Qualitative characteristics of the Longissimus thoracic lumborum muscle of Nellore cattle during different maturation periods

Abstract

The effect of maturation on the physical (pH, color, weight loss on cooking, and shear force) and biological (microbiology, concerning mesophiles and psychrotrophiles, and sarcomere length) characteristics of the Longissimus thoracic lumborum muscle of adult Nellore cattle was assessed over four maturation periods (0, 7, 14, and 21 days) and two cut thicknesses (2.5 and 7.5 cm). Sixty-four Longissimus thoracic lumborum muscles from castrated Nellore males were purchased from Frigorífico Nutrial, Sergipe, Brazil. The study was performed using a completely randomized design, corresponding to a 2 x 4 factorial with eight replicates. The microbiological analysis revealed the sanitary conditions in which the samples were handled and stored, yielding counts of psychrotrophiles (2.18 x 105 CFU g-1) and mesophiles (2.4 x 105 CFU g-1) well below the critical deterioration level (106 CFU g-1). The pH (5.57) and the loss on cooking (24.13%) were not influenced by the evaluated variables (P > 0.05). The other evaluated parameters significantly varied as a function of the maturation period and the cut thickness (both P < 0.05). Meat luminosity varied with both the cut thickness and maturation period. The 2.5-cm-thick cut matured for 14 days and the 7.5-cm-thick cut matured for 21 days were darker than the 2.5-cm-thick cut matured for 7 days and the 7.5-cm-thick cut matured for 14 days, which were the lighter-colored samples (similar to non-matured meat). The intensity of the red color of the meat was different beginning after 14 days of maturation in the 7.5-cm cuts (P < 0.05) but differences were not evident in any of the 2.5-cm cuts (P > 0.05). Regarding the b* intensity, the 2.5-cm cut yielded a darker staining at time zero, which decreased with the maturation period. However, the 7.5-cm cut differed between the non-matured and the matured samples. Regarding the red and yellow color of the meat fat (a* and b*, respectively), a* displayed lighter intensity at 7 days of maturation or the 2.5-cm cut (P < 0.05), while the intensity of b* was similar from 7 days of maturation onwards for both cuts (P > 0.05). The shear force of the meat decreased to 4.49 kgf at 21 days of maturation. The sarcomere length varied for the 2.5-cm cut (P < 0.05) but not for the 7.5-cm cut, which remained constant (P > 0.05). Longissimus thoracic lumborum muscle of adult Nellore cattle should be matured as a larger, vacuum-packed cut for a minimum of 14 days to produce meat with improved quality.