Johnson M H, Calkins C R, Huffman R D, Johnson D D, Hargrove D D
Dept. of Anim. Sci., University of Nebraska, Lincoln 68583.
J Anim Sci. 1990 Aug;68(8):2371-9. doi: 10.2527/1990.6882371x.
Activities of acidic proteases (cathepsin B + L) and neutral, calcium-dependent proteases (CDP) were quantified to determine whether differences in proteolytic activity could explain differences in meat tenderness among breed types. Steers (n = 32) of known percentage Angus (A) and Brahman (B) breeding were used to establish differences in meat tenderness (A; 3/4A-1/4B; 1/2A-1/2B; 1/4A-3/4B). Samples were removed from the longissimus muscle within 1 h postmortem and within 2 h were frozen for subsequent determination of cathepsin B + L, CDP-I, CDP-II and CDP-inhibitor activities. Warner-Bratzler shear (WBS) was assessed after 1, 5 and 10 d of postmortem aging. Taste panel evaluations, conducted on steaks that were subjected to 5 d of aging, detected no differences. At d 1, WBS did not differ among breed types; however, by d 10 of aging, steaks from Angus steers were more tender (P less than .05) than steaks from 1/2B and 3/4B steers. The Angus and 1/4B steaks had significantly more (P less than .05) cathepsin B + L activity than the 3/4B. The CDP had no relationship with WBS; however, CDP-inhibitor was positively related to d-1 WBS (r = .41, P less than .05). Cathepsin B + L activity was negatively related to WBS at d 10 (r = -.44, P less than .05). These data suggest that differences in meat tenderness among breed types may be explained partially by differences in proteolytic enzyme activity.
对酸性蛋白酶（组织蛋白酶B + L）和中性钙依赖性蛋白酶（CDP）的活性进行定量，以确定蛋白水解活性的差异是否可以解释不同品种类型肉嫩度的差异。使用已知安格斯（A）和婆罗门（B）育种百分比的阉牛（n = 32）来确定肉嫩度的差异（A；3/4A - 1/4B；1/2A - 1/2B；1/4A - 3/4B）。在宰后1小时内从背最长肌取样，并在2小时内冷冻，以便随后测定组织蛋白酶B + L、CDP - I、CDP - II和CDP抑制剂的活性。在宰后成熟1、5和10天时评估沃纳 - 布拉茨勒剪切力（WBS）。对经过5天成熟的牛排进行的味觉小组评估未发现差异。在第1天，不同品种类型的WBS没有差异；然而，到成熟第10天时，安格斯阉牛的牛排比1/2B和3/4B阉牛的牛排更嫩（P小于0.05）。安格斯和1/4B牛排的组织蛋白酶B + L活性明显高于3/4B牛排（P小于0.05）。CDP与WBS没有关系；然而，CDP抑制剂与第1天的WBS呈正相关（r = 0.41，P小于0.05）。在第10天时，组织蛋白酶B + L活性与WBS呈负相关（r = -0.44，P小于0.05）。这些数据表明，不同品种类型肉嫩度的差异可能部分由蛋白水解酶活性的差异来解释。
