant (P ≤0.01) correlation with the storage time. The changes in lipid oxidation indices (PV and TBA) and enzymatic deterioration indices (FFA and TVN) show that all the fish species are susceptible to significant change during the frozen storage, especially if the storage time is long and can be stored for five months in a frozen state with low undesirable changes of lipid and protein quality.

Keywords: Caspian sea, correlation analysis, enzymatic deterioration indices, enzymatic hydrolysis, free fatty acid, fish species, frozen storage, oxidation products, total volatile nitrogen.