Koohmaraie M, Shackelford S D, Wheeler T L
USDA, ARS, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE 68933-0166, USA.
J Anim Sci. 1998 May;76(5):1427-32. doi: 10.2527/1998.7651427x.
The effect of rapid prerigor freezing and postrigor freezing and postrigor calcium chloride injection on the tenderness of callipyge longissimus was studied. Ewe and wether lambs (n = 49; 1/2 Dorset x 1/2 Romanov) were grain-fed and slaughtered at approximately 250 d of age. Based on leg conformation scores, 23 of the carcasses had the callipyge phenotype. Within each phenotype, approximately one-half of the carcasses were chilled conventionally (24 h at -2 degrees C). At approximately 17 min postmortem, the remaining carcasses were submersed in liquid nitrogen for 15 min and then held at -2 degrees C for 4 d. At 1 d postmortem for carcasses chilled conventionally and at 4 d postmortem for carcasses frozen in liquid nitrogen, the longissimus muscles from both sides were removed. The longissimus from one side of each carcass was vacuum-packaged and aged (1 degrees C) conventionally for 7 or 14 d. The remaining muscles were injected with a 2.22% solution of food-grade calcium chloride at 5% by weight, vacuum-packaged, and aged as above. Liquid nitrogen freezing was effective in limiting sarcomere shortening (1.99 vs 1.63 microm; P < .05). Warner-Bratzler shear force values of callipyge longissimus were 222 and 232% of that of normal longissimus after 7 and 14 d postmortem, respectively (P < .001). Also, trained panel tenderness rating was decreased by 49.4% in untreated callipyge longissimus after 14 d postmortem. Liquid nitrogen, calcium chloride injection and their combination did not affect d-14 longissimus shear force and sensory tenderness for normal lambs because untreated muscles were already tender. Liquid nitrogen freezing improved the shear force and sensory tenderness rating of callipyge longissimus by 30 and 86.2% after 14 d postmortem, respectively. Calcium chloride injection improved the shear force and sensory tenderness of callipyge longissimus by 36.7 and 86.2% after 14 d postmortem, respectively (P < .001). The most effective treatment for mitigating the callipyge effect on tenderness was the combination (freezing and calcium chloride injection) treatment, which improved the shear force and sensory tenderness by 51.2 and 124.2% after 14 d postmortem, respectively (P < .001). We conclude that either treatment can effectively mitigate the negative effect of callipyge phenotype on longissimus tenderness. Callipyge lamb carcasses subjected to the combination of prerigor liquid nitrogen freezing, postrigor calcium chloride injection, and 14 d postmortem storage had tenderness similar (P > .05) to that of normal, untreated carcasses after 14 d of postmortem storage.
研究了快速宰前冷冻、宰后冷冻以及宰后注射氯化钙对臀肌丰满型绵羊背最长肌嫩度的影响。选用母羊和羯羊（n = 49；1/2多塞特羊×1/2罗曼诺夫羊），进行谷物育肥，约250日龄时屠宰。根据腿部形态评分，23头胴体具有臀肌丰满型表型。在每种表型中，约一半的胴体采用常规冷却方式（在-2℃下放置24小时）。宰后约17分钟，其余胴体浸入液氮中15分钟，然后在-2℃下保存4天。对于采用常规冷却的胴体，在宰后1天；对于在液氮中冷冻的胴体，在宰后4天，取出两侧的背最长肌。将每头胴体一侧的背最长肌进行真空包装，并在1℃下常规成熟7天或14天。其余肌肉注射5%（重量）的食品级氯化钙2.22%溶液，真空包装，并按上述方式成熟。液氮冷冻有效地限制了肌节缩短（1.99对1.63微米；P < 0.05）。臀肌丰满型绵羊背最长肌的Warner-Bratzler剪切力值在宰后7天和14天分别是正常背最长肌的222%和232%（P < 0.001）。此外，经过训练的感官评价小组对未经处理的臀肌丰满型绵羊背最长肌在宰后14天的嫩度评分降低了49.4%。液氮、氯化钙注射及其组合对正常羔羊宰后14天的背最长肌剪切力和感官嫩度没有影响，因为未经处理的肌肉已经很嫩。液氮冷冻使臀肌丰满型绵羊背最长肌在宰后14天的剪切力和感官嫩度评分分别提高了30%和86.2%。氯化钙注射使臀肌丰满型绵羊背最长肌在宰后14天的剪切力和感官嫩度分别提高了36.7%和86.2%（P < 0.001）。减轻臀肌丰满型对嫩度影响的最有效处理方法是联合处理（冷冻和氯化钙注射），该处理使宰后14天的剪切力和感官嫩度分别提高了51.2%和124.2%（P < 0.001）。我们得出结论，两种处理方法均可有效减轻臀肌丰满型表型对背最长肌嫩度的负面影响。经过宰前液氮冷冻、宰后氯化钙注射以及宰后14天储存处理的臀肌丰满型羔羊胴体，其嫩度与正常未处理胴体在宰后14天的嫩度相似（P > 0.05）。
