Shackelford S D, Koohmaraie M, Miller M F, Crouse J D, Reagan J O
Anim. Sci. Dept., Univ. of Georgia, Athens 30602.
J Anim Sci. 1991 Jan;69(1):171-7. doi: 10.2527/1991.691171x.
Postmortem aging of carcasses obtained from Angus-Hereford (n = 8) and 5/8 Brahman crossbred (n = 8) heifers was investigated to determine the cause of variation in meat tenderness. Raw longissimus muscle (LM) myofibril fragmentation index was lower and cooked LM Warner-Bratzler shear force was greater for the 5/8 Brahman crossbreds (P less than .05). The activities of calcium-dependent protease (CDP) -I and -II were not affected (P greater than .05) by breed; however, CDP inhibitor activity was higher (P less than .05) in the 5/8 Brahman carcasses. The activities of cathepsins B and B + L were not affected by breed or postmortem storage time (0, 1, 3, 7 or 14 d). Hereford-Angus carcasses were fatter opposite the 12th rib and had higher USDA yield grades and marbling scores (P less than .05). Hereford-Angus crossbreds had less dark, coarse band formation around the exterior of the LM and lighter, finer-textured lean (P less than .05). Cooking loss (%) and cooking rate (g/min) were not affected by breed or postmortem aging (P greater than .05). The increased toughness in the 5/8 Brahman carcasses may be due to increased CDP inhibitor activity.
对安格斯-海福特杂交（n = 8）和5/8婆罗门杂交（n = 8）小母牛的胴体宰后成熟情况进行了研究，以确定肉嫩度差异的原因。5/8婆罗门杂交牛的生腰大肌（LM）肌原纤维断裂指数较低，熟制LM的沃纳-布拉茨勒剪切力较大（P < 0.05）。钙依赖性蛋白酶（CDP）-I和-II的活性不受品种影响（P > 0.05）；然而，5/8婆罗门胴体中的CDP抑制剂活性较高（P < 0.05）。组织蛋白酶B和B + L的活性不受品种或宰后储存时间（0、1、3、7或14天）的影响。海福特-安格斯杂交牛第12肋相对处更肥，美国农业部产量等级和大理石花纹评分更高（P < 0.05）。海福特-安格斯杂交牛在LM外部周围形成的深色、粗带较少，瘦肉颜色较浅、质地较细（P < 0.05）。烹饪损失率（%）和烹饪速率（克/分钟）不受品种或宰后成熟的影响（P > 0.05）。5/8婆罗门胴体韧性增加可能是由于CDP抑制剂活性增加所致。
