Date of Graduation

12-2013

Document Type

Thesis

Degree Name

Master of Science in Animal Science (MS)

Degree Level

Graduate

Department

Animal Science

Advisor/Mentor

Jason K. Apple

Committee Member

Steve Seideman

Second Committee Member

Casey Owens

Keywords

Biological sciences, Bull trim, Cooked color, Ground beef, Mature bull, Precooked, Reheated

Abstract

Two experiments were conducted to compare the color and cooked attributes of steaks and ground beef produced from mature bulls. Beef from mature bulls was used to test the effects of lactic acid (LA) enhancement solution pH (2.5, 3.0, or 3.5; B25, B30, B35, respectively) on fresh (5 d of display) and cooked color and tenderness of strip loin steaks (Exp. 1) and the effect of high pH trim on precooked ground beef patties (Exp. 2). In experiment 1, mature bull strip steaks were enhanced to 111% with a LA, sodium bicarbonate, and tap water solution, in comparison to USDA Select strip loin steaks (Sel). On d 0 of display, Sel steaks were redder (higher a*) than B0 steaks, but, on d 4 and d 5, Sel steaks were less red than B0, B25, B30, and B35 (treatment × time, P < 0.01). Steaks from B0 were least (P < 0.05) yellow (lowest b*), and Sel steaks were more (P < 0.05) yellow than B25 and B30 steaks. Instrumental cooked color was similar (P ≤ 0.08) among the treatments; however, Sel and B35 steaks received greater (P < 0.05) visual cooked color scores than B0, whereas Sel, B25, and B35 were rated higher (P < 0.05) for internal doneness than B0. Sel steaks had lower (P < 0.05) WBSF, values than steaks from bull strip loins, regardless of LA enhancement solution pH. In experiment 2, ground beef patties were formulated from mature bull necks, USDA Select peeled knuckles, and 50:50 beef trimmings to a target lean to fat ratio 85:15. Internal cooked color was lighter (P < 0.001) in patties reheated on the charbroiler than in the microwave; otherwise, reheating method did not (P ≥ 0.406) affect the internal color of reheated patties. Conversely, internal color of reheated patties remained redder (greater a*values and lower HA) as the percentage of bull trim increased from 0 to 100% of the lean portion (linear, P < 0.001). Potentially, steaks or products formulated from mature bull beef could lead to consumer discrimination resulting from an undercooked appearance.

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