At a temperature of 16 degrees, the average density of olive oil is 0.916 kg/litre. As the temperature increases, the density decreases as the olive oil expands. In other words, the higher the temperature, the less the oil weighs. In the table Density of olive oil we can see how the density decreases as the temperature increases.
Why is density important in the production of olive oil?
To understand how olive oil is extracted from the mass, it is necessary to understand that oil is less dense than water and mass. In other words, olive oil weighs less than water and dough. This is why in a glass of water the olive oil floats on the surface and the vegetable remains at the bottom of the glass. This difference in density will allow the oil to be extracted from the mass, firstly by means of a horizontal centrifuge process and secondly by means of a vertical centrifuge process or, as Suerte Alta argues, by means of a decanting process.
- Horizontal centrifuge. When the olive mass is centrifuged, a ring is formed in which the oil remains in the centre and the vegetable water and the solid part remain on the outside. In this way it is possible to extract the oil with some vegetable water.
- Vertical centrifuge or decanting system. The second step is to purge the oil from the vegetable water and the remaining impurities. For this purpose, most oil mills use a vertical centrifuge system. This process centrifuges the liquid oil to completely remove the residual moisture and impurities in the oil. To facilitate this cleaning, a part of hot water is added to the oil. This process has the advantage of being very fast and the oils are cleaned of vegetable moisture. However, the polyphenols, being soluble in the added water, are partly lost, reducing their content in the oil.
Cortijo de Suerte Alta uses another method to clean the oil from the horizontal centrifuge. This involves static decantation in small decanter tanks. The oil is kept in these tanks for a day and since the water and suspended solids are heavier than the oil, they are deposited on the conical bottom of the decanter and it is possible to purge the oil. This method is slower and requires daily cleaning of the tanks used, but the oil obtained retains all its polyphenols as it has not been washed with water.
Density in vegetable oils
Olive oil is a vegetable oil. All vegetable oils are less dense than water: they all weigh less than water. However, within this group, some are denser than olive oil, such as sunflower oil, soybean oil or peanut oil. Others are less dense, such as palm oil, coconut oil, corn oil, rapeseed oil, linseed oil, cottonseed oil and safflower oil. You can see the density of the different vegetable oils at 20ºC in the table Density of the different vegetable oils.