热泵式长豇豆干燥工艺优化

为保证热泵干燥后长豇豆产品的复水性和色泽等品质参数良好，同时降低豇豆干燥过程中的能量消耗，提高豇豆干燥生产的效率，采用Box-Behnken试验设计，分析干燥温度、漂烫时间和铺料密度3 个因素对豇豆产品的复水率、色差、单位耗能量和耗时4 个参数的影响，建立多元回归模型，并对干燥工艺参数进行优化，得到热泵式长豇豆干燥工艺的最佳条件为漂烫时间3 min、铺料密度2 kg/m2、干燥温度50 ℃。在该工艺条件下，实际测得长豇豆复水率1.15，色差值22.39，单位耗能量14.31（kW·h）/kg，耗时7 h，与预测值误差极小，为豇豆在实际热泵式干燥设备生产加工中的应用提供一定的理论依据。

Optimization of Heat Pump Drying Process for Long Cowpea

This study aimed to improve the quality parameters of heat pump dried long cowpea such as rehydration characteristics and color, and simultaneously to lower energy consumption during heat pump drying and increase drying efficiency. The rehydration ratio, color difference, per-unit energy consumption and drying time were investigated with respect to three independent variables, namely drying temperature, blanching time and material density. A multiple regression model was developed for each of these response variables in order to optimize the selected independent variables. A blanching time of 3 min, a material density of 2 kg/m2 and a drying temperature of 50 ℃ were determined as the optimal conditions. Under these conditions, the experimental values of rehydration ratio, color difference, per-unit energy consumption and drying time were 1.15, 22.39, 14.31 (kW·h)/kg and 7 h, respectively, which were very close to the predicted ones. These optimized process conditions can provide a useful basis for heat pump drying of cowpea.