The Number That Surprises Most Cooks

Ask a room of British home cooks what temperature extra virgin olive oil smokes at, and most will guess low. Somewhere around 150°C is the figure that gets repeated in kitchens and on the internet, usually followed by the advice to keep the good oil for drizzling and reach for something "safer" for the frying pan. It is a sensible-sounding rule, and it is out of date.

Good extra virgin olive oil typically starts to smoke somewhere between 190°C and 210°C. That is hotter than the oil in most domestic deep-fat fryers, hotter than a tray of roast potatoes needs, and comfortably above the temperature required for a proper shallow fry or a hard sear. The gap between olive oil and the refined oils usually recommended for high heat is far narrower than the old advice suggests, and the story does not end at smoke point anyway.

What the Smoke Point Actually Means

Smoke point is simply the temperature at which an oil's fat molecules begin to break apart. As they do, free fatty acids and glycerol are released, and those break down further into compounds that show up as a faint blue haze and a sharp, acrid smell. Push past that point and the oil starts to taste tired and bitter, and the food cooked in it picks up the same dullness.

Two things move that number up or down. The first is how refined the oil is: the more processing, the more the free fatty acids and flavour compounds are stripped out, and the higher the smoke point climbs. The second, and the one most cooks overlook, is freshness. Free fatty acid content rises as oil ages, is exposed to light, or is heated repeatedly, and the smoke point falls with it. A fresh, well-made extra virgin olive oil might have a free fatty acid level of 0.1 to 0.3 per cent, which is very low indeed, and it will hold its composure in a hot pan far better than a bottle that has been sitting on a sunny windowsill since last summer.

Why Extra Virgin Weathers the Heat So Well

Smoke point tells you when an oil will visibly protest. It says nothing about how gracefully it behaves beforehand. What matters in a hot pan is how quickly the oil oxidises, and here extra virgin olive oil is unusually robust.

• Monounsaturated fat dominates its make-up, mostly oleic acid, which is far more stable under heat than the polyunsaturated fats that make up the bulk of sunflower, corn and grapeseed oils.
• Polyphenols and vitamin E occur naturally in extra virgin oil and act as antioxidants, slowing the chemical reactions that lead to breakdown.
• Low polyunsaturated content means fewer of the fragile molecules that oxidise quickly and form off-flavours and unwanted compounds.

The practical upshot is that extra virgin olive oil can be heated for longer, and reheated more often, before it degrades to the same extent as a refined seed oil at a similar temperature. Smoke point is a useful guide; oxidative stability is the more telling one.

Frying and Roasting at Home

Here are temperatures that work in an ordinary British kitchen, using an ordinary bottle of extra virgin oil.

• Deep frying chips: 175°C to 180°C is well within range. Use a decent depth of oil, keep the pan no more than a third full, and fry in small batches so the temperature does not crash.
• Roast potatoes and root vegetables: a 200°C oven is fine. Toss the vegetables in a generous glug of oil rather than a teaspoon, and give them room on the tray.
• Shallow frying and sautéing: onions, peppers, courgettes and garlic all cook happily between 160°C and 180°C.
• Oven roasting generally: most roasting sits between 180°C and 200°C, which is comfortably below the smoking point of a fresh oil.
• Baking: olive oil cakes and traybakes baked at 170°C to 180°C work beautifully and stay moist for longer.

Where you might reasonably choose something else is prolonged cooking above about 220°C, such as a very hot wok session or a serious deep-fry marathon. Even then, fresh extra virgin oil will cope better than its reputation suggests.

Reading the Signs and Looking After Your Oil

You do not need a thermometer to cook well with olive oil, though it helps when you are learning. Watch the surface instead. A gentle shimmer means the oil is ready. A thin wisp of smoke is your cue to lower the heat. Thick, fast-rising smoke and a sharp, unpleasant smell mean the oil is well past its best and the food will taste of it.

• Store bottles in a cool, dark cupboard, away from the oven and the hob. Light and heat age oil faster than time alone.
• Buy by harvest date where you can, not just by best-before date, and choose dark glass or a tin.
• Once opened, use it within a few weeks for the best flavour. A litre is not a lifetime supply.
• After frying, let the oil cool, strain it through muslin into a clean jar, and reuse it two or three times at most. Discard it if it looks sticky, foams, or smells odd.

Cooking the Way the Mediterranean Does

Across Spain, Italy, Greece and southern France, olive oil is not a finishing touch reserved for salads. It is the base, the cooking medium and the final flourish, all from the same bottle. A generous glug in a hot pan, an onion softened slowly in it, a spoonful stirred through a stew at the end: that is the rhythm of the cooking, and it is entirely suited to a British kitchen.

The olives themselves deserve a place at the table too. A small bowl of good green or black olives, a dish of tapenade whizzed up with capers and anchovies, a handful of chopped olives through a tomato sauce, all add the salty, savoury depth that olive oil alone cannot quite reach. Buy them loose from a deli where you can, and they will taste of something other than brine.

So keep the extra virgin oil by the hob, not hidden away. Use it with confidence, keep it fresh, mind the heat, and let the pan tell you when it has had enough. That is the whole trick, and it has been working in Mediterranean kitchens for centuries.