Cholesterol oxides in Swedish food and food ingredients: Lard and bacon

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Abstract
Lard samples, manufactured from adipose tissue, were found to contain traces and/or quantifiable concentrations of certain cholesterol oxides, viz., 5α‐, 6α‐epoxycholestanol, 7‐ketocholesterol, 7α‐hydroxycholesterol, 20α‐hydroxycholesterol and 25‐hydroxycholesterol at the detection limit 0.1 ppm. The influence of steam refining and chemical refining on the cholesterol oxide levels in a few of the crude lard samples was investigated. The analyses showed that these processes had no appreciable effect on the concentrations of cholesterol oxides, compared with the controls. Analysis of cold‐stored consumer packages of lard (2‐mo old up to 18‐mo old samples) indicated that there were no differences in the pattern of cholesterol oxides. On the other hand, storage of refined superior and regular grade lard samples at 50°C for up to 18 days caused only a slight increase in the levels of the isomeric 5,6‐epoxycholestanols. Raw bacon, bacon fried at 170°C for 10 and 20 min and bacon dripping were analyzed. The analyses showed that quantifiable levels of 5α‐,6α‐epoxycholestanol, C‐7 oxidation derivatives of cholesterol and 25‐hydroxycholesterol could be detected only in the fried rind. A substantial amount (about 0.5 ppm) of a cholesterol metabolite was detected in the lard samples. Its identification as 7α‐hydroxycholest‐4‐en‐3‐one was based on the comparison of RRT value and mass spectral information, as TMS‐ether, to that of synthetic 7α‐hydroxycholest‐4‐en‐3‐one.