Olive Oil 101: Know your oil. Trust your taste.
Both are produced exclusively through mechanical processes, without the use of any chemicals. The difference lies entirely in the quality:
- Extra Virgin Olive Oil (EVOO): The gold standard. A panel of tasters (some call them olive oil sommeliers) must confirm a total absence of sensory defects, and a laboratory analysis must measure an "acidity" level of less than 0.8%. It is the richest in polyphenols and vitamins.
- Virgin Olive Oil: High quality, but allows for a slightly higher acidity (up to 2.0%) and/or very slight sensory defects.
Olive oil is a vegetable fat composed mainly of triglycerides. Imagine these as a "cluster" of three fatty acids (like oleic acid) held together by a central structure (glycerin) in an E-shape. In this state, the fats are like a "securely wrapped parcel"—stable, protected, and healthy.
When an olive is bruised, attacked by insects or fungi, or waits too long to be milled, this "E-shape" structure breaks down. This releases the fatty acids, which are then called Free Fatty Acids.
Why are Free Fatty Acids "bad"?
While the fats themselves aren't bad for you, they become unstable once they are "free." Think of it as if that parcel that has been ripped open; the contents are now exposed to the air. These free acids begin to oxidise (go rancid) much faster. Furthermore, the healthy polyphenols (antioxidants) in the oil have to "work overtime" to try and stabilise these free acids. By the time you consume the oil, many of the health benefits have already been "used up" fighting this internal damage.
Therefore, the lower the acidity, the healthier the fruit was and the more care was taken during harvest and production. Low acidity is fundamental because it signifies:
- Higher Quality: The fruit was fresh and processed immediately.
- More Potent Health Benefits: A greater quantity of "unused" polyphenols, vitamins, and minerals.
- Longer Shelf Life: Better oxidative stability means the oil stays fresh in your cupboard for longer.
Also note, acidity is a purely chemical parameter and is imperceptible to the taste.
Yes, within the European Union. According to EU legislation (specifically Delegated Regulation (EU) 2022/2104), any oil labelled as "Extra Virgin" must undergo a mandatory sensory evaluation by a certified tasting panel.
- The Rule: To be classified as Extra Virgin, the oil must have zero defects (a median of 0) and a "fruity" attribute greater than zero.
- The Panel: A panel consists of 8 to 12 trained tasters led by a panel leader. They taste the oil in dark blue glasses to ensure the oil's colour does not influence their judgement.
- The Process: Tasters limit the number of oils per day to avoid sensory fatigue. Between tastings, they eat a piece of green apple or a plain cracker to cleanse the palate, using smell, taste, and touch to evaluate the oil.
Tasters sample the olive oil checking for over a dozen possible defects including: Fusty, Musty, Muddy Sediment, Rancid, Vinegary, Metallic, Rot, or Damp Wood.
Conversely, a high-quality oil should show a balance of three positive attributes:
- Fruity: Aromas of fresh olives (green or ripe) and other fruits or vegetables.
- Bitter: A characteristic taste of oil obtained from green olives.
- Pungent (Peppery): A biting or stinging sensation in the throat, common in oils from the start of the harvest.
This third type of oil is the most commercially sold because it is cheaper. It is specifically intended for cooking, particularly frying, and should not be consumed raw.
The extraction process is completely different from Virgin or Extra Virgin. Bottles must explicitly state on the label if the product is majority Refined Olive Oil (>80%).
It is produced from "lampante" oils (low quality) that have been treated with heat and chemicals to remove impurities and lower acidity. This process also removes natural antioxidants and flavours.
In English-speaking markets, the term "Olive Oil" (without the words Virgin or Extra Virgin) is the legal name for what you described as Refined Olive Oil.
Because it sounds like the "standard" or "pure" version of the product to many average shoppers, it often confuses people into thinking it is the highest quality or at least just like the others, when in fact, it is the refined/cheaper version with few to no health benefits.
It is a good oil for high-heat frying due to its high smoke point, which is the context in which it should be used.
The short answer: Yes, absolutely. In fact, high-quality Extra Virgin Olive Oil (EVOO) is one of the safest and most stable fats to cook with, even at high temperatures. Here is why:
It’s about Stability, not just the Smoke Point
Many people worry about the "smoke point" (the temperature at which an oil starts to burn and smoke). For high-quality EVOO, the smoke point is between 190°C and 210°C (375°F to 410°F).
However, recent science shows that oxidative stability is more important than the smoke point. Because EVOO is packed with natural antioxidants (polyphenols) and high levels of monounsaturated fats (oleic acid), it resists breaking down and forming harmful compounds better than most "high-heat" seed oils.
A landmark study published in the journal Modern Agriculture compared several oils and found that EVOO was the most stable oil when heated, outperforming oils with much higher smoke points (like Grapeseed or Avocado oil) because its antioxidants acted as a "shield" against heat damage.
Should you use it for everything?
