Measuring Color, and Why It’s Hidden in Tasting
There is a neat contradiction at the heart of olive oil colour. Laboratories can measure it to fine tolerances, and pigments do carry real information about the fruit. Yet the official tasting glass is deep blue, designed precisely to stop the taster seeing colour at all. Both make sense once you separate two questions.
Olive oil gets its colour from pigments in the fruit — green from chlorophylls, gold and yellow from carotenoids — and the balance shifts with variety, ripeness at harvest and age. Labs can quantify this with simple optical measurements, and it tells a real story. So colour is not meaningless. The trouble starts only when a shopper tries to read quality from it, which is a different question entirely — and the reason the official tasting glass hides it.
What colour can be measured
A green oil often comes from olives picked early; a more golden one from riper fruit or an oil that has aged, as chlorophylls fade. In the right hands, colour is a clue to how and when an oil was made, and it can be tracked objectively rather than guessed at by eye. Pigment analysis is a genuine tool for growers and researchers watching ripeness and freshness. It just answers ‘when and how’, not ‘how good’.
| Green pigments | Chlorophylls — more abundant in early, green-picked fruit |
|---|---|
| Yellow/gold pigments | Carotenoids — relatively more prominent in riper or aged oil |
| What colour signals | Variety, ripeness at harvest, and age |
| What colour does not signal | Quality — a green oil can be faulty, a gold one superb |
| Official method | Oil served in a cobalt-blue glass to hide colour |
| Why | To stop colour biasing the assessor’s verdict |
Why tasters refuse to see it
The problem is bias. People associate deep green with quality and freshness, and pale gold with tiredness — associations that simply are not reliable. A brilliant green oil can be flat and faulty; a modest golden one can be superb. To keep the panel honest, the International Olive Council’s official sensory method serves oil in a cobalt-blue glass so the assessor judges aroma, fruitiness, bitterness and pungency without colour whispering in their ear. It is the same logic as a blind tasting: remove the cue that misleads and judge what actually matters.
What it means for you
Colour is measured when you want data about pigments, and hidden when you want an unbiased verdict on how the oil actually smells and tastes. For a shopper, the lesson is to stop reading quality off the glass. Don’t buy oil by its colour, and ignore the green-tinted bottles meant to flatter it. If you want to assess an oil at home, borrow the panel’s trick: judge by nose and palate, not by eye.
- Don’t buy by colour — green does not mean good.
- Ignore green-glass bottles designed to make oil look fresher.
- To assess at home, pour into an opaque or coloured cup.
- Warm it in your hand and judge by nose and palate.
- Save curiosity about colour for what it really signals — ripeness and age.
Olive oil colour: common questions
Does green olive oil mean better quality?
No. Colour reflects variety, ripeness and age, not quality. A brilliant green oil can be flat or faulty, and a modest golden one can be superb, which is why colour is hidden in official tasting.
Why is the tasting glass blue?
To hide the oil’s colour. The International Olive Council’s method uses a cobalt-blue glass so assessors judge aroma, fruitiness, bitterness and pungency without colour biasing them, like a blind tasting.
What does olive oil colour actually tell you?
It signals variety, ripeness at harvest and age — green from chlorophylls in early fruit, gold from carotenoids in riper or aged oil. Useful data, but about when and how, not how good.
Can you measure colour objectively?
Yes. Labs quantify the pigments with simple optical measurements, tracking ripeness and freshness far more reliably than the eye can guess.
Should I judge oil by its colour at home?
No. Borrow the panel’s trick: pour into an opaque or coloured cup, warm it in your hand and judge by nose and palate. Colour only tempts you into unreliable assumptions.
Don’t buy oil by its colour, and ignore the green-glass bottles meant to flatter it. If you want to assess an oil at home, pour it into an opaque or coloured cup, warm it in your hand, and judge it by nose and palate. Save curiosity about colour for what it actually signals — ripeness and age — not quality.
Based on the optics of olive-oil pigments and the International Olive Council’s blue-glass sensory method.