宰后盆骨吊挂方式及成熟时间对黄牛牛肉品质的影响

Effect of pelvic suspension and aging time on meat quality of Chinese yellow cattle

为研究宰后盆骨吊挂技术对中国黄牛牛肉品质的影响,该试验选取12头品种、年龄和活体质量相近的鲁西黄牛杂交西门塔尔牛,屠宰后左半胴体采用跟腱吊挂,右半胴体采用盆骨吊挂。分别成熟1、4、7、14和21 d后测定pH值、汁液损失率、蒸煮损失率、肉色、剪切力、肌节长度等指标。研究发现,和传统跟腱吊挂相比,盆骨吊挂能够显著降低肉牛背最长肌宰后7 d之内的剪切力值,并使背最长肌宰后14 d的剪切力值50.71 N低于跟腱吊挂宰后21d的剪切力值58.48 N,此外,盆骨吊挂可以显著增加肌节长度,增值为0.44μm,使牛肉的汁液损失由5.44%降低到4.29%。因此,盆骨吊挂技术具有工业化推广的价值,可以达到快速提高牛肉嫩度,减少牛肉成熟时间的目的。

Beef toughness and variation in tenderness are two major problems that the meat industry has to face, so it has become necessary to solve these problems through the use of technology. One of these techniques is pelvic suspension （PS）, in which carcasses are hung from the obturator foramen of the pelvic bone or from the pelvic ligament during the period between slaughter and the commencement of rigor. Achilles suspension is a traditional method to hang carcasses. This method cannot restrict myofibril shortening of the LL during rigor. However, pelvic suspension can reduce myofibril shortening. In pelvic suspension, the hind leg is perpendicular to the vertebral column;thus, the vertebral column and the muscles around the vertebral column are straightened and slightly stretched compared to Achilles tendon suspension. However, little information is available about the effects of suspension methods on beef quality in Chinese yellow cattle. So, objectives of the present study were to evaluate the effects of suspension methods on quality traits of Chinese yellow cattle M. Longissimus lumborum （LL）. Twelve Chinese yellow cattle of the same breed （Luxi ＆#215; Simmental）, age, and mean live weights were selected on the slaughter line from a commercial feedlot. The cattle had a rest for at least 12 h before stunning and were slaughtered by the Halal method. The carcasses hanging method was changed at the end of the slaughter line within 45 min postmortem;the right sides of the carcasses were re-hung from the pelvic bone obturator foramen, while the left sides remained hung by the achilles tendon suspension （AS）. All the carcasses were pushed into the chilling tunnel （air temperature （2 ＆#177; 2）℃） after pH45min was measured. At 24 h postmortem, the ultimate pH value of LL was measured. The LL with suitable pH values （pH value 5.3-5.8） between the 12th thoracic and the last lumbar vertebrae was removed from each carcass. LL muscles were aged for 1, 4, 7, 14 and 21 days. After that, samples were stored at-20℃ until evaluated for pH, purge loss, cooking loss, color, Warner-Bratzler Shear force, and sarcomere length. It indicated that pelvic suspension significantly decreased the WBSF of LL at 1, 4 and 7 d postmortem compared to AS. The tenderness with PS at 14 d postmortem was similar to that of achilles tendon suspension at 21 d, and the WBSF had no significant difference. Moreover, pelvic suspension increased sarcomere length and decreased purge loss of LL significantly, but had no significant effect on pH and meat color. In addition, ageing time had significant effects on pH, meat color, Warner-Bratzler shear force, but had no effect on sarcomere length. In conclusion, PS is a valuable technique that should be introduced to the beef industry in China for rapid improvement of beef tenderness and decreased aging time of Chinese yellow cattle.