- For Sautéing, Roasting, and Baking: EVOO is perfect. It adds flavour and maintains its health benefits.
- For Deep Frying: You can use it, but since you need a large volume of oil, many people choose a high-quality refined olive oil for cost reasons.
- The "Luxury" Rule: While you can cook with it, we often recommend using your finest, early-harvest oils raw (as a finishing oil) to preserve the most delicate aromas and the highest concentration of vitamins that can be diminished by intense heat.
Source: Acta Scientific Nutritional Health (Volume 2 Issue 6)
To keep your oil fresh, protect it from its four enemies: Light, Heat, Air, and Time.
- Store it in a cool, dark place (a cupboard is better than a kitchen worktop).
- Keep the cap tightly closed when not in use.
- Avoid storing it near the stove or in direct sunlight.
- Note: If the oil begins to solidify or look "cloudy" in the cold, don't worry—this is a sign of quality. It will return to normal as the temperature rises.
Source: Olive Oil Times and UC Davis Olive Center
Unlike wine, olive oil does not improve with age; it is a fresh fruit juice. Most oils maintain peak quality for 12 to 18 months after the bottling date. Once opened, it is ideal to consume the bottle within 2 to 3 months for maximum flavour and health benefits.
EVOO is rich in monounsaturated fats (oleic acid) and polyphenols (antioxidants). It is scientifically proven that these compounds help reduce inflammation, support cardiovascular health, and help manage cholesterol levels.
Source: New England Journal of Medicine
The short answer is: No. In fact, the most prized oils often come from "unripe" olives.
While you can make oil from very ripe, black olives, the timing of the harvest completely changes the flavor, health benefits, and quality of the oil. Most premium producers use a mix or focus on the "Early Harvest" stage.
The Ripeness Spectrum
- Early Harvest (Green Olives): These olives are technically "unripe." They produce less oil, but the quality is incredibly high. This is where you get those vibrant, grassy flavors and that famous "peppery kick" in the back of the throat.
- Mid-Season (Purple Olives): As the olive matures and turns purple, the flavor becomes more balanced and fruity. This is often the "sweet spot" for a versatile, all-purpose Extra Virgin Olive Oil.
- Late Harvest (Black Olives): Fully ripe olives are softer and easier to press, yielding much more oil. However, the oil is very mild, buttery, and has significantly fewer antioxidants.
Why Quality Matters Over Quantity
At Casa Féteira, we focus on the earlier stages of ripeness. Even though it takes significantly more green olives to produce a single liter of oil than it does with ripe black ones, the result is a superior product.
Harvesting early preserves the Polyphenols—the powerful natural antioxidants that provide the health benefits olive oil is famous for. Choosing an "Early" or "Mid" harvest oil means you are getting the freshest, most nutrient-dense "juice" the olive can provide.
The riper the olive, the more susceptible it is to bruising, pests and natural degradation, which all increase acidity, making it harder to achieve extra virgin olive oil.
Source: UC Davis: Olive Maturity Index
The Olive is a sacred tree that has existed for thousands of years. It provides us with lighting, food, cosmetics, energy, wood, and medicine without ever needing to be cut down.
There are hundreds of varieties. Trees generally begin to fruit after 5 to 7 years, reaching peak production between 30 and 150 years. One of the oldest trees in Portugal, the "Oliveira do Mouchão" in Abrantes, was genetically tested and proven to be approximately 3,350 years old—and it is still producing!
The short answer is: Technically yes, but you really wouldn't want to.
While olives straight from the tree aren't poisonous, they are incredibly bitter—so bitter that most people find them completely inedible.
Why can't you eat them immediately?
The reason for this intense bitterness is a phenolic compound called Oleuropein. In nature, this compound acts as a defense mechanism for the tree, protecting the fruit from being eaten by animals or insects before the seed is ready.
To make an olive "table-ready," it must undergo a process called curing. This involves soaking the olives in brine (saltwater), water, or even lye to leach out the Oleuropein. Depending on the method, this can take anywhere from a few weeks to several months. Only after this process does the olive become the salty, savoury fruit we recognise.
Source: National Geographic
Follow the four "S" steps used by official panels:
- Swirl: Pour a tablespoon of oil into a small glass. Cover the top with one hand and cup the base with the other. Gently swirl for 60 seconds to warm the oil and release the aromas.
- Sniff: Uncover the glass and inhale deeply. It should smell fresh (cut grass, tomato leaf, artichoke, or green apple). Warning: If it smells like old peanuts, wax, or putty, it is likely rancid.
- Slurp: Take a small sip but don't swallow yet. Draw air through your mouth (making a "slurping" sound) to spread the oil across your palate.
- Swallow: Notice the sensations in your throat
- Pungency: You should feel a "peppery" kick or a slight burn. This indicates the presence of Oleocanthal (a powerful antioxidant).
- Bitterness: Early harvest oils will have a pleasant bitterness, similar to dark chocolate or rocket (arugula).
Source: IOC Sensory Analysis Guide
