Lipids of Cod Muscle and the Effect of Frozen Storage

Abstract

The lipid composition of fresh and frozen cod (Gadus morhua) muscle was studied using silicic acid chromatography. Dark cod muscle contained about three times as much total lipid as white muscle but the composition was quite similar. The most significant difference was that the dark tissue lipid contained more esterified cholesterol and less phosphatidyl choline. Frozen storage for up to 9 months at −12 C showed that the free fatty acid content increased from 5 to 326 mg/100 g tissue due to the hydrolysis of phosphatidyl ethanolamine and phosphatidyl choline. Other phospholipids were not hydrolyzed. Phosphatidyl ethanolamine hydrolysis ceased after storage for 4 months, whereas hydrolysis of phosphatidyl choline continued thereafter at a slower rate. After 9 months, the phospholipid content of the total lipid had dropped from 84 to 32% and only 13% of the original phosphatidyl ethanolamine and phosphatidyl choline remained unhydrolyzed.