Effect of aging times on tenderness of five muscles from carcass of Nellore young bulls
The objective of this study was to evaluate the aging effects on cooking losses (CKL) and Warner-Bratzler shear force (SF) of five muscles: biceps femoris (BF), gluteus medius (GM), longissimus (LD), semitendinosus (ST) and trapezius thoracis (TT) of Nellore young bulls fed in feedlot. Fourteen animals, with 15 mo of age were confined in individual pens with feeders and drinkers. The diet was consisted of 40% corn silage and 60% concentrate. After 60 days of feedlot, the animals were slaughtered and the carcasses were chilled to 0° C for 24 h. The muscles were removed, cut into steaks of 2.54 cm and individually vacuum packed and chilled to 0 - 2° C for one, seven and 14 days post-mortem. Steaks of 2.54 cm were removed and same samples were used to analysis of WBSF and CKL. The experiment was conducted according to a completely randomized design in a 3 × 5 factorial arrangement (3 aging times x 5 muscles) with 14 replicates. The data were analyzed by PROC MIXED procedure of the SAS and the Tukey test considering 5% probability. The interaction between muscles and aging times was significant (P<0.01) to CKL and SF. The greater value for CKL was observed in muscle ST (36.73%) on d seven, being that muscles BF (33.82%) and TT (35.68%) at d seven did not differ from the ST. Muscle LD (29.65%) on d seven, GM (28.64%, 29.60%) on d one and seven, BF (28.42%) on d one and TT (28.14%) at d 14 showed smallest values for CKL. The CKL at d one compared to d 14 was not different to muscles LD, ST and TT (P>0.05). ST muscle (5.56 kgf) showed the highest values of SF in all aging times (P<0.01). GM muscle (4.03 kgf) and BF (3.73 kgf) was not changed the SF at aging times. The LD muscle had the SH decreased with seven d of aged, not differing from d 14. The smallest SF was obtained for TT (2.96 kgf) in 14 d of aged. The ST muscle not changes the tenderness as an aging time up to 14 d. GM and BF muscles are considered tenderness on the d one.
Keywords: beef cattle, meat quality, shear force.