| The overall objective of the study was to compare the quality and storage stability of restructured beef from mature cull cows. Intact longissimus muscle and forequarter trimmings were obtained from postrigor carcasses of nine cows, equally representing three animal age groups (2--4, 6--8 and 10--12 yr). Tenderness and proteolytic changes were examined in intact beef after 1, 3 and 10 d of storage at 2°C. Trimmings were formulated with propyl gallate, alone or in combination with a beefy flavoring agent, into restructured steaks to enhance palatability and storage stability. Formulation treatments included: (1) control (1.5% NaCl + 0.25% sodium tripolyphosphate); (2) antioxidant (control + 0.02% propyl gallate); and (3) antioxidant + beefy flavoring (control + 0.02% propyl gallate + 0.75% beefy flavoring). Raw and fully cooked steaks were stored aerobically and in vacuum, respectively, or 0, 1, 3 or 6 mo at -29°C prior to physicochemical and sensory evaluation.; Postmortem myofibrillar protein degradation was more rapid and extensive in beef from less mature carcasses, but it did not affect the muscle shear value. Intact muscle tenderness was inversely related (P < 0.05) to maturity, but differences were eliminated through restructuring. Propyl gallate retarded (P < 0.05) lipid oxidation and rancidity development in raw steaks stored aerobically, but provided minimal (P > 0.05) added protection in fully cooked steaks that were vacuum packaged. The beefy flavoring agent masked rancid and off-flavors typical of mature, grass-fed cattle, intensified beefy flavor, and improved tenderness, juiciness, cooking yield, and overall acceptability of cooked restructured steaks. Palatability, cooking yield and oxidative stability decreased (P < 0.05) in raw and fully cooked steaks during storage, notably beyond 3 mo. Thus, beef from mature cows can be considered a tender-homogeneous meat block when restructured into steaks under a similar protocol, and the inclusion of a beefy flavoring agent when combined with propyl gallate or vacuum packaging provides an effective means to improve the product overall quality and frozen storage stability. |
