Lipid Peroxidation and Phospholipid Hydrolysis in Fish Muscle Microsomes and Frozen Fish

The interaction between lipid peroxidation and phospholipase A 2 was investigated in fish muscle microsomes and frozen fish muscle. Lysophosphatidylcholine (LPC), a phospholipid hydrolysis product produced by the activity of phospholipase A 2 , was detected in the lipids extracted from microsomes peroxidized by incubation with NADH and ADP‐Fe 3+ . No detectable level of LPC was found in the microsomal lipids when NADH was withdrawn from the reaction mixture nor in the untreated microsomal lipids. LPC level in the lipids extracted from unheated microsomes was considerably higher than that from heat‐treated microsomes when both were peroxidized by incubation with ascorbate and Fe 3+ . Phospholipase A 2 was activated by either NADH‐dependent or ascorbate‐induced lipid peroxidation in vitro . The levels of lipid peroxidation in fish muscle were higher when fish were stored at higher frozen storage temperatures and so were the levels of LPC.