板栗微波真空干燥特性及干燥工艺研究

研究微波真空干燥方式下,微波强度、腔体压力等参数对板栗干燥过程中质热传递的影响规律。采用Box-Behnken中心组合试验设计,以水分含量和白度值为评价指标,确定板栗微波真空干燥过程中微波功率、压力、干燥时间的最适工艺参数。结果显示:板栗微波真空干燥过程主要为加速和降速阶段,恒速阶段持续时间较短。微波功率和真空度均对干燥时间有显著影响,功率越大,真空度越高,干燥速率越快,干基含水率和水分比都随着干燥时间的延长而逐渐下降。由回归模型得出板栗微波真空干燥的最佳工艺参数为时间12min,压力-56kPa,功率3kW。微波真空干燥的微波功率、腔体压力、干燥时间均对板栗品质有影响,以模型得出的干燥参数进行干燥,可保证板栗干燥后的品质,且干燥效率高、能耗低。

Microwave-vacuum drying characteristics and drying process of Chinese chestnut

With the purpose of providing theoretical basis for further processing and utilization of Chinese chestnut, the microwave-vacuum drying characteristics and the optimum process parameters of chestnut were investigated. The effects of microwave intensity and chamber pressure on the mass and heat transfer in the drying process of chestnut were studied. The microwave power, pressure and drying time were optimized using Box-Behnken design and response surface methodology for achieving minimum moisture content and maximum whiteness value. The results showed that the microwave-vacuum drying process of chestnut slices was mainly divided into acceleration and deceleration stages, and the constant velocity phase was shorter. Both microwave power and vacuum degree had a significant influence on the drying time, the higher the power, the higher vacuum, the faster the drying rate was. The dry moisture content and moisture ratio decreased gradually with the extension of drying time of Chinese chestnut. The optimum process parameters of microwave-vacuum drying of chestnut were obtained by regression model, with the time of 12 min, the pressure of -56 kPa and the power of 3 kW. The microwave power, chamber pressure and drying time had a significant influence on the quality of drying Chinese chestnut by Microwave-vacuum. The drying parameters obtained from drying-mode ensure the edible value of Chinese chestnut with high efficiency and low energy consumption.