The objective of this study was to determine the impact of quality grade and steak location on color stability of semitendinosus (ST) steaks during a 9-d refrigerated study. Twenty-one ST muscles (12 Choice and 9 Select) were purchased from a commercial beef packing plant and fabricated into twelve 2.54-cm thick steaks per muscle. Steaks 1, 6, and 12 were designated for immunohistochemistry while remaining steak locations of proximal (steaks 2 to 4), middle (5 to 8), and distal (9 to 11) were randomly assigned to 0, 4, or 9 d of simulated retail display. Surface color attributes of day-9 steaks were recorded daily by a visual color panel and spectrophotometer. On days 0, 4, and 9 of display, steaks were analyzed for metmyoglobin reducing ability (MRA) and oxygen consumption (OC). Grade × day of display (DOD) interactions were detected for L*, a*, surface oxymyoglobin (OMb) and metmyoglobin (MMb) percentages, and visual panel surface redness and discoloration scores (P ≤ 0.02); however, no Grade × DOD interactions were observed for MRA or OC (P > 0.17). There were location main effect (LOC) × DOD interactions for L*, a*, surface MMb, visual panel surface redness and discoloration, and MRA (P ≤ 0.02). Distal steaks had lower L* values compared with the other locations (P < 0.01), which coincided with steaks being rated visually darker red (P < 0.01). Proximal steaks had greater a* values and had less surface discoloration than middle steaks (P < 0.05), which had an increased percentage of surface MMb (P ≤ 0.04). Distal and proximal steaks had increased MRA compared with middle steaks on days 0 and 4 (P < 0.05), and distal steaks had greater OC than the other locations throughout display (P < 0.01). There were fewer type I fibers at the proximal end with a greater percentage located at the middle and distal ends, and an increased percentage of type IIX fibers at the middle and proximal locations (P ≤ 0.01). Less type IIA fibers were detected at the middle LOC compared with the other two locations (P < 0.10). Larger type I, IIA, and IIX fibers were located at the proximal and middle locations compared with the distal LOC (P < 0.01). ST color and color-stability characteristics were influenced by DOD and LOC, which may partially be explained by differences in fiber types among locations.

中文翻译：

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品质等级和肌肉内位置对牛肉半腱肌纤维特性，NADH含量和颜色稳定性的影响。

这项研究的目的是在9天的冷藏研究中确定质量等级和牛排位置对半腱肌（ST）牛排颜色稳定性的影响。从商业牛肉包装厂购买了21条ST肌肉（12 Choice和9 Select），每条肌肉被制成12块2.54厘米厚的牛排。牛排1、6和12被指定用于免疫组织化学，而剩余的牛排近端（牛排2至4），中部（5至8）和远端（9至11）的位置随机分配给第0、4或9天模拟零售展示。每天通过视觉颜色面板和分光光度计记录第9天牛排的表面颜色属性。在展示的第0天，第4天和第9天，分析牛排的肌红蛋白还原能力（MRA）和耗氧量（OC）。显示的品位×日（DOD为L *，A *，表面氧化肌红蛋白（被检测的）相互作用OMB）和肌红蛋白（MMB）的百分比，以及视觉面板表面发红和褪色的分数（P ≤0.02）; 但是，没有观察到MRA或OC的Grade×DOD相互作用（P > 0.17）。有位置的主效应（LOC）×为L *，A *，表面MMB，视觉面板表面发红和褪色DOD的相互作用，和MRA（P ≤0.02）。与其他位置相比，远距离牛排的L *值较低（P <0.01），这与牛排在视觉上被评定为深红色（P<0.01）。近侧牛排有更高的*值和具有比中间牛排表面变色少（P <0.05），其具有表面MMB（的增加的百分比P ≤0.04）。与第0天和第4天的中间牛排相比，远端牛排和近端牛排的MRA升高（P <0.05），而整个展示期间远端牛排的OC均高于其他位置（P <0.01）。有在与位于中间和远端的更大百分比，和类型IIX纤维在中间和近端位置的增加的百分比（近端更少的I型纤维P ≤0.01）。与其他两个位置相比，在中部LOC处检测到的IIA型纤维更少（P<0.10）。与远端LOC相比，较大的I，IIA和IIX型纤维位于近端和中间位置（P <0.01）。ST的颜色和颜色稳定性受DOD和LOC的影响，这可能部分由位置之间纤维类型的差异引起。