小麦粉水分的吸附与解吸特性

Moisture Adsorption and Desorption Characteristics of Wheat Flour

在4种温度(10、20、30、40℃)和相对湿度11%～87%的条件下,采用静态平衡称量法测定高、中、低筋小麦粉的吸附与解吸平衡水分,并绘制吸湿等温线,拟合Logistic模型建立吸湿等温线的经验公式。结果表明:在特定温度条件下,高、中、低筋小麦粉的吸湿等温线基本重合,吸湿等温线为"S"型;以中筋小麦粉为实验对象时,得出了以下结论:在等温线图中,10、20、30℃吸湿等温线依次向右下方移动,40℃吸湿等温线与30℃的基本重合;在10、20、30℃条件下,存在吸附滞后现象,温度越低,滞后环越明显。在40℃条件下,未出现滞后现象。建立的吸湿等温线经验公式是有效的。

High-gluten, middle-gluten and low-gluten wheat flours were determined by static equilibrium gravimetric method for adsorption and desorption equilibrium moisture contents under different conditions of temperature （10, 20, 30 ℃ and 40 ℃） and humidity （11%-87%）. Based on the obtained data, moisture adsorption isotherms were plotted and a logistic model was fitted to establish an empirical formula. Substantially the same moisture adsorption isotherms of high- gluten, middle-gluten and low-gluten wheat flours were observed as an ‘S＇-shaped pattern under specific conditions. The adsorption isotherms of middle-gluten wheat four at 10, 20 ℃and 30 ℃ displayed a shift towards the bottom right of the coordinate. Middle-gluten wheat four revealed basically the same adsorption isotherm at 40 ℃ and 30 ℃. Adsorption hysteresis was observed at 10, 20 ℃ and 30 ℃ and the lower the temperature, the larger the hysteretic loop area. In contrast, hysteretic loop disappeared at 40 ℃. Therefore, a valid empirical formula of moisture adsorption isotherm for wheat flour has been developed in this study.