Glossary: Know Your Olive Oil
The Ultimate Olive Oil Glossary: A Sommelier’s Guide to Buying, Tasting and Understanding Extra Virgin Olive Oil
Written by olive oil sommeliers Irini Tzortzoglou and Astrid Liakou
Olive oil is one of the world’s oldest foods and a superfood, yet the language surrounding it can often feel confusing. Terms such as polyphenols, cold extraction, early harvest and acidity are frequently used, but what do they really mean?
Standing in front of a shelf filled with olive oils at very different price points, or comparing them online, can leave you wondering what really matters and what you are actually paying for.
Understanding the language of olive oil makes it much easier to recognise quality, compare products and choose an oil with confidence.
How we got here:
Some collaborations feel almost inevitable.
Although we both spent our adult lives in the UK, our relationship with olive oil began much earlier – in Greece, surrounded by olive trees, Mediterranean landscapes and the food traditions that shape so much of who we are.
Like many Greeks, we grew up with olive oil not simply as an ingredient, but as part of everyday life: playing amongst the olive trees as children, being part of the yearly cycle of the olive grove and a bottle of our own olive oil always on the table drizzled over fresh salads, vegetables, legumes, grilled fish and family meals shared around the table. It was a taste of home and of connection with loved ones over shared meals.
Decades later, having both built our lives in the UK, we found ourselves drawn to the same mission: helping people understand and appreciate what exceptional extra virgin olive oil can be.
While our careers followed different paths, they ultimately led us to the same place. Astrid founded Opus Olea to bring exceptional extra virgin olive oil to people who value authenticity, quality and provenance. Irini, MasterChef UK Champion 2019, an olive oil sommelier, honey sommelier, cookbook author and culinary retreat host, has spent years helping people understand not only how to cook well, but why exceptional ingredients matter.
We were both among the very first certified olive oil sommeliers in the UK, driven by curiosity, respect for tradition and a desire to share the remarkable diversity and quality that exists within the world of olive oil.
Our paths finally crossed in person a few years ago. It was a meeting that brought together shared experiences, shared values and a shared belief that excellent olive oil deserves to be understood, celebrated and enjoyed.
We wanted to create the resource we both wished had existed when we first began studying olive oil professionally. One place where consumers could find clear, evidence-based explanations without the jargon or marketing hype.
This glossary is the result of that shared passion: a guide to the language of olive oil, created to help consumers become more confident in recognising quality, freshness and authenticity.
Whether you are standing in front of a supermarket shelf, comparing online retailers or investing in a premium extra virgin olive oil for the first time, we hope this guide helps you understand what really matters and gives you the confidence to make informed choices.
We hope it inspires you to look at olive oil differently – not simply as a kitchen staple, but as a remarkable expression of nature, craftsmanship and Mediterranean heritage.
Irini Tzortzoglou and Astrid Liakou
Irini Tzortzoglou is MasterChef UK Champion 2019, a food writer and cookbook author, olive oil and honey sommelier, and Guild of Fine Food judge. (link to Irini's website here).
Astrid Liakou is the founder of Opus Olea, an olive oil educator and sommelier dedicated to bringing her family's exceptional extra virgin olive oil to the UK.
Olive oil is one of the most regulated foods by law. When olive oil is of high quality it is a functional food that is also one of the most researched and evidence-based foods in the world. At the time of writing, a search for “olive oil” on www.pubmed.com (the US National Library of Medicine) produces 16,600 items of original medical, scientific research on olive oil. A search for the term “extra virgin olive oil” produces about 2,500 results. Europe PMC, a similar site to PubMed, containing original scientific research has 76,000 citations for olive oil and about 9,500 citations for extra virgin olive oil.
Jump to a term (in alphabetical order):
Bottled at Source vs Imported in Bulk and Bottled on Demand
Fruitiness in Extra Virgin Olive Oil
Virgin Olive Oil (without the Extra)
A
Acidity (Free Fatty Acidity)
Acidity is a laboratory measurement that indicates the percentage of free fatty acids in an olive oil. It is an important indicator of quality, but it cannot be detected by taste. It can provide information about the condition of the olives and how well they were handled before and during production.
