An olive press is a device that extracts oil from olives by applying mechanical pressure to the fruit. The technology has existed for at least 5,000 years — making olive oil one of the oldest processed foods in human history. Today, the traditional stone press has been almost entirely replaced by continuous centrifuge mills, which produce higher-quality oil faster and with greater control over the factors that determine polyphenol content and flavor.
The History of the Olive Press
According to the International Olive Council, olive cultivation and oil production dates back more than 5,000 years, originating in the eastern Mediterranean and spreading throughout the ancient world. The olive tree — originally from the Middle East — made its way to Greece, then to the broader Mediterranean basin including Italy, Spain, Morocco, and Portugal, carried along ancient trade routes by Phoenician and Greek merchants.
The development of the press was a landmark moment in food history. Oil was not only a nutritious fat for cooking and eating — it was used to preserve foods like fish and vegetables for months or years, giving Mediterranean populations access to nutrients year-round. The same basic principle of sott'olio preservation — storing foods under olive oil — is one Lina, Giuseppe's mother, still practices in Calabria today, just as her family has for generations.
How the Traditional Stone Press Worked
Traditional stone presses — still visible in ancient ruins and museums across Italy and Greece — operated on a simple mechanical principle. A large stone wheel or millstone sat vertically inside a circular stone basin. Livestock, typically oxen or donkeys, were harnessed to a wooden beam and walked in a circle, rotating the upper stone around the basin. Olives poured into the basin were crushed beneath the rotating stone into a thick paste.
That paste was then scooped into woven baskets called frails or fiscoli. The filled baskets were stacked on top of one another and a heavy stone weight was placed on top, applying downward pressure. A mixture of oil and water slowly dripped out and was collected below. The mixture was left to settle and decant — oil rising naturally to the surface — and then separated by hand.
The process was slow, labor-intensive, and limited in scale. A single press could take hours to process a relatively small amount of fruit. By the time the oil was extracted, the olives had often been sitting long enough for quality to begin declining. But for thousands of years, it was the only method available — and it worked.
The Modern Mill: What Changed and Why It Matters
Since the mid-20th century, mechanical engineers redesigned the olive oil production process entirely. Today virtually all serious producers use continuous centrifuge mills — and the difference in quality is significant.
A modern mill processes olives in a continuous sequence:
- Receiving and washing. Olives arrive from the harvest and are run through a washer to remove leaves, twigs, and field debris.
- Crushing. A hammer mill or disc crusher breaks the fruit — pit and all — into a coarse paste. The speed and temperature of this step can be controlled to affect the final oil's aroma and polyphenol profile.
- Malaxation. The paste moves into a malaxer — a slow-turning horizontal mixer — where it is gently kneaded for 20 to 45 minutes. This step is critical. It allows the microscopic oil droplets in the paste to coalesce into larger droplets that can be separated effectively. The temperature of malaxation directly affects the final oil's chemistry. Based on articles retrieved from PubMed, research published in the Journal of Agricultural and Food Chemistry (University of Castilla-La Mancha, 2009) found that phenolic compound content in the oil is far more affected by malaxation temperature than by kneading time — a key reason why producers who care about polyphenol levels carefully control their mill temperature.
- Centrifuge separation. The malaxed paste is pumped into a horizontal centrifuge (decanter) which spins at high speed, separating the oil from the water and solids by density. A second vertical centrifuge then separates the oil from any remaining water.
- Filtration or decanting. The fresh oil is either filtered mechanically or allowed to decant to remove fine olive particles. Read our guide to filtered vs. unfiltered olive oil here.
The whole process — from olive to oil — can be completed in as little as two to four hours. Speed matters enormously: research from the University of Barcelona published in Antioxidants (2021) confirmed that earlier harvest timing and well-controlled processing conditions produce significantly higher secoiridoid phenolic content — the compounds responsible for bitterness, pungency, and the health benefits that make extra virgin olive oil nutritionally valuable. The mill is not just a processing tool — it is where the quality of the oil is either protected or compromised.
Why the Modern Mill Produces Better Oil
The traditional stone press had one fundamental problem: time. Olives sitting in baskets waiting for slow extraction were already oxidizing and fermenting. Fruit left on the ground or in bins before pressing develops acidity and sensory defects. The modern continuous mill eliminates most of that waiting — olives go from tree to mill to bottle in hours rather than days.
Temperature control is another critical advantage. The traditional press had none. A modern mill operator can set precise temperatures throughout crushing and malaxation, choosing conditions that maximize polyphenol extraction, preserve volatile aromatics, and avoid heat damage to the oil. Read our full guide to how extra virgin olive oil is made here.
Do People Still Use Traditional Presses?
Almost entirely no — at least not for commercial production. Traditional stone presses are still displayed in museums and agritourism venues across the Mediterranean as beautiful artifacts of agricultural history. Italy, Greece, and Spain all have ancient presses you can visit. In Calabria, many of the oldest masserie still have stone press ruins on the property.
But for producing oil that meets extra virgin standards, they are not practical. The quality ceiling is simply lower — too slow, too much oxidation, too little temperature control. The romantic image of the ancient stone press is real, but the oil it produced was a different product from what a modern mill creates.
Frequently Asked Questions
What is the difference between an olive press and an olive mill?
Technically, an olive press refers to the traditional method of applying downward pressure to extract oil — the stone wheel and frail stack method. An olive mill is the modern term for the full mechanical facility, including the crusher, malaxer, and centrifuge system. Today "olive mill" is the standard term for any facility that processes olives into oil.
What does "cold pressed" mean?
Cold pressed means the oil was extracted at a temperature below 27°C (80.6°F), preserving more of the natural antioxidants and aromatic compounds. All genuine extra virgin olive oil is cold pressed by definition — it is a legal requirement under EU standards. Read our full explanation of first cold pressed here.
How long does it take to make olive oil?
In a modern mill, the process from olive to fresh oil takes approximately two to four hours. The olives are washed, crushed, malaxed, centrifuged, and filtered in a continuous sequence. Speed matters — the faster from tree to mill, the lower the acidity and the better the sensory profile of the final oil.
Can you visit an olive mill?
Yes — during harvest season (typically October through January in southern Italy) many producers open their mills to visitors. Watching the fresh oil emerge from the centrifuge and tasting it immediately is one of the most vivid sensory experiences in food. The oil is intensely green, cloudy, and alive in a way that bottled oil rarely captures.
Why does the mill matter for olive oil quality?
Because the mill is where polyphenol content, acidity, and sensory profile are determined or destroyed. The same olives processed at different temperatures, with different malaxation times, or with different delays between harvest and milling will produce dramatically different oils. A great harvest processed poorly produces mediocre oil. This is why we mill within hours of harvest at EXAU — read more about how we make our oil here.
Shop our 100% Italian extra virgin olive oil, made in Calabria, single origin, and family farmed since 1927.
We wrote a book called The Olive Oil Enthusiast. Order your copy today.
You May Also Like:
How Extra Virgin Olive Oil Is Made: A Step-by-Step Guide
What Does First Cold Pressed Actually Mean?
Filtered vs. Unfiltered Olive Oil: What Is the Difference?
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