Oil extraction by pressing and oil extraction by leaching are two common methods for extracting vegetable oil, and they are obviously different in raw material requirements, processing technology and nutritional components.

Different material requirements
The pressing method is suitable for oils with high oil content, such as peanuts, soybeans and cottonseed, while the leaching method is more suitable for oils with low oil content, such as rapeseed and sunflower seeds. Since only pressing is carried out, the residual oil in the cake is high, so in order to save resources and pursue benefits, large enterprises will use leaching method to fully extract the oil from the pressed cake again.
Different processing techniques
Oil production by pressing is a method of making oil from oils by physical pressing, which originated from the traditional oil production method in workshops. The method of leaching refers to the processing method of cleaning, crushing, cooking and other processes, leaching with solvent (such as n-hexane), and then evaporating the solvent to obtain oil.
Different nutritional components
Oil-making by pressing is to make oil by squeezing oil with the help of manpower or machinery, so pressing oil can retain the original flavor of raw materials to a greater extent and retain various nutrients in raw materials, such as the fragrance of sesame oil. However, the oil extracted by leaching method is mostly colorless and tasteless, which can retain the main nutrients in raw materials, such as oryzanol in rice bran oil.
Strictly speaking, the basis for measuring the quality of edible oil is not the oil-making process (whether it is pressing or leaching), but the index system formulated by the state for all kinds of edible oil. As long as it meets the quality standards and hygiene standards of edible oil, it is safe to eat.