For an olive oil to qualify as extra virgin, its free acidity must not exceed 0.8%. Lower acidity can be an indicator of carefully harvested and handled fruit, and many high-quality extra virgin olive oils have acidity levels considerably below this legal limit, sometimes below 0.4%.
Acidity, however, is only one measure of quality and is not a measure of flavour. An olive oil may have exceptionally low acidity yet still fail to qualify as extra virgin if it has a sensory defect. This is why laboratory analysis and professional sensory assessment are both important.
🌿 Did you know?
Despite the name, acidity does not mean an olive oil tastes acidic or sour. Free fatty acidity cannot be detected by tasting the oil.
An olive oil can therefore have very low acidity and still not qualify as extra virgin if a sensory defect is present.
Aroma
The aromas of a high-quality extra virgin olive oil come from natural volatile compounds created during the olive’s growth and processing.
Depending on the olive variety, the harvest and storage conditions, aromas may include freshly cut grass, tomato leaf, green apple, almond, herbs, artichoke and others.
🌿 Did you know?
In the olive oil sommelier world there are a little over 20 approved terms to describe both positive and negative attributes of aromas in olive oil.
Awards
The olive oil industry holds a number of yearly competitions, where olive oils are judged by panels of highly experienced professionals who are specially trained in olive oil. Some competitions are more prestigious, mainly because of their size and the high number of professionals in the field they attract. Following the intense scrutiny of each olive oil, an award represents a solid third party endorsement for an olive oil label.
B
Best Before Date
This is set by the producer and represents their guarantee for how long their product is in its best shape. Depending on the quality of the olive oil and its content in antioxidant polyphenols, which also preserve the oil, the “best before” date is usually set at 12 months for lower quality oils and at 18 or 24 months for higher quality ones.
Olive oil is an anaerobic substance, therefore it does not develop pathogens or a microbial load. The changes that happen in olive oil with age are at the molecular level and are of a chemical nature (see “Oxidation” and “Rancidity”).
A quality producer will have had their oil tested in a lab for how long it can “last”. Producers who cut corners will just place an arbitrary “best before” date on their label. For more detail tap this link.
🌿 Did you know?
Often a high quality olive oil is fine to consume for months after its “best before” date, it may just taste a little less vibrant than a fresh olive oil, but it can still be free of sensory defects and great for cooking with.
Bitterness
Bitterness is one of the three positive sensory characteristics of extra virgin olive oil, together with fruitiness and pungency.
It comes from natural phenolic compounds and is often stronger in oils made from early-harvest green olives.
🌿 Did you know?
Bitterness is not a defect. In fact, a pleasant bitterness is often a sign of freshness and high antioxidant content. Having said that, a truly high quality extra virgin olive oil will have a balanced bitterness, not an overpowering or acrid one.
Blend
A blend is an olive oil made by combining two or more oils. Not all blends are the same.
Some producers deliberately blend different olive cultivars to achieve a particular sensory profile, much like a winemaker blends grape varieties, to create a more balanced, more complex olive oil. Some of the world's finest extra virgin olive oils are carefully created blends of different olive varieties.
At the other end of the spectrum, commodity distributors may blend together oils from different lots (often ones that have remained unsold at the end of a season), regions, countries or even different harvest years to move them onto the market or to conceal defects. Rather than creating a deliberate sensory profile, this kind of blending can dilute the distinctive character of the individual oils and produce something generic. While this is perfectly legal, consumers should look carefully at the label to understand exactly what is being blended and why.
🌿 Did you know?
The word blend doesn’t tell you whether an olive oil is exceptional or ordinary. A carefully crafted blend can be greater than the sum of its parts; indiscriminate blending can have the opposite effect. The difference lies in the intention, skill and quality of the oils being combined. Blending itself is not the issue. Transparency is.
Bottled at Source vs. Imported in Bulk and Bottled on Demand
Bottling olive oil in the country of production provides greater transparency and traceability. Once bottled, the oil is already in its final packaging, with its provenance and harvest information established at source.
By contrast, some operators import olive oil to the UK in large bulk containers of 1,000 litres or larger and bottle it in the UK according to demand. This creates the possibility and temptation of older oils being blended with fresher oils over time and marketed as new-season products – in particular when someone has not been able to sell all their oil by the end of the next harvest. Because the oil remains in bulk, it can be stored and blended across multiple harvests without the consumer necessarily knowing its true age or composition.
