The objective in this study was to evaluate meat quality of longissimus thoracisi muscle during ageing. Samples from 22 Nelore bovines and 22 Red Norte males at 24 months of age were collected at 24 hours post mortem, kept at 2ºC and analyzed on days 1, 7, 14 and 21. The animals were finished in confinement (112 days) with corn silage (50%) and concentrate (50%) ad libitum. Values of final pH, cooking loss, moisture, protein, fat and ash were similar among samples of Nelore and Red Norte animals. The red level (a*) and the yellow intensity (b*) were similar among meats of the two genetic groups, however, luminosity (L*) was higher in samples of Red Norte animals. Ageing significantly affected luminosity, level of red and yellow, chroma, tone angle (H*) and subjective perception of the color (ΔE), thus, the most important changes in color occurred from 7 to 14 days. Shear force in the meat of Red Norte animals was approximately 0.9 kg lower than in Nelore animals. Ageing influenced shear force during maturation with a reduction of 1.09 kg, 0.21 kg and 0.56 kg in the periods from 1 to 7, from 7 to 14 and from 14 to 21 days, respectively. The myofibrillar fragmentation index was higher in the meat of Red Norte animals and in samples aged for 21 days. The meat of Red Norte animals showed more tenderness and luminosity. Ageing improves the tenderness of meat because it reduces shear force, however, it changes the color, whose most important changes take place from 7 to 14 days. The choice of the most appropriate ageing time for beef depends on which attribute will be considered.
color; cooking loss; miofibrilar fragmentation index; pH; protein; shear force