Mbegbu N N, Nwajinka C O, Amaefule D O
Department of Agricultural and Bioresources Engineering, Nnamdi Azikiwe University, Awka, Nigeria.
Heliyon. 2021 Jan 13;7(1):e05945. doi: 10.1016/j.heliyon.2021.e05945. eCollection 2021 Jan.
The effect of air temperature on the drying kinetics and characteristics of scent and lemon basil leaves were investigated using a vacuum oven dryer at 30 °C, 40 °C, 50 °C, 60 °C and 70 °C. Suitable drying models were obtained to describe the drying process. Falling rate drying phenomenon was observed for both leaves. Six thin layer drying models namely: Lewis model, Page model, Modified Page model, Logarithmic model, Two term model and Midilli model were fitted to the moisture ratio data for both scent and lemon basil leaves. Highest coefficient of determination (R), and least sum of square error (SSE) and root mean square error (RMSE) values were determined for the Logarithmic model for scent leaf as 0.9998, 0.0002, 0.0081, and 0.9961, 0.0034 and 0.0222 for lemon basil leaf. The Two term model showed the same values for scent leaf as the Logarithmic model and 0.9967, 0.0024 and 0.0185 for lemon basil leaf. They were the best fit models for all the drying temperatures. The results showed that scent and lemon basil leaves can best be dried at 70 °C and 60 °C, respectively. The specific energy consumption and the effective moisture diffusivities of scent and lemon basil leaves were determined at different drying air temperatures. ranged from to m/s and to m/s for scent and lemon basil leaves respectively, as temperature increased. Using the Arrhenius equation, the activation energy and pre-exponential factor were determined as 25.01 kJ/mol and m/s for scent leaf and 32.35 kJ/mol and for lemon basil leaves. Therefore, the Logarithmic and Two term models are recommended as the best models for the drying kinetics of scent and lemon basil leaves from the experiment.
使用真空烘箱干燥器在30℃、40℃、50℃、60℃和70℃下研究了空气温度对薄荷和柠檬罗勒叶片干燥动力学以及香气和特性的影响。获得了合适的干燥模型来描述干燥过程。两种叶片均观察到降速干燥现象。将六个薄层干燥模型，即Lewis模型、Page模型、修正Page模型、对数模型、双项模型和Midilli模型，拟合到薄荷和柠檬罗勒叶片的水分比数据。薄荷叶片对数模型的决定系数（R）最高，平方误差和（SSE）和均方根误差（RMSE）最小，分别为0.9998、0.0002、0.0081，柠檬罗勒叶片的分别为0.9961、0.0034和0.0222。双项模型对薄荷叶片显示出与对数模型相同的值，对柠檬罗勒叶片为0.9967、0.0024和0.0185。它们是所有干燥温度下的最佳拟合模型。结果表明，薄荷和柠檬罗勒叶片分别在70℃和60℃下干燥效果最佳。测定了不同干燥空气温度下薄荷和柠檬罗勒叶片的比能耗和有效水分扩散率。随着温度升高，薄荷叶片的有效水分扩散率范围为 至 m/s，柠檬罗勒叶片的为 至 m/s。使用阿伦尼乌斯方程，确定薄荷叶片的活化能 和指前因子 分别为25.01 kJ/mol和 m/s，柠檬罗勒叶片的为32.35 kJ/mol和 。因此，根据实验，对数模型和双项模型被推荐为薄荷和柠檬罗勒叶片干燥动力学的最佳模型。
