微波干燥温度分布对胡萝卜干燥特性与品质的影响

Effect of Microwave Drying Temperature Distribution on Drying Characteristics and Quality of Carrot

为提升胡萝卜的干燥品质,减少局部过热和过分干燥问题,采用多物理场仿真与微波干燥试验,研究胡萝卜微波干燥中旋转运动与不同微波缓苏时间对温度分布、干燥特性、品质(色差、复水比、VC含量、感官评价)的影响。结果表明:水分比的模拟值与试验值的RMSE<5%,模型有效模拟了胡萝卜微波干燥热质传递的过程。旋转样品的温度均匀度指标λ较不旋转减至0.092,干制品品质及其均匀性显著提高,其中色差值标准差减到0.18。R1/4(旋转条件下加热20 s缓苏60 s)条件下胡萝卜样品温度分布区间为65~75℃,色差、VC含量均为最优。采用旋转与1/4的缓苏时间的干燥条件较优。本研究成果为胡萝卜微波干燥应用提供理论参考依据。

In order to improve the quality of dried carrot,and reduce the overheating area and excessive drying problem,the combination of multi-physical field simulation and microwave drying test system was performed in the study.The effect of carrots rotation and tempering time on the temperature distribution,drying characteristics and quality(color,rehydration rate,VC content and sensory evaluation)under microwave drying was also investigated.The results showed that the RMSEs of simulated moisture ratio and experimental value were all less than 5%under the developed drying modes,which accurately simulated the heat and mass transfer process of microwave drying for carrot.The temperature uniformity indexλof rotating samples decreased to 0.092 compared with that of non-rotating samples,which indicated that the temperature uniformity of dried products could be improved significantly.The quality of carrot was also improved during rotation,wherein the standard deviation of color difference was decreased to 0.18.Under R1/4(the samples were rotated during drying,and tempered for 60 s in a single cycle stage)condition,the temperature distribution range of carrot samples was 65-75℃.In addition,the color difference and VC content were the best among all drying modes.Therefore,the combination of rotation and tempering could be used to improve temperature uniformity and quality during microwave drying.Those results can provide a guidance for industrial application of microwave drying carrot.