Crispy duck legs were stored at different constant temperatures (5 and 30 ℃) and relative humidities (50%, 70% and 90%) for 0, 2, 4, 6, 8 and 10 h, respectively. Meanwhile, moisture content, water activity, shear force, and microstructure of crispy duck legs were measured. The aims were to analyze the effect of moisture migration on the crispness of crispy duck legs during storage and transportation to investigate the underlying mechanism of crisp deterioration. The results showed that during storage at 5 ℃, a decrease of the moisture content in skin was firstly presented followed by an increase, tending to a constant value after 6 h. Water activity of skin increased to reach a plateau after 6 h. However, water activity of meat first decreased rapidly from 0 to 2 h and then slowly after 4 h. Shear force of skin increased from 0 to 6 h and then decreased quickly. During storage at 30 ℃, moisture content of skin increased at first and then decreased, and the changes in water activity and shear force were similar to those observed at 5 ℃. Moisture content and water activity of skin increased with an increase of relative humidity; at the same time, shear force increased and crispness decreased. Only a few big pores in skin were observed just after being fried, and the amount of pores with smaller diameter increased with the migration of moisture. The findings indicated that temperature and relative humidity significantly influenced moisture migration between skin and meat during storage and transportation of crispy duck. The slow moisture migration rate observed at 5 ℃ resulted in low moisture content and water activity in duck. Moisture content and water activity in duck skin increased with an increase of relative humidity. Furthermore, the microstructure of skin was destroyed due to the continuous moisture migration among skin, meat, and the environment, resulting in an increase of shear force and a decrease of crispness.%将香酥鸭腿放入恒温恒湿箱中贮存,测定不同温度(5、30 ℃)、相对湿度(50%、70%、90%)和贮藏时间(0、2、4、6、8、10 h)条件下香酥鸭腿的水分含量、水分活度、剪切力及微观结构,分析香酥鸭腿贮运过程中的水分迁移对脆性的影响,探讨脆性劣变机制.结果显示:5 ℃鸭皮水分含量先降低后升高,6 h后趋于平缓.鸭皮水分活度先增加,6 h后趋于平缓,鸭肉水分活度0~2 h降低,4 h后趋于平缓.鸭皮剪切力0~6 h增加,6 h后降低;30 ℃时鸭皮水分含量先升高后降低,水分活度和鸭皮剪切力变化类似5 ℃.随着相对湿度的升高,鸭皮的水分含量和水分活度增加,剪切力增大,脆性降低.油炸后鸭皮气孔数量少而大,随着水分的迁移,鸭皮气孔数量增加且较小.表明香酥鸭腿贮运过程中温度和相对湿度明显影响了鸭皮和鸭肉中的水分迁移.低温条件下水分迁移速率低,鸭皮水分含量和水分活度小;随着相对湿度增加,鸭皮的水分含量和水分活度增加.由于鸭皮、鸭肉与环境水分不断的迁移,香酥鸭腿的微观结构被破坏,剪切力增大,脆性降低.
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