干燥介质相对湿度对红枣热风干燥特性的影响

Effects of relative humidity of hot air on drying characteristics of red jujubes

以新郑大枣为实验材料,利用单因素实验法,在控湿阶段相同温升范围(35~65℃),相同风速(1m/s)条件下,研究了控湿阶段不同相对湿度(持续排湿、40%、50%、60%)对红枣内部升温、干燥时间、能耗、感官品质的影响。结果表明,在控湿阶段增加热风相对湿度可以提高红枣内部升温速度,避免表皮硬化,增加红枣内部水分向外迁移的速度,从而提高整体干燥速率,缩短干燥时间,降低干燥过程中的能耗。当控湿阶段相对湿度为60%时,干燥时间比整个阶段持续排湿干燥减少了15.30%,能耗降低了34.78%。红枣干制品收缩均匀,颜色鲜亮。目前的研究结果有助于了解热风相对湿度对大枣干燥特性的影响,为提高干燥率和干燥品质以及降低干燥能耗提供了理论依据。

Using Xinzheng jujubes as experimental material,the effects of different relative humidity (continuous dehumidification,40%,50%,60%) on internal temperature rise,drying time,energy consumption,and sensory quality of jujubes were studied. The jujubes were dried at 35-65 ℃ with constant wind speed (1 m/s) and humidity. The internal temperature of jujube was measured by T-type thermocouple and data acquisition instrument,and the energy consumption during drying was recorded by electric energy meter. The results showed that increasing relative humidity of hot air could increase the internal heating rate of red jujubes and avoid skins hardening. Moreover,the internal moisture migration rate of red jujubes increased,which improved overall drying rate,shortened the drying time and reduced energy consumption during drying. When the relative humidity was 60%,the drying time and energy consumption during the whole stage reduced by 15.38% and 34.78%,respectively,compared against that of continuous dehumidification,and the dried jujube products shrank evenly with bright color. Overall,current research provides a theoretical basis for improving the drying rate and drying quality,as well as for reducing energy consumption when drying jujubes.