An industrial process that reduces the acidity of the oil (olive oil or olive-pomace oil). It also removes oxidized substances and defects from oils.
Following refining, the olive oil, as tasted, presents as a defect-free fat. Before being consumed, it must be blended under controlled (calibrated) conditions with an extra virgin olive oil or a virgin olive oil. Such oils determine the color and flavor of this material.

The law does not establish minimum quantities (%) of virgin olive oil or of extra virgin olive oil to be blended with the refined product. The general practice points to a 5-8% blend. The better producers may even reach 30%, and will use only extra virgin olive oils, to produce a more pleasingly palatable “olive oil”.