Vitamin losses during frozen storage of Liza aurata (Risso, 1810), Cyprinus carpio L. 1758, Clupeonella cultriventris caspia (Nordmann, 1840), Rutilus frisii kutum (Kamenskii, 1901) and Sander lucioperca (L., 1758)

The objective of this study was to determine the fat and water‐soluble vitamins contents (A, E, D, K, B₁, B₂, B₆, B₁₂, niacin, biotin, ascorbic, folic and pantethonic acids; in mg kg^?1 fresh weight) lost during frozen storage (?24°C) in time intervals of 0, 1, 2, 3 and 4 months. Studied species included: Liza aurata (golden grey mullet), Cyprinus carpio (common carp), Clupeonella cultriventris caspia (common kilka or sprat), Rutilus frisii kutum (Caspian kutum) and Sander lucioperca (pike perch). Results showed that A, D and K vitamin losses occurred in all samples during storage, but no statistically significant differences were observed. Vitamin E losses under frozen conditions were significant in common kilka, Caspian kutum and pike perch, however, not in golden grey mullet or common carp. A decrease in vitamin C was significant in all fish species, but there were no significant decreases in other water‐soluble vitamins (B₁, B₂, B₆, B₁₂, niacin, folic acid, pantothenic acid, biotin).