Why it is worth tasting olive oil properly

Olive oil is fruit juice. It is pressed from olives within hours of picking, and from the moment it leaves the mill it begins a slow decline: the bright, grassy notes fade, the pepperiness softens, and eventually it goes flat. Most of us buy a bottle, use it for months and never once taste it on its own. That is a shame, because a proper taste tells you three useful things — whether the oil is fresh, what it will suit in the kitchen, and whether it is worth the money.

You do not need a tasting laboratory or an expensive set of blue glasses. You need a tablespoon of oil, a small glass, ten quiet minutes and a second bottle to compare it with. Here is how to do it at home.

Gather your kit

Set yourself up before you pour anything. Strong smells in the room — washing-up liquid, coffee, a scented candle — will flatten your ability to pick up aromas, so taste before cooking dinner rather than after.

• Two small glasses, ideally with a slight curve, such as a sherry glass or a wine glass. Wash them in hot water and dry them thoroughly; a trace of detergent will ruin the taste.
• About a tablespoon of oil per glass. Fifteen millilitres is plenty. Do not fill the glass.
• A glass of water and a slice of plain apple to clean your palate between oils. Apples work better than bread, which absorbs oil and blunts your palate.
• Paper and a pen. You will not remember the details of the first oil once you taste the second.
• Two bottles to compare, ideally a supermarket extra virgin and a fresher, single-estate oil. A bottle with a harvest date on the label is the one to look for.

Warm the oil, then sip it

Cold oil hides its character. Pour your tablespoon, then cup the glass in the palm of your hand and cover the top with your other hand or a small saucer. Leave it for a minute or two until the oil reaches roughly body temperature, around 27°C. This is the one step people skip, and it makes a real difference: the aromas lift and the bitterness and pepperiness become much easier to read.

Swirl the glass gently, take the covering off and sniff. Then sip a small amount, no more than half a teaspoon, and — this is the slightly odd bit — draw air in through your teeth as you hold the oil in your mouth, as though you were slurping soup. This spreads the oil across your tongue and up into the back of your nose, where most of the flavour actually registers. Let it sit for a few seconds, swallow, then breathe out slowly through your nose.

The three things to look for

Official tasters judge olive oil on three positive attributes. Learn them and you can describe any bottle in your kitchen.

• Fruitiness. The smell and taste of fresh olives. Green fruitiness is grassy, leafy, artichoke-like, sometimes with a hint of tomato leaf or green apple. Ripe fruitiness is rounder and softer, closer to ripe olive, almond or butter. Neither is better; they suit different foods.
• Bitterness. Felt at the back of the tongue as a clean, sharp tang — think rocket, chicory or the skin of a walnut. In a fresh extra virgin this is a sign of the polyphenols that keep the oil stable, not a flaw.
• Pungency. That catch at the back of the throat, the peppery tickle that can make you cough. It arrives a few seconds after you swallow and is the clearest marker of a very fresh, high-polyphenol oil.

Faults, by contrast, are easy to spot once you know them: fusty and musty oils smell of damp earth or old cellars, and rancid oil smells like crayons or stale peanuts. If a bottle smells like that, it is past its best.

Compare two bottles side by side

This is where tasting gets genuinely useful. Pour both oils into separate glasses, warm them both, and taste the milder or cheaper one first so it is not overshadowed. Sip water, bite a sliver of apple, then taste the second.

Ask yourself simple questions: which has more aroma? Where do you feel the bitterness — front, sides, back? Does one make you cough and the other not? Does one taste of green grass and the other of very little? Most people are surprised by how obvious the difference is once the oils are warm and tasted on their own. Score each out of five for fruitiness, bitterness and pungency, and jot down the harvest date and origin if the label gives them.

Use what you have learned

A bold, peppery oil with pronounced bitterness is wasted in a hot pan, where those compounds fade; keep it for raw finishes — drizzled over tomatoes, white beans, grilled courgette, or simply on bread. A softer, riper oil is friendlier for baking, mayonnaise and gentle cooking. Neither is the "right" oil; matching is the point.

Write your notes on a scrap of paper: the bottle, the harvest year, what you thought and what you ate with it. A short record turns a vague preference into a real one, so your next bottle is a deliberate choice rather than a guess. Store oil somewhere cool and dark, away from the hob, and use it within about eighteen months of harvest. Taste it again every few weeks — you will notice the pepperiness fading long before the bottle is empty, which is the surest sign that a litre tin was a better idea than you thought.