|Van Laack, Riette|
Submitted to: Journal of Muscle Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 31, 1996
Publication Date: N/A
Interpretive Summary: Typically, the internal color of cooked meat changes from red to pink to grey as endpoint temperatures increase. In the light of foodborne illnesses associated with the bacteria E. coli O157:H7 and inadequately cooked ground beef, consumers have been advised to cook patties until the center is no longer pink; an event presumed to occur at 160 deg F. Products with a high pH have been shown to retain a reddish color despite thorough cooking. In a previous study, we found that cooked patties containing Lean Finely Textured Beef (LFTB) had a well-done color despite a high pH. LFTB, is derived from beef fatty trimmings by means of a unique low temperature separation process. In the present study, we evaluated the effects of inclusion of LFTB on cooked color of low fat (10%) patties prepared from meat with a normal pH (N) or with a high pH (DC). Patties were cooked to an internal temperature of 160 deg F, or until patties were "well-done". A higher LFTB content in N-patties resulted in a more red cooked color. In DC patties, a higher LFTB content resulted in a less red cooked color with a more well-done appearance. The less red color was associated with increased denaturation of the meat pigment, myoglobin. To appear well-done, DC patties without LFTB had to be cooked to 192 deg F, whereas DC patties with 75% LFTB had to be cooked to 181 deg F. Cooked patty color is an inaccurate indicator of cooked temperature. Different raw materials will affect the cooked color. An accurate temperature measuring device is the method of choice to insure safety.
Technical Abstract: Color of cooked patties prepared from pH=5.7 (normal = N) or pH=6.2 (dark cutting = DC) beef and either 0, 25, 50 or 75% Lean Finely Textured Beef (LFTB) was evaluated. Patties were cooked to 68.3C, 71C, or until >75% of the patties were "well-done". Since LFTB had a pH of 6.2, increasing the content of LFTB in N patties resulted in a higher pH. Inclusion of LFTB in N patties resulted in higher a*-values, but did not affect either visual color scores or myoglobin (Mb) denaturation. Inclusion of LFTB in DC patties did not affect pH. A higher LFTB content resulted in lower a*-values, higher hue, a more well-done visual color and increased Mb denaturation. To appear well-done, DC patties without LFTB had to be cooked to 89C, whereas DC patties with 75% LFTB had to be cooked to 83C. Possibly, conditions during production of LFTB are responsible for the increased heat sensitivity of Mb from LFTB.