How do you store olive oil so it doesn't go stale?

Good olive oil is fresh produce, not a bottle that lasts forever. It starts losing its fruity, peppery character from the moment it is made, and how you store it decides whether that happens slowly or fast. The good news: storing it well is simple and costs nothing.

The three enemies

The International Olive Council advises keeping olive oil away from excessive heat, air and humidity and, above all, from light. Its consumer storage guidelines, summarised by Olive Oil Times Lab, add the practical detail.

Light

The guidelines name light as the main threat to quality. Store oil in a dark place, or wrap a clear bottle in something opaque such as foil. That handsome clear bottle on the windowsill is the worst possible spot.

Heat

Keep oil roughly between 13 and 25 °C, the guidelines suggest, and away from radiators, burners and sunny windows. The shelf right beside the cooker is convenient and too warm. A cupboard on the other side of the kitchen is better.

Air

Once opened, oxygen gets to work. The guidelines advise keeping containers tightly sealed and keeping the air space above the oil to a minimum. That is why the bottle size matters.

Bottle size and containers

The IOC's guidelines suggest buying amounts you'll use within one to three months, and moving oil from large tins into smaller dark glass, ceramic or stainless-steel containers. They advise against iron containers.

What that looks like in practice:

• Tins keep out light completely and are a good way to buy larger amounts. Decant a small bottle for daily use and keep the tin closed and cool.
• Dark glass bottles are good. Clear glass works only if it lives in a dark cupboard.
• Pourers and spouts look nice but let air in. Use a cap, or one that closes.
• Don't top up an old bottle with new oil. The old oil spoils the new.

If you use a little oil a week, buy small. If you cook with it every day, a large tin is good value, as long as you decant it.

The fridge?

The same guidelines note that refrigeration slows oxidation, and that oil may turn cloudy or solidify in the cold, which reverses when it warms and doesn't affect quality. Most people don't need to bother; a cool, dark cupboard is enough for oil you'll use within a few months.

Signs your oil is past it

Smell it. Pour a little into a glass or spoon, warm it in your hand and sniff.

• Fresh oil smells green, grassy, fruity or of tomato leaf, sometimes like almonds or artichoke, and the good stuff has a peppery catch at the back of the throat.
• Rancid oil smells flat, waxy or stale: crayons, putty, old walnuts or cardboard. The guidelines describe a rancid smell or taste as the sign of oxidation.
• Taste: if it seems dull and fatty rather than lively, it's past its best.

Rancid oil won't make any dish better, so we replace it rather than trying to hide it.

When buying

Look for a harvest date on the label, which tells you how fresh it is; the best-before date is less useful. Choose the most recent harvest you can find, store it well at home, and use it generously. Our page on choosing olive oil in a supermarket covers the labels.