Bottling at source removes this incentive. Once the oil has been bottled and shipped, rebottling or refreshing unsold stock is economically impractical. The oil’s journey and harvest information are much more clearly traceable.
🌿 Pro Tip
Check the label for the place where the olive oil has been bottled.
C
Cold Extraction (sometimes referred to as “Cold Pressed”)
Cold extraction refers to producing olive oil at temperatures below 27°C. Lower temperatures help preserve delicate aromas, flavours and natural compounds.
Today for an olive oil to be of extra virgin quality grade it must, by definition, come from the first extraction and it must be extracted cold. The term “First Cold Pressed” that can be found on some labels is an empty marketing term that has no true meaning.
🌿 Did you know?
In industrial olive oil production temperatures exceed 35°C+ and are often well over that temperature.
Colour
The colour of olive oil tells you surprisingly little about its quality. Depending on the olive variety, harvest stage and natural pigments, an excellent extra virgin olive oil may appear bright green, golden yellow or anywhere in between.
Professional olive oil tastings are carried out using blue tasting glasses so that colour cannot influence the judgement of the taster.
🌿 Myth Buster
A greener olive oil is not necessarily a better olive oil. Sometimes (not always) an intensely green olive oil is simply an oil that had a large amount of olive leaves crushed together with the olive fruit, leaving chlorophyl pigments in the oil. This practice removes the production cost of properly de-leafing the olives before oil extraction, but this extra pigment does not add sensory or nutritional value.
Cultivar
A cultivar is a specific variety of olive. Just as grape varieties influence wine, olive varieties influence the flavour, aroma and characteristics of olive oil.
Examples include:
- Koroneiki
- Arbequina
- Picual
- Frantoio
🌿 Did you know?
Every olive variety has its own personality. Some taste naturally peppery and robust, while others are softer, fruitier and more delicate. Some cultivars have naturally high polyphenols and others don’t. Some will stay fresh longer, while others are more fragile and oxidise (ie. deteriorate) faster.
D
Dark Glass Bottles
Light is one of olive oil's greatest enemies. Dark glass bottles help protect the oil from oxidation by reducing exposure to light.
For everyday household use, dark glass bottles and plastic-free tins are both excellent choices, provided they are stored correctly.
Defective Olive Oil
In olive oil sommelier terms, a defective olive oil is one that has developed undesirable aromas or flavours as a result of poor-quality fruit, improper processing, or inadequate storage. Common defects include fusty (fermented or anaerobic olives), musty (mouldy or damp), rancid (oxidised and stale), and winey-vinegary notes. A true extra virgin olive oil must be free from sensory defects and have a positive, fresh fruity character. These defects are not simply a matter of personal taste – they mean that the oil does not meet the sensory standards required for the extra virgin classification.
A lot of defective oils end up on shelves marked as “extra virgin” even though they do not meet that standard from an organoleptic assessment point of view (see term below).
🌿 Pro Tip
Olive oil competition awards (see term above), where olive oils go through a panel of many experienced graders of olive oil are a good cross check of whether your oil is a true extra virgin. Always check that the award relates to the bottle you have bought and is not just an award that has been won for an entirely different product and sometimes even by a different producer.
E
Early Harvest
Early-harvest olives are picked while still green or just beginning to ripen. These oils often have:
- stronger aromas,
- higher bitterness,
- greater pepperiness,
- and higher levels of natural phenolic compounds.
Early-harvest is not a calendar date (ie. an earlier calendar date in a given year vs. a later calendar date in the same year). Instead it relates uniquely to the olive grove’s specific conditions of terroir, altitude, olive varietal and agricultural practices and its specific harvest time. A grove in the south will be harvested earlier than one in the north – same as with other crops in the Northern hemisphere. Under-ripe olives make higher quality oil, but in lower quantities. Early harvest, low-yield olive oil therefore tends to be higher in price.
Extra Virgin Olive Oil (EVOO)
Extra virgin olive oil is the highest quality category of olive oil.
