ABSTRACT Water adsorption properties are necessary for determining and analyzing water sorption in dried and roasted cocoa beans during storage. Thus, this study aimed to determine the water adsorption isotherms and thermodynamic properties at temperatures of 25, 30, and 40°C and water activities between 0.10 and 0.85 using dynamic dew point method. Thirteen different models were fitted to experimental data to represent the dependence of the equilibrium moisture content. Additionally, the thermodynamic properties were determined using the best-fit isotherm model. The isotherms of dried and roasted cocoa beans showed typical behavior of products rich in soluble components, according to Brunauer-Emmett-Teller (BET) classification, which was satisfactorily modeled using the Iglesias and Chirife and Kuhn equations, respectively. The thermodynamic properties showed that the net isosteric heat of adsorption and the Gibbs free energy decreased with the equilibrium moisture content, indicating the energy changes and spontaneity during the adsorption process. The integral entropy of adsorption indicated the best conditions for product stability during storage.

中文翻译：

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干燥和烘烤可可豆 (theobroma cacao L.) 的水动力学吸附特性

摘要 水吸附特性对于确定和分析干燥和烘焙可可豆在储存过程中的吸水情况是必要的。因此，本研究旨在使用动态露点法确定 25、30 和 40°C 温度以及 0.10 至 0.85 之间的水活度下的水吸附等温线和热力学性质。将 13 个不同的模型拟合到实验数据以表示平衡水分含量的依赖性。此外，热力学性质是使用最佳拟合等温线模型确定的。根据 Brunauer-Emmett-Teller (BET) 分类，干燥和烘焙可可豆的等温线显示出富含可溶性成分的产品的典型行为，该分类分别使用 Iglesias 和 Chirife 以及 Kuhn 方程进行了令人满意的建模。热力学性质表明，净等量吸附热和吉布斯自由能随着平衡含水量的增加而降低，表明吸附过程中的能量变化和自发性。吸附的积分熵表明产品在储存过程中稳定性的最佳条件。