Olive Processing – How We Do It
Modern technology has rendered the terms “cold pressed”, “first press” or “first cold press” obsolete. Extra virgin olive oils today are largely made in a single, continuous process using very modern and technologically advanced equipment.
The Crusher – Hammer Mill
Olives are fed to the crusher through a short screw-conveyor assembly that leads the olives into the zone where rotating hammers equipped with wear-resistant metal plates crush the olives against a stationary grid. The diameter of the holes in the interchangeable grid determines the thickness of the paste. After passing through the grid, the paste drops into a hopper or the malaxing section.
Two malaxers are placed beside each other and are connected to a common feed manifold and a common discharge manifold. Each malaxer has its own shaft with a specially designed agitator that constantly blends the paste while continuously removing paste from the vessel wall to prevent overheating. Water is circulated through the jacket of each malaxing vessel to control the temperature of the paste.
The Decanter Centrifuge
The decanter centrifuge design ensures separation of the incoming olive paste into two phases – oil and wet solids.
The olive paste is fed into the bowl through a stationary inlet tube and is then smoothly accelerated by an inlet rotor. Separation takes place in a horizontal cylindrical bowl equipped with a screw conveyor. Centrifugal force causes instant sedimentation of the wet solids on the wall of the bowl.
The conveyor rotates in the same direction as the bowl, but at a different speed, and conveys the wet solids to the conical end. Because it is lighter, the oil flows on the inside, and the wet solids move towards the outer perimeter. Separation takes place along the entire length of the cylindrical part of the bowl. The liquid phases pass to their outlet via a vibrating filter and is then discharged into the vertical decanter (see Clarification).
The last main stage of the olive oil production process is the final clarification, in which a vertical centrifuge separates the oil from any remaining water and olive residue. This involves a specially designed unit where separation takes place inside a rotating bowl that uses centrifugal force to extract the suspended solids and traces of water. The olive oil is then discharged to the collecting tanks.
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