It must:
- be produced only by mechanical means (ie. no heating to extract higher volume, no chemical deodorising, no bleaching, no colouring etc.)
- meet strict and regulated by law criteria when analysed in a lab,
- have no sensory defects (no undesirable tastes and smells as evaluated by a panel of experts),
- and display positive attributes such as fruitiness.
Also see the terms “Organoleptic Assessment”, “Virgin Olive Oil”, “Refined Olive Oil” and “Olive Pomace Oil”.
🌿 Did you know?
Extra virgin olive oil is essentially fresh fruit juice. Like other fresh foods, its quality is best preserved when it is protected from heat, light and oxygen.
An olive oil can have good lab results yet have a taste or smell defect and as such not technically qualify for extra virgin quality grade.
F
Filtered Olive Oil
Filtration removes small particles of water and suspended solids of olive skin, pulp and other solids after extraction. All of the above, when left in a crude and unfinished oil, lead to its early oxidation and a much reduced life of often no more than a month or two.
Filtered vs unfiltered olive oil is a lot more than just an olive oil style. Filtering, which is a very similar process to filtering coffee through a paper filter to remove the coffee grounds, costs money and time. Only the coffee is consumed immediately whereas an unfiltered olive oil sits somewhere for months with the solids still in it.
Correct filtration improves stability and extends shelf life while preserving quality. It is the mark of a quality olive oil. Omitting it for an evoo that has to travel across the continent before it comes in the hands of the consumer often ends up with a rancid evoo by the time you open the bottle or tin in your kitchen. Unfiltered olive oil has higher weight and volume, as it contains the particles of vegetal waters and the solids. It means one ends up paying more for undesirable items in this unfinished product.
Many consumers associate cloudy olive oil with freshness. In reality, cloudiness simply means tiny particles of olive pulp and water remain suspended in the oil. While this may look attractive, it generally shortens the oil’s shelf life. For further reading tap this link.
Food Pairing
Like wine, different olive oils suit different foods.
Robust, peppery oils complement grilled meats, legumes and bitter greens.
Medium-intensity oils pair beautifully with tomatoes, pasta and roasted vegetables.
More delicate oils enhance fish, fresh cheeses and subtle dishes without overpowering them.
There is no single "best" olive oil, only the best olive oil for the dish in front of you.
Fruitiness in Olive Oil
Fruity describes the fresh aromas and flavours associated with healthy olives.
A fruity olive oil may remind you of:
- green grass,
- tomato leaves,
- fresh herbs,
- green almond,
- apple
Fruitiness cannot be found in chemically processed olive oils.
H
Harvest Date
The harvest date tells you when the olives were picked and transformed into oil. Harvest date alone does not allow you to establish whether an olive oil is a higher-quality “Early-Harvest”, as this is not a calendar date measurement. Harvest dates become especially important when one buys olive oil that does not come from an actual producer, but that comes to you having gone through middlemen. Producers always sell what is in their vats to make room for the next harvest. Middlemen however do not always manage to sell off the oil they have purchased from others and have to store it for longer periods of time.
🌿 Did you know?
Unlike wine, olive oils do not improve with age. The harvest date is often one of the most useful pieces of information on a label because it tells you when the olives were actually picked. Whenever possible, buy the freshest harvest available.
Freshness is one of olive oil’s greatest qualities. Also see the term “Seasonality”.
Health Claim
Olive oil is one of the most highly regulated foods. Because of the many health benefits olive oil offers it is also one of the most researched and most evidence-based foods available. High polyphenol olive oil is not just a healthy food, but also acts like a nutritional supplement.
Under European Union regulation (No. 432/2012) an olive oil can legally make a health claim if it has a total polyphenols count of over 250mg/kg and a hydroxytyrosol count of over 5mg per 20 grams of olive oil. Also see terms “Lab Analysis” and “Polyphenols”.
Hydroxytyrosol
t is one of the 30+ different types of polyphenols (see term “Polyphenols”) found in extra virgin olive oil and a powerful antioxidant and anti-inflammatory that has even been found to have a cancer fighting effect. It is one of the most studied phenolic compounds especially in relation to antioxidant, cardiovascular, and neuroprotective mechanisms.
