Edible Oil Pretreatment
Before pressing, soybean should undergo a series of pretreatment like selecting and cooking,etc.
1.The soybeans are stored in abundance. oil.
2. Selecting. As the weight and size between soybeans and residues are different, the relative move on the revolving screen can discard them.
3. Then crushing machine is needed here for crushing soybeans to small pieces for easily pressing. It ensures the regular amount of average soybean pieces, neither oil,block nor powder. After crushing, the oil rate will be improved.
4. Cooking is necessary here to destroy cell structure of the oil seeds and protein, at the same time, the phospholipid adopts water and swell for pressing.
Edible Oil Pressing
The pretreated soybean are fed into the screw oil press by elevator if in bulk. Here the integrated screw oil press is used.
1.Before pressing, the oil press should be tested and warm up, so oil cakes are necessary at this moment. Several minutes are enough and then begin to press.
2.When pressing, soybean feeding should be continuous and average to make sure the normal working of oil press.
3.As the filtering system is equipped with oil press, so the pressed oil is filtered directly which saves time and trouble.
4. After filtering, the oil enter the receiving tanks for storage.
5. The oil cakes discharged from the outlet consist of 8-10% vegetable oil and can be repressed. Then cakes are consumed used as animal feed.
Edible Oil Refining
Refining is to process pure soybean oil for edible standard. We adopts chemical refining method and it consists of the following four steps.
By adding into hot water, degumming is to remove the agglomerated and deposited hydrosol and phosphatide. The separated gum (after being dried) can be made into lecithin or added into cakes or meals in the extraction workshop. Hydration degumming process can improve oil edibility, storage and do well to downstream neutralization section.
Oil containing fatty acid is mixed mechanically with a slight excess of alkali to react with fatty acids present to form soaps. The mixture is centrifuged to separate oil from soap stock. After washing with water, the water is separated from the oil in a second centrifuge.
Degummed and neutralized oil are pumped into this system and mixed with by the use of bleaching earth, a special soap, gum, and pigment attracting adsorbent. The mixture enters the Pre-filtration Dryer where the moisture in the oil and adsorbent is evaporated. Then the oil is pumped through an automatic closed filter to remove clay.
The oil contains the disagreeable flavor and odors that are naturally present or created during processing. All odoriferous matter is distilled off by injecting high pressure steam through vacuum system. Then the product achieves the national standard.