EVALUATION OF OXIDATIVE-DEGRADATION OF CHOLESTEROL IN FOOD AND FOOD INGREDIENTS - IDENTIFICATION AND QUANTIFICATION OF CHOLESTEROL OXIDES

Cholesterol oxidation derivatives display a wide range of undesirable biological properties, and their presence in foodstuffs has raised much concern and attention. We have developed a method allowing quick, simple, and reliable quantification of cholesterol oxidative degradation in food. After lipid extraction and mild saponification, the unsaponifiable fractions from food samples are deposited on thin-layer chromatography plates and developed in hexane-ether (70:30); cholesterol oxides, migrating in a single band, are resolved from cholesterol, and both areas are scraped and analyzed as trimethylsilyl derivatives by capillary gas chromatography. 19-Hydroxycholesterol and cholestanol are used as internal standards for the quantification of cholesterol oxides and of cholesterol, respectively. We have shown that moderate heating of butter leads to the formation of cholesterol oxides, in amounts increasing with temperature, length of heating, and storage times. Cholesterol oxides are also present in commercial egg powder, egg mixes, and butter cookies or cakes. This method is a useful tool in assessing the quantitative importance of cholesterol oxides in the human diet and their formation during food processing or storing. © 1990, American Chemical Society. All rights reserved.