包装方式和宰后不同时间包装对羊肉品质的影响

为探究包装方式和宰后不同时间包装对羊肉贮藏品质的影响，本研究对宰后1 h热分割羊肉和冷却成熟24 h后的分割羊肉分别进行热收缩包装、真空包装、贴体包装、50%（体积分数，下同）O2＋50% CO2气调包装，测定其在（2±2）℃贮藏过程中pH值、色泽、贮藏损失率、蒸煮损失率、离心损失率、剪切力、挥发性气味的变化。结果表明：与宰后24 h包装相比，宰后1 h包装羊肉pH值在贮藏14 d时更高，但其贮藏期间色泽较好，色泽稳定性更高，贮藏损失率更低。从整体来看，3 种真空处理（热收缩包装、真空包装、贴体包装）羊肉嫩度均优于气调包装羊肉，且宰后1 h包装时真空条件处理对羊肉嫩化效果最好，宰后24 h羊肉在贮藏前期气调包装对羊肉嫩化效果较好；而无论何时包装，热收缩包装和气调包装羊肉贮藏损失率均显著小于其他处理组（P＜0.05），在贮藏前期色泽及稳定性较好，但贮藏后期色泽稳定性下降明显，气调包装羊肉在14 d时已部分发绿，贮藏21 d时挥发性气味变化显著。综上，宰后1 h包装有利于提高羊肉贮藏期间色泽及持水力，改善真空处理羊肉嫩度，宰后24 h包装可提高50% O2＋50% CO2气调包装羊肉贮藏前期的嫩度；其中热收缩包装和气调包装羊肉持水力高，贮藏前期色泽及稳定性好，真空包装、贴体包装羊肉品质变化相对稳定，适宜长期贮藏。

Effects of Packaging Methods and Packaging at Different Postmortem Times on the Quality of Lamb Meat

This study was conducted in order to explore the effects of packaging methods and packaging at different postmortem times on the quality changes of lamb meat during postmortem storage. Lamb Longissimus thoracis et lumborum muscle, obtained from carcasses hot-boned at 1 h postmortem or chilled carcasses boned at 24 h postmortem, were packaged by four different methods, heat shrink packaging (HSP), vacuum packaging (VP), skin packaging (SP), modified atmosphere packaging (MAP) with 50% O2 + 50% CO2, and were stored at (2 ± 2) ℃. The pH, color, purge loss, cooking loss, centrifugal loss, shear force and volatile odor of lamb meat were analyzed during storage. Results showed that compared with that packaged at 24 h postmortem, lamb meat packaged at 1 h postmortem had a higher pH after 14 days of storage, maintained its color better during the storage period, and exhibited a lower purge loss. Overall, lamb meat subjected to the three vacuum treatments (HSP, VP and SP) had a higher tenderness than that in MAP packaged lamb meat; lamb meat vacuum-packaged at 1 h postmortem had the highest tenderness, while that packaged in modified atmosphere at 24 h postmortem had higher tenderness at early period of storage. Irrespective of packaging time, HSP and MAP significantly lowered purge loss compared with the other treatments (P < 0.05). The color and color stability of lamb meat in the HSP and MAP groups remained good during the early period of storage, whereas the color stability declined noticeably during the late period of storage. The color of MAP packaged lamb meat became partly green after 14 days of storage, and the volatile odor greatly changed after 21 days. In conclusion, packaging at 1 h postmortem contributes to maintain the color and water-holding capacity of lamb meat during storage and improve the tenderness of vacuum-packaged meat. Packaging at 24 h postmortem is beneficial to improve the tenderness of MAP packaged lamb meat during the early period of storage. HSP and MAP packaged lamb meat has a higher water-holding capacity, and their color and color stability remain good during the early period of storage. The quality of VP and SP packaged lamb meat remains relatively stable and thus, they can be stored for a long period of time.