花椒微波烘干效果试验研究

Effects of drying fresh Zanthoxylum bungeanum fruits with microwave

为给鲜花椒微波烘干效果的研究和花椒微波烘干机的研制奠定基础,分别利用小型平板层式微波炉及自制大型微波炉对鲜花椒进行了间断式和连续式烘干试验。试验结果表明:无论采用旋转式微波炉还是平板层式微波炉,烘干时间均随鲜花椒投料量的增加而延长,干燥后花椒香味降低;填料约700 g,以小型旋转式微波炉和平板层式微波炉烘干所用时间分别约为44、62 min,前者的烘干效率比后者提高20.48%;鲜花椒在旋转式微波炉中水分蒸散过程表现为抛物线型,在烘干过程中花椒种子集中脱出,烘干效率高,但其在平板层式微波炉中水分蒸散过程呈缓慢降低的斜线型,种子在烘干过程的最后阶段才脱出,烘干效率低;以自制大型微波炉烘干,填料3.45 kg,最佳加热上限温度和运行温度分别为55℃和41～50℃,加热—除湿循环中加热8 min、除湿90 s,烘干时间为45 min,较以小型平板层式微波炉烘干所用时间缩短29%。研究结果还表明:以微波炉烘干鲜花椒,可极大地缩短鲜花椒的干燥时间;以自制大型微波炉烘干鲜花椒,最大填料量约8 kg,可以满足农户对小批量鲜花椒的烘干要求。

In order to provide some bases for the studies on effect of drying fresh Zanthoxylum bungeanum fruits with microwave and on development of microwave dryer for Z.bungeanum,fresh Z.bungeanum fruits was discontinuously and continuously dried by using small flat-layer microwave oven and large self-made microwave oven.The results showed that drying time was prolonged with increase of amount of fresh fruits,whether using rotary or flat-layer microwave ovens,and aroma of dried fruits reduced.Drying time of about 700 g materials by using small rotary and flatlayer microwave ovens were about 44 and 62 min respectively,and drying efficiency of the former was 20.48%higher than that of the latter.Transpiration process of water in fresh fruits showed a parabolic type in rotary microwave oven,seeds were intensively taken off during drying process,and drying efficiency was high.However,transpiration process of water showed a oblique descent linear type in flat-layer microwave oven,seeds were taken off only at the final stage of drying process,and drying efficiency was low.Drying time of 3.45 kg materials by using large self-made microwave oven was 45 min,the optimal heating upper limit and operating temperature were 55℃and 41-50℃,respectively,heating time was 8 min and dehumidifying time was 90 s during heating-dehumidifying cycle,and drying time was reduced by 29%than that by using small flat-layer microwave oven.The results also showed that drying fresh Z.bungeanum fruits in microwave oven could greatly shorten drying time,and the maximum filling capacity of large self-made microwave oven was about 8 kg,which could meet drying requirements of farmers for small amount of fresh Z.bungeanum fruits.