Study of Food Processing using Superheated Steam and Humid Air : Effect of Gas Humidity on Drying Characteristics of Porous Material with Sugar Solution

Abstract

Effect of wet-bulb temperature on a drying rate of porous material containing water or sugar aqua solution in high-temperature (160℃) gas flow was investigated experimentally. Glass beads were used as the sample porous material. Mass and surface temperature changes of the sample during drying were measured with a test apparatus, in which wet-bulb temperature could be controlled from 48℃ to 100℃. From these results, it was shown that when the wet-bulb temperature was higher, the drying rate was smaller and the distribution of local sugar concentration was more even in this experiment. Whereas the water in the sample maintained a constant drying rate, the sucrose solution's drying rate decreased gradually after drying was commenced.