Drying and colour characteristics of Cleome gynandra L. (spider plant) leaves

Abstract Drying characteristics of Cleome leaves in an oven dryer was studied. The impact of oven drying temperature (50, 60 and 70 °C) on moisture composition of the plant at a uniform air speed was considered. Eight drying models, namely, simple exponential, Page, Verma, modified Henderson and Pabis, Lewis, two term exponential, Newton, logarithmic, and Wang and Singh were fitted to drying data. Modified Henderson and Pabis model satisfactorily depicts the drying behaviour of Cleome leaves. Effective moisture diffusivity of Cleome ranged from 1.03 × 10−6 to 1.77 × 10−5 m2/s. Reliance of the calculated effective diffusivity on oven temperature was unavoidable. The required activation energy for oven drying of Cleome leaves was found to be 24.46 kJ/mol. The colour characteristics of Cleome leaves in terms of L*, a* and b* were determined. Based on the colour characteristics results, drying condition of 70 °C 90 min was found to be optimum for oven drying of Cleome leaves.

摘要：本研究以白花菜属（Cleome）叶片为研究对象，探究其在烘箱干燥过程中的干燥特性。实验设定恒定空气流速，考察烘箱干燥温度（50、60、70℃）对该植物水分组成的影响。选取8种干燥动力学模型对干燥实验数据进行拟合，分别为单指数模型、Page模型、Verma模型、修正Henderson-Pabis模型、Lewis模型、双指数模型、Newton模型、对数模型以及Wang-Singh模型。结果显示，修正Henderson-Pabis模型可较好地拟合白花菜属叶片的干燥行为。白花菜属叶片的有效水分扩散系数范围为1.03×10^-6 至1.77×10^-5 m²/s。计算所得有效水分扩散系数必然随烘箱干燥温度变化。白花菜属叶片烘箱干燥的表观活化能为24.46 kJ/mol。本研究还测定了白花菜属叶片在CIE L*、a*、b*色彩空间下的色泽特性。基于色泽特性实验结果，确定白花菜属叶片烘箱干燥的最优工艺条件为70℃、干燥90分钟。