Morgan J B, Wheeler T L, Koohmaraie M, Savell J W, Crouse J D
Roman L. Hruska U.S. Meat Animal Research Center, ARS, USDA, Clay Center, NE 68933-0166.
J Anim Sci. 1993 Jun;71(6):1471-6. doi: 10.2527/1993.7161471x.
The objectives of this study were to examine the effects of castration on the calpain proteinase system (mu-calpain, m-calpain, and calpastatin) activities and meat tenderness. Six each, MARC III bulls and steers were slaughtered at approximately 12 mo of age. Longissimus muscle samples were obtained for determining myofibril fragmentation index, Warner-Bratzler shear force, and sensory panel evaluation at 1, 7, and 14 d postmortem, and mu- and m-calpain and calpastatin activities at 24 h postmortem. Bulls produced leaner carcasses with lower (P < .05) quality grades than did steers. Meat from bulls had higher (P < .05) shear force values than meat from steers; however, sensory panelists were unable (P > .05) to detect differences in tenderness or other sensory traits between bulls and steers. Activities of mu- and m-calpain were not affected (P > .05) by castration; however, calpastatin was higher (P < .05) in muscles from the bull carcasses. Lower (P < .05) myofibril fragmentation index values indicate that less proteolysis occurred in muscle from bulls than in muscle from steers during the first 7 d postmortem. Greater calpastatin 24-h activity may be associated with the increased shear force of meat from bulls.
本研究的目的是检验去势对钙蛋白酶系统（μ-钙蛋白酶、m-钙蛋白酶和钙蛋白酶抑制蛋白）活性及肉嫩度的影响。选取6头MARC III公牛和6头阉牛，在约12月龄时屠宰。采集背最长肌样本，用于测定宰后1、7和14 d的肌原纤维破碎指数、沃纳-布拉茨勒剪切力和感官评定，以及宰后24 h的μ-和m-钙蛋白酶及钙蛋白酶抑制蛋白活性。公牛的胴体比阉牛更瘦，质量等级更低（P < 0.05）。公牛的肉比阉牛的肉具有更高（P < 0.05）的剪切力值；然而，感官评定员无法（P > 0.05）检测到公牛和阉牛肉在嫩度或其他感官特性上的差异。去势对μ-和m-钙蛋白酶的活性没有影响（P > 0.05）；然而，公牛胴体肌肉中的钙蛋白酶抑制蛋白含量更高（P < 0.05）。较低（P < 0.05）的肌原纤维破碎指数值表明，宰后前7 d公牛肌肉中的蛋白水解程度低于阉牛肌肉。钙蛋白酶抑制蛋白24 h活性较高可能与公牛肉剪切力增加有关。
