کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
224510 464446 2010 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
State diagram of dates: Glass transition, freezing curve and maximal-freeze-concentration condition
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
State diagram of dates: Glass transition, freezing curve and maximal-freeze-concentration condition
چکیده انگلیسی

The state diagram of Deglet Nour dates was developed using freezing curve, glass transition line, and maximal-freeze-concentration condition. Freezing points and glass transition temperature were measured by differential scanning calorimetry (DSC) as a function of water content. Freezing points were fitted to the Clausius–Clapeyron equation adjusted with un-freezable water, and glass transition was fitted to the Gordon–Taylor model. Glass transition decreased with a decrease in solids content, confirming the plasticizing effect of water on date solids. Freezing point data indicated the temperature when ice formed and dates would be most stable in terms of its deterioration if it can be stored below its glass transition. Maximum-freeze-concentration conditions was found as Xs′ (characteristic solids content) = 0.78 g/g sample, with the characteristic temperature as Tg′ (characteristics glass transition) = −48 °C and Tm′ (characteristic end point of freezing) = −38.2 °C. These characteristics indicated that 0.22 g/g sample water in date was un-freezable (i.e. bound with solids or unable to form ice). The developed state diagram can be used in determining the stability of dates during storage as a function of temperature and moisture content. Moreover, it can be used to determine optimum drying and freezing conditions.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Food Engineering - Volume 99, Issue 1, July 2010, Pages 92–97
نویسندگان
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