Abstract
The current Venezuelan beef carcass classification and grading system provide a mean for sorting carcasses into 5 quality grades, designated as AA, A, B, C, and D, in a descending order of expected eating quality. Brahman cull heifers and cows (n = 21 and 18, respectively) and entire males (bulls; n = 17) were finished on native savannah grass, slaughtered and graded by the official standards to compare carcass traits, cutability, cookery traits, and palatability characteristics between graded (A, B, or C) female classes and bulls. The B-graded bulls dressed heavier carcasses, with a more convex leg muscle profile and larger ribeye area (P < 0.05) followed by C-graded cows in carcass weight and ribeye area (P < 0.05). Marbling score described as “Slight” did not differ among carcass grades (P > 0.05). The B-graded bulls had the highest proportion of total bone-in and boneless cuts (P < 0.05); however, carcasses from females surpassed (P < 0.05) or did not differ (P > 0.05) from bull carcasses in fabrication yield values for 16 of 18 individual cuts. Cooking loss (%) did not vary with carcass grades (P > 0.05). Cooked meats from A/B-graded heifers and C-graded cows had lower shear force values, were rated as more tender and flavorful (P < 0.05), and exhibited a higher proportion of tender steaks (with shear force < 4.09 kg) than B-graded bull counterparts (P < 0.05). Advantageous palatability traits of C-graded cows and A/B-graded heifers fattened on pasture can be used in developing and marketing new value-added products.
Highlights
The characteristic bright cherry-red color of beef is the primary determinant that influences consumers’ decision to purchase meat (Mancini and Hunt, 2005)
0 to 1,600 μM of oxygen was allowed to bind with myoglobin at pH 5.6, 6.4, or 7.4
The homology-based myoglobin modeling indicates that the porcine myoglobin has a shorter distance between distal histidine and heme than bovine (Table 2 and Fig. 2)
Summary
The characteristic bright cherry-red color of beef is the primary determinant that influences consumers’ decision to purchase meat (Mancini and Hunt, 2005). Myoglobin is the protein primarily responsible for meat color, and it can exist in 3 different forms; namely deoxy-, oxy-, or metmyoglobin. The iron present in the heme has 6 coordination sites, of which, 4 are occupied by protoporphyrin ring, fifth by His-93 residue, and the sixth site by ligands such as oxygen, water, or carbon monoxide. The ligand attached to the central heme and the valence state of iron determines. Heme is in the ferrous state and no ligand is attached. Oxygen binding to ferrous heme results in the formation of oxymyoglobin. Oxidation of oxy- and deoxymyoglobin leads to metmyoglobin formation (AMSA, 2012; Jayasingh et al, 2001). Processes that can promote oxymyoglobin formation (oxygenation) and metmyoglobin reducing activity can influence meat color
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