Stop choosing olive oil by colour

Put two bottles of extra virgin olive oil side by side. One is a deep, almost luminous green; the other is golden yellow. It is tempting to assume that the greener oil is fresher, healthier or somehow closer to the olive grove. But colour cannot settle any of those questions. A beautiful green oil can disappoint when you taste it, while a golden one can be lively, aromatic and every bit as good.

Olive oil gets its colour chiefly from two families of natural pigments: chlorophylls, which contribute green tones, and carotenoids, which contribute yellow ones. Their balance changes with the olive variety, the fruit’s stage of ripeness, growing conditions and the way the oil is made. Pigments also change during storage. That is why even oils produced in the same region can look strikingly different. The colour tells you something about the pigments in the bottle; on its own, it cannot tell you how carefully the olives were handled or how the oil tastes today. Researchers at the University of Pisa explain the role of these pigments, while UC Davis Food Quality notes the many factors that influence an oil’s appearance.

What colour can and cannot tell you

Oil made from less ripe olives is often greener, which helps explain why some intensely flavoured early-harvest oils have that vivid appearance. Yet “often” matters here. Variety and processing affect the final colour too, so a green bottleful is not proof of an early harvest, a stronger flavour or higher quality. Equally, golden oil is not necessarily old. It may simply have a different balance of pigments. You cannot judge an oil’s freshness by comparing its shade with another bottle on the shelf.

There is a good reason professional tasters try to set colour aside. The International Olive Council’s standard for tasting glasses calls for dark glass so tasters cannot see the oil and form expectations before smelling and tasting it. In the Council’s sensory assessment method, virgin olive oils are assessed for fruitiness and defects; colour is not the test that makes an oil extra virgin.

That does not mean appearance is never interesting. Pouring a new oil and noticing its colour is part of the pleasure of eating it. The mistake is treating green as a quality mark or yellow as a warning sign. Neither shade can do the work of a label, proper storage or, above all, your nose and palate.

What to look for instead

When you are buying, start with information you can check. Look for extra virgin olive oil on the label and, where the producer gives one, the harvest date. That date tells you when the fruit was picked; a best-before date alone does not. It is still only one clue: a recent harvest cannot make up for poor handling or storage. Consider the container and where it sits in the shop, too. Dark glass, a tin or another light-blocking package helps protect the oil, and a bottle kept away from direct light and heat has a better chance of reaching your kitchen in good condition. Packaging helps preserve quality; it does not create it. UC Davis offers the same distinction in its consumer guidance.

Once the bottle is open, smell the oil and taste a little on its own. Fresh olive oil can suggest grass, herbs, tomato leaf, almond or ripe fruit, depending on the olives and the style. Bitterness on the tongue and a peppery sensation in the throat are normal positive characteristics, though they can be gentle or pronounced. A mild oil does not have to make you cough to be good. What is more concerning is an oil that smells or tastes stale, rancid or unpleasantly fermented. The International Olive Council’s sensory method distinguishes these defects from the positive attributes of fruitiness, bitterness and pungency.

Finally, buy a size you will actually use and keep it closed, away from the stove and out of the light. Olive oil does not improve in the bottle with age. The greenest oil on the shelf may be wonderful, but it has to earn that judgment in the glass and on your food. Give the golden one the same chance.