High polyphenol olive oil with a health claim (see term “Health Claim”) is the most accessible and bio-available source of this powerful compound. The European Food Safety Authority (EFSA) has set the threshold for the protection of blood lipids from oxidative stress at a min of 5mg of total hydroxytyrosol in a daily dose of 20 grams (appr. 1 tablespoon) of olive oil. If your olive oil contains more than 5mg in 20grams you will experience health benefits from its daily consumption. Classic Opus Oléa Extra Virgin Olive Oil contains more than 2.5x the minimum amount of hydroxytyrosol.
L
Lab Reports
Not all laboratory analyses of olive oil are created equal. It is important that the lab analysis originates in a laboratory accredited by the IOC (International Olive Council) to ensure that it uses the correct analysis methods and equipment and that it consequently produces credible results.
Having the right analysis to hand is only half the story. One must also be able to read a lab report correctly, as not everyone of us is a trained chemist. For one thing the language of the report must be one we understand. Reading the numbers alone without being able to read comments on the report may not be sufficient. There are differences in how sensitive the measurements of different labs are. Even with a lab report in hand in a language we understand, there are still misinterpretations, one of the most common ones being of which compounds can be included in the important hydroxytyrosol number of mg per 20 grams, which in turn feeds into an olive oil’s health claim.
🌿 Pro Tip
When comparing olive oils for their health benefits it is best to compare between analyses from the same accredited laboratory.
M
Mediterranean Diet
The Mediterranean Diet is not simply a list of foods. It is a way of eating and living that has evolved over thousands of years in countries bordering the Mediterranean Sea. It places emphasis on vegetables, legumes, fruit, whole grains, nuts, herbs, fish and moderate amounts of dairy, while limiting highly processed foods.
At the heart of this dietary pattern is extra virgin olive oil, which is its principal source of fat and one of its defining ingredients. Rather than being used sparingly, olive oil is enjoyed generously every day, drizzled over vegetables, salads, legumes, grains and fish, and used in everyday cooking.
Decades of scientific research have linked the Mediterranean Diet with numerous health benefits, including better cardiovascular health, reduced inflammation and healthy ageing. For these reasons, it is consistently recognised by international experts as one of the healthiest dietary patterns in the world and has repeatedly been ranked the world's healthiest diet.
🌿 Did you know?
The Mediterranean Diet is recognised by UNESCO as an Intangible Cultural Heritage of Humanity, celebrating not only the food itself but also the traditions of growing, cooking and sharing meals around the table.
Microplastics
Many premium olive oil producers take considerable care to reduce the use of plastics throughout growing, harvesting, production and storage. Packaging is another consideration. Glass bottles and tins provide alternatives to plastic packaging and also offer practical advantages for storing olive oil.
For consumers wishing to reduce their use of plastic, choosing olive oil packaged in dark glass or a pastic-free tin is a simple option. Both also provide good protection for the oil when stored correctly.
O
Oleocanthal
This polyphenol type found in olive oil has attracted a lot of attention, particularly for its anti-inflammatory properties and its similarity in some biological effects to ibuprofen. It is the presence of oleocanthal that gives you a sting in your throat and a sharp cough when having a sip of high polyphenol olive oil. In contrast an oil that is smooth and flat will not contain much oleocanthal.
See term “Polyphenols”.
Olive Mill
Contemporary extraction of olive oil from olives no longer takes place in an “olive press”. The olive press of the previous century has long been replaced by stainless steel olive mills that can maintain strict hygiene and quality standards which the old, grimy olive presses could not. Today an olive press can mostly be found in museums or a few of them will occasionally be used for demonstrations to tourists. Today the reality is that it is the contemporary hygienic mills that produce the highest quality extra virgins. For more detail tap here.
Olive Oil Fraud
Olive oil is one of the world's most regulated foods, yet it is also one of the most misunderstood.
Consumers should look beyond attractive packaging and marketing claims. Trustworthy producers provide evidence of quality through harvest information, accredited laboratory analysis, sensory assessment and, where applicable, recognised competition awards.
Education remains one of the best protections against misleading marketing.
