The acidity of olive oil is not perceptible to taste. It is a chemical parameter, measured in a laboratory, that indicates the proportion of free fatty acids in the oil—not its aromatic intensity or its strength on the palate. Understanding this number means making better choices when purchasing.
What Olive Oil Acidity Really Measures
From Triglycerides to Free Fatty Acids
In a healthy olive, oil is stored as triglycerides: three fatty acids linked to a glycerol molecule. As long as the olive is intact, this structure remains stable. As soon as the skin breaks—due to impact, an insect bite, falling to the ground, or prolonged storage before milling—oxygen penetrates and begins to degrade these bonds. Fatty acids are released. This proportion of free fatty acids, expressed as a percentage of oleic acid, is what is called free acidity.
What European Regulations Say
European regulations set precise thresholds depending on the oil category. Here they are in increasing order of quality:
- Extra virgin olive oil: maximum free acidity of 0.8%
- Olive oil (refined + virgin blend): maximum free acidity of 1.0%
- Virgin olive oil: maximum free acidity of 2.0%
- Lampante olive oil (inedible raw): free acidity greater than 2.0%
An extra virgin oil must therefore have an acidity equal to or less than 0.8%. But this threshold is a necessary condition, not a sufficient one. An oil can meet this ceiling and still have other defects: rancidity, fermentation notes, musty aromas. This is why regulations also require a sensory panel test to validate the extra virgin category.
The Time Before Milling, a Decisive Factor
What few articles mention: the acidity of an oil is largely determined in the hours following harvest. The longer olives wait before being milled, the higher the acidity. In Calabrian mills working with the Carolea variety, milling generally takes place within four to six hours of picking. This speed, combined with the early maturity of Carolea, structurally produces oils with very low acidity—often under 0.3%—without any production artifices. This is an advantage of the Calabrian terroir, not a technical feat. You can find this profile in the organic green fruity olive oil, from this same tradition of rapid milling.
The Misconception to Debunk: Low Acidity = Better Oil?
Why This Shortcut is Misleading
An acidity of 0.2% is better than an acidity of 0.7% if all else is equal. But in reality, that's never the case. A refined oil—meaning chemically treated to correct its defects—can show very low acidity, sometimes less than 0.3%. It will never be classified as extra virgin, but it can bear the label "olive oil" with a displayed low acidity. This number says nothing about its aromas, freshness, or origin.
Conversely, an organic ripe fruity olive oil from olives harvested at full maturity may show slightly higher acidity than an early harvest oil, while having superior aromatic quality. The maturity of the olive at the time of picking influences the final acidity, but also the taste profile: fruitiness, bitterness, pungency.
What to Look For Besides Acidity
If the producer displays acidity on the label, regulations require them to simultaneously mention three other parameters:
- Peroxide value (measure of primary oxidation, threshold: 20 mEq O₂/kg for extra virgin)
- Ultraviolet absorption K232 and K270 (measure of secondary oxidation)
- Median of defects and median of fruitiness (results of the sensory panel test)
A producer who displays acidity alone without these parameters does not comply with regulations. A producer who displays all of them provides a complete and honest picture of their oil. This is a sign of seriousness.
How to Read Acidity on a Label When Buying
Three Concrete Situations
Here's how to react depending on what you read on the label:
- Acidity is not mentioned. This is the most frequent case. Regulations do not require it. The absence of acidity on the label does not mean the oil is bad. Instead, look for: the extra virgin mention, precise origin (estate, region, variety), harvest date, and bottle type (dark or opaque).
- Acidity is mentioned alone, without other parameters. This practice does not comply with European regulations. Be wary.
- Acidity is mentioned with the peroxide value and UV values. This is a sign of a rigorous producer. Acidity below 0.3% with a peroxide value below 10 mEq O₂/kg indicates a fresh, well-produced, and well-preserved oil.
Bottle Format Matters as Much as the Number
An oil with 0.2% acidity stored in a transparent bottle exposed to light will degrade faster than an oil with 0.5% in a dark, airtight bottle. Acidity measures the state of the oil at the time of bottling, not when you open it. The discovery duo in 500ml bottles allows you to compare two profiles—green fruity and ripe fruity—in capacities suitable for quick consumption after opening, which preserves quality to the last drop.
For professionals wishing to delve deeper into technical sheets and laboratory analyses, the dedicated space for cafes, hotels, and restaurants offers customized support.
Frequently Asked Questions
Can olive oil acidity be tasted?
No. Free acidity is a chemical parameter that is not perceived on the palate. What you feel as "pungent" or "bitter" in an olive oil is related to other compounds—oleocanthals for throat pungency, other molecules for bitterness. A smooth oil can have high acidity, and a very intense oil can have very low acidity.
What acidity should you look for in quality olive oil?
For extra virgin, the legal threshold is 0.8%. The best estate oils generally range between 0.1% and 0.4%. But acidity alone is not enough: also check the peroxide value, harvest date, and precise origin. The trio of organic olive oils in 200ml is a good way to compare different profiles on the same quality basis.
Why do some oils display acidity of 0.4° or 1° rather than a percentage?
Degrees (°) and percentage (%) express the same measurement. One degree of acidity corresponds to 1 gram of free oleic acid per 100 grams of oil, which is 1%. This degree notation is a legacy of commercial usage, without regulatory basis. European regulations require expression as a percentage (%). If you see "0.4°", read "0.4%".
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