食品玻璃化转变温度测量方法的比较

COMPARING OF MEASUREMENT METHODS FOR GLASS TRANSITION TEMPERATURE OF FOOD

利用差示扫描量热仪用经过退火处理的连续扫描法、不经过退火处理的连续扫描法和分步扫描法,对20％和50％蔗糖水溶液的玻璃化转变温度进行了测量。结果显示,退火处理的连续扫描法测量结果最好,测得蔗糖水溶液的玻璃化转变温度大致为-34．6℃,Tg'不受退火温度和溶液浓度的影响。三种方法测得20％蔗糖水溶液的Tg'的差别不大。退火方法和不退火方法测得50％蔗糖水溶液的Tg'差别很大。用两种不同的连续扫描方法做了几组测新鲜西瓜汁玻璃化转变温度的实验,结果在-42--44℃之间。

In this paper, glass transition temperature of 20% and 50% sucrose solutions were determined by Differential Scanning Calorimetry with three different scanning methods, i.e. annealing continuous scan, continuous scan and stepwise scan. The conclusions indicate that the results determined by the first scanning method is relatively the best method. The glass transition of sucrose solution is around -34.6℃, and its Tg' is not influenced by the annealing temperaure and the concentration of solutions. To 20% sucrose solution, these three methods don't have a big influence on Tg', but to 50% sucrose solution, if it's not annealed, then Tg' will differ from each other very largely. Besides that two different continuous scans are used to determine the glass transition temperatures of several groups of fresh watermelon juice. The results are between -42^-44℃.