King D A, Dikeman M E, Wheeler T L, Kastner C L, Koohmaraie M
Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506, USA.
J Anim Sci. 2003 Jun;81(6):1473-81. doi: 10.2527/2003.8161473x.
Our objectives were to examine the effects of prerigor excision and rapid chilling vs. conventional carcass chilling of two muscles on proteolysis and tenderness during the postmortem storage, as well as the effects of fast and slow rates of cooking on myofibrillar characteristics and tenderness. The longissimus thoracis (LT) and triceps brachii (TB), long head muscles were removed 45 min after exsanguination from the left side of 12 carcasses and chilled in an ice bath to induce cold shortening (excised, rapidly chilled). At 24 h postmortem, the corresponding muscles were removed from the right side (conventionally chilled). All muscles were cut into 2.54-cm-thick steaks and assigned to one of two postmortem times (1 or 14 d), and to raw and cooking treatments. Steaks were cooked at 260 degrees C (FAST) or 93 degrees C (SLOW) in a forced-air convection oven to an internal temperature of 70 degrees C. Cooking loss, cooking time, and Warner-Bratzler shear force (WBSF) were measured on cooked steaks. Sarcomere length (SL) and the extent of proteolysis of desmin were measured on raw and cooked steaks. As expected, the excised, rapidly chilled muscles had a much more rapid (P < 0.05) temperature decline than those that were conventionally chilled. The excised, rapidly chilled treatment resulted in shorter (P < 0.05) SL, and SL was shorter (P < 0.05) in LT than in TB steaks. Raw steaks had longer (P < 0.05) SL than cooked steaks, regardless of chilling treatment. The FAST cooking resulted in shorter (P < 0.05) SL than SLOW cooking in conventionally chilled steaks, but cooking rate had no effect (P > 0.05) on SL of rapidly chilled steaks. Generally, TB steaks required longer (P < 0.05) cooking times and had higher (P < 0.05) cooking losses than LT steaks, and FAST-cooked steaks had greater (P < 0.05) cooking losses than SLOW-cooked steaks. Rapidly chilled steaks had less (P < 0.05) degradation of desmin than conventionally chilled steaks (31 vs. 41%). Aging for 14 d increased (P < 0.05) desmin degradation. Rapid chilling of muscles resulted in much higher (P < 0.05) WBSF values, whereas aging resulted in lower (P < 0.05) WBSF values. The SLOW-cooked TB steaks were more tender (P < 0.05) than FAST-cooked TB steaks and LT steaks cooked at either rate. Excised, rapidly chilled muscles underwent proteolysis, but it occurred at a slower rate during the first 24 h postmortem than it did in conventionally chilled muscles. Cooking rate did not affect tenderness of LT steaks, but SLOW cooking resulted in more tender TB steaks.
我们的目标是研究宰后僵直期切除并快速冷却与传统胴体冷却对两块肌肉在宰后储存期间蛋白水解和嫩度的影响，以及快速和慢速烹饪速率对肌原纤维特性和嫩度的影响。从12头胴体左侧放血45分钟后取出胸最长肌（LT）和肱三头肌（TB）的长头肌，置于冰浴中冷却以诱导冷收缩（切除后快速冷却）。宰后24小时，从右侧取出相应肌肉（传统冷却）。所有肌肉均切成2.54厘米厚的牛排，并分配到两个宰后时间点（1天或14天）以及生肉和烹饪处理组。牛排分别在260摄氏度（快速）或93摄氏度（慢速）的强制对流烤箱中烹饪至内部温度达到70摄氏度。测量熟牛排的烹饪损失、烹饪时间和沃纳-布拉茨勒剪切力（WBSF）。测量生牛排和熟牛排的肌节长度（SL）以及结蛋白的蛋白水解程度。正如预期的那样，切除后快速冷却的肌肉温度下降比传统冷却的肌肉快得多（P<0.05）。切除后快速冷却处理导致SL更短（P<0.05），并且LT牛排的SL比TB牛排更短（P<0.05）。无论冷却处理如何，生牛排的SL比熟牛排更长（P<0.05）。在传统冷却的牛排中，快速烹饪导致SL比慢速烹饪更短（P<0.05），但烹饪速率对快速冷却牛排的SL没有影响（P>0.05）。一般来说，TB牛排比LT牛排需要更长的烹饪时间（P<0.05）且烹饪损失更高（P<0.05），快速烹饪的牛排比慢速烹饪的牛排烹饪损失更大（P<0.05）。快速冷却的牛排结蛋白降解比传统冷却的牛排少（P<0.05）（31%对41%）。储存14天会增加（P<0.05）结蛋白降解。肌肉的快速冷却导致WBSF值高得多（P<0.05），而储存则导致WBSF值降低（P<0.05）。慢速烹饪的TB牛排比快速烹饪的TB牛排以及以任何一种速率烹饪的LT牛排更嫩（P<0.05）。切除后快速冷却的肌肉会发生蛋白水解，但在宰后最初24小时内其发生速率比传统冷却的肌肉慢。烹饪速率对LT牛排的嫩度没有影响，但慢速烹饪会使TB牛排更嫩。
