Diffusion of lipolysis and lipid oxidation in fried and oven-baked mackerel

The processes of lipolysis and lipid oxidation during frying, oven-baking and subsequent storage under refrigeration of mackerel previously stored at −18 °C for six months were studied. The lipids and fatty acid content of the fish were characterized. The acid number, peroxide number, thiobarbituric acid reactive substances, and the conjugated diens and triens were traced dynamically. It was observed that the defrosted mackerel was characterized by advanced stage lipolysis and accumulated lipid oxidation primary products. During the frying and oven-baking of the defrosted mackerel, the lipolysis spread throughout the fish. The hydroperoxide content decreased 4.7–4.9 times and mostly secondary derivatives of lipid oxidation accumulated. During the process of frying the mackerel, the lipid oxidation chain was widespread. More conjugated triens and fewer conjugated diens were formed, and the polyene indices increased. In contrast, oven-baking did not cause changes to the conjugated lipids, and the polyene indices decreased more than 60%