The Free Fatty Acid Test, Explained
The single number that gates ‘extra virgin’ is free acidity. It doesn’t measure how sharp the oil tastes — it measures how gently the olives were treated, from tree to press.
What it actually measures
Free fatty acidity (FFA), given as a percentage of oleic acid, counts how many fat molecules have broken loose from the oil’s triglycerides. Bruised, fly-damaged, overripe or slowly-processed fruit lets enzymes split the fat, raising the number. Pristine fruit pressed fast keeps it low. For extra virgin, FFA must be no more than 0.8%; the best oils come in far lower.
What it isn’t
Crucially, you can’t taste free acidity — it’s odourless and flavourless. So a low number doesn’t promise a delicious oil, only a well-made one; an oil can be chemically perfect and still dull. That’s why the grade needs the taste panel too. FFA is a measure of care, not of flavour.
This one number quietly rewards everything good about how oil is made: healthy fruit, an early harvest, a clean mill, and pressing within hours, not days. A very low free acidity is the fingerprint of a careful producer — and a clue, on the rare label that prints it, that you’re holding the real thing.
A olives101 science explainer.