Effects of Various Cooking and Re-heating Methods on Cholesterol Oxidation Products of Beef Loin

The objective of this study was to define the effects of various cooking and re-heating methods (pan roasting, steaming, oven grilling and micro-waving) on the cholesterol and formation of cholesterol oxidation products in beef loin during storage at 4°C. Raw samples showed lower total cholesterol content than cooked products sampled during storage for 6 d. The following cholesterol oxidation products (COPs) were separated by gas chromatography: 7β-hydroxy cholesterol, 20α-hydroxy cholesterol, 25hydroxy cholesterol, cholestane-3β, 5α, 6β triol (triol), α-epoxide and 7-ketocholesterol. Total amounts of COPs/cholesterol at 0 d were 0.74, 0.63, 0.76, 1.23 and 0.83% for the raw sample, pan roasting, steaming, oven grilling and micro waving methods, respectively. After 6 d storage almost of the samples had higher content of total COPs than at 0 and 3 d; the lowest (0.55%) COPs was found in the steaming cooking and re-heating method. The highest (5.96%) of COPs was found in the pan roasting cooking and re-heating method after 6 d storage. In conclusion, the concentration of total cholesterol and cholesterol oxidation of beef loin were increased as a consequence of cooking and re-heating methods. Steaming and micro-waving methods showed the lowest of cholesterol oxidation products under refrigerated storage for 6 d. However, each cooking and re-heating method had its own distinctive cooking effects. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 5 : 756-762)