Department of Food Science Rutgers, The State University of New Jersey, 65 Dudley Road, New Brunswick, NJ 08901, United States.
Carbohydr Res. 2012 Nov 1;361:120-6. doi: 10.1016/j.carres.2012.08.013. Epub 2012 Sep 4.
The effect of glycerol on molecular mobility and hydrogen bonding in amorphous glucose matrix was studied. Phosphorescence from erythrosin B (Ery B) was used to characterize the temperature dependence of mobility in glucose/glycerol films over the temperature range from 100 °C down to -10 °C. Analysis of emission energy and excited state decay kinetics from Ery B provided information about thermally activated modes of matrix dipolar relaxation around and collisions with the excited triplet state of the probe. Both the average rate of matrix mobility and the width of the distribution of matrix mobility rates largely scaled with the effect of glycerol on the glass transition temperature of the glucose/glycerol mixture. The IR hydrogen bond bandwidth increased at higher glycerol content, suggesting that the strength of the bond became more widely distributed with the added glycerol. An increase with temperature in the hydrogen bond peak frequency indicated the transformation of associated hydroxyl to free hydroxyl. These results support a model in which glycerol plasticizes the glucose matrix at mole ratios of 0.1 and above while providing no evidence for the antiplasticization seen in other sugar matrices.
研究了甘油对非晶态葡萄糖基质中分子迁移率和氢键的影响。使用赤藓红 B（Ery B）的磷光来研究葡萄糖/甘油薄膜在 100°C 到-10°C 的温度范围内的迁移率对温度的依赖性。从 Ery B 的发射能量和激发态衰减动力学分析中获得了关于基质偶极弛豫的热激活模式以及与探针激发三重态的碰撞的信息。基质迁移率的平均速率和基质迁移率速率分布的宽度都与甘油对葡萄糖/甘油混合物玻璃化转变温度的影响密切相关。随着甘油含量的增加，IR 氢键带宽增加，表明随着甘油的加入，键的强度分布更加广泛。氢键峰频率随温度升高而增加，表明缔合羟基向游离羟基的转变。这些结果支持了一种模型，即甘油在摩尔比为 0.1 及以上时使葡萄糖基质增塑，而没有提供其他糖基质中观察到的反增塑作用的证据。