Olive Oil Sommelier
An olive oil sommelier is trained to evaluate olive oil through professional sensory analysis. Their main value added is the organoleptic assessment (see term “Organoleptic Assessment” below) as well as understanding production methods, quality and food pairings. It takes many years of practice after any certification to become a truly good sommelier. In many cases olive oil sommeliers have many years of other complementary qualifications such as in culinary training, milling, agronomy, chemistry, nutrition and many others. It helps for one to originate from an olive producing country as there is so much lived experience that ties into olive oil making that is simply not replaceable by just theoretical later-life learning.
Organic Olive Oil
Organic certification refers to the way olives are grown rather than the sensory quality of the finished olive oil.
An organic extra virgin olive oil may be exceptional, average or poor, just as a conventionally produced extra virgin olive oil may range from outstanding to disappointing.
Organic and quality are not the same thing.
🌿 Did you know?
Some outstanding olive oil producers choose not to become organically certified because of cost or bureaucracy, despite farming using virtually identical practices.
Organoleptic Assessment
Organoleptic assessment is the evaluation of olive oil using the senses, primarily smell and taste. It is carried out by trained olive oil tasters who learn to recognise both the positive characteristics of an oil and any sensory defects.
Why is this important? Laboratory analysis alone cannot determine whether an olive oil qualifies as extra virgin. An oil may have excellent chemical results but still have a sensory defect. If such a defect is confirmed through the recognised sensory assessment process, the oil cannot be classified as extra virgin.
This is why sensory assessment is such an important part of evaluating olive oil. A good olive oil is more than its chemical composition. Its aromas, flavours, bitterness, pungency, balance and overall character all contribute to its quality.
Our sense of flavour is particularly complex. The aromas we perceive combine with taste and other sensations such as texture, pungency and astringency to create the overall experience of an olive oil. Extra virgin olive oil contains numerous aromatic compounds, which explains the extraordinary range of aromas and flavours found in different oils.
Two people may describe the same olive oil slightly differently because aroma is interpreted through sensory experience, memory and learned associations. This is why professional assessment relies on trained tasting panels and consensus rather than the opinion of one individual taster.
Training provides an important foundation, but experience matters too. Developing the ability to recognise defects, assess balance and understand the finer differences between olive oils takes considerable tasting and practice.
This is why one sometimes falls onto beautifully marketed, expensive olive oils with acrid, repellent tastes and smells even though their labs look great. An olive oil is not just its chemical formula.
The human brain naturally recognises and categorises well over 10,000 different smells as well as the five tastes of sweet, sour, salty, bitter, and umami. Together, taste and smell as well as some other sensations such as texture, spiciness, astringency, viscosity and others create what we call flavour. An extra virgin olive oil contains hundreds of aromatic compounds, together with all other sensations they create the extraordinary complexity of extra virgin olive oil.
Sommeliers do not just analyse and categorise for “extra” virginity, they also go a step further and look for categories of quality, as defined by an olive oil’s balance of positive attributes, its vibrancy, overall differentiation in taste profile etc.
Oxidation
Oxidation occurs when olive oil and especially suspended particles of solids and water in it react, with oxygen, light or heat. Over time, oxidation reduces freshness and creates undesirable flavours.
To protect your oil:
- store it away from sunlight,
- keep it tightly closed,
- avoid heat exposure.
- chose a correctly filtered (never refined) olive oil
P
PDO and PGI
PDO (Protected Designation of Origin) and PGI (Protected Geographical Indication) are European certification schemes that protect the geographical origin of agricultural products.
A PDO olive oil must be produced, processed and bottled within the defined region according to specific standards.
A PGI olive oil has a recognised link to a particular region but allows greater flexibility.
These certifications provide reassurance about provenance but do not automatically guarantee superior sensory quality. Similarly to the organic certification PDO/PDI labels also add cost to the producer and are therefore often dropped.
🌿 Pro Tip
Treat PDO and PGI as indicators of authenticity and traceability rather than guarantees that one olive oil will taste better than another.
Peppery / Pungent
Pungency is the peppery sensation felt at the back of the throat when tasting fresh extra virgin olive oil.
It is associated with phenolic compounds (polyphenols), including oleocanthal.
🌿 Did you know?
That slight throat-catching sensation in a fresh olive oil can be a sign of quality and the presence of powerful polyphenols, not a problem.
