The extraction pressure comprises a series of stages well determined and characterized by the discontinuity.
On the kneaded compound is applied to a pressing which separates the liquid portion from the pomace. The resulting fluid must then centrifuged (centrifugation) in order to obtain a first separation of water from oil; the deleted portion is defined vegetation water. The compound obtained is then subjected to filtration, from which you get the virgin olive oil.
The extraction by centrifugation is instead composed of a single continuous process which allows to obtain simultaneously all three trailing components; NB. the extraction by centrifugation shows a high cost in terms of energy.
The extraction of the centrifuge braked exploits the difference of 3 specific weights obtained separately but continuously: pomace, virgin olive oil and vegetable water.
The extraction by percolation and selective filtration adopts a different physical process; this technique uses the higher surface tension of oil as compared to that of water.
In kneaded is immersed a large steel plate which, on the difference in surface tension between the two fluids, it wets mainly oil; this is then removed and drained into another container.
The leachate can originate oil and must subsequently centrifuged to extract more oil at the expense of the vegetation water. Or can generate oil and pomace not definitive, are obtained by centrifugation which must (treated as described above) and residue.
The one or the other method is applied based on the type and effectiveness of percolation.”
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