Walnut peel changes from dark green to yellowish green or yellowish when it is ripe. Some of the total bracts crack and a few fruits drop, which can be harvested for processing. When peeling, walnuts should be stacked in a shady place or indoor, with a stacking height of 30 - 50 cm, covered with walnut leaves or grass. After 3 - 5 days, when the green skin is removed from the shell, it is stripped manually or carved with a knife.

After peeling, put walnuts in a basket, then put them in water, stir them with bamboo broom, wash them for 5 minutes each time, change 2-3 batches of water, and then bleach them. Heating water with 1 kg bleaching powder is 6 - 8 kg. After dissolving, the residue is filtered out and then diluted with 60 - 80 kg clear water to form a bleaching solution. After the walnut is put into the bleaching solution, it is stirred continuously. When the shell changes from blue-red to yellow-white, it can be fished out. The remaining white spots of bleaching powder can be washed out repeatedly with clean water until light white. Bleaching is carried out in a vat, not in an iron bucket, in order to prevent the walnut shell from turning green. Each rinse 80 kg walnuts, bleaching time is 8 - 10 minutes. After the walnut is fished out, 0.5 kg of bleaching powder is added to the bleaching solution and reused for 7 - 8 times. Walnuts can be bleached for half a day and then spread out after most of the water evaporates.

The drying time is between 15 and 20 hours, and temperature is between 40 and 50 ℃. The system can use 7 degrees of electricity per hour, and customers can also adjust the temperature and drying time according to the actual situation.