[continued from above]
After the oil is extracted through the hydraulic press it is placed in a centrifuge to separate the particulate matter from the oil. This helps clarify the oil and increases the temperature at which it burns during cooking (although it’s not really ready to use for cooking until it is filtered after aging).

Following the centrifuge, the oil is ready to be aged. For this, it is stored in ceramic-lined cisterns in the ground from 6 months to 3 years, depending on the style of product being produced. For example, mosto, which is used for drizzling over salads and never used for cooking, is bottled directly from the cistern after 6 months to a year. It is very green in color, is somewhat cloudy and has quite a noticeable taste of olives and a bit of a bite of black pepper in the back of the throat as it goes down.
As the oil ages it becomes more and more refined. The color changes from green to gold, and after filtering through cotton up to 20 times it has a higher level of clarity. The aged and filtered oil is better for cooking and for using on fish or foods with a very subtle flavor that mustn’t be masked or overpowered by the flavor of the oil.
My favorite part of the factory visit is when Vincenzo dips a pitcher into the cistern, pulls out a couple liters and pours it back in and allows guests to put their face into the pitcher. One whiff and your whole head is filled with the pungent aroma of olives. It is really quite incredible.
Vincenzo is always very careful around the cisterns. Since people are mostly water and water is heavier than oil, swimming is not an option if one falls in – sinking immediately and dying an agonizing death is.

I asked about the “meat hooks” hanging from the ceiling of this old building. Vincenzo told me that contrary to my belief that tourists were hung from them and aged in a back room like a scene from “Hostel,” they were actually used to drag the bottom of the cisterns to retrieve jugs and other utensils that occasionally fell in in times gone by.

So what makes olive oil Extra Virgin Olive Oil? (Anyone?)
Hint: It’s not that it’s the first time the olives have been pressed. (That’s called "first pressed").
–No, it's the low acid content that makes EVOO. Olives that are picked from the trees and not allowed to sit on the ground have less acid than those that fall naturally and hang out on the ground for a while. So you see, EVOO actually has more to do with the handling and harvesting of the olives, and the quality of the product produced by them, than it does with how many times they've been pressed.
Another common term, "cold pressed," means that the olives have been squeezed slowly in a special hydraulic press, so they will not be exposed to the oil-damaging heat of conventional presses. Also, with cold pressing, there has been no steam applied to extract additional oil from the paste.
Beautiful olive oil, made by a friend, is one of many things that has brought me back to this part of the world, time and time again.