The Mill

Extra virgin olive oil is made by harvesting ripe olives, removing leaves and washing them, then crushing the fruit — stones and all — into a paste. The paste is slowly churned (malaxation) to allow oil droplets to coalesce, then spun in a horizontal decanter to separate the oil from water and solids. A vertical centrifuge makes a final separation. The result is fresh oil with no heat, no chemicals and no refining — only cold mechanical extraction below 27°C.

Cold extraction means the entire milling process — crushing, malaxation and centrifugation — is carried out at temperatures below 27°C. Higher temperatures increase oil yield but degrade polyphenols, antioxidants and volatile aromatics. Cold extraction preserves these compounds at their highest concentration, which is why Castruriali tests at 410 mg/kg total polyphenols.

Malaxation (gramolatura in Italian) is the slow churning of olive paste in heated troughs, typically at 25–27°C, for 20–40 minutes. The gentle mixing breaks water-in-oil emulsions and causes tiny oil droplets to join into larger ones that separate more easily in the decanter. It is the single most important variable in yield and quality — shorter malaxation preserves more polyphenols but slightly reduces yield.

Pieralisi is the world's leading manufacturer of continuous-cycle olive oil extraction equipment. A Pieralisi line handles all eight stages on one automated production line: leaf removal, washing, crushing, malaxation, horizontal decanting (two-phase or three-phase), vertical centrifugal separation and collection. The Mandanici mill in Castroreale uses a Pieralisi line that processes our olives within hours of harvest, minimising oxidation.

From the moment an olive is picked, enzymatic activity and micro-oxidation begin degrading its polyphenols and raising free fatty acid levels. Pressing within 24 hours — ideally the same day — arrests this process and locks in the oil's chemical integrity. Every extra day on the pile reduces quality. Castruriali olives go directly from the grove to the Mandanici mill.