Gruber S L, Tatum J D, Scanga J A, Chapman P L, Smith G C, Belk K E
Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523-1171, USA.
J Anim Sci. 2006 Dec;84(12):3387-96. doi: 10.2527/jas.2006-194.
Forty USDA Select and 40 upper two-thirds USDA Choice beef carcasses were used to determine the effects of postmortem aging on tenderness of 17 individual beef muscles. Biceps femoris-long head, complexus, gluteus medius, infraspinatus, longissimus dorsi, psoas major, rectus femoris, semimembranosus, semitendinosus, serratus ventralis, spinalis dorsi, supraspinatus, tensor fasciae latae, teres major, triceps brachii-long head, vastus lateralis, and vastus medialis muscles were removed from each carcass. Seven steaks (2.54-cm thick) were cut from every muscle, and each steak was assigned to one of the following postmortem aging periods: 2, 4, 6, 10, 14, 21, or 28 d postmortem. After completion of the designated aging period, steaks were removed from storage (2 degrees C, never frozen), cooked to a peak internal temperature of 71 degrees C, and evaluated using Warner-Bratzler shear force (WBSF). Analysis of WBSF revealed a 3-way interaction (P = 0.004) among individual muscle, USDA quality grade, and postmortem aging period. With the exception of the Select teres major, WBSF of all muscles (both quality grades) decreased with increasing time of postmortem storage. Nonlinear regression was used to characterize the extent (aging response) and rate of decrease in WBSF from 2 through 28 d postmortem for each muscle within each quality grade. In general, WBSF of upper two-thirds Choice muscles decreased more rapidly from 2 to 10 d postmortem than did corresponding Select muscles. Muscles that had greater aging responses generally had greater 2-d WBSF values. The upper two-thirds Choice psoas major, serratus ventralis, and vastus lateralis muscles required similar aging times to complete a majority of the aging response (< or =0.1 kg of aging response remaining) compared with analogous Select muscles. The upper two-thirds Choice complexus, gluteus medius, semitendinosus, triceps brachii-long head, and vastus medialis muscles required 4 to 6 d less time to complete a majority of the aging response than did comparable Select muscles. Aging times for Select biceps femoris-long head, infraspinatus, longissimus dorsi, rectus femoris, semimembranosus, spinalis dorsi, supraspinatus, and tensor fasciae latae muscles were > or =7 d longer than those for corresponding upper two-thirds Choice muscles. Results from this study suggest that muscle-to-muscle tenderness differences depend on quality grade and aging time and that postmortem aging should be managed with respect to individual muscle and USDA quality grade.
选用40个美国农业部精选级和40个美国农业部上三分之二级优质牛肉胴体，以确定宰后成熟对17块牛肉个体嫩度的影响。从每具胴体上取下股二头肌长头、复合肌、臀中肌、冈下肌、背最长肌、腰大肌、股直肌、半膜肌、半腱肌、腹侧锯肌、背棘肌、冈上肌、阔筋膜张肌、大圆肌、肱三头肌长头、股外侧肌和股内侧肌。从每块肌肉上切下7块牛排（厚2.54厘米），每块牛排被分配到以下宰后成熟时间段之一：宰后2、4、6、10、14、21或28天。在规定的成熟时间段结束后，将牛排从储存环境（2℃，从未冷冻）中取出，煮至内部温度峰值71℃，并使用沃纳-布拉茨勒剪切力（WBSF）进行评估。WBSF分析显示，个体肌肉、美国农业部质量等级和宰后成熟时间段之间存在三因素交互作用（P = 0.004）。除精选级的大圆肌外，所有肌肉（两个质量等级）的WBSF均随宰后储存时间的延长而降低。采用非线性回归来描述每个质量等级内各肌肉从宰后2天至28天WBSF的下降程度（成熟反应）和速率。一般来说，上三分之二级优质肌肉的WBSF在宰后2至10天的下降速度比相应的精选级肌肉更快。成熟反应较大的肌肉通常在宰后2天的WBSF值也较大。与类似的精选级肌肉相比，上三分之二级优质的腰大肌、腹侧锯肌和股外侧肌完成大部分成熟反应（剩余成熟反应≤0.1千克）所需的成熟时间相似。上三分之二级优质的复合肌、臀中肌、半腱肌、肱三头肌长头和股内侧肌完成大部分成熟反应所需的时间比可比的精选级肌肉少4至6天。精选级的股二头肌长头、冈下肌、背最长肌、股直肌、半膜肌、背棘肌、冈上肌和阔筋膜张肌的成熟时间比相应的上三分之二级优质肌肉长≥7天。本研究结果表明，肌肉间的嫩度差异取决于质量等级和成熟时间，宰后成熟应根据个体肌肉和美国农业部质量等级进行管理。
