Cooking from a Frozen State, Endpoint Temperature, and Post-Cookery Chilling Affect Internal and External Color and Cooking Losses in Ground Beef Patties.

To determine the effects of cooking state (frozen vs. thawed), endpoint temperature (65.5 vs. 73.9°C), and post-cookery chilling on color of ground beef patties, 85% coarse-ground beef was purchased and ground through a 9.5-mm plate, formed into 115-g patties (n = 240), and crust frozen before patties were vacuum packaged and stored at -10 °C. Packages were either thawed in a water bath for 2 h prior to cooking or cooked directly from frozen. Within each package, patties were weighed before being cooked to their assigned temperature and either allowed to cool at room temperature on paper plates or placed in a plastic baggie and submerged in an ice water bath. Patty temperature was monitored at 0, 1, 5, 10, 15, and 30 min post-cooking, and patties were reweighed to calculate cook loss percentage before external and internal instrumental color (L*, a*,and b*) was measured on each patty. Patties cooked from frozen, to 73.9°C, or cooled at room temperature had greater (P < 0.05) cooking losses than those cooked from a thawed state, to 65.5°C, or cooled in an ice bath, respectively. External color of patties cooked from a thawed state was lighter (greater L*; P < 0.05), more red (greater a*; P < 0.05), and more yellow (greater b*; P < 0.05) than those cooked from frozen. Moreover, L*, a*, and b* values were greater (P < 0.05) for the surface of patties cooked to 65.5 than 73.9°C, whereas L*, a*, and b* values were greater (P < 0.05) externally for patties cooled in an ice bath than those cooled at room temperature. Internally, patties cooked from frozen, cooked to 65.5°C, or cooled in an ice bath were lighter (P < 0.05) than those cooked from a thawed state, cooked to 73.9°C, or cooled at room temperature, respectively. Patties cooked to 65.5°C from a thawed state had the greatest (P < 0.05) internal a* and b* values, whereas frozen patties cooked to 73.9°C had the least red and yellow (P < 0.05) internal color. Moreover, thawed patties cooked and chilled in an ice bath were more red (P < 0.05) internally than other cooking state × cooling method combinations. It was expected that cooking to 65.5°C would result in redder internal cooked color, but persistent redness was also observed when patties were cooked from a thawed, rather than frozen, state and when cooled in an ice bath.