Expeller pressure

An expeller press is a screw-type machine. The principle of the expeller press is to force the material to be extracted into a tapering tube by means of a rotating screw. The tube is perforated along its length by narrow slits and terminates in an adjustable cone that gives a variables gap between the cone and the tube exit.

The machine uses friction and continuous pressure from the screw drives to move and compress the material. The fat is forced out through the tube slit.

In processing of natural oils, the oils are crushed from seeds or grain, using the hydraulic action of an expeller press. No heat is involved in the pressing and no chemical antioxidants are added to preserve the oils. The oils seeps though small openings that do not allow seed fiber solids to pass through.

Expeller pressing yields less oil than solvent extraction, usually 50 to 70 percent of the oil, so expeller-pressed oils are usually more expansive than conventionally processed oils.
Expeller pressure