高湿预处理对怀山药热风干燥特性及复水性的影响

Effect of high humidity preconditioning on hot air drying and its rehydration of Chinese yam

怀山药片经高湿预处理后进行热风干燥,研究相对湿度、处理时间等因素对怀山药片热风干燥特性和复水特性的影响规律,进而获取最佳的怀山药切片热风干燥工艺参数。结果表明:与直接热风干燥处理相比,控制较高的相对湿度可显著缩短干燥时间,而且干燥产品的复水性也优于直接热风干燥处理;切片厚度为3 mm的物料在恒湿(相对湿度40%)条件下处理30min后,进行热风干燥处理(风温60℃、风速3.5m/s)时,干燥能耗最低(19 056kJ/kg·H_2O);该条件下得到的怀山药片的ΔE值和多糖含量分别为8.17、5.14%,而直接热风干燥怀山药片的分别为12.35、4.96%。

The effect of the drying properties on hot air drying by rel- ative humidity control of Chinese yam was studied. The test material was treated with high humidity after the hot air drying, and factors on the drying characteristics and rehydration characteristics were in- vestigated, including the treatment time of humidity, slice thickness, dying temperature, and drying air velocity. The L9（34 ） ortbogonal test was used to get the best drying process parameters on energy consumption, the content of polysaccharide and the color of two kind of yam （prepared by the best drying process parameters on energy consumption and hot air drying without relative humidity） were determined. The results showed that, compared with direct hot air dying, high relative humidity control could not only greatly short- en the drying time, but also improve the rehydration characteristics. Moreover, the energy consumption was the minimum of 19 056 kJ/kg H2O when material under the conditions of constant temperature and humidity （ Slice thickness of 3 ram, temperature of 60℃, relative humidity 40%, treat time 30 min）, hot air drying treatment （air temperature of 60 ℃, air velocity of 3.5 m/s）. Under this condition the △E value of yam chip and polysaccharide content were 8.17% and 5.14%, respectively, while those of directly hot-dr- ying were 12.35% and 4.96%.