Soybeans contain a large amount of protein (35% - 45%) and fat (19% - 22%), its seed coat consists of four layers of cells, the outer layer of the cell row is very dense, the cell wall is also particularly hard, so that the seed coat becomes a resistance to moisture transfer when drying soybeans, the role of high-temperature drying medium in the grain grain of water under the heat, the pressure rises, when it can not be smoothly transferred, the epidermis is easy to swell and crack. When over-drying, soybean grains can be divided into two halves. Another characteristic of soybean grain structure is the germination hole is large, soybeans are not easy to store, its moisture content usually has to be reduced to 13%, the newly harvested soybeans must be naturally dried or artificially dried to meet the storage standards.
Soybeans can only be dried using softer methods, with tower drying, the heat temperature of the grain does not exceed 30-35 degrees, the drying medium temperature of 80-90 degrees, grain drying time of 40-45min. then drying soybeans will have good quality, not reduced, etc.
When using double drying, a drying medium temperature of 90 degrees, grain temperature of 25 degrees, the second medium temperature of 80 degrees, grain temperature of 35 degrees, can also ensure quality, soybean burst waist rate of less than 0.5%. In production practice, there is drying industrial frying oil with soybeans, using a drying medium temperature of 150 degrees, grain temperature of 55 degrees, using such drying conditions, soybean burst waist rate of 10%, although this has little impact on the oil yield of soybeans, but the quality of soybeans are subject to a lot of damage, is not recommended.