Differential lipid damage in various muscle zones of frozen hake (Merluccius merluccius)

A comparison of the lipid damage produced in different hake zones was carri ed out during frozen storage at -11 and -18 degrees C. Three light muscle z ones and the dark muscle were considered. Lipid oxidation [conjugated diene s; thiobarbituric acid index (TBA-i); fluorescence formation] and hydrolysi s (free fatty acids, FFA) were determined. The most predominant lipid damag e in all zones was hydrolysis, at the end of storage reaching values of abo ut 40% (for the light muscle zones) and 12% (for the dark muscle) of the to tal lipids at -11 degrees C. Significant (P<0.05) correlation Value (r = 0. 67-0.85) relationships between the frozen storage time and the FFA content were obtained for the four muscle zones at both temperatures. A comparison of the regression lines slopes in the different zones showed that a lower ( P<0.05) lipolitic activity was produced in the dark muscle compared to the three light zones at both temperatures. A low lipid oxidation development w as produced in the three light muscle parts, so that no significant differe nces between them could be assessed. However, the dark muscle showed a high er oxidation development (TBA-i and fluorescence formation) as a result of a higher lipid content and the presence of prooxidant constituents.