Striking a balance between quantity and quality is the real challenge of Research in the field of extraction technologies for extra virgin olive oil.

Even though in recent years, attention has gradually shifted to quality, obtaining high extraction yields remains a priority for millers and olive growers in order to optimise farm economics.

Extraction: problems and key factors

Only a high extraction yield can pay back a year of hard work the costs incurred looking after the olive trees, but it is not easy to work this way. In fact, it is well-known that in the olive oil production process, in order to improve extraction yields, you often need to extend malaxing times or, alternatively, increase process temperatures. However, this compromise may, in turn, decrease the polyphenol content and reduce the organoleptic qualities and health benefits of the end product.

This is also due to the fact that current malaxing machines, in terms of their system, are inefficient heat exchangers.


But if it is true that the yield is the result of the oil extraction process, it should not be forgotten that the factors on which one can act to increase it, without affecting the quality of the product, can be of different types:

  • agronomic factors, which indirectly affect the olive tree;
  • technological factors, i.e. specific methods that can be used at the olive oil mill during olive processing.

The agronomic factors that influence extraction yields

The extraction yield of extra virgin olive oil can be influenced by various parameters, such as lipogenesis, the preservation of the aromatic component and the harvest.

The preservation of the aromatic component

In fact, we should not forget that the quality of the oil is heavily influenced by the sensations detected from its smell and taste, which are expressed with a relatively intense fruitiness that represents the flavour of the olives based on the cultivar and growing area. 

The aroma of virgin oil is formed by a complex blend of volatile compounds, aldehydes, alcohols, ketones, hydrocarbons and esters, which can be easily lost during veraison of the fruit due to oxidation, but also in the various processing steps if they are done too slowly or at high temperatures.

It is therefore proven that from olives harvested at an early stage of ripening, you get intensely fruity, green, bitter and spicy oils, while from olives harvested at an advanced stage of ripening, you get oils with a less intense, less bitter, ripe fruitiness.

The technological factors that influence extraction yields

The technological principles that affect the extraction yield are linked to the structure of the olive’s cell wall and to the presence of pectolytic enzymes.

When the concentration of pectin in the cell walls is very high, just like in olives harvested at an early stage of ripening, it can therefore be particularly difficult, and inefficient, to extract the oil found inside the mesocarp cells. In fact, during the initial ripening stages, the plant’s endogenous enzymes have not yet developed.


Furthermore, a second function of endogenous enzymes is to oxidise the phenolic component in order to encourage the skin to turn brown, which helps defend the fruit and the genetic material inside the seeds from solar radiation, although it also loses the aromatic component.

AEB’s contribution: field trials

Numerous tests were carried out for experimental purposes at various oil mills by the University of Bari (Italy) and the University of Jaén (Spain), have proven that the combination of agronomic and technological factors can have excellent results in terms of increasing yields during extraction.

Harvesting the olives at the peak of their lipogenesis in combination with the use of selected enzymes acting only on the pectic component, would allow the producer to obtain not only a larger amount of oil for the same weight of harvested olives but, above all, a much more fragrant oil with bolder, more intense aromatic notes.

The data collected from the experimental tests showed that, with the use of exogenous enzymes, it would be possible to increase the efficiency of the whole process of malaxing and centrifugation. The data collected by the universities showed a considerable difference emerged between the malaxing carried out with or without exogenous pectolytic enzymes: in fact, even after a few minutes from adding the enzyme, the oil starts to surface above the paste during malaxing, a phenomenon which – without the use of enzymes – only happens from halfway through the malaxing process.



Higher extraction

Smoother workflow by the malaxing machine

Less handling of the paste

Greater energy efficiency with a subsequent reduction in consumption




Operational malaxing system

Malaxing machine with olive paste

Detailed view of the malaxing machine with olive paste at an advanced stage

The extra virgin oil rising surface during processing

Oil flowing out of the separation centrifuge

Harvesting the finished product

Graph of the increased extraction yield using exogenous enzymes

Enzymes for oil: a sustainable choice

Enzymes provide numerous advantages in terms of energy consumption and impact on the environment. Let us look at them together:

  1. Reduced water and energy consumption: less water is used because the extraction efficiency is higher than with traditional mechanical methods. At the same time, there is a decrease in the time required for extraction with a consequent reduction in energy expenditure.
  1. Faster extraction process: Reducing the extraction time means reducing production costs but also optimising the 'go to market' timing.
  1. Reduced process waste: the specificity of enzymes and their action on certain substrates, with more targeted chemical reactions, results in fewer unwanted by-products. This results in less process waste and therefore in a lower impact on the environment.
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