3. Press out the oil. The shape of oil soybean is different from other oilseeds. Therefore, in the process of pressing, the requirements for screw pressing and chamber pressing are different from those for other oils. In production, it is required to have serrated curve and conical surface, which is conducive to the full destruction of soybean molecules and the maximum oil production.
The main colloidal impurity in crude oil is phosphorus. The existence of colloidal substances, such as phospholipids, not only reduces the quality of oil, but also promotes the transition emulsification between oil and lye in the process of alkali refining and deacidification, increases the difficulty of separation of Gleditsia sinensis, and aggravates the loss of neutral
oil.Therefore, it should be removed first.
Oil deacidification is mainly to remove free fatty acids in crude oil, as well as a small amount of gum, pigment and trace metal substances in oil. Deacidification is one of the important factors that directly affect the yield and quality of refined oil. The most widely used method in industrial production is alkali refining deacidification.
The color of oil and some other impurities must be decolorized to reach the product quality standard. At the same time, it
provides more favorable conditions for deodorization and refining. Decolorization should meet the final color requirement of the product; Remove the relevant pigment and metal amount; Further remove the residual trace saponin, phospholipids and other colloidal impurities and some odor substances in the oil; Removal of polycyclic aromatic hydrocarbons and pesticide residues; Reduce the peroxide value of oil.
The purpose of oil deodorization is to remove the odor causing substances and other volatile substances, improve the smell and color of oil, and improve the stability of oil quality. The peculiar smell of oil, the peculiar smell produced in
decolorization,the clam odor produced by oil oxidation, etc. In the deodorization stage, it is required to directly spray these
undesirable odors into steam distillation at high temperature in vacuum to remove them.