冻干怀山药贮藏条件研究

Study on the Critical Preservation Conditions for Freeze Dried Chinese Yam

通过试验获得了冻干怀山药得到在不同温度范围（5℃~35℃）的等温吸湿特性曲,引入了几个典型模型（GAB、BET和Smith模型）来对冻干怀山药的等温吸湿特性进行了模拟,结果表明Smith方程可准确拟合冻干怀山药的水分活度和平衡含水率的关系。使用差示量热扫描仪（DSC）测定了不同含水率条件下怀山药的玻璃化转变温度,Gordon-Taylor方程可较为准确地预测怀山药玻璃化转变温度与含水率的关系。在怀山药的水分活度和玻璃环转变温度构建的状态图指导下,可根据其贮藏温度条件精确选择关键贮藏水分活度和含水率。

Desorption isotherms of freeze dried Chinese yam were obtained at different temperatures in the range 5 ℃-35 ℃. Several models（GAB, BET and Smith model） were tested to describe the experimental desorption data. The Smith equation gave the best fit over the whole range of water activity and temperature. The glass transition temperature of freeze dried Chinese yam was measured using DSC. The Gordon-Taylor equation was used to model glass transition temperature and moisture content relationship. At a given storage temperature of the freeze dried Chinese yam, the critical water activity and water content can be obtained using the Smith equation and Gordon-Taylor equation.