Between the olive harvest and the bottle, there's a step few consumers know about and almost no producer explains: malaxation. Yet it's right there, in stainless steel tanks turning slowly for twenty to forty minutes, that most of the aromatic profile of an extra virgin olive oil is decided.
Why malaxation is the most decisive step in production
Crushing and malaxation: two separate steps
Crushing and malaxation are often confused. They are two successive and quite distinct operations.
Crushing is the first transformation: whole olives — fruit, pit and sometimes leftover leaves — are reduced to a coarse paste by granite millstones or metal hammer crushers. At this stage, the pulp cells are simply broken. The oil is released as micro-droplets, scattered through the paste but not yet separable.
Malaxation comes right after. The olive paste is placed in cylindrical tanks — called malaxers — fitted with helical arms that slowly and continuously stir the mass. This slow movement gradually gathers the oil micro-droplets into larger and larger drops, until they form a continuous oily phase that can be extracted mechanically. Without malaxation, the centrifugation that follows would be far less effective, and the oil yield would drop.
For organic olive oil in a 5 L tin or everyday formats, this control over malaxation is what keeps the profile consistent from one harvest to the next.
Temperature and time: the malaxer's two dials
Malaxation is governed by two parameters the miller sets by hand according to the olive variety, its ripeness and the aromatic profile being sought.
Temperature is the first dial. For an oil to be called cold-extracted, the paste must not exceed 27 °C during malaxation, in line with EU Regulation No 1019/2002. Below that limit, the volatile aromatic compounds — the ones that give an oil its notes of fresh grass, artichoke or green tomato — are preserved. Above it, yield goes up, but the aromas evaporate and the polyphenols break down. It's an economic trade-off every producer makes consciously, or not.
Time is the second dial. Malaxation that's too short doesn't let the droplets fully gather, and yield suffers. Malaxation that's too long exposes the paste to oxidation: prolonged contact with air, even at low temperature, starts to degrade the finest aromas. The optimal window is usually between twenty and forty minutes, depending on the variety.
From olive paste to a drizzle of oil: centrifugation
Vertical or horizontal centrifuge?
Once malaxed, the olive paste goes into a centrifuge — also called a decanter — which separates the phases using the difference in density between the oil, the vegetation water and the solids.
There are two main systems:
- The three-phase system: the paste is diluted with water to make separation easier. You get oil, vegetation water and pomace. Adding water dilutes some soluble compounds and can slightly flatten the aromatic profile.
- The two-phase system: no water is added. You get oil on one side and a solid-water mix on the other. The oil yield is a little lower, but the aromatic concentration is higher. It's the system you'll find in most quality Calabrian mills.
After decanting, the oil goes through a vertical centrifuge that removes the last traces of water and fine particles. It's then either filtered or stored straight in stainless steel to settle naturally.
The organic olive oil discovery duo 500 ml is a good way to compare two profiles from different malaxations: green fruity on one side, ripe fruity on the other.
Why the delay before milling determines everything
Malaxation can't make up for what has already deteriorated before it. It's the golden rule of serious millers: the longer olives wait between the harvest and the mill, the more their quality declines.
In Calabria, the Carolea variety — which makes up a large share of regional production — is especially sensitive to this delay. Milled within twelve to twenty-four hours of harvest, it gives an intense green fruity oil, with clear notes of fresh grass and a nice pungency on the finish. After forty-eight hours, fermentation starts in the pulp cells: the peroxide value rises, the fine aromas fade, and the oil may no longer meet the thresholds for the extra virgin category. It's a real logistical constraint, which explains why quality Calabrian mills work around the clock during harvest, at night if needed.
The 2.5 L jeroboam of organic extra virgin olive oil you'll find in a limited edition comes from this kind of fast milling: harvest and mill on the same day, stored in stainless steel until bottling.
What you read in the glass: the traces of malaxation
Green fruity or ripe fruity: a question of malaxation
An oil's aromatic profile — green fruity or ripe fruity — is determined by two closely linked factors: how ripe the olives are at harvest, and the malaxation conditions.
- An olive harvested early, still green or just at veraison, malaxed at low temperature for a short to moderate time, will give a green fruity oil: notes of fresh grass, artichoke, sometimes green almond, with marked bitterness and pungency.
- An olive harvested later, fully ripe and black, malaxed at a slightly higher temperature, will give a ripe fruity oil: notes of ripe tomato, red fruit, olive butter, with a rounder softness and little pungency.
Neither profile is better than the other. They just have different uses: organic green fruity olive oil is ideal as a finish on bitter vegetables, fresh cheeses or legumes. Organic ripe fruity olive oil works better with roast meats, autumn mushrooms or soups.
How to recognise a well-extracted oil
A few clues in the glass give away how the oil was made:
- A colour from intense green to golden yellow depending on ripeness, but never excessively cloudy if the oil is filtered.
- A clean, well-defined nose as soon as you open the bottle. An oil extracted at the right temperature doesn't smell musty, of damp cellar or of vinaigrette: those are defects linked to overly long malaxation, too high a temperature or olives stored too long.
- A frank pungency on the finish, often misunderstood yet a sign of freshness: it shows the presence of phenolic compounds that haven't been destroyed by heat.
- A short bitterness on the tongue, clear but not aggressive: it's the signature of a well-handled green fruity oil.
If you want to compare these profiles before buying a larger format, the trio discovery box of 200 ml olive oils lets you taste them side by side.
For professionals who want to build these criteria into their selection or train their team, the professionals area brings together the formats suited to restaurants.
Frequently asked questions
What exactly is olive oil malaxation?
Malaxation is the step that follows crushing the olives. The resulting paste is stirred slowly in stainless steel tanks for twenty to forty minutes. This movement lets the oil micro-droplets scattered through the paste gradually gather into a continuous oily phase, which is then separated by centrifugation. Without malaxation, extraction would be far less effective.
Why does cold extraction give a better oil?
Keeping the paste below 27 °C during malaxation preserves the volatile aromatic compounds and polyphenols that give the oil its character. Above that temperature, yield goes up but the finest aromas evaporate. Cold extraction doesn't mean the oil is cold, but that the paste wasn't heated beyond that limit during the process.
How long between picking the olives and taking them to the mill?
Ideally, olives should be milled within twelve to twenty-four hours of harvest. Beyond that, fermentation starts in the pulp, the peroxide value rises and the aromas deteriorate. Serious mills — especially in Calabria, where the Carolea variety is very sensitive to this delay — often work non-stop during the harvest to stay within this window.
lucangeli.it
