Author: Cécile Le Galliard

Unlocking the mysteries of the olive mill

by Cécile Le Galliard

For many producers, the olive mill is a “black hole”: we know what enters (olives) and the general outcome (oil).
Sentences such as: “I have no idea why the oil is like that (too bitter, too flat, too pungent, too green/ripe), this is the way it is this year” are common at the mill or in storage when the oil is tasted.
But olive mills are not black holes. The olive oil that comes out of the separator (or the decanter) is not a predestination, but a result of a process that we can affect and direct to our desire.

The crusher: follow the yellow brick road

The method we use to crush the olives into paste will affect the first step towards our desirable oil.

What we need to consider, record and be known about:

  • The olives: temperature, size, stone/flesh ratio, water content in the fruit (below/above 50%).
  • Crushing method: stone, discs, hammers, knives, combined, with or without pre-crushing, with ot without de-pitting.
  • Velocity of crushing (RPM, depending on the method of crushing)
  • The net: diameter of the holes, the shape of the holes (round, oval, elongated hexagon)
  • Internal ambient: adding water (yes/no), cooling device, adding oxygen/inert gases

These factors will affect the first step we are taking on the road towards the requested oil:
📌 The size of the particles
📌 The temperature of the paste
📌 The temperature of the paste in the crusher will affect which enzyme groups begin to work in the kneading cell (malaxer), and these enzyme groups will determine the oil’s characteristics: aroma, taste, and color.
📌 Particle size determines how easily enzymes can break down the paste, thereby creating aroma, taste, and color.

Crushing is only the beginning of the process. If we can’t choose between methods (we have only discs/hammers/knives/stones), we can still affect the aromatic profile in the kneading cell, but adjusting the crusher to our needs will make the process later much easier.

The Malaxation phase – where magic happens

The kneading cell is the core of the mill, where the oil profile is determined. In order to have that, we need to understand two reasons for malaxation:

🖊️To extract olive oil
🖊️ To create the aroma, flavors, and taste in the oil

The oil droplets bond together due to the rupture of oil bubbles within the plant cell.

The aromas, flavors, taste, and color are created due to the breakdown of the polyunsaturated fatty acids (omega-6, omega-3) and the polyphenols.

❓ What affects these two pathways:
🖊️Temperature of the paste
🖊️Duration of malaxation
🖊️Amount of available oxygen

📌 The temperature will determine which enzymes will be active, and what type of oil we will have

📌 The duration of malaxation will determine the quantity of minor compounds in the oil, the quantity of oil, and the possibility of the creation of undesirable aromatic compounds (which are not necessarily defects, but aromas we didn’t intend to have in the oil)

📌 The amount of oxygen will determine the balance between aromas and bitterness/pungency.
We are taught that oxidation in the olive oil process is always bad, but in the malaxation phase, oxidation is fundamental.

🗒️ So many dilemmas:

Higher temperature in the kneading cell➡️less aromas and flavors, but➡️more polyphenols and color (and vice versa)

More oxygen➡️more aromas and flavors, but➡️less polyphenols and color (and vice versa)

More malaxation time➡️more minor compounds and oil (and vice versa)

⚠️ However, too much time in the kneading cell will lead to undesirable aromatic compounds, a higher possibility for the appearance of defects, and the loss of minor compounds.

What started in the crusher can now be enhanced, changed, or manipulated in so many ways: ripe Arbequina can turn highly bitter and pungent, green Picual or Coratina can turn mild or even adopt significant ripe notes. The sky is the limit, with the right equipment and the understanding of the process.

Separation – oil is coming….

For many, the separation phase seems trivial: the paste goes in one side, and on the other side, there is oil (and water and pomace). But there are many factors to consider, and the innovativeness in this phase is exciting.

Factors in the decanter:

✏️Degree of emulsion – usually in a paste from ripe olives (some varieties tend to be more emulsified than others). Adding water and/or slowing the stream of paste into the decanter will solve it

✏️Amount of water in the paste – in a paste of olives that are full of water (55% water and more). This situation will dictate slowing the stream of paste into the decanter.

✏️Temperature of the paste and of the water added to the decanter – both need to be similar to have good separation.

✏️Amount of water added to the decanter – more water will allow faster streaming (in a “normal” paste), but will lead to a loss of taste and aroma

✏️ The level of the pipes inside the decanter – the deeper they are screwed, the clearer the oil will be. That means fewer sediments, but a possible oil loss. The more open the pipes are, the more water will be added to the oil before the separator, leading to frequent separator washes and potentially water flowing into the oil after the separator.

✏️Innovative solutions: micro-talc, enzymes, ultrasound, magnetic fields, electric pulses. Some are already in industrial use, some are still being investigated and tested. In my opinion, this is where the most exciting innovations in the mill are taking place right now. It is worth following.

📋Two phases vs. Three phases:
The debate was settled, regarding the concentration of taste and aroma: two phases can increase the quantity of volatile compounds and taste by 30%-45%. The only reason to still use three phases, in my opinion, is the issue of treating the wet pomace. Some places don’t have the option of managing it well enough.

