Olive Oil Types and Quality

Olive Oil Categories

Olive oil is one of the most widely consumed fats in the world, yet not all olive oils are created equal. The European Union, through Regulation (EC) No 29/2012 and the standards of the International Olive Council (IOC), classifies olive oils into four main categories. This classification rests on precise chemical criteria (acidity, peroxide index, UV absorbance) and on a sensory evaluation carried out by a panel of certified tasters.

Understanding these categories is essential for any quality-conscious consumer. Each grade reflects the level of care taken in the cultivation, harvesting and processing of the olives. From exceptional artisan products to industrial oils, the differences are considerable in terms of taste, nutritional value and health benefits.

The four main categories are as follows:

• Extra virgin olive oil: the highest grade, obtained by mechanical extraction, with zero sensory defects.
• Virgin olive oil: also obtained by mechanical extraction, but tolerating slight sensory defects.
• Olive oil (regular): a blend of refined oil and virgin oil, the most common product on supermarket shelves.
• Olive pomace oil: extracted from the solid residue (pomace) using chemical solvents, then refined.

Let us examine each of these categories in detail to understand what truly sets them apart.

Extra Virgin — The Gold Standard

Extra virgin olive oil (EVOO) represents the pinnacle of quality. It is obtained exclusively through mechanical processes — centrifugation or pressing — at a temperature below 27 degrees Celsius. No chemical solvents and no excessive heat treatment are involved in its production. It is a pure fruit juice, the juice of the olive.

To earn the "extra virgin" designation, an oil must satisfy strict criteria on three fronts:

Chemical criteria. Free acidity, expressed as oleic acid, must be below 0.8%. The peroxide index, which measures primary oxidation, must not exceed 20 milliequivalents per kilogram. The extinction coefficients K232 and K270, which evaluate secondary oxidation via ultraviolet absorbance, also have maximum thresholds. These parameters guarantee the freshness and chemical integrity of the oil.

Sensory criteria. The oil must display a "fruity" attribute — green or ripe — with an intensity greater than zero. Conversely, it must exhibit no sensory defects whatsoever: no rancid, no musty, no fusty (anaerobic fermentation), no winey, no metallic notes. This is the most discriminating condition: even perfect acidity is insufficient if the panel detects a defect.

Panel test. The sensory evaluation is conducted by an official jury of eight to twelve trained tasters accredited by the IOC. Each taster evaluates the oil independently, assigning intensity scores to positive attributes (fruity, bitter, pungent) and to any defects. The median of defects must be equal to zero to achieve the extra virgin grade.

Our Domaine Boeglin olive oil boasts an acidity of 0.2% or less, well under the regulatory threshold. This low acidity testifies to the quality of the olives, harvested at perfect ripeness and pressed on the same day as the harvest. It reveals notes of fresh grass, olive leaf and green apple, with balanced bitterness and a clean pungency at the back of the throat — the hallmarks of an oil rich in polyphenols and antioxidants.

Virgin vs Extra Virgin — What Are the Differences?

Virgin olive oil shares the same extraction method as extra virgin: purely mechanical, with no solvents and no excessive heat. The difference lies in the tolerance thresholds for chemical and sensory parameters.

In terms of acidity, the ceiling rises from 0.8% (extra virgin) to 2.0% (virgin). A slightly higher peroxide index is also tolerated. But it is above all on the sensory front that the distinction becomes clear: virgin oil may present slight defects — a hint of fusty, a faint rancid note — provided the median of defects remains below 3.5 on the panel test scale.

In practice, this means that virgin oil often comes from olives of slightly lower quality: harvested a little too late, stored too long before pressing, or grown under less optimal conditions. The result is a less complex, less vibrant aromatic profile, sometimes with slight off-notes.

The price reflects this difference: virgin oil typically costs 30 to 50% less than an extra virgin of the same origin. For cooking at moderate temperatures (sauces, stews, slow-cooked dishes), a good virgin oil can be a sensible choice. But for raw use — salads, bruschetta, a drizzle on fish — only extra virgin delivers the full aromatic richness one expects.

It is worth noting that in some countries, labelling can be misleading. Investigations conducted in Italy, Spain and the United States have shown that a significant proportion of oils sold as "extra virgin" did not meet the sensory criteria. This is why quality labels (DOP, PDO) and knowing your producer are so important.

Refined Olive Oil: What You Need to Know

When a virgin olive oil has defects too significant to be sold as-is — acidity above 2%, marked sensory defects, undesirable colour or odour — it is sent to a refinery. The refining process involves several industrial steps:

• Neutralisation: treatment with caustic soda to reduce free acidity.
• Bleaching: passage over bleaching earths to standardise the colour.
• Deodorisation: injection of steam at high temperature (200-250 degrees Celsius) to eliminate the volatile compounds responsible for undesirable odours and flavours.
• Winterisation (sometimes): controlled cooling to remove waxes and prevent cloudiness at low temperatures.

The result is a neutral, odourless, nearly colourless oil with acidity close to zero. But this neutrality comes at a considerable nutritional cost. Refining destroys the vast majority of polyphenols (up to 90% according to studies), tocopherols (vitamin E), chlorophyll pigments and aromatic compounds. The oil loses the antioxidants that underpin olive oil's reputation for cardiovascular health.

The product found on supermarket shelves under the simple label "olive oil" is in fact a blend of refined oil (typically 85 to 95%) and a small proportion of virgin or extra virgin oil added to give it a minimum of flavour and colour. It is a functional product, suitable for cooking, but devoid of the complexity and benefits of a true extra virgin.

