The Oil



Extra Virgin Olive Oil

Virgin olive oil (Virgin and Extra Virgin) is the natural oily juice that conserves all the taste, aroma and other properties of the fruit.


It is only obtained by mechanical or physical procedures under suitable thermal conditions that do not cause any alterations to the oil. 


It is practically the only vegetable oil that can be directly consumed in virgin form, which conserves all its content of vitamins, essential fatty acids and other natural products that are important to health. 


Oil quality depends on environmental factors, the variety of olive, cultivation and harvesting techniques, and on grinding, storage and packaging.




Refining consists of eliminating the unwanted components in the oil, such as high free acidity, unpleasant tastes and aromas by means of chemical and physical processes. 


Refining commences with the removal of the free acidity in the oil, which takes place in wash centrifuges to which phosphoric acid and sodium hydroxide (caustic soda) is added. The phosphoric acid removes the gums from the oil and the sodium hydroxide neutralises the free acids. Then the neutralised acid and removed gums are taken to deodorisation towers where they fall due to the effect of gravity onto trays at high temperature; here, the volatile substances and aldehydes migrate from the oil body and then are condensed for final disposal. 


Refining produces an oil without taste, aroma or colour and not suitable for direct consumption which, moreover, goes rancid quite easily because it’s natural preservatives have been eliminated (refined olive oil). 


In order to market this oil, it requires a preservative and the only one allowed is the actual virgin olive oil, so a little virgin olive oil is mixed with it, which provides it with some colour and aroma and resulting in olive oil, previously known as pure olive oil).




Degree of acidity or acid index: this indicates the amounts of free fatty acids in the oil and is expressed as a percentage of oleic acid. Fatty acids are freed when the olive is damaged by pests, disease, poor harvesting or production, so the better the process, the lower the acid index of the obtained virgin olive oil.


It is usually thought that olive oil quality is largely determined by it acid index, in other words, oil with an acid index of 0.4º is better than one with 0.8º, for example. This is only true when talking about virgin olive oil, because the acid index is only of interest when comparing virgin olive oil qualities. It is of NO use with “olive oils”, because these are mixtures of refined oils and virgin oils and can be given whatever acid index is desired.


In virgin olive oils, on the other hand, the acid index can only be lowered by improving cultivation, harvesting and production techniques. There is therefore, no sense in comparing the acid index of an “olive oil” with that of a virgin or extra virgin olive oil.


A virgin or extra virgin olive oil will always be better than an “olive oil”, whatever the acid index of the latter. Only when comparing virgin olive oils can it be said that the one with a lower acidity is better than the one with a higher value.


Another common mistake is that of believing that a higher acid index in virgin or extra virgin olive oils means a stronger flavour. Oil flavour mainly depends on the variety of the olive, whether harvesting is early or late and on the production method. Oils produced early in the season normally have intense aromas and flavours, together with more bitterness and “bite”, whereas those from the end of the season are usually sweeter, with less bitterness and “bite”.




“Orujo” is the mass that remains after the oil extraction process.


This mass still contains a small percentage of oil that cannot be extracted by mechanical means. In the extraction industry it is obtained through the use of a solvent, hexane. However, this solvent can extract other substances in addition to the oil.


The solvent is eliminated after the extraction process by distillation and what remains is the crude olive “oruja” oil.


It is now necessary to also remove the undesired substances that were extracted by the solvent and this requires refining (see refining).


The final result is the refined olive “oruja” oil which, just like the refined olive oil cannot be marketed in this state; it must be mixed with extra virgin olive oil and put onto the market as olive “oruja” oil.


Oils produced from seeds, such as sunflower, rapeseed and soy etc, are produced in the same way as refined olive “orujo” oil.


It cannot be produced at an olive mill.