North American Olive Oil Association

Olive oil extraction

Written by About Olive Oil | April 27, 2017

Contrary to popular belief, olive oil is not typically "pressed". Rather, the oil is extracted from olives using modern equipment. Contemporary olive oil extraction processes result in higher quality olive oil and better yields from the fruit. Read on to learn more about how olive oil is extracted.

Here is a breakdown of what is depicted in the above graphic

Crushing/Grinding/Milling
After the olives are prepared for extraction, they are crushed or ground using mills or grinders. The mills may be stone or metal hammer mills.

 

Malaxing
The olive paste is put into a malaxer which is a trough with spiral mixing blades. The temperature within the malaxer is monitored to ensure that the olive paste is not heated above 27ºC (80.6ºF). Malaxation takes 20-45 minutes.

 

Separate solids and water from oil
After malaxation, the mix is passed to a centrifugal extractor.  The objective is to separate the pomace (skins, pits and olive solids) from the oil.

 

Polishing/separating
The olive oil may be passed to another separator which spins the olive oil and removes any remaining water from the olive oil.  

Why isn't olive oil pressed anymore?

Traditionally, the olives would be ground with stones and then the paste would be pressed on straw or burlap mats.  In modern times, a hydraulic press made of metal can be used to press the olive paste.  However, most manufacturers have moved to centrifuges.
 
If there are no presses involved, why is extra-virgin olive oil still sometimes called "cold pressed"? Cold-pressed is a marketing term that has no regulated definition.  According to the International Olive Council, all extra-virgin olive oils are extracted at temperatures under 27ºC (80.6ºF).  So by definition all extra-virgin olive oils are "cold-pressed" or "cold extracted".
 
Watch this video for to learn more about the olive oil extraction process.
 


Image credit:  This image has been created during "DensityDesign Integrated Course Final Synthesis Studio" at Polytechnic University of Milan, organized by DensityDesign Research Lab. Image is released under CC-BY-SA license. Attribution goes to "Cecilia Della Longa, DensityDesign Research Lab". - Own work, CC BY-SA 4.0, Link