Effects of grilling on formation of cholesterol oxides in seafood products rich in polyunsaturated fatty acids

The effect of grilling on the formation of cholesterol oxides in marine fish processed foods was investigated by using commercially available boiled and dried anchovy as a model food rich in polyunsaturated fatty acids. Grillings at 220 degrees C for up to 6 min did not affect the level of peroxide values (PV) of the total lipids, however, further grilling for Lip to 15 min decreased the PV. The levels of 20:5n-3 and 22:6n-3 decreased significantly during the first 6 min of grilling. Typical cholesterol oxides accumulated in the boiled and dried anchovy were 7 beta-hydroxycholesterol (64.4 mu g/g on dry weight basis), 7-ketocholesterol (49.6 mu g/g), a-epoxide (22.3 mu g/g), beta-epoxide (61.9 mu g/g), cholestane triol (17.9 mu g/g) and 25-hydroxycholesterol (11.8 mu g/g). The levels of cholesterol oxides increased during grilling for the first 6 min, but significantly decreased on further grilling. During refrigerated storage at 5 degrees C of the sample previously grilled for 6 min at 220 degrees C, there was a correlation between the levels of cholesterol oxides and the PV. Both thermal decomposition of peroxides in polyunsaturated fatty acids and oxidation of cholesterol contributed to the oxidation of cholesterol during grilling of marine fish processed foods. Autoxidation of cholesterol was, however, slight during short-term refrigeration of this grilled food. (C) 1996 Academic Press Limited.