Frequently Asked Questions
What does cold pressed mean?
"Cold pressed" is an extraction specification regulated by the International Olive Council (IOC): the olive paste must be processed at or below 27°C (80.6°F) during the mechanical separation stage. For a complete overview, see our Extra Virgin Olive Oil guide.This temperature limit preserves the polyphenol fraction and volatile aromatic compounds that would degrade at higher temperatures. The term "first cold pressed" additionally indicates that only the first mechanical pressing was used — no second pressing or solvent extraction.1
Is cold pressed better than expeller pressed?
Cold pressed and expeller pressed are different things: "cold pressed" is a temperature specification; "expeller pressed" is a mechanical pressing method. Olive oil can be cold pressed (temperature ≤ 27°C) AND expeller pressed (using an expeller machine). The quality of the oil depends on both the temperature achieved and the overall quality management during pressing, not on whether it uses the word "cold pressed" or "expeller pressed."1
Extraction Methods: How Olive Oil Is Made
The process of extracting oil from olives involves two stages: breaking the olive paste (malaxation) to allow oil droplets to coalesce, and then separating the oil from the solid and water phases. Every extraction method does these two things — but through different mechanical means and with different effects on the resulting oil's quality.
Traditional hydraulic pressing: The oldest method, used until the mid-20th century and still used by some premium producers. Olive paste is placed between fiber discs and stacked in a hydraulic press, which applies pressure to separate liquids (oil and water) from solids. Traditional presses operate at ambient temperature (no heating) but the process can generate heat through friction if not carefully managed. Genuine cold pressed oil from a well-managed traditional press can have exceptional quality and high polyphenol content.
Expeller pressing: A mechanical method using a screw press or expeller machine that compresses olive paste against a cylindrical screen (a cage), forcing oil out through the screen while leaving solids behind. Modern expeller presses can be operated at controlled temperatures and are used by many mid-to-premium producers. The term "expeller pressed" alone doesn't indicate temperature — the temperature must be specified as "cold" if the ≤27°C limit is met.
Decanter centrifugation: The modern industrial standard for large-scale production. The olive paste is fed into a decanter centrifuge — a horizontal rotating drum that uses centrifugal force to separate oil, water, and solids by density. Decanters generate heat through friction, but modern systems with temperature-controlled jackets can operate within the cold pressed specification (≤27°C). The majority of supermarket EVOO is produced using decanter centrifuges.1
Cold Pressed: What the Term Requires
For an olive oil to be labeled "cold pressed" or "first cold pressed," it must meet the IOC specification of ≤27°C during extraction. The temperature limit is important because:
Above 27°C, polyphenol degradation accelerates measurably — hydroxytyrosol and other phenolic compounds begin to oxidize and the antioxidant capacity of the oil decreases. The volatile aromatic compounds that give fresh EVOO its fruity, grassy, floral notes are partially lost to evaporation at higher temperatures. At very high temperatures (above 60°C), the oil begins to be physically degraded — color changes, flavor compounds break down, and the oil quality deteriorates visibly.
The IOC specification of 27°C was established based on research showing that oils extracted below this temperature consistently showed better scores on both chemical markers (polyphenol content, oxidation markers) and sensory evaluation. However, the temperature specification alone does not guarantee quality — other factors (olive freshness, extraction speed, hygiene, storage) are equally important.1
Centrifugation vs. Pressing: Quality Implications
Modern centrifugation (decanter centrifuge) and traditional pressing represent two different approaches to oil extraction with different quality implications:
Pressing: A batch process that compresses olive paste in a single action. The quality of pressing depends heavily on how the paste is prepared (how thoroughly the olives are crushed, the duration of malaxation), the pressure applied, and how cleanly the oil is separated from the water and solids. Well-managed traditional pressing can produce oil with exceptional polyphenol content and complex flavor — but poorly managed pressing can produce oil with off-flavors from fermentation or inadequate extraction.
Centrifugation: A continuous process that separates oil as the paste flows through the decanter. The decanter's design (2-phase vs. 3-phase) matters: 3-phase decanters add hot water during separation, which can dilute and degrade the polyphenol content; 2-phase decanters use no added water and preserve more of the polyphenol fraction. Modern 2-phase centrifugation at controlled temperature can produce oil equal or superior to quality pressing.2
What to Look For: Beyond the Extraction Method
For the consumer, the extraction method is less important than the verifiable quality indicators on the label:
- Harvest date — this tells you how fresh the olives were when extracted, which matters more for quality than the specific extraction method.
- Polyphenol content — if disclosed, this tells you the health-relevant compound concentration, independent of extraction method.
- PDO/IGP certification — third-party verification of origin and quality standards.
- Producer information — a named producer who stands behind their oil is more reliable than an anonymous blend.
The terms "cold pressed" and "first cold pressed" on a label provide a temperature specification — but the same quality can be achieved with modern centrifugation at controlled temperature. Look beyond marketing language to verifiable quality markers.^12
References
- [1] Olive Oil Source — Olive Oil Classification and Extraction: https://www.oliveoilsource.com/info/olive-classification
- [2] International Olive Council — Culinary Cultures: https://www.internationaloliveoil.org/our-products/culinary-cultures/