Olive oil myths: 18 beliefs put to the scientific test
In Umbria, olive oil is handed down like recipes: within the family. Along with it came advice that science has since disproved. We hold on to tradition, but not the mistaken kind. Put yourself to the test: true or false?
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They say
“You can fry with extra virgin olive oil.”
True.
The smoke point varies from oil to oil (a good extra virgin generally exceeds 190–200 °C), but what matters most is stability: thanks to oleic acid and natural antioxidants, extra virgin olive oil stands up well to home frying and forms fewer polar compounds than many other oils.
At our mill: For frying, we recommend the tin: it's better value per litre.
Cooking · Sources:De Alzaa et al., 2018
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They say
“Extra virgin olive oil and olive oil are the same thing.”
False.
By law they are two different categories. Extra virgin olive oil is obtained solely by mechanical means, with a maximum acidity of 0.8%. “Olive oil” is a blend of refined and virgin oils: refining removes most of the aromas and polyphenols.
At our mill: We produce only extra virgin olive oil, with no refined oils.
Buying · Sources:Commissione europea
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They say
“Bitterness is a defect in olive oil.”
False.
Fruity, bitter and pungent are the three positive attributes in official tasting; defects are something else, such as fustiness or mustiness. Bitterness signals fresh olives rich in polyphenols.
At our mill: We aim for a balance between bitterness and pungency.
Buying · Sources:COI, analisi sensoriale
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They say
“Olive oil, like wine, improves with age.”
False.
Quite the opposite: extra virgin olive oil is at its best in the months after milling. A University of Perugia study measured a drop in polyphenols of almost half over 24 months, even when stored in the dark.
At our mill: That's why we ship it fresh, including by subscription.
Storage · Sources:Blasi et al., Foods 2025
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They say
“Frying oil can be reused several times, as long as you strain it.”
False.
Every time oil is used for frying, it oxidises and builds up polar compounds. In Italian restaurants the limit is 25%; at home, throw it away once it smokes, darkens, foams or smells acrid, and never top it up with fresh oil.
At our mill: Extra virgin olive oil degrades more slowly, but it doesn't last for ever.
Cooking · Sources:Martín-Torres et al., Foods 2023
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They say
“Extra virgin olive oil is more fattening than other oils.”
False.
All oils have the same calories, about 9 kcal per gram: extra virgin olive oil is no more fattening than any other. Quantities still matter.
At our mill: A little, used raw, is all it takes to taste it.
Health · Sources:Reg. UE 1169/2011
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They say
“The best oil is “first cold pressed”.”
False.
There is no such thing as a “second pressing” of extra virgin olive oil: the term simply indicates the method using traditional presses below 27 °C. Producers using centrifugation, below the same temperature, state “cold-extracted”. Quality depends on healthy olives and prompt milling.
At our mill: We cold-extract within 24 hours of the harvest.
Buying · Sources:Reg. UE 2022/2104
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They say
“New-season oil is more pungent and bitter, then mellows over the months.”
True.
The pungency of early-season oils, made from olives that are still green, is a mark of quality. It already fades in the first few months of storage: the oil becomes softer, but it also loses some of its polyphenols.
At our mill: With a subscription, you receive oil from the current harvest.
Cooking · Sources:COI, analisi sensoriale Blasi et al., Foods 2025
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They say
“Cloudy, unfiltered oil is more genuine.”
False.
Cloudy oil is neither more genuine nor healthier: it is simply less processed. It is excellent freshly milled, but should be used sooner, because over time the water and enzymes in the sediment can cause defects.
At our mill: If you love freshly milled new-season oil, enjoy it in the first few weeks.
Storage · Sources:UC Davis, Filter or Not?
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They say
“The bottle should be kept next to the hob, within easy reach.”
False.
Light and heat oxidise oil and dull its aromas: by law, the label must advise storing it away from light and heat.
At our mill: Keep the tin in the pantry and refill a small oil cruet.
Storage · Sources:Reg. UE 2022/2104
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They say
“Tins or dark glass protect oil better than a clear bottle.”
True.
Light speeds up oxidation and reduces polyphenols, even at home. A tin blocks out light completely: just close it tightly and keep it somewhere cool.
At our mill: We sell in tins: once opened, decant a little at a time into a dark oil cruet.
Storage · Sources:De la Torre-Robles et al., JAOCS 2019
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They say
“Olives are better left to rest for a few days before going to the mill.”
False.
It is an old habit, but olives left piled up ferment and develop the “fusty” defect – and an oil with a defect can no longer be extra virgin.
At our mill: We mill cold, within 24 hours of the harvest.
Storage · Sources:Glossario COI, riscaldo
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They say
“The lower the acidity, the better the oil.”
False.
Acidity below 0.8% is the minimum requirement for extra virgin status, not a ranking. On its own it says nothing about how fresh or aromatic the oil is: that is why the law forbids stating it on the label without peroxides, waxes and UV absorbance.
At our mill: What counts for us is healthy olives and milling within 24 hours.
Buying · Sources:Reg. UE 2022/2104
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They say
“The greener the oil, the better it is.”
False.
Colour depends on the variety and ripeness of the olives, not on quality. So much so that the International Olive Council prescribes dark tasting glasses, precisely to avoid being influenced by it.
At our mill: We judge oil by nose and palate, not by eye.
Buying · Sources:COI, il bicchiere d’assaggio
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They say
“If the brand is Italian, the oil is Italian.”
False.
By law, the origin is the country where the olives were harvested and milled, not that of the brand or the bottler. Read the origin statement on the label: “Italy”, “blend of EU oils”, “non-EU”, or PDO and PGI.
At our mill: Always read the origin statement, on our label too.
Buying · Sources:Reg. UE 2022/2104 Guida etichette olio, Camera di Commercio
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They say
“If it solidifies in the fridge, it's genuine extra virgin.”
False.
The “fridge test” doesn't work: in a University of California test, no oil, extra virgin included, solidified completely in the refrigerator. Only chemical analysis and the panel test can tell whether an oil is extra virgin.
At our mill: Quality is certified by laboratory analysis, not by the fridge.
Buying · Sources:UC Davis Olive Center, 2013
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They say
“If it catches your throat, the oil is acidic.”
False.
The peppery sting comes largely from oleocanthal, a natural olive polyphenol: it is a mark of quality. Acidity, by contrast, is a laboratory measurement (free fatty acids) and cannot be perceived on the palate.
At our mill: Pungency is one of the qualities we look for in our oil.
Buying · Sources:Beauchamp et al., Nature 2005
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They say
“All olive oils contain the same polyphenols.”
False.
Polyphenols vary widely with variety, ripeness and processing, and decline over time; in refined oils they all but disappear. The EU permits a polyphenol claim only for oils that contain a measured minimum amount.
At our mill: Making the claim requires a batch analysis: we will publish it.
Health · Sources:Reg. UE 432/2012
The rule that always applies: cool, dark, tightly closed.
Extra virgin olive oil is a fruit juice: it is at its best in the months after milling. That’s why we also sell it in tins, which protect it from light and air, and on subscription, so it arrives fresh when you need it.
