🌀 Malaxation

Malaxation is the slow, continuous mixing of olive paste before the oil is separated from it. After crushing, the oil is broken into very small droplets that are hard to separate. During mixing the droplets' coatings break down and they merge into larger ones, so about 5 per cent more oil is obtained.

The paste is mixed in malaxers, usually several in a row. Most studies recommend 30–40 minutes at 18–27 °C. Under these conditions phenolic compounds pass into the oil and pleasant aroma compounds form. A temperature below 27 °C also matters for the label: only then can the oil be called cold extraction oil.

Malaxation is called a "necessary evil". The longer and warmer the paste is mixed, the more oil is obtained, but the fewer beneficial phenols it has: heat speeds up the enzymes that destroy them. At 35 °C and above unwanted smells appear, while at 25 °C and below pleasant "green" notes form.

Air matters too. If there is less oxygen in the malaxer, the oil has more phenolic compounds, although slightly fewer aromas form. That is why some olive mills replace the air above the paste with nitrogen.