The separation is where all the good intentions and practices we had so far can be damaged. Understanding how the decanter operates is essential to the olive oil we want.

….And she’s buying the filtration to heaven (and shelf-life)

Olive oil is not “just oil”. It’s a fruit juice that holds both the keys to incredible culinary enjoyment and the seeds of organoleptic defects that will appear if we have mistreated the olive and the oil during the process. To extend shelf life, olive oil should be filtered after extraction.

Following the separator, there are three ways to walk on:

✏️No filtering: A sediment of tiny particles that remained in the oil will accumulate at the bottom of the storage receptacle. This sediment comprises particles of the flesh, peel, waxes, phospholipids, bacteria, yeasts, etc. While the oil will become clear and transparent, the sediment will eventually degrade its quality, and it won’t be extra virgin according to the international standard.

✏️Active filtration: filtering the oil with different kinds of filters: micro nets, cellulose, and Diatomaceous earth (DE). Active filtering may change a bit the aromatic profile of the oil, but it is a nuance – a small price to pay, for the long shelf life the oil will gain in return.

✏️Passive filtration: using a series of conical receptacles to filter the oil through quick sedimentation of the tiny particles. This method is costly and requires significant effort. Still, eventually, after several days of constant shifting of the oil from one receptacle to another, the sediments will be removed, and the oil will be transparent and ready for bottling. Due to the high cost and labor, it is extremely rare to find this method in use on a large scale

📝 During my professional life as an olive oil consultant, I met many producers who believe that filtration spoils the oil. That it removes essential aromas and even some of the oil’s “identity”.

That is an unfortunate misconception.

Refusing to filter the oil, or even worse, selling it with the sediment at the bottom of the bottle, will lead to the appearance of defects during the year after extraction.
A correct process for extra virgin olive oil must include filtration.

The process in the mill, from olives to oil, is the final step of our wishes and plans as olive oil producers/millers/farmers.

We have to ask ourselves: “Do we know the parameters of every step? What can we modify in the mill to achieve the oil we want?

Many times it won’t be 100%, but when we know what we want, and we are willing to learn how get there, we can start directing the oil to our desired outcome

‼️Master the process, and you master the oil

Ehud Soriano, olive oil consultant

L’article en français Percer les mystères du moulin

Organoleptic Analysis Should Be Appreciated

by Cécile Le Galliard

Cécile Le Galliard, Ehud Soriano

Imagine a driver driving near the separation line. Sometimes he/she is almost touching, sometimes just touching a bit. Yet this driver keeps complaining about getting fined by the police, claiming the cameras should be more accurate.

We may agree that the cameras should be more accurate, but for most of us, the better suggestion for the driver would be “just drive in the middle of the road, instead of playing games with the cameras, then complaining about their accuracy.”

After reading the article about the inconsistency of sensory panels (Olimerca), regarding borderline olive oil (some determined they were extra virgin, some determined they were virgin), we would like to give another point of view on this subject:

The organoleptic assessment of olive oil was originally developed as a research tool, linking the result (the oil after the mill) to the production chain. This tool has been pushed to the forefront of fraud fighting since the 80’s and into the 90’s, and has since evolved into an irreplaceable tool for analyzing olive oil quality.

Organoleptic assessment has two main virtues:

1)     It uses the human nose as a tool of analysis. Our nose is extremely sensitive to changes in aroma, as its role in evolution is to give us feedback on the safety of the food we eat.

2)     It is the most effective tool to analyze backwards the quality of the process since every defect (and even nuances of defects) is connected to a different part of the process. By understanding the defects, a producer can dramatically improve the oil’s quality.

Over the last 30 years, organoleptic assessment has been a key factor in improving olive oil quality worldwide, helping authorities remove so many defective oils from the market.

Indeed, like every other testing method, including laboratory testing methods, it is not perfect. Like every other method, borderline olive oils are tough to assess.

We should remember, though, that a ‘borderline oil’, as the name suggests, is an oil on the border of a defect. It is not yet presenting a clear defect, but the sprout of a defect is noticeable, indicating this oil has zero, or close to zero, shelf-life.

Some olive oils can show off-odors as soon as the bottle is opened, even though all chemical analyses are fully compliant with the extra virgin category. This happens because chemistry and the human nose do not detect problems simultaneously.

Certain defects appear first as smells — slightly fermented, musty, or oxidized notes — long before laboratory values exceed legal limits. The human nose can detect and distinguish an extremely large number* of volatile compound combinations, often at concentrations far below those detectable by standard analytical instruments. This makes sensory evaluation a fast, highly sensitive early-warning tool that detects quality problems before instruments can measure them.

Rather than opposing human judgment, the solution may lie in accepting external support to help decision-making. Analytical tools, data models, or instrumental methods do not replace the panel, but they can confirm, question, or clarify borderline situations.

