|Van Laack, Henriette|
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 28, 1995
Publication Date: N/A
Interpretive Summary: Foodborne illnesses associated with the bacteria E. coli O157:H7 and inadequately cooked ground beef patties have highlighted the need for a reliable indicator of thorough cooking. People lacking a meat thermometer have been advised to cook patties until the center is no longer pink, an event presumed to occur at 71 deg C (160 deg F). In the present study, we evaluated the cooked color of 17 patty formulations, 16 with fat levels < 12 percent and one with 19 percent fat. Eight of the products remained red at 71 deg C. This redness was due to incomplete denaturation of the meat pigment myoglobin (Mb). Although there was a relationship between meat pH and cooked color, other unknown factors seem to interfere with Mb denaturation. When products were reanalyzed after 1 yr storage at -27 deg C, 16 of the 17 products were red or pink when cooked to 71 deg C. This increase in redness could not be explained. Cooking to internal temperatures between 81 and 87 deg C (178-189 deg F) was necessary for complete disappearance of the red/pink color. Such high temperatures may be expected to have a negative impact on eating quality. Premature browning, e.g., the phenomenon that a product looks well-done at temperatures lower than 71 deg C, occurred in one product. Cooked patty color is an inaccurate indicator of cooked temperature. Consumers should use an accurate temperature measuring device to insure safety.
Technical Abstract: Seventeen patty formulations, 16 with reduced fat levels (< 12 percent) and one with 19 percent fat, were cooked to an internal temperature of 71 deg C. Red cooked color occurred in eight of the products and was due to incomplete denaturation of myoglobin. Although there was some relation between pH and cooked color, other factors seem to be involved. Products were reanalyzed after 1 year storage at -27 deg C. At that time, 16 products were red/pink when cooked to 71 deg C. This increase in redness after frozen storage could not be explained. Cooking to internal temperatures between 81 and 87 deg C was necessary for complete disappearance of the red/pink color. Premature browning, e.g., the phenomenon that a product looks well-done at temperatures lower than 71 deg C, occurred in one formulation.