Olive Oil extraction
The process to obtain oil from olives is achieved through 3 phases: crushing, mixing and kneading. Each of these phases must be carried out in the best way to safeguard the intrinsic properties of the oil.
The transformation of olives into oil must be carried out according to a precise method in order to guarantee the typical fragrance and an unmistakable flavor. There are three types of extraction systems:
- Discontinuous: traditionally, this uses the old method, with two grindstones that crush the olives. The resulting olive paste is then worked by a worm-screw to aggregate the tiny droplets of oil (malaxation). At this point the paste is spread on special nylon filter disks stacked on top of one another and put between hydraulic presses to extract the oil.
- Continuous: the grinding here is done by modern hammer crushers that crush the olives against a perforated cylinder. After malaxation, the oil is extracted by percolation-centrifuging or just centrifuging the paste. Percolation separates water from oil by means of thin stainless steel blades that enter and exit the paste and extract, by adhesion, only the oil, which drips down the outside. This method extracts from 40% to 60% of the product. The remaining oil is separated out in a horizontal centrifuge called a decanter in which the high speed of rotation separates the paste (called pomace) from the oil and water.
- Semi-continuous: the grindstone method is followed by the decanter. The extracted product (water/oil emulsion) is separated out by a vertical centrifuge. The remaining pomace is sent to a facility that uses special solvents to extract the residual oil. Following extraction, each product undergoes stringent tests to determine its product category and compliance with standards. If its acidity as a percentage of free oleic acid is under 0.8% and its organoleptic contents are "absolutely impeccable,” the resulting product is extra virgin olive oil (extravergine); otherwise it will be virgin olive oil (maximum acidity 2%) or lampante olive oil (acidity > 2%) with organoleptic characteristics that make it not directly edible.