How do olives become olive oil?

Very "pressing" Question. All Olives are pressed for their oil. Some are chilled hence cold press others are pressed untill they are drained resulting in the "grades" extra virgin means first pressed etc...

Olive oil has been a staple food in the Mediterranean for thousands of years, and some olive trees which are hundreds of years old still bear fruit. The process for making olive oil is relatively simple, especially as it is practiced in rural areas of Greece and Italy. Commercial olive processing is somewhat more complex, but it still relies on the same basic principle: crushing the olives to release the oil trapped inside. The process can also be used to extract oils from nuts and grains as well.

The olive harvest is the first step in making olive oil. Traditionally, olive trees were beaten by hand to release the fruit, although many processors use commercial machinery today to strip the trees. Once the olives have been picked, the clock starts ticking: they must be brought to an olive mill as soon as possible, or the acidity level will climb too high, ultimately affecting the flavor. After being brought to the mill, the olives are picked through to remove large branches and leaves, and then sent through a cleaner which removes dirt, leaves, and twigs, leaving plain olives behind.

The cleaned olives are run through a mill which turns them into a paste. Traditionally made olive oil still uses a stone grinder to mill olives, although commercial processors have turned to high volume metal grinders which can operate continuously. The resulting paste is subjected to the malaxation process, which means that it is slowly mixed so that droplets of oil begin to adhere to other droplets in the mixture.

After being mixed, the olive paste is put under pressure to extract the liquid oil along with water from the fruit, leaving the paste or pomace behind. The olive oil is separated from the water, usually in a centrifuge, and the olive oil is bottled while the water is discarded. The resulting olive oil is called virgin, because it is made through a purely mechanical technique. Olive oil with acid levels measured at less than 1% is considered “extra virgin” and usually has a particularly rich and intense flavor. Olive oil with a higher acid level (1-3%) is labeled “virgin.”

Refined olive oil is olive oil that has been chemically treated to reduce the acidity. Sometimes olives which have been allowed to sit too long before processing make a high acid olive oil, which must be refined. This reduces the value of the oil, so farmers try to avoid this whenever possible. The pomace can be further chemically processed to extract more olive oil which is usually blended with other oils or used for processes like soap making.

If you want to make your own olive oil you will have to buy a press.

Olive oil is obtained by cleaning the olives and then pressing them. That's it.

As for the grades of olive oil, that has to do with the process used to make the oil as well as the amount of acid and aroma or flavor.

Extra Virgin olive oil is oil that is pressed by purely mechanical means, once, with no other processing other than washing, centrifuging and filtering. It has an acidity of <1% (of oleic acid) and has exceptional aroma and flavor.

Virgin olive oil is oil that is pressed as extra virgin is, but has an acidity of 1-3 % and has good aroma and flavor.

Olive oil, or pure olive oil, can be the 'leftovers', that is, it can be oil that is extracted from the dregs of other pressings, and extracted with other means. It is usually blended with other grades of olive oil.

Olives are pressed and squeezed to get the oil out of them. The difference between the virgin and extra virgin is the size of the olives used. Smaller olives that have not completely achieved their maximum size are picked early to make the extra virgin variety. Since it takes more of them the extra virgin type is usually more expensive.

They are pressed. Extra Virgin olive oil is first press, Virgin is second press, etc.

They press the oil out of olives.

Press the oil out. The first pressing is extra virgin and so forth. Less sediment in the first pressing.