Polyphenols
Polyphenols are naturally occurring antioxidant compounds found in olives.
They contribute to:
- bitterness,
- pungency,
- stability,
- and many of the recognised and widely documented health properties associated with extra virgin olive oil.
Some of the most discussed types of polyphenols found in extra virgin olive oil are hydroxytyrosol and oleocanthal. See terms “Hydroxytyrosol” and “Oleocanthal”. Polyphenols are the olive tree’s defense mechanism.
🌿 Did you know?
High quality olive oil contains 30+ different types of polyphenols, some of which do not occur in any other plant species and are unique to olive oil. For an olive oil to be marked as “high polyphenol” it must contain over 250 mg/kg of total polyphenols, as measured in an accredited laboratory.
Pomace Olive Oil
Pomace is the mass of olive solids that is left over after olives have been pressed “cold” at below 27°C. This leftover mass is sold by olive mills to industrial producers who then process it further using heat and chemicals such as the industrial solvent hexane to extract the remaining roughly 5% of fat still remaining in what effectively is a by-product of olive oil production.
Pomace oil can still have the word ‘olive’ in its name, but it is very different from extra virgin olive oil. The refining process removes most of the natural aromas, flavours and polyphenols associated with high-quality extra virgin olive oil. While olive pomace oil is sold for culinary use, consumers looking for the flavour, freshness and naturally occurring beneficial compounds associated with olive oil should choose extra virgin olive oil instead.
(In the above image you can see the leftover olive material that comes out of an olive mill. This is what is used to make pomace oil.)
R
Rancidity
Rancidity is an oxidation defect. Oxidation is the deterioration of a material when exposed to oxygen, similar to an iron rod rusting or a slice of apple browning and rotting when left out. Oxidation creates stale aromas in olive oil often described as stale, old nuts, waxy, cardboard-like or a feeling in the mouth that is unpleasantly heavy, clogging and oily. Rancidity occurs very soon after extraction in unfiltered olive oils, often as early as one month after production. This is due to the suspended solid particles oxidising fast in the presence of suspended particles of water (H2O) that have not been correctly removed from the actual oil.
A fresh extra virgin olive oil should never smell or taste rancid.
🌿 Did you know?
Polyphenol antioxidants protect olive oil from oxidation, consequently a high polyphenol olive oil remains fresh for longer.
Refined Olive Oil
Similar to Pomace Olive Oil (see term above), refined olive oil has been made by using chemical methods of deodorising, bleaching and stripping to remove the bad tastes and bad smells of olive oil that has spoiled due to poor handling, or that has simply aged. Another older term for spoiled and inedible olive oil is “lampante oil”, ie. oil that can only be used to light oil lamps. Poor quality oil can be chemically transformed to a completely neutral tasting and smelling oil that is permitted for consumption, but has no real health benefits. Any oil that goes through the above mentioned processes can not be described as virgin or extra virgin.
S
Seasonality
Olive trees can be harvested once a year and olives are a finite resource. In the Northern Mediterranean harvest takes place between October and December. In the Southern Hemisphere, for example in South Africa, harvest takes place between March and May. Depending on the olive cultivar, the terroir and on agricultural practices there are differences within the same region. This ties into the fact that an “Early Harvest” olive oil is not represented by the calendar date of its harvest.
Single-varietal Olive Oil
Olive varietal is another name (a synonym) for olive cultivar. A single varietal extra virgin olive oil is made exclusively of one olive variety and (similar to a single malt whiskey) maintains all its character if produced well.
In contrast a multi-varietal olive oil is made of a blend of different olive varieties. Blending is a practice that tends to make more palatable something that would be less well placed to stand on its own or to conceal something undesirable. Blending can invite temptation for deceptive practices.
Smoke Point
The smoke point refers to the temperature at which an oil begins to smoke.
Despite common misconceptions, modern research has shown that high-quality extra virgin olive oil is one of the most stable cooking oils available. Its natural antioxidants help protect the oil during cooking, making it an excellent choice not only for salads but also for roasting, sautéing and shallow frying. For more information see our article here.
🌿 Did you know?
