qualities of the olive oil

Olive oil is a food oil extracted from olive fruits. But how many types of olive oil exist? Which ones are comestible? And what are their characteristics? The finest olive oil is extra virgin olive oil, which is obtained from the mechanical pressing of the fruit, without the use of chemical additives, usually no more than 24-48 hours from harvesting . To obtain the extra virgin olive oil, pressing must take place cold, that is, at a temperature lower than 27°C, in order not to alter the organoleptic qualities and physical-chemical properties of the product. To be considered extra virgin, an olive oil should not contain a percentage of oleic acid greater than 0.8%. The same pressing process is used for the production of virgin olive oil, which differs from extra virgin oil because of lower quality and free acidity, that is a content of oleic acid not greater than 2%. Besides its use as food, this type of oil is used to refine olive and olive-residue oils. Olive oil consists in the mixture of refined olive oils, which have then undergone an industrial process that reduces acidity and eliminates oxidised sub-stances. It includes a percentage (maximum 10%) of extra virgin or virgin olive oil, which partially reinstates the nutritional substances that refined olive oil does not contain, such as polyphenol. This type of oil can have a free acidity not greater than 1%. Through the use of solvents from olive pomace, that is production waste, skins and kernels, olive-residue oil is then produced. Also in this case, to make the previously already refined olive-residue oil comestible, it is necessary to mix it with extra virgin or virgin olive oil in variable quantities, usually around 5%. Olive-residue oil can also have a maximum of 1% free acidity. The characteristics and related production methods of these different variety of oils were included in Regulation (EC) No 702/2007 of the European Commission of 21 June 2007 amending Regulation (EEC) No. 2568/91 concerning the characteristics of olive oils and olive-residue oils and on the relevant methods of analysis.