Effects of postmortem calcium chloride injection on meat quality traits of steaks from cattle fed with zilpaterol hydrochloride

Date
2011-08
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Abstract

Two experiments were conducted to determine the effects of zilpaterol hydrochloride supplementation (ZH; 6.8 g/ton on a 90% DM basis for 20 d) and calcium chloride injection (CaCl2 200 mM at 5% wt/wt into 72 h postmortem) on palatability traits (Exp. 1) and shelf-life (Exp. 2) of beef strip loin steaks. Select (USDA) strip loins were obtained from control (non-ZH-fed) and ZH-fed cattle carcasses (Exp. 1= 39; Exp. 2= 20) and right and left sides were selected alternatively to serve as a control (non-injected) or CaCl2-injected and immediately vacuum packaged and stored at 4 °C. Before injecting the subprimals (at 72 h postmortem), two initial steak were cut for proximate, sarcomere length and myofibrillar fragmentation index (MFI) analysis, and stored at -20 °C (for proximate) and -84 °C (for sarcomere length and MFI). For Exp. 1, at 7 d postmortem each strip loin was portioned into steaks, vacuum packaged and aged until 28 d for Warner-Bratzler shear force values (WBSF; 7, 14, 21, and 28 d) and trained sensory analysis (14 and 21 d), purge loss (at 7d) and myofibrillar fragmentation index (MFI; at 3, 7, 28 d). For Exp. 2, treatments were evaluated at 7, 14, and 21 d postmortem using color analysis (trained panelist and Hunter colorimeter), pH, steak purge loss, metmyoglobin reducing activity (MRA) and lipid oxidation (TBARS) on steaks which were PVC-overwrapped and placed in retail cabinets for three days at 3 °C. Results from Exp. 1 indicate both feeding groups and injection treatments diminished their WBSF values as days of postmortem aging were increased; however, WBSF values of ZH-fed steaks were greater (P < 0.05) than non-ZH-fed steaks during all postmortem aging periods. The CaCl2-injected steaks showed lower WBSF values (P < 0.05) than non-injected steaks. Furthermore, trained panelist gave a lower tenderness score to ZH-fed steaks than none-ZH-fed steaks at 14 d and 21 d; contrary, the injection of CaCl2 improved (P < 0.05) tenderness ratings and flavor intensity, compared with their non-injected cohorts at 21 d. Non-ZH-fed steaks and CaCl2-injected presented higher MFI values (P < 0.05) with respect to their controls steaks indicating a higher postmortem proteolysis activity. Sub-primals from ZH-fed and CaCl2-injected showed higher purge loss (P < 0.05). Results from Exp. 2 indicate ZH-fed steaks showed better initial color (lighter; P = 0.04) and color stability during retail display than non-ZH-fed (P = 0.02); though there were no differences in discoloration over aging (P = 0.06). Similarly, injected steaks were lighter on initial color score than non-injected steaks (P = 0.005). Nonetheless, at 14 d of aging, injected steaks started to be more discolored and less color stability (P = 0.0001) than those non-injected steaks. These results were in accordance with the instrumental color results. On MRA values, feeding groups were not different (P = 0.2); but injection treatments groups diminished their MRA percentage at 21 d postmortem aging, but injected steak with CaCl2 showed better reducing ability than non-injected steaks. Regard of initial pH values and steaks purge loss, there was not any difference between feeding groups; while CaCl2-injected steaks became acid; but was not affected steak purge loss between injection treatments (P < 0.05). Respect to TBARS values, non-ZH-fed and CaCl2-injected steaks increased lipid oxidation compared to counterpart steaks (P = 0.05). Overall, the postmortem injection of CaCl2 solution to either ZH-fed or non-ZH subprimals can improve beef steak tenderness; however, it can be detrimental to shelf-life when aging is extended beyond 14 d.

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Keywords
Beef, Calcium chloride, Shear force, Shelf-life, Tenderness, Zilpaterol hydrochloride
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