Effect of cooking method on carnosine and its homologues, pentosidine and thiobarbituric acid-reactive substance contents in beef and turkey meat.

Commercial samples of beef and turkey meat were prepared by commonly used cooking methods with standard cooking times: (1) broiled at 200°C for 10min, (2) broiled at a medium temperature (140°C) for 10min, (3) cooked by microwave (MW) for 3min and then grilled (MW/grill) for 7min, (4) cooked in a domestic microwave oven for 10min, and (5) boiled in water for 10min. The raw and cooked meats were then analysed to determine the carnosine, anserine, homocarnosine, pentosidine, and thiobarbituric acid-reactive substance (TBARS) contents. It was observed that boiling beef caused a loss of approximately 50% of the carnosine, probably because of the high water solubility of carnosine and its homologues; cooking by microwave caused a medium loss of the anti-oxidants of approximately 20%; cooking by MW/grill led to a reduction in carnosine of approximately 10%. As far as the anserine and homocarnosine contents were concerned, a greater loss was observed for the boiling method (approximately 70%) while, for the other cooking methods, the value ranged from 30% to 70%. The data oscillate more for the turkey meat: the minimum carnosine decrease was observed in the cases of MW/grill and broiling at high temperature (25%). Analogously, the anserine and homocarnosine contents decreased slightly in the case of MW/grill and broiling at a high temperature (2-7%) and by 10-30% in the other cases. No analysed meat sample showed any traces of pentosidine above the instrumental determination limits. The cooked beef showed an increased TBARS value compared to the raw meat, and the highest values were found when the beef was broiled at a high temperature, cooked by microwave or boiled in water. The TBARS value of the turkey meat decreased for all the cooking methods in comparison to the TBARS value of the fresh meat.