CHANGES IN MOLECULAR SPECIES COMPOSITIONS OF GLYCEROPHOSPHOLIPIDS IN THE ADDUCTOR MUSCLE OF THE GIANT EZO SCALLOP PATINOPECTEN YESSOENSIS DURING FROZEN STORAGE

Changes in lipid components, particularly glycerophospholipids, in the adducto; muscle of giant ezo scallop during storage at −20C were investigated. During storage, the contents of total lipids (TL) and polar lipids (PL) decreased, but that of nonpolar lipids increased. Thiobarbituric acid reactive substances and peroxide values of the TL increased with duration of storage. Glycerylphosphorylcholine (GPC) and glycerylphosphrylethanolamine (GPE) decomposed considerably during storage, and decreased by 50% and 15% of the initial content, while lyso-PC (LPC) and free fatty acids (FFA) increased, respectively. The percentages of polyunsaturated fatty acids (PUFAs) such as 20:5n-3 and 22:6n-3 in the TL and PL during storage decreased, however, those of the PUPAs in the NL increased. Diacylglycerylphosphorylcholine (diacyl-GPC) and diacylglycerylophosphorylethanolamine (diacyl-GPE), major components in the GPC and GPE subclasses, showed a marked decrease with duration of storage. Particularly, diacyl-GPC decreased by 68% of the initial contents of the PL. In the alkenylacyl-GPE and diacyl-GPC, the percentages of the molecular species having longer hydrocarbon chains on the sn-l positions of glycerol moieties decreased at