Formation of Cholesterol Oxides in Marine Fish Products Induced by Grilling

Abstract

The effect of grilling of marine fish products on the oxidation of cholesterol was investigated by using seveyral kinds of salted-dried and boiled-dried marine fish products. The contents of total lipids decreased slightly in most of samples. However, no remarkable differences in the contents of residual cholesterol were observed before and after grilling. In the marine fish products rich in eicosapentaenoicacid (EPA) such as dried products made from Japanese whiting, squid buccal mass and northern cod, the decrease in the levels of polyunsaturated fatty acids (PUFA) after grilling was fairly large. Contrary to this, in the products withthe lower levels of EPA such as salted-dried Pacific round herring and fermented-dried horse mackerel, the decrease in the level of PUFA was relatively small. 7β-hydrox-ycholesterol, 7-ketocholesterol, α-epoxide, β-epoxide, cholestane triol, and 25-hydroxycholesterol were found as cholesterol oxides in the samples used in the present study. For the fatty fish products such as the salted-dried Pacific round herring and the salted-dried Japanese whiting, the total amounts of cholesterol oxides increased after grilling. Contrary to this, no remarkable changes were observed in the processed foods produced from lean fish.