Effect of accumulated free fatty acid on reduction of salt soluble protein of cod flesh during frozen storage.

The effect of the free fatty acid (FFA) released from phospholipids by the action of lipolytic enzymes on protein denaturation of fish flesh during frozen storage was studied. The FFA content and the salt soluble protein extractability of commercially available frozen “surimi” were determined. The results obtained suggest that there may be a definite negative interrelation between the FFA content and the salt soluble protein extractability.Minced cod flesh was washed thoroughly with cold water, mixed with phospholipase A2 specimen, and stored at -16°C for 24 weeks. The FFA content incerased rapidly accompanied with marked decreases of polar lipids due to added phospholipase A2 during storage for first one week. The content of salt soluble protein increased during storage for up to 1-2 weeks and then decreased gradually to the minimum amount after storage for 6 weeks. The length of storage period up to the time when the content of salt soluble protein reached the minimum amount was shorter in the test-sample than in the control-sample without added phospholipase A2.From these results, it is presumed that the FFA released from phospholipids by the action of added phospholipase A2 induces the reduction of salt soluble protein extractability, though some oxidation products of lipids may contribute to the reduction of salt soluble protein extractability to some extent