Duckett S K, Klein T A, Leckie R K, Thorngate J H, Busboom J R, Snowder G D
University of Idaho, Moscow 83844-2330, USA.
J Anim Sci. 1998 Jul;76(7):1869-74. doi: 10.2527/1998.7671869x.
The longissimus muscles (LM) from 12 lambs (eight = callipyge [CLPG] and four = normal [NML]; 48 kg) were used to 1) assess the effect of freezing with or without prior immersion in liquid nitrogen on calpastatin activity (CA) and on Warner-Bratzler shear force (WBS) in CLPG, 2) determine the freezing time required to reduce CA and WBS of CLPG to that of NML, and 3) compare sensory panel ratings for CLPG that is aged fresh to CLPG that is aged after freezing. At 24 h postmortem, chops (.64 and 2.54 cm) were removed from each CLPG LM and randomly assigned within side to one of six freezing times (0, 2, 4, 8, 20, and 42 d). Left-side chops were vacuum-packaged and frozen at -20 degrees C for the assigned time (FROZEN) and right-side chops were treated similarly, except that they were frozen in liquid nitrogen first (FLASH). After freezing for the assigned time, the .64-cm chop was immediately assayed for CA, and 2.54-cm chop was thawed, aged at 2 degrees C for 14 d, and refrozen for subsequent WBS measurement. Chops (.64 and 2.54 cm) were also removed from the longissimus of NML lamb carcasses. The d-0 CLPG and NML chops (2.54 cm) were vacuum-packaged, aged at 2 degrees C for 14 d, and frozen for subsequent WBS measurement. Calpastatin activity did not differ between freezing treatments (P = .99) or with the freezing treatment x freezing time interaction (P = .80). Freezing reduced (P = .01) CA in CLPG by 44% from d 0 to d 42. Calpastatin activity for CLPG was similar (P > .05) to that of NML lamb after freezing for 8, 20, or 42 d. Freezing at -20 degrees C for 42 d and then aging for 14 d reduced (P = .01) WBS in CLPG by 44% from d-0 values. Shear force values for CLPG-FROZEN were similar (P > .05) to NML after 8, 20, or 42 d of freezing. Sensory panel tenderness scores were higher (P < .05) for CLPG aged after freezing 42 d than for those aged fresh. Juiciness and flavor ratings did not differ (P > .05) between CLPG aged fresh or after freezing. Freezing for at least 8 d before aging seems to be a viable method for increasing the tenderness of CLPG LM without reducing juiciness or flavor ratings.
选取12只羔羊（8只臀肌肥大羊[CLPG]和4只正常羊[NML]；体重48千克）的背最长肌（LM）用于：1）评估在液氮中预浸或不预浸后冷冻对CLPG中钙蛋白酶抑制蛋白活性（CA）和Warner - Bratzler剪切力（WBS）的影响；2）确定将CLPG的CA和WBS降低至NML水平所需的冷冻时间；3）比较新鲜成熟的CLPG与冷冻后成熟的CLPG的感官评定得分。宰后24小时，从每只CLPG的LM上取下肉排（厚度分别为0.64厘米和2.54厘米），并在同一侧随机分配到六个冷冻时间（0、2、4、8、20和42天）中的一个。左侧肉排真空包装后在-20℃下冷冻指定时间（FROZEN），右侧肉排处理方式相同，只是先在液氮中冷冻（FLASH）。在冷冻指定时间后，立即对0.64厘米厚的肉排进行CA检测，将2.54厘米厚的肉排解冻，在2℃下成熟14天，然后重新冷冻以进行后续的WBS测量。还从NML羔羊胴体的背最长肌上取下肉排（0.64厘米和2.54厘米）。宰后0天的CLPG和NML肉排（2.54厘米）真空包装，在2℃下成熟14天，然后冷冻以进行后续的WBS测量。冷冻处理之间的钙蛋白酶抑制蛋白活性无差异（P = 0.99），冷冻处理×冷冻时间的交互作用也无差异（P = 0.80）。冷冻使CLPG中的CA从第0天到第42天降低了44%（P = 0.01）。冷冻8、20或42天后，CLPG的钙蛋白酶抑制蛋白活性与NML羔羊的相似（P > 0.05）。在-20℃下冷冻42天然后成熟14天，使CLPG的WBS从宰后0天的值降低了44%（P = 0.01）。冷冻8、20或42天后，CLPG - FROZEN的剪切力值与NML的相似（P > 0.05）。感官评定的嫩度得分显示，冷冻42天后成熟的CLPG比新鲜成熟的CLPG更高（P < 0.05）。新鲜成熟或冷冻后成熟的CLPG之间的多汁性和风味评分无差异（P > 0.05）。在成熟前冷冻至少8天似乎是一种可行的方法，可以提高CLPG的LM嫩度，而不降低多汁性或风味评分。
