文章基本信息

标题：Thermal analysis of amorphous lactose and $\alpha$-lactose monohydrate
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作者：Yuan Listiohadi ; James Arthur Hourigan ; Robert Walter Sleigh 等
期刊名称：Dairy Science & Technology
印刷版ISSN：1958-5586
电子版ISSN：1958-5594
出版年度：2009
卷号：89
期号：1
页码：43-67
DOI：10.1051/dst:2008027
语种：English
出版社：EDP Sciences
摘要：It is common to find that some of the lactose in dairy powders and pharmaceutical tablets is present in the unstable amorphous state. If stored at inappropriate temperatures and humidities amorphous lactose is susceptible to crystallization. The integration of thermal gravimetric analysis (TGA) with single differential thermal analysis (SDTA) provided a descriptive method for a sequential and direct determination of surface water, water of crystallization and amorphous lactose in a single analysis on one sample. Peaks and mass changes on the TGA/SDTA thermograms characteristic of surface water, water of crystallization and amorphous lactose were identified. The content of water of crystallization was used to estimate $\alpha$-lactose monohydrate. The loss of surface water was indicated on the TGA/SDTA thermograms as weight loss between 40 and 130 °C and the loss of water of crystallization occurred at 153 °C. Amorphous lactose was indicated by an exothermic crystallization peak at 174 °C. The area under the exothermic crystallization peak was linearly related to the proportion of the amorphous lactose in mixtures with $\alpha$-lactose monohydrate ($r = 0.989$). This work presented the TGA/SDTA thermograms of lactose samples containing some crystalline forms of lactose and amorphous lactose. The study compared the methods for determining surface water and total water content of lactose accepted by official bodies worldwide with the TGA/SDTA approach. The potential of new methods for qualitatively detecting the amorphous and crystalline forms of lactose by thermochemistry and Fourier transform infra-red (FT-IR) was also explored and compared.
关键词：TGA-SDTA;differential thermal analysis;thermal gravimetric analysis;water content;amorphous lactose