Pork and sardine were fried in soybean oil and the amounts of cholesterol that migrated to the frying oil from pork and sardine were determined by preparative thin-layer chromatography and gas chromatography. A model experiment on the decomposition of tocopherol in oil was carried out and the influence of cholesterol, pork fat, and sardine oil on oil deterioration was assessed. Soybean oils containing cholesterol, pork fat, and sardine oil were heated in glass tubes at 180°C.
Increase in cholesterol content in frying oil was observed during frying. Addition of cholesterol failed to prevent the deterioration of oil. The sardine oil accelerated the deterioration of oil and decomposition of tocopherol in oil.