What cold extraction means

"Cold pressed" is the most used and least understood phrase on a label. It is not a quality grade but a production method, and it has a legal definition. This page covers both the definition and what actually happens to the oil on the line.

The heart of it: heat the paste and you get more oil, but you lose the smell and much of the benefit. Cold extraction means taking a little less oil in order to take the better oil. And to print it on a label, the temperature has to stay under 27 °C.

Two phrases in the legislation

The Turkish Food Codex defines them separately and restricts their use:

• "First cold press" — only for extra virgin and virgin oils obtained from the first mechanical pressing of the paste using a hydraulic press below 27 °C.
• "Cold extraction" — only for extra virgin and virgin oils obtained by percolation or centrifugation of the paste below 27 °C.

Two consequences follow: neither phrase may appear on a Riviera or pomace oil label; and "cold pressed" does not on its own prove an oil is extra virgin — virgin oil may use it too. See our legislation page.

Why 27 °C?

Temperature cuts both ways. The higher it goes, the more easily oil separates from the paste — yield rises. But the same heat:

• Evaporates the volatile compounds that carry aroma — the smell simply leaves.
• Accelerates oxidation of phenolic compounds — polyphenols fall, and with them bitterness and pungency.
• Starts the oxidation chain early, shortening shelf life.

27 °C is the compromise struck where those two curves cross. Staying below it means giving up some yield in exchange for aroma and antioxidants.

The line, step by step

1. Defoliation and washing

Leaves, twigs and soil are removed. Excess leaf carries a grassy note and extra chlorophyll into the oil, while soil residue is the source of the earthy defect. The cleanliness of the wash water is itself a defect risk.

2. Crushing

The olive, stone included, is crushed into a paste. The method affects character directly:

• Hammer mill: fast and high-speed, it ruptures cell walls hard and extracts more phenols — a more bitter, more pungent oil. Friction raises paste temperature, so cooling is needed.
• Disc or blade crusher: an intermediate option.
• Stone mill: slow and cool, giving a softer, less bitter profile. It is traditional, low in capacity and harder to keep hygienic.

3. Malaxation

The heart of the line. The paste is stirred slowly in jacketed troughs so that microscopic oil droplets coalesce enough to be separated. Two competing processes run at the same time:

• The lipoxygenase (LOX) pathway builds the aroma compounds — the source of the green grass and apple notes. That takes time.
• Polyphenol oxidase and peroxidase break phenols down — and that also increases with time and oxygen.

Malaxation time is therefore an optimisation problem: typically 20–45 minutes below 27 °C. Too short and you lose yield and aroma; too long and you lose polyphenols and freshness. Quality-focused mills tune both variables lot by lot.

4. Separation: two-phase or three-phase?

The paste is separated in a horizontal centrifuge (decanter). The choice of system shapes both quality and environmental load:

Phenolic compounds are water-soluble. In a three-phase system the added water carries a substantial share of them out of the oil and into the vegetation water. That is why mills targeting high-polyphenol oil favour two-phase decanters. For what becomes of the pomace, see olive pomace oil.

5. Vertical centrifuge and settling

Residual water and fine solids are removed in a vertical centrifuge, after which the oil rests in stainless steel tanks. Two rules govern this stage: separate it from its lees in good time and keep air away from it — many mills blanket the tank headspace with nitrogen.

6. Filtration

Unfiltered oil looks fresh and "natural", but suspended sediment ferments over time and produces the muddy sediment defect. For oil that will be stored, filtration is an advantage. It is not a loss of quality but a choice in favour of stability.

Time from harvest to mill

This is where cold extraction alone is not enough. Hydrolysis begins the moment the olive leaves the branch: free acidity rises in waiting fruit and fatty acid ethyl esters form. Olives milled the same day and olives held for three days do not give the same oil, even at the same mill and the same temperature.

Hence the golden rule of quality production: pick from the tree, mill the same day. If you must wait, hold the fruit in shallow ventilated crates, cool and shaded — never heaped in sacks.

Three things that get confused

Does cold pressed mean extra virgin?

No. Cold extraction describes the method, not the grade. A cold-extracted oil can still fall to virgin. The grade is set by the analysis values and the panel.

What does "first press" mean?

In today's centrifugal systems the paste is separated in a single pass; there is no "second pressing". The phrase "first cold press" comes historically from hydraulic presses, and the legislation ties it to that method alone.

Is warm extraction bad?

Not bad — different: it raises yield and lowers aroma and polyphenols. It is chosen in high-volume, price-driven production. It simply may not be labelled "cold pressed".

How we work

At our facility in Düziçi we run the line under temperature control and record every lot with the district and date it came from. To see the line and the laboratory in person, get in touch; our product values are published on the products page.