By: Francesca Montillo, ISDA Food + Travel Writer 

Ever wonder how olive oil is made? You’ve come to the right place! I grew up in Italy and one of my fondest memories is helping my family pick olives for the production of olive oil.

We had a sizeable plot of land not far from our home in which our family grew olive trees. This plot of land also contained many fig trees, and since our home didn’t have a back yard, we would visit here for picnics, and just so us kids could roam around freely and safely.

Now, as a young child, the “help” I provided was minimal at best, but I recall being handed a big white bucket and my mom saying, “go and fill it, and don’t come back until it’s full!” Truth be told, I ran around like a wild child more than help, and my favorite part was not the manual labor, but waiting until mom set the picnic table and take out lunch!

She would prepare many wonderful dishes to enjoy during the course of the day, including cutlets, baked pasta dishes, various breads, and let’s not forget the antipasto plates filled with cheeses and salami! Yes, lunch was definitely the favorite part of my “work day” on the farm!  

Our love affair in the U.S. with imported EVOO is strong. Since it’s fall, and all of Italy is currently in the midst of their olive oil production, I thought it would be appropriate to put together a guide to the 7 stages of production. 

Phase 1: Collection  

The olive harvest is a very important phase for the production of oil. From the techniques used and the period in which this operation is put in place, the taste of the oil and its quality depend on it. For a good harvest it is advisable to wait for the change in the color of the fruit to change from green to black, this is in fact the phase in which there is a greater quantity of oil and nutrients that lead the final product to have superior quality. Collection can be done in two ways: manual and mechanical. 

Manual
Bacchiatura
This consists in “beating” the branches of the olive tree with sticks in order to make the olives fall, and then collecting them with nets placed on the ground. 

Brucatura
This involves picking the olives by hand directly from the branches. It has the great advantage of not damaging the olives and is suitable for producing top quality oils as all the fruits are selected by hand individually.

Mechanics 

Shaking
In shaking, the olives are harvested thanks to mechanical arms that wrap around the trunk or branches of the tree that are lightly beaten to favor the fall of the fruit.  

Combing
The branches are “combed” by special tools that detach the olives, these are then collected by nets attached under the trees.  

Phase 2: Storage 

This stage of processing should not be underestimated; in fact if the olives remain on the branches for too long or are left on the ground, they can undergo a maceration process, which can compromise the quality of the oil. The ideal approach would be to take them to the mill within 48 hours of harvesting.  A lot of attention must also be paid to the type of container used for storage. The olives must be collected in specially ventilated boxes in plastic, and then stored away from sources of heat. This guarantees that the olives do not ferment.

Phase 3: Defoliation and washing  

Before being introduced into the actual processing cycle, the olives must undergo defoliation and a washing process both for hygienic and sanitary reasons and for quantitative reasons of the oil. Furthermore, removing the material that often accompanies the olives is particularly appropriate when the oil mill adopts the metal crusher for the preparation of the olive paste and the centrifugal decanter for oil separation. The presence of leaves could affect the characteristics of the oil.  

Phase 4: The pressing of the olives  

In the milling process, the harvested olives, after being cleaned and washed, are subjected to mechanical actions in the mill with the aim of causing the cell wall and membranes that compose them to break. In this way, the oil comes out of the fruit allowing for the collection of the oil. The breaking is carried out in a natural way by rubbing the stones against the ends of the fruit. In this way, a “raw” olive oil is extracted, also called oil paste, a semi-fluid compound that is the main product of the pressing of the olives.  

Phase 5: Kneading 

It is the process that follows the milling or pressing, and has the purpose of breaking the emulsion between water and oil and making the micelles of oil flow into larger drops that tend to spontaneously separate from the water.

This phase is very important to determine the relationship between quantitative yield and oil quality. Heating will increase the effectiveness of the kneading allowing the increase of the oil yield, however it will negatively affect the quality. 

Phase 6: The extraction of the oil 

Extraction is the process that finally sees the appearance of a product close to the one we know. There are different techniques to bring this phase of olive oil production to completion: 

• Pressure (classic and discontinuous method) 
• Centrifugation (modern and continuous method) 
• Percolation by selective filtration 

Pressure 

Extraction by pressure is characterized by a series of well-defined phases. On the compound kneaded a pressing is applied that separates the liquid portion from the pomace. The resulting fluid must then be centrifuged (centrifugation) in order to obtain a first separation of the water from the oil. The compound obtained is then subjected to filtration from which virgin olive oil is obtained. 

Centrifugation 

With centrifugation, on the other hand, all 3 final components are obtained simultaneously with a single and continuous process.  

Percolation 

A large sheet of steel is immersed in the malaxer machine, which, thanks to the difference in surface tension between the two fluids, gets wet mainly with oil, causing the latter to be drained into another container.   

Phase 7: Storage and bottling the oil  

Storage 

At this point the product obtained is ready for consumption, however it still contains solid residues and is muddy to the eye. It therefore needs to be stored in stainless steel tanks, following chemical and organoleptic tests. Its optimum storage temperature is 15° -17° C in the absence of sunlight. 

Bottling 

The final part of the oil production, bottling is certainly one of the most delicate phases precisely because it is necessary to limit contact with the air during the transfer. Packaging is carried out by specific equipment that allows the oil to be poured into suitable containers. 

The oil is then bottled and sealed, avoiding the alteration of its organoleptic properties.
The containers must be made of dark glass to avoid contact with light, or alternatively, special tinplate containers can be used, previously treated with antioxidant materials.