Center of Excellence for Food Safety Research (CEFSR), Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan Malaysia.
Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan Malaysia.
J Food Sci Technol. 2014 Oct;51(10):2656-63. doi: 10.1007/s13197-012-0799-4. Epub 2012 Sep 1.
Understanding the water sorption characteristics of cereal is extremely essential for optimizing the drying process and ensuring storage stability. Water relation of rough rice was studied at 20, 30, 40 and 50 °C over relative humidity (RH.) between 0.113 and 0.976 using the gravimetric technique. The isotherms displayed the general sigmoid, Type II pattern and exhibited the phenomenon of hysteresis where it was more pronounced at lower temperatures. The sorption characteristics were temperature dependence where the sorption capacity of the paddy increased as the temperature was decreased at fixed (RH). Among the models assessed for their ability to fit the sorption data, Oswin equation was the best followed by the third order polynomial, GAB, Smith, Chung-Pfost, and Henderson models. The monolayer moisture content was higher for desorption than adsorption and tend to decrease with the increase in temperature. Given the temperature dependence of the sorption isotherms the isosteric heats of sorption were calculated using Claussius-Clapeyron equation. The net isosteric heats decreased as the moisture content was increased and heats of desorption were greater than that of adsorption.
了解谷物的水分吸附特性对于优化干燥过程和确保储存稳定性至关重要。使用重量法研究了糙米在 20、30、40 和 50°C 下相对湿度（RH）在 0.113 至 0.976 之间的水分关系。等温线呈现出一般的 S 形、II 型模式，并表现出滞后现象，在较低温度下更为明显。吸附特性与温度有关，在固定（RH）下，稻谷的吸附能力随着温度的降低而增加。在所评估的模型中，Oswin 方程最适合拟合吸附数据，其次是三阶多项式、GAB、Smith、Chung-Pfost 和 Henderson 模型。解吸的单层水分含量高于吸附，且随着温度的升高而趋于降低。鉴于吸附等温线的温度依赖性，使用克劳修斯-克拉佩龙方程计算了吸附等焓。随着水分含量的增加，净吸附等焓降低，解吸焓大于吸附焓。
