What Are the Methods for Removing Residues in the Extraction Process?

Solvent extraction is one of the primary processes for producing edible oils and is very common in today's edible oil processing industry. Extraction equipment utilizes organic solvents to fully contact the oilseeds, dissolving and extracting the oil to form a mixture called miscella. The solvent is then separated and recovered from this miscella through processes like evaporation and stripping to obtain the extracted crude oil.

Residues, which may include solvent, oil, and other impurities, can remain during the oil extraction process. These need to be treated to ensure product quality and safety. 

The following methods are commonly used in production to separate and recover the solvent:

Solvent Recovery System: 

The solvent used in oil extraction must be recovered and treated to reduce environmental impact and lower costs. The solvent recovery system uses equipment like condensers, water separators, and solvent holding tanks to separate the solvent from the miscella. The solvent is then purified and recycled for reuse.

Desolventizer-Toaster (DT): 

The wet meal (spent flakes after extraction) enters the desolventizer-toaster. Through desolventization and drying, a dry meal is obtained that meets the required standards for solvent residue. This system ensures the meal's nutritional value is preserved and that it meets safety standards.

Refining Equipment: 

In the solvent extraction production line, oil refining equipment is crucial for ensuring oil quality. The refining process includes steps such as degumming, dehydration, deodorization, deacidification (neutralization), and decolorization (bleaching). The purpose is to remove impurities and enhance the quality of the oil.

The role of refining equipment in production includes:

Although the extracted oil undergoes desolventization, slight residues may remain. Refining equipment further removes mechanical impurities and inherent oil components like phospholipids, pigments, and waxes.

Deodorization removes volatile compounds causing off-flavors and odors, adjusting the flavor profile of the oil.

Decolorization improves the appearance and quality of the oil by removing color bodies.

Through the methods described above, the miscella obtained from solvent extraction can be effectively processed to handle residues from the oil extraction process, ensuring the quality and safety of the final edible oil product.