Abstract: 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.

Key words: packaging time; heat shrink packaging; vacuum packaging; skin packaging; modified atmosphere packaging; meat quality