Olive oil, from the tree to the bottle

HARVEST TIME
The olive harvest is the starting point of the production process. Olives usually ripen in late autumn, turning from green to black—even if there are clear differences depending on each variety and geographical area. Producers should only pick fresh olives that are still hanging on the branches, taking care to avoid bruising or lacerations that may damage their surface. ‘Cropping’, a manual method, is doubtlessly the best way to harvest, as it ensures in-depth screening. Yet, due to today’s production needs and efforts to significantly lower costs, many companies opt for mechanical systems. ‘Combing’ is particularly essential in this sense; it foresees an ‘oscillating’ procedure which shakes each tree, causing the riper olives to fall.

MILLING
Transport to the mill should be done as quickly as possible as this is the most delicate, important stage. During processing, the olives are washed and separated from the leaves. They are then pressed and reduced to pulp. Traditional stone grinders can be used for this process. Otherwise, experts can adopt modern presses, that usually work thanks to a hammer or toothed disks.
The next step involves constantly stirring the oily paste, which is slightly heated. This procedure facilitates the subsequent extraction of oil, which tends to form increasingly large drops. Possible disadvantages that may arise due to oxidation are often solved in modern facilities with the addition of nitrogen, a harmless, neutral gas.
The separation of solids and liquids occurs thanks to stacked fiber disks where small amounts of oily paste are deposited. Once isolated, this mixture of water and oil is subjected to a brief centrifugation process.
 
THE FINAL PRESS
The final press is then isolated and bottled. Left-over pulp and water is sent to special refineries where it undergoes further squeezing. The derived oils are then sold for industrial use or as fertilizer. The traditional method just described is also called the ‘off-cycle’ system because each individual step is carried out with at different times and with various tools. Many mills are now equipped with machines capable of combining all these stages—now called ‘a continuous cycle’. The use of one method, does not influence the oil’s final quality, which is not affected by the production process used.