In this study we are going to use 24 Nellores bullocks 32-month age divided in two treatments: (T1) animals (n = 12) with a subcutaneous back fat (BF) measured in the Longissimus dorsi (L. dorsi) muscle at 12th - 13th rib below 3.0mm and (T2) animals (n = 12) with BF over 6.00mm. Animals will be house in feedlot around 90 to 100 days and slaughter with weight exceeding 500kg. Animals with similar age, slaughter weight and feedlot time are going to be used. Just after the slaughter, the carcasses are going to be cooled by 24 to 48 hours and then we are going to take four samples of L. dorsi muscle from 13th rib in the cranial direction of left half carcass, with thickness of 2.5 cm. The samples are going to be vacuum packed and kept for 21 days of maturation in 0 to 2ºC. The tenderness objective analysis is going to be done by determination of pH and shear force, using a Warner Bratzler probe and sensorial analysis, in 21 days maturation samples. In another sample are going to be taken aliquots of L. dorsi every three days during the 21 days maturation period to determine the degree of muscle tissue proteolysis. The quantitative determination of proteolysis is going to be done by the determination of myofibrillar fragmentation index (MFI). Tests of shelf life and objective determination of instrumental meat color are going to be performed at the same time. In the end, the results are going to be compared between individuals of different treatments and meat quality between individuals of the same group.
News published in Agência FAPESP Newsletter about the scholarship: