7-Ketocholesterol and 7-hydroxycholesterol in pork meat and its gravy thermally treated without additives and in the presence of onion and garlic

The effect of onion and garlic on the formation of two cholesterol oxidation products (COPs): 7-ketocholesterol and 7-hydroxycholesterol was evaluated by comparing their concentrations in meat and gravy samples obtained from three pork dishes prepared in the presence and absence of these flavourings. The concentration of these compounds in meat samples was between 82.4 and 1331.6 ng/g of cooked meat. Gravies contained lower amounts: from 18.3 to 45.6 ng/g of cooked meat. The addition of onion (30 g/100 g of meat) caused a decrease in 7-ketocholesterol and 7-hydroxycholesterol concentrations in all of the investigated pork dishes by 9.5–79%, whilst the addition of 15 g of garlic to 100 g of meat lowered the concentration by 17 to 88%. The greatest decrease was found in grilled minced chops. The quantitative assessment of 7-ketocholesterol and 7-hydroxycholesterol was carried out by thin-layer chromatography with densitometric detection.