TEXTURAL CHANGES IN GROUND BEEF PATTIES DURING COOKING

Ground beef patties were cooked in a convection oven or on a flat-top electric grill using a 3 x 5 factorial arrangement of treatments in a split plot design (rep = 3). Each cook method was compared at three temperatures (121, 148 and 177(DEGREES)C). Five internal patty temperatures (10, 25, 40, 55 and 70(DEGREES)C) were evaluated. Meat blocks were adjusted to 18% fat prior to final grinding and patty formation. Data were collected on cook yield, dimension alterations, and color score. Laboratory analyses consisted of proximate composition, pH, water-holding capacity, Instron textural measurements, protein solubility and hydroxyproline content. As cooking time and internal patty temperature increased, patty yield significantly (P < 0.01) decreased for both grill and oven cooked patties. Higher cooking temperatures result in greater (P < 0.01) yields for both methods of cooking. Diameter was less (P < 0.05) for patties grilled at 177(DEGREES)C than at lower grill temperatures and greater (P < 0.05) for oven cooked patties at 177(DEGREES)C than at lower oven temperatures. Protein solubility decreased (P < 0.01) as internal patty temperature increased. Myofibrillar proteins heated at low temperatures, were less soluble (P < 0.05) at 55(DEGREES)C than at high temperatures. Patties cooked at 121(DEGREES)C had less (P < 0.01) expressible moisture than patties cooked at higher temperatures. Oven cooked patties exhibited an increase (P < 0.01) in expressible moisture. Low oven temperatures (121(DEGREES)C) yielded greater (P < 0.05) expressible moisture than higher oven temperatures. Oven cooked patties at low temperature (121(DEGREES)C) exhibited less springiness than at higher temperatures. Cohesiveness in grilled and oven cooked patties increased (P < 0.05) as internal temperature increased except for patties grilled at 177(DEGREES)C where no change was shown. No difference in Kramer peak height or compression hardness were observed. Differences exist in the time-temperature relationship when different methods of cooking are used. This affects the extent of protein denaturation and the subsequent effects on water-holding capacity, yield and texture. Patties are more tender and juicy when cooked at high oven temperatures while tests on grilled patties indicate a more desirable product at lower cooking temperatures.