Cooking with olive oil
There is an old idea that extra virgin olive oil is too good, or too delicate, to cook with. In most Mediterranean kitchens it is simply the cooking fat: it goes into the pan, the oven and the salad bowl.
This foundation explains what heat changes in an oil, what the much-quoted smoke point does and does not tell you, how to fry well, and how to choose the right oil for each job. A few questions at the end let you check yourself.
Three ways to use it
- RawDressing and finishing, where every aroma survives.
- Gentle heatSautéing, roasting and baking.
- FryingShallow or deep, kept below smoking.
Raw or cooked
Heat changes an oil. The fresh, green aromas of a good extra virgin are delicate, and in studies that heated oils at 180 and 220 °C they faded faster the hotter the oil became. In the pan the oil still brings richness and a gentle fruitiness to food, but the finest aromas are at their best raw.
Raw
dressingfinishingdipping
Every aroma survives. Use your freshest, most aromatic oil here.
Cooked
fryingsautéingroastingbaking
The oil carries heat and flavour. A good everyday extra virgin does the job.
Finishing means adding oil at the end: a thread over soup, beans or grilled vegetables just before serving, so you taste the oil as well as the dish.
Match the strength. A robust, bitter and peppery oil stands up to grilled meat and bitter greens; a delicate one suits fish and fresh cheese.
What smoke point tells you
The smoke point is the temperature at which an oil starts to give off a steady stream of smoke under test conditions. It is judged by eye, so measurements vary from one laboratory to the next, and a single famous number for any oil should be treated with care.
For olive oil, the smoke point depends above all on free acidity: the lower the acidity, the higher the smoke point. A fresh, well-made extra virgin, which must stay at or below 0.8 per cent acidity, smokes later than a tired or poor oil. Frying raises the acidity, so an oil used again and again smokes sooner each time.
Smoke point is also only part of the story. What matters in the pan is how slowly an oil breaks down while it is hot, and that depends on its fats. Olive oil is mostly oleic acid, which oxidises far more slowly than the linoleic acid that dominates many seed oils. In one study that deep-fried potatoes until the oils reached the usual discard limit, olive oils, extra virgin among them, lasted 24 to 27 hours, against 15 hours for a blended vegetable oil.
Smoke means too hot. With any oil, steady smoke tells you the pan is too hot. Turn the heat down.
Frying with extra virgin
Frying with extra virgin olive oil is straightforward. Most of it comes down to moderate heat and attention.
Heat gently. Warm the pan and the oil together over medium heat rather than on full.
Test before you add. When the oil shimmers and a small piece of food sizzles at once, it is ready.
Stay below smoking. If the oil starts to smoke, turn the heat down, or off, and let it cool a little.
Never leave it. Hot oil needs watching the whole time it is on the heat.
For deep frying, fill the pan no more than a third full, and never pour water on burning oil: it can turn the fire into a fireball. Turn off the heat if you can do so safely, leave the room, close the door and call the fire service.
Oil from shallow or deep frying can be strained and used again a few times. Keep it closed, in the dark, and let it go when it darkens, smells stale or smokes early.
Frying in a professional kitchen
- Keep frying temperatures moderate and steady; overheating shortens the life of the oil.
- Skim and strain regularly. Food particles left in the oil speed its breakdown.
- Many countries set a limit for polar compounds in frying oil. A simple meter tells you when to change it.
- Keep your finest extra virgin for the pass: a few drops on the finished plate show it off far better than the fryer.
Baking and roasting
Olive oil works well in the oven. Vegetables, potatoes and fish roast evenly in it and take on its fruitiness, and it can replace other fats in many breads, biscuits and cakes.
For baking, choose the oil by taste. A mild oil disappears into a sponge or a shortbread; a greener, more peppery one adds character to a savoury bread or a chocolate cake. The heat softens the bitterness and pungency, so the result is milder than the oil tasted raw.
Potatoes and vegetables roasting in olive oil, a loaf of olive oil bread beside them.
Which oil for which job
You do not need a special oil for each job, but it helps to think in two kinds of bottle.
An everyday extra virgin
Good, fresh and sensibly priced, for the pan and the oven. Bought in a size you will finish while it is fresh.
Your finest bottle
The freshest, most aromatic oil you have, used raw: to dress, to finish, to taste on bread.
Refined olive oil and olive-pomace oil are also sold for cooking. They are neutral in taste, because refining removes most of what makes an extra virgin taste of olives. They can fry well, but they bring nothing of the olive to the dish.
Four common misconceptions
A few ideas about cooking with olive oil are repeated so often that they sound like facts. Four are worth putting right.
Myth “Extra virgin olive oil is only for cold use.”
It is a good cooking oil. Mostly oleic acid, it breaks down slowly in the pan, and in frying tests it outlasted a blended vegetable oil.
Myth “The smoke point tells you everything.”
It is judged by eye and depends mostly on free acidity. How slowly an oil breaks down while hot matters at least as much.
Myth “Your best bottle belongs in the frying pan.”
Heat dulls the finest aromas. Fry with a good everyday extra virgin and keep the special bottle for the table.
Myth “Frying oil can be used again and again.”
Each use raises its acidity and lowers its smoke point. Strain it, keep it closed, and let it go when it darkens, smells stale or smokes early.
A quick check
Six short questions, if you would like to check yourself. Pick an answer, check it and read why. Nothing is recorded beyond this browser tab.
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Your score
What to take with you
- Extra virgin olive oil is a cooking oil as well as a dressing. Heat dulls its finest aromas, so use your best bottle raw.
- Smoke point is judged by eye and depends mostly on free acidity: fresh, low-acidity oil smokes later.
- Olive oil is mostly oleic acid, which breaks down slowly when hot. In frying tests it outlasted a blended vegetable oil.
- Fry over moderate heat, stay below smoking and never leave hot oil. Never put water on burning oil.
- Keep an everyday extra virgin for the pan and oven, your finest bottle for the table.
What olive oil means: the six foundations together
Understand. Extra virgin is a legal grade, earned twice: in the laboratory and at a tasting panel. A minimum standard, not a style.
Origin. Olive oil is the oil of a fresh stone fruit, shaped by variety, ripeness and how quickly the olives reach the mill.
Taste. Smell, taste, finish: fruitiness, bitterness and pungency are its qualities, not its faults.
Choose. The label, a laboratory report and your own taste each tell you part of the story.
Keep. It is best young. Light, heat and air age it.
Cook. It belongs in the pan as well as on the plate; the finest bottle belongs on the table.
Put together: olive oil is a fresh fruit product, made by mechanical means alone, judged by your senses as much as by its grade, and best used, not saved.
