Date of Graduation

12-2016

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

Casey M. Owens-Hanning

Second Committee Member

Steven C. Seideman

Keywords

Biological sciences, Citric acid enhancement, Color, Dark-cutting beef

Abstract

In two experiments, dark-cutting (DC) beef strip loins were used to test the effects of citric acid-enhancement pH on visual and instrumental color of fresh and cooked steaks. Dark cutting and normal pH strip loin were injected to 111% of raw product weight with pH 3.5, 4.0, 4.5, or 5.0 solutions by mixing citric acid in either 0.05% phosphate solution or tap water (Exp 1), or with pH 2.0, 2.5, 3.0, and 3.5 solutions made by mixing citric acid in either a 0.5% orthophosphate solution (PO4) or a 0.5% tripolyphosphate solution (STP) (Exp2). Loin sections were cut into 2.5-cm-thick steaks and assigned to either simulated retail display for five days or cooked. Post-enhancement pH of enhanced DC steaks did not (P ≥ 0.180) differ from that of non-enhanced DC steaks, regardless of solution pH (Exp 1); however, decreased linearly (P < 0.001) as solution pH decreased from 3.5 to 2.0, and the proportions of free and bound moisture of DC steaks enhanced with pH 2.5 solution were comparable (P ≥ 0.141) to that of CH (Exp 2). On d 1 and 3 of display, fresh color scores of enhanced DC steaks were greater (P < 0.001) than untreated DC (Exp 1), but color scores of CH steaks were greater (P < 0.001) than enhanced DC steaks (Exp 1 and 2). Conversely, in experiment 1, degree of doneness scores increased linearly (indicating greater doneness; P = 0.032) as solution pH increased from 3.5 to 5.0, and steaks enhanced with pH 4.0 and 4.5 solutions received lower (more red; quadratic, P = 0.012) cooked color scores than non-enhanced DC steaks, but neither score was comparable (P < 0.001) to those for CH steaks. While in experiment 2 enhancing DC sections with pH 2.5 solutions produced cooked color and degree of doneness scores that were similar (P ≥ 0.113) to non-enhanced CH steaks. Thus, enhancement with pH 2.5 citric acid solutions can effectively eliminate the persistent red cooked color typically associated with DC beef; however, citric acid enhancement failed to improve the fresh color of DC beef comparable to that of CH beef.

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