Crystallization kinetics of lactose in sytems co-lyofilized with trehalose. Analysis by differential scanning calorimetry
Crystallization kinetics of lactose in sytems co-lyofilized with trehalose. Analysis by differential scanning calorimetry
复制标题
乳糖与海藻糖共冻干系统中的结晶动力学。
DOI：
10.1016/s0963-9969(01)00115-6
复制
发表时间：
2001
影响因子：
8.1
通讯作者：
M. Buera
中科院分区：
文献类型：
--
作者：
M. F. Mazzobre;Gonzalo Soto;J. Aguilera;M. Buera
本工作的目的是通过差示扫描量热法研究相/状态转变的无定形乳糖和乳糖与海藻糖共冻干模型系统。所获得的参数，如玻璃化转变温度（Tg）和结晶的结晶度被用来测试不同的建议模型来预测这些系统的行为的适用性。低水分乳糖-海藻糖混合物的热谱图仅显示一个玻璃化转变温度，表明两种糖之间存在相容性。海藻糖浓度的增加，在混合物中促进延迟乳糖结晶的等温运行，和结晶温度（Tcr）的动态实验。海藻糖的存在延迟乳糖结晶，而不影响Tg值。若干因素（热力学、几何学、动力学）可改变组合系统中的分子环境，从而影响成核和/或晶体生长。三个模型[Arrhenius，Williams-Landel-Ferry（WLF）和Vogel-Tamman-Fulcher（VTF）]被用来研究结晶时间的温度依赖性。尽管在Tg值以上14 °C至59 °C的温度范围内，所有这些模型都能很好地拟合实验点，但VTF方程似乎更适用于糖。
The objective of the present work was to study by differential scanning calorimetry phase/state transitions in model systems of amorphous lactose and lactose co-lyophilized with trehalose. The obtained parameters, such as glass transition temperatures (Tg) and enthalpies of crystallization were employed to test the applicability of different proposed models to predict the behavior of these systems. Thermograms of low moisture lactose–trehalose mixtures showed only one glass transition temperature indicating that compatibility exists between both sugars. The increase of trehalose concentration in the mixture promoted a delay of lactose crystallization in isothermal runs, and of the crystallization temperature (Tcr) in dynamic experiments. The presence of trehalose delayed lactose crystallization, without affecting the Tgvalue. Several factors (thermodynamic, geometric, kinetics) may modify the molecular environment in the combined systems, affecting nucleation and/or crystal growth. Three models [Arrhenius, Williams–Landel–Ferry (WLF) and Vogel–Tamman–Fulcher (VTF)] were used to study the temperature dependence of the crystallization time. Although experimental points were fitted fairly well by all these models in the range of temperature from 14 to 59 °C above Tgvalue, the VTF equation appears to apply better for sugars.