How do I choose olive oil?

Olive oil is a fruit juice and it deteriorates. Most of what makes an expensive bottle worth the money — the peppery bitterness, the grassy aroma — is lost within a year of pressing and degrades quickly once opened. Freshness matters more than almost anything else on the label.

Step by step

1. Look for 'extra virgin' as the baseline quality grade.It's a legally defined grade meaning mechanically extracted with low acidity and no defects. 'Pure' or 'light' olive oil is refined and much less flavourful.
2. Look for a harvest date, not just a best-before.Olive oil is best within about 18 months of harvest. A best-before two years out tells you nothing about when it was pressed.
3. Choose dark glass or a tin.Light degrades olive oil quickly. Clear bottles on a bright shelf are a bad sign about how the producer thinks about quality.
4. Buy a size you'll finish within a few months of opening.Once opened, oxidation accelerates. A large tin is only good value if you use it.
5. Use a cheaper extra virgin or light olive oil for cooking.Heat destroys the delicate aromatics you paid for. There's no point frying with a bottle chosen for its flavour.
6. Save the good bottle for dressings, drizzling and anything uncooked.That's where you actually taste the difference between a good and an ordinary oil.
7. Store it in a dark cupboard away from the hob.Not next to the cooker, however convenient. Heat and light are what turn oil rancid.
8. Taste it — good extra virgin should be slightly peppery at the back of the throat.That peppery catch is polyphenols, and it's a genuine quality indicator. Flat, greasy or crayon-like flavours mean it's old.

Tips

• The smoke point of extra virgin olive oil is higher than commonly claimed and it's perfectly usable for normal frying and roasting — you're just wasting the flavour you paid extra for.
• Rancid oil smells like crayons or putty rather than fruit. Once you've noticed it, you'll spot it in a lot of supermarket oil.
• Single-origin oils vary enormously in character — Tuscan tends peppery and grassy, Spanish often milder and more almondy.
• Cloudy or 'unfiltered' oil isn't better. The sediment shortens its shelf life.

Common mistakes

• Buying oil in a clear bottle — Light degrades it, and clear packaging suggests the producer isn't prioritising quality.
• Storing it next to the hob — Heat accelerates rancidity considerably.
• Frying with an expensive finishing oil — Heat destroys the aromatics that justified the price.
• Keeping an open bottle for years — It goes rancid. Buy a size you'll finish in a few months.

Questions people ask