Drying characteristics of ginger puree with refractance window drying method

To evaluate the adaptability of a thin-layer drying processing for liquid materials which cannot be dried with spray drying or that are heat sensitive, drying characteristics of ginger puree with refractance window method were investigated in the present study. The results showed that the temperature of ginger puree dried with refractance window at the range of 75 to 95℃ rapidly reached 60-70℃ at the initial drying period. Then it kept a slow changing trend at the later stage. But the temperature of the product was always lower than that the heated water, with a temperature range of 15 to 25℃. The temperature curve of ginger puree with 1-3 mm of thickness showed a similar trend at the same drying temperature and air velocity. The temperature of the product could be decreased through increasing the air velocity. The constant drying strength was not found when dried with higher temperature. The drying strength went up and the final moisture content of the product decreased respectively with thinner thickness of ginger puree, higher temperature or higher air velocity. The current findings show the potential of refractance window method for drying of liquid or puree materials.