Milling is the first phase of extra virgin olive oil extraction. Using a mechanical process, the olives are crushed, with the consequent release of the juices and oil contained in the fruits. The result of this process is oil paste, a semi-fluid product consisting of fragments of kernels, peel, pulp and an emulsion of water and oil. The oil paste can be produced in two different ways: through classic milling or through continuous cycle pressing.
Traditional milling is performed using a muller, a machine derived from ancient millstones, in which the whole olives are pressed by one or more wheels. In particular, these wheels grind not only the pulp of the olives, but also the kernels: the rubbing of the pulp and kernel fragments encourages the release of the oil from the olives. This processing requires from 20 to 40 minutes given the slow rotation of the grinder.
Continuous cycle pressing
The most modern plants use hammer crushers in a continuous cycle. These machines are composed of a series of disks with sharp edges, or hammers, which rotate at a speed of 1200-1300 rpm, chopping the pulp of the olives. With continuous cycle pressers, the load comes from above, along belts conveying the olives, and the paste produced is discharged at the bottom, then directly placed in a kneader.