Soybean oil is extracted from soybeans using either pressing or solvent extraction methods. Most soybean oil on the market is produced using the solvent extraction method because soybeans have a low oil content. The pressing method leaves about 6-8% residual oil, affecting yield. Solvent extraction, on the other hand, fully extracts the oil from soybeans, increasing the oil yield and producing high-quality soybean meal. This meal can be used in food and feed industries, generating revenue for oil factories. Therefore, most soybean oil on the market is solvent-extracted.

The basic principle and elements of the solvent extraction method involve using a solvent that can dissolve oils. Through wetting, penetration, molecular diffusion, and convective diffusion, the oil is extracted from the seed embryos. The mixed oil, composed of solvent and fat, is then separated, and the solvent is recovered to obtain crude oil. Similarly, the solvent in the soybean meal is also recovered to obtain extracted meal. The key elements in this process are the solvent, the seed embryos, and the extraction method and process parameters that determine the extraction efficiency.

Regardless of the process or equipment used, the crude oil needs to undergo a series of refining treatments such as degumming, deacidification, decolorization, and deodorization to meet soybean oil standards and be sold on the market.

In a complete soybean oil extraction production line, refining equipment is crucial for ensuring the quality of soybean oil.

The roles of refining equipment in production are as follows:

1. Refining and Removing Impurities: 

Although the crude soybean oil obtained through extraction has undergone desolventizing, it may still have slight solvent residues. Additionally, mechanical impurities produced during production, as well as phospholipids, free fatty acids, and contamination residues inherent in the oil, need to be removed through refining equipment to improve quality.

2. Improving Color: 

The grade of soybean oil requires specific oil color standards. The crude soybean oil needs to undergo decolorization to remove pigments and improve its appearance, resulting in clear, standard-compliant soybean oil.

3. Removing Odors: 

Many consumers cannot accept the beany smell of soybean oil, along with burnt or clay odors formed during production. These "off-flavors" need to be removed through deodorization processes in refining equipment to make the soybean oil acceptable to the general consumer taste