What is the free acidity of olive oil?
Free acidity has nothing to do with a sour taste. It is a chemical parameter that measures the proportion of free fatty acids in the oil, expressed in grams of oleic acid per 100 grams of oil. The lower this figure, the healthier the olives from which the oil was produced, and the better the harvesting and milling conditions.
Why do fatty acids become free?
In an intact olive, fatty acids are bound in triglycerides. When the fruit is damaged by shock, mold, olive fly infestation, or over-ripeness, triglycerides degrade through hydrolysis. Fatty acids detach and circulate freely in the oil. This is what free acidity measures.
A Calabrian producer who harvests olives by hand at the beginning of veraison and takes them to the mill within twelve hours will mechanically obtain very low acidity. This delay between harvesting and milling is one of the most determining factors for the final result, and it's precisely what the label doesn't tell you.
What acidity does not measure
Free acidity does not measure taste. It does not measure aromatic intensity, richness in phenolic compounds, or perceived freshness in the mouth. An oil can have very low acidity and still be bland if the olives were not ripe enough or if the extraction was poorly conducted.
Not to be confused with pungency: this pungent sensation in the throat, sometimes intense in early-season oils, has no connection with free acidity. Pungency is a sign of fresh oil, harvested early. High acidity is a sign of oil from degraded olives. These are two opposing things.
Regulatory thresholds to know
European regulations set maximum levels for free acidity depending on the oil category, defined by Regulation (EC) No 2568/91 and its successive revisions. Here are the four main categories:
- Extra virgin olive oil: maximum free acidity of 0.80 g per 100 g.
- Virgin olive oil: maximum free acidity of 2.00 g per 100 g.
- Lampante virgin olive oil: free acidity greater than 3.30 g per 100 g, not intended for direct consumption.
- Olive oil (blend of refined and virgin): maximum free acidity of 1.00 g per 100 g.
What the 0.8% ceiling doesn't say
All extra virgin olive oils meet the 0.8% threshold. But there's a world of difference between an oil at 0.79% and an oil at 0.15%. The best Italian monovarietal oils, from varieties like Coratina or Carolea from Calabria, regularly fall below 0.3%, sometimes even below 0.2%. This is no accident: it's the result of early harvesting, rapid transport, and careful milling.
Why serious producers display their acidity
A producer who displays an acidity of 0.18% or 0.22% on their label does so not out of obligation. Regulations only require the category to be mentioned. They do it because it's verifiable proof of quality. If you don't see an acidity figure on a bottle of extra virgin, it's often because the producer prefers not to show it.
How to read acidity on a label
Mandatory and optional mentions
The mention "extra virgin olive oil" is mandatory. Displaying the exact acidity level is optional, but if it appears, it must be accompanied by the peroxide value and wax content. This is a requirement of the European regulation to avoid misleading partial displays.
What to look for first
Here's the information to read in order on an extra virgin olive oil label:
- The category: extra virgin is the only level that guarantees the absence of organoleptic defects and an acidity below 0.8%.
- The origin: an oil whose label mentions "blend of olive oils from the European Union" offers no traceability. Prefer a single origin, ideally a designation like Olio di Calabria IGP.
- The harvest date: more useful than the best-before date. An oil harvested in November and consumed within the following eighteen months is at its best.
- The acidity level: if displayed, it's a good sign. If it's below 0.4%, it's an oil of superior quality to the average.
- The olive variety: an identified monovarietal allows you to understand the expected aromatic profile.
The case of organic oils
An organic olive oil is not automatically more or less acidic than a conventional oil. Acidity depends on harvesting and milling conditions, not on the cultivation method. However, an organic oil from sustainable agriculture, with hand-picked olives milled quickly, often combines both advantages: traceability and low acidity. This is the case with the 500 ml bottle discovery duo, which has an acidity below 0.4%.
Frequently asked questions about olive oil acidity
Can free acidity be tasted in olive oil?
No. Free acidity is a chemical parameter that cannot be directly perceived in the mouth. An oil with 0.8% acidity will not taste more acidic than an oil with 0.2%. What is perceived is pungency, the pungent sensation in the throat, which is related to phenolic compounds and not free acidity.
What acidity for a quality extra virgin olive oil?
The legal threshold is 0.8%. A common quality oil is between 0.4% and 0.8%. A superior quality oil falls below 0.4%, and the best artisanal productions reach 0.1% to 0.2%. If you want to explore this range, the 200 ml olive oil trio allows you to compare three different profiles side by side.
Does acidity increase over time?
Very little, in the case of filtered oil correctly stored away from light and heat. However, unfiltered or poorly preserved oil can see its acidity increase. This is another reason to choose a dark bottle and consume it within twelve to eighteen months of harvest. For professionals working with large volumes, the 5-liter can is conditioned to limit oxidation and maintain quality until the last use. To learn more about formats suitable for professional use, consult the space dedicated to cafes, hotels, and restaurants.
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