CHOLESTEROL OXIDATION IN MEAT-PRODUCTS DURING COOKING AND FROZEN STORAGE

The effect of cooking time and method and freezer storage on the oxidation of cholesterol in muscle food such as beef, veal, and pork was studied by capillary gas chromatography. Cholesterol was oxidized in meat samples during household cooking, and the rate of oxidation differed according to the cooking time and cooking temperature. The range of total amount of oxysterols produced varied from 0.3 to 0.8% cholesterol. There was a greater increase in primary oxysterols (oxidized on carbon 7 or side chain) than in secondary derivatives (cholesterol epoxides and cholestanetriol) during cooking of fresh meat. All oxidized derivatives increased progressively in meat samples stored for 3 months at -20-degrees-C in both raw and cooked meat. The sum of oxysterols doubled in the commercially available precooked frozen meals after 3 months at -20-degrees-C with the secondary oxysterols showing the highest increase. We may assume from our observations that the daily dietary intake of oxysterols derived from meat source must probably include between 0.5 and 1% total cholesterol.