紫薯片热风与微波联合干燥特性及品质评价

Characteristics of combined hot-air and microwave drying for purple sweet potato slice and quality evaluation

对紫薯片热风与微波联合干燥特性进行了研究,考察了6种数学模型的适用性,对干燥后紫薯片的色泽、复水比以及干燥时间和能耗进行了分析,并与单独干燥进行比较。结果表明:紫薯片热风-微波联合干燥前期与单独热风干燥相应阶段一致,后期分为升速和降速阶段。微波-热风联合干燥前期与单独微波干燥相应阶段一致,后期只有降速阶段;联合干燥的热风干燥过程和微波干燥过程分别采用Verma模型和Modified Page模型进行描述;联合干燥所得紫薯片褐变较热风干燥严重,与微波干燥差异不显著。微波-热风联合干燥花青素降解最严重,热风-微波联合干燥花青素保留效果最好。联合干燥复水比低于热风干燥,高于微波干燥。热风-微波联合干燥干燥时间和能耗都介于微波干燥和热风干燥之间。微波-热风联合干燥干燥时间最长,能耗最高。热风-微波联合干燥具有干燥产品品质好、能耗较低的特点,更适合于紫薯片的干燥。

The characteristics of combined hot-air and microwave drying for purple sweet potato slice was studied, and the applicability of six mathematical models for the process was evaluated. The color rehydration ratio drying time and energy consumption of dried samples from combined drying were compared with those from single drying. The results showed that the early period of combined hot-air and microwave drying （HD-MD） was same to hot-air drying （HD） and the late period was divided into accelerated drying stage and falling rate drying stage. The early period of combined microwave and hot- air drying （MD-HD） was same to microwave drying （MD） and the late period included falling rate drying stage only. The best models for describing HD process and MD process in combined drying were Verma and Modified Page, respectively. The dried samples obtained by combined drying browned more seriously than HD and there was no significant difference in browning degree between the samples obtained by combined drying and MD. Anthocyanin of dried samples obtained by MD-HD degraded most seriously and anthocyanin of dried samples obtained by HD-MD was reserved best. Rehydration ratio of combined drying was lower than that of HD and higher than that of MD. Drying time and energy consumption of HD- MD was between MD and HD. Drying time of MD-HD was longest and energy consumption was highest. HD-MD was more suitable for drying of purple sweet potato slice with good quality of products and low energy consumption.