Effect of vacuum‐packaging on the changes of Russian sturgeon muscle lipids during frozen storage

The changes in fatty acid composition, non‐polar (triglycerols) and polar lipids (phospholipids), total free fatty acids and total cholesterol of Russian sturgeon (Acipenser gueldenstaedtii) were studied during 360 days of storage at ?18°C. It was established that total neutral lipids and phospholipids content decreased and total free fatty acids concentration increased significantly during the frozen storage. Lower non‐polar and polar lipids content and higher free fatty acids concentration of vacuum‐packaged samples in comparison with air‐packaged samples were found. The changes in total cholesterol concentration and phospholipid classes of frozen stored sturgeon were not influenced by the frozen storage period and the type of packaging. It was established that the sturgeon polar lipids consisted mainly of phosphatidylcholine – 54.98 ± 0.85%, phosphatidylethanolamine – 28.42 ± 0.61%, and phosphatidylserine – 8.64 ± 0.45%. The increase of the total free fatty acids concentration was associated with the free n ? 3 PUFA accumulation as a result of hydrolysis of non‐polar and polar lipids. During the frozen storage DHA percentage of non‐polar lipids and phospholipids decreased approximately 3 and 1.75%, respectively. After 360 days of storage at ?18°C the n ? 3/n ? 6 PUFA ratio of total lipids decreased 4.9%.