For your health, always choose extra virgin olive oil. To learn more about the nutritional benefits, visit our dedicated olive oil page.

Labels and Certifications

DOP / PDO (Protected Designation of Origin)

The DOP label (Denominazione di Origine Protetta, in Italian) or PDO (Protected Designation of Origin, in English) is the highest guarantee of origin and quality for a food product in Europe. For olive oil, it certifies that the entire production chain — olive cultivation, harvesting, extraction and bottling — takes place within a delimited geographical area, according to a strict set of specifications.

These specifications define the authorised olive varieties, cultivation methods, harvest dates, extraction techniques and expected organoleptic characteristics. Each DOP/PDO is unique: it reflects a terroir, a climate and an ancestral know-how.

Europe has more than 130 DOP/PDO designations for olive oil. Italy holds the greatest number (over 40), followed by Greece, Spain and Portugal. Portuguese PDOs, such as Moura, Norte Alentejano and Alentejo Interior, are gaining international recognition for the quality of their single-variety oils. To learn more about the Portuguese olive-growing terroir, explore our guide to the Alentejo region.

PGI (Protected Geographical Indication)

The PGI is a European label less restrictive than DOP/PDO. It guarantees that at least one stage of the production process (cultivation, processing or packaging) takes place within the designated geographical area. The criteria are less strict than for a PDO, but the PGI still offers traceability and an origin guarantee superior to a generic product.

For consumers, a PGI oil represents a good compromise between certified quality and accessible pricing. The great Mediterranean olive-growing regions offer well-known PGIs: Toscano PGI in Italy, Aceite de Jaen PGI in Spain, or Azeites do Alentejo PGI in Portugal.

Organic Certification

The European organic certification (the "Euro-leaf" logo) guarantees that olives were cultivated without synthetic pesticides, without chemical fertilisers and without GMOs. Permitted treatments are limited to natural products (copper, sulphur, plant-based preparations). Certification requires regular inspections by an independent body.

It is important to understand that the organic label certifies a farming method, not a level of gustatory quality. An organic oil can be extra virgin or merely virgin. It can be excellent or mediocre on the organoleptic front. Organic is a plus, but it does not replace the pursuit of extra virgin status and a trustworthy producer.

Early Harvest

Early harvest refers to olives picked at the beginning of the season, typically in October or early November in the Northern Hemisphere, when the fruit is still green or undergoing veraison (colour change). At this stage, olives contain their peak concentration of polyphenols, those powerful antioxidants responsible for the bitterness and pungency characteristic of great oils.

The trade-off is a lower yield: green olives produce 30 to 50% less oil than ripe ones. This explains the higher price of early harvest oils, but also their incomparable aromatic profile — notes of freshly cut grass, green tomato, artichoke, sometimes green banana — and their superior nutritional benefits.

Our Domaine Boeglin oil comes from an early-to-moderate harvest, allowing us to achieve a balance between aromatic intensity and smoothness, with a high polyphenol content.

How to Choose a Quality Olive Oil

Faced with the profusion of olive oils on the shelves, here are the essential criteria for making an informed choice:

Read the label carefully. Look for the words "extra virgin". Check the origin: a precise indication of the country, region, or even the estate is a sign of traceability. The harvest date (not merely the best-before date) is the best indicator of freshness. An oil less than 12 months old is ideal.

Choose dark glass or metal. Light is olive oil's primary enemy. Transparent bottles, even glass ones, expose the oil to photo-oxidation. Opaque containers — dark glass, stainless steel, ceramic — preserve polyphenols and aromas.

Check the acidity. For an extra virgin, acidity must be below 0.8%. The finest oils often display 0.2 to 0.4%. Ours is at or below 0.2%. Note that acidity is not a taste indicator (it is undetectable on the palate) but a marker of chemical quality.

Be wary of prices that are too low. A quality extra virgin olive oil cannot cost less than 8 euros per litre. Below 5 euros per litre, it is almost certain that the product does not meet extra virgin criteria, regardless of what the label states. Quality has a cost: careful harvesting, rapid pressing, stainless steel storage, protected bottling.

Avoid misleading marketing terms. Labels such as "light", "pure", "classic" or "mild" are not quality indicators. "Light" refers to attenuated flavour (i.e. refined), not to calories. "Pure" simply means 100% olive, with no specification of grade. Only the terms "extra virgin" and official labels (DOP, PDO, Organic) carry regulatory weight.

Taste it. On the palate, a good extra virgin presents fruitiness (vegetal, fruity notes), bitterness (a sign of polyphenols) and pungency at the back of the throat (oleocanthal, a natural anti-inflammatory). If the oil is bland, greasy on the mouth with no character, or presents rancid, musty or vinegary notes, it is not a quality product.

Our Quality Commitment

At Domaine Boeglin, we make no compromises on the quality of our extra virgin olive oil. Every step of our production is designed to deliver an exceptional product:

• Acidity at or below 0.2%, four times lower than the regulatory extra virgin threshold.
• Cold-pressed on the same day as the harvest, to preserve freshness and minimise oxidation.
• Two indigenous Portuguese varieties — Cobrançosa (80%) and Cordovil (20%) — grown in the Alentejo, a region with an exceptional olive-growing terroir.
• Traditional grove management at moderate density, allowing each tree to develop a deep root system and draw minerals from the schistous soil.
• No refining, no blending: our oil is a pure olive juice, unfiltered, bottled on site.

To discover our production process in detail, visit our dedicated process page.

"Choosing an olive oil is like choosing a wine. The origin, the terroir, the producer's expertise and the harvest year make all the difference. Never rely solely on price or packaging."