No matter by what kind of drying equipment, the drying temperature changing process is as follows: Low temperature→high temperature→low temperature.
Exact drying temperature:30—35℃, 50℃, 30℃.
Exact drying time: 12—15 hours, 12 hours, 16 hours.
First phase: Entering into the drying room for dehumidifying in time （30－35℃→12－15 hours )
Within 8 hours after stripping off its green husk, the walnuts should be put on the shelf for dehumidifying and drying.The dehumidifying temperature should be 30- 35℃ and the drying time should be 12- 15 hours. The dehumidifying process will not be ended until the moisture on the husk surface disappears and the husk color turns from black brown to brown.
Second phase: Color forming and preliminary drying （50℃→12 hours）
After the dehumidifying process, it will enter into color forming and preliminary drying process. At this time the temperature should be increased to 50℃ and the drying time should be 12 hours. The drying finished feature is: There is no water vapor inside the kernel after opening. The color has been formed, the walnut is 70 percent dry and the kernel coating can be stripped off.
Third phase: Drying the kernel with gentle heat （30℃→16 hours）
The temperature should be controlled at 30℃ and drying time should be about 16 hours in this kernel drying period. The water content of walnut kernel should reach at about 10%.
After the kernel drying period, the drying unit should be shut down and the dried walnuts on the drying shelf must be fully covered with gunny bags in order to preserve the heat for several hours and promote water content volatilizing and reaching the uniform drying effect.