The stability of extra virgin olive oil comes not only from its smoke point but also from its natural antioxidants/polyphenols.
Storage
Extra virgin olive oil should be stored away from heat, direct sunlight and unnecessary exposure to air.
The ideal place is a cool kitchen cupboard, away from the oven or hob.
Once opened, keep the bottle tightly closed and enjoy it while it is fresh.
🌿 Did you know?
Olive oil is much like freshly roasted coffee. The fresher it is, the more vibrant its aromas and flavours.
T
Tasting Olive Oil
To properly taste olive oil, pour a small amount into a small glass and warm it gently in your hands to release its aromas. First, smell the oil deeply and notice what comes to mind - fresh grass, herbs, tomato, fruit or other aromas. Then take a small sip, drawing in a little air as you taste. Pay attention to its fruitiness, bitterness and pungency, and notice how these sensations develop and linger. A good extra virgin olive oil should taste fresh, vibrant and balanced, with no unpleasant or stale flavours.
Terroir
Terroir describes the combination of soil, climate, altitude, geography and farming practices that influence an olive oil’s character.
Tin versus Glass Bottle
Both plastic-free tins and dark glass bottles protect olive oil well.
Tins completely exclude light and are often preferred for larger quantities or long-term storage.
Dark glass bottles allow consumers to pour more easily and are ideal for everyday kitchen use.
Clear glass bottles may look attractive but offer little protection against light.
Traceability
One of the strongest indicators of a quality producer is transparency.
Look for information such as:
• harvest date
• olive variety
• country and region of origin
• producer's name
• bottling location
• batch or lot number
The more information a producer is willing to provide, the easier it is for consumers to understand exactly what they are buying.
🌿 Pro Tip
Exceptional producers are usually proud to tell you exactly where their olive oil comes from.
V
Virgin Olive Oil (without the Extra)
This is a cold extracted olive oil that has been made without chemical processing that however does not meet the quality grade of extra virgin olive oil. Virginity is not a scale of “more virgin” or “less virgin” – it is a black or white determination of “if it’s not extra virgin then it is virgin”. An olive oil can have the chemical characteristics of an extra virgin, yet have failed the confirmation of the “Organoleptic Assessment” (see term).
10 Things Every Olive Oil Buyer Should Know
- Colour tells you almost nothing about quality.
- Freshness matters more than age.
- Bitterness is a positive characteristic.
- Pepperiness is a positive characteristic.
- Harvest date is for when the oil was made, best before date is for how long it will be at its best.
- Not all extra virgin olive oils are equal.
- Store olive oil away from heat and light.
- High-quality extra virgin olive oil is excellent for cooking.
- Awards and accredited laboratory reports provide valuable reassurance.
- The best way to learn about olive oil is to taste different styles side by side.
Further Reading
The world of extra virgin olive oil is constantly evolving. The books below provide an excellent starting point for anyone wishing to deepen their understanding of olive oil, its production, health benefits and place within Mediterranean culture.
The Olive Oil Diet
Dr Simon Poole & Judy Ridgway
A practical introduction to the health benefits of extra virgin olive oil and the Mediterranean Diet, written by one of the UK's leading advocates of Mediterranean nutrition. (see link here)
Extra Virginity: The Sublime and Scandalous World of Olive Oil
Tom Mueller
The book that first brought the subject of olive oil fraud and quality to the attention of a global audience. An engaging blend of investigative journalism, history and food culture.
Olives and Olive Oil in Health and Disease Prevention
Edited by Victor R. Preedy & Ronald Ross Watson
A comprehensive scientific reference covering olive oil chemistry, nutrition, production and health research.
The Olive Oil Encyclopedia
The Olive Oil Times Education Lab
An accessible reference covering production methods, tasting, terminology and the latest developments in the olive oil world.
Olive Oil Sensory Science
edited by Erminio Monteleone and Susan Langstaff
An in-depth exploration of olive oil flavour, aroma and sensory evaluation, particularly valuable for those interested in professional tasting.
🌿 Our Recommendation
Reading is an excellent beginning, but olive oil is ultimately understood through tasting. Try oils made from different olive varieties, countries and harvests, and compare them side by side. Nothing develops confidence more quickly than experiencing the differences for yourself.