Olive oil is graded according to factors of pressing and quality of the oil. Extra Virgin Olive Oil is the finest grade, and the grade is given to oil from the first pressing. In Italian, the method used is cold pressing (in which no heat is used above about 60 degrees Fahrenheit.
Olive oils are classified and described as follows:
Extra Virgin Olive
This is oil extracted from the olives solely by mechanical, of other physical means, which cause no alteration to the oil, and which has not been subjected to any other treatment than washing, decantation, centrifugation and filtration.
Extra-virgin olive oil represents the top quality of olive oil production. European regulations lay down that an oil can be defined as extra-virgin only if it conforms to a series of chemical parameters (more specifically, the acidity of the oil must not exceed 0.8%) and if the Panel Test, performed by a group of tasters who assess the quality of the oil, it is judged to be without defects.
Virgin Olive Oil
Produced using the same methods as for the extra-virgin, virgin olive oil must conform to the chemical and organoleptic parameters laid down for this category by the EEC Regulation. The acidity must not exceed 2% and only slight defects which may compromise taste and fragrance should be discerned in the Panel Test.
This is produced through an industrial process of chemichal or physical refinement and the blending of the different types of oil. This is generally oil which has emerged from the oil mill with a high acidity and other defects. The industrial process and the blending with extra-virgin olive oil improves the product and renders it edible. However the acidity must not be greater than 1%. No organoleptic test is prescribed for this type of oil.
Olive Pomace Oil
This is produced by extracting the oil remaining in the pomace, the residue of the mechanical processing of the olives. This operation entails the use of chemical solvents and the addition of virgin oil.The acidity must not exceed 1%; for this category too no organoleptic test is prescribed.