In other words, instead of doubting the necessity of sensorial analysis, wouldn’t it be much simpler to grow, harvest, extract, and store a better olive oil in the first place? Wouldn’t it be easier to produce better-quality olive oil with all the knowledge and great equipment we have in the olive oil industry?

If we go back to the beginning of the article, wouldn’t it be much simpler to drive in the middle of the road, instead of arguing with the police whether you touched the separation line or not?

 

*C. Bushdid et al., “Humans can discriminate more than 1 trillion olfactory stimuli”, Science, 2014.

Texte traduit en francais et en espagnol
Relance du débat sur l’analyse sensorielle
El análisis organoléptico debe apreciarse

Olive oil production : Latest global outlook (2025/26)

by Cécile Le Galliard

oliveraie espagnole avec filets de récolte “Image générée par IA / OpenAI”

Spain, the world’s top producer, sets the tone for 2025/26. The MAPA’s first forecast puts output at 1,371,938 tons, down 3% year-on-year yet 19% above the six-year average affected by drought. Spring bloom/fruit set was strong, but summer heat capped potential. Figures are preliminary and will be updated during harvest.

Within Spain, Andalusia—nearly four-fifths of national output—projects 1,080,900 t (–5.5% vs 2024/25; +19.8% vs the five-year average). Provincial highlights: Jaén 475,000 t (–15.3%), Córdoba 269,100 t (–7.5%), Seville 130,000 t (+16.5%), Granada 117,200 t (–5.5%), with sharp gains in Málaga (54,600 t, +54.8%) and Cádiz (16,400 t, +95%).

On pricing, trade sources indicate early-harvest new oils changing hands near €6.00/kg, suggesting no abrupt shift so far despite the forecasts.

Globally, early signals point to ~2.65 million tons across leading producers, pending national updates. In this setting, Spain’s final volume (~1.37 Mt) and oil yields—weather-dependent in autumn—will heavily influence world balance.

SOURCES:

España superará los 1,37 M de toneladas de aceite de oliva
Las previsiones de cosecha no alteran el mercado del aceite de oliva
Aforo: Andalucía prevé que su producción de aceite de oliva se sitúe en 1.080.900 t. en la campaña 2025/26, un 5,5% menos
Se prevé que la producción de aceite de oliva en los principales países caiga a 2.65 millones de toneladas
Primera estimación del MAPA: la producción de aceite de oliva en España se situará en 1.371.938 toneladas en la campaña 2025/26
Balance récolte 2024-2025, les derniers chiffres

The Increase In Harvests From The Mediterranean Countries Offsets Spain’s Decline

by Cécile Le Galliard

Posted By World Olive Oil Exhibition

Tunisia, Greece, Italy and Portugal increase their production whilst Spain will drop by 25% which represents 1.36 million tonnes.

Although it is still too early to assess the definitive data on the olive oil production from the 2019-2020 season, it should be pointed out the upsurge in volume from Mediterranean countries. Tunisia will experience a three-fold growth in its harvest compared to the previous year and will account for 370,000 tonnes; and Greece will increase by 50% reaching 295,000 tonnes. It also should be highlighted the recovery of Italy that managed to double its scarce production from the previous season and reached 360,000 tonnes; while Portugal may grow up to 135,000 tonnes and Algeria: 90,000 tonnes.

Besides the Mediterranean countries, it should also be noted the production rise in countries such as Argentina, which accounts for 40,000 tonnes, Jordan that will reach 29,000 tonnes, Australia with 22,000 tonnes and Chile with 20,000 tonnes.

The increase in production in the aforementioned countries will globally offset the slump in the Spanish harvest, which is largely caused by drought. The consultant Juan Vilar assures that “the Spanish production will decline by around 25% accounting for 1.36 million tonnes compared to 1.8 million tonnes harvested last year. Thus, the global harvest could increase by slightly above 3% reaching 3.29 million tonnes”.

However Spain is not the only country that drops in its production. It also happened to Turkey, which might account for 180,000 tonnes, which is 20,000 more tonnes than what Morocco will produce; and Syria will once again account for 80,000 tonnes.

Way more modest is the production in countries such as the United States and Libya that might reach 15,000 tonnes each; Egypt: 25,000 tonnes; while Israel and Palestine may account for 16,000 tonnes each. Furthermore, France expects a harvest of 7,000 tonnes, whilst Croatia and Iran might account for 5,000 tonnes each.

The olive oil stored from previous seasons could drop thanks to the expected increase in consumption that is due to the 10%-price drop and to promotion policies carried out in Spain, Italy, Tunisia, Jordan and the United States. In the US, producers have requested Trump’s Administration not to include tariff barriers to olive oil.

The olive grove covers 11.68 million hectares across the world. There are 64 olive oil-producing countries and already 180 olive oil-consuming countries from across the five continents.

[Source] THE INCREASE IN HARVESTS FROM THE MEDITERRANEAN COUNTRIES OFFSETS SPAIN’S DECLINE 
Posted By World Olive Oil Exhibition Sep 2019