Cholesterol oxides in swedish foods and food ingredients: Butter and cheese

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Abstract
Fresh butter manufactured by batch or continuous technologies in Sweden contained only traces of 7‐ketocholesterol at the detection limit (0.1 ppm in the lipids) and no detectable levels of other common cholesterol oxides. Storage at 4°C for up to four mo caused an increase in the levels of the isomeric 5,6‐epoxycholestanols, the epimeric 7‐hydroxycholesterols, 20α‐hydroxycholesterol and 7‐ketocholesterol as revealed by Lipidex chromatography, TEAP‐Lipidex chromatography and GLC. Heating of butter for 10 min at the temperature interval 150–200°C under conditions similar to that in shallow‐pan kitchen frying caused a gradual increase in the total amount of cholesterol oxides from 0 to 2.5 ppm, while at 200°C the total amount of cholesterol oxides was 1.6 ppm. Butter heated five min at 200°C also had less cholesterol oxides than that heated at 190°C for 10 min. Industrially manufactured butter oil and cream oil contained only low levels of some of the cholesterol oxides. Further, three types of processed cheese (soft‐melted, hard‐melted and grated cheese) were investigated. The soft‐melted and the hard‐melted cheese types contained only traces of some of the oxides, while the grated cheese samples had 0.5–2.2 ppm of the total cholesterol oxides in the lipids.