The master stares me straight in the mouth. "No lipstick," he warns. "No coffee within the past four hours! No cigarettes or sweets within the past hour! No meals for several hours at least! All of these things ruin your ability to taste." At Sol, the international olive oil fair in Verona, I am in mid-tutorial with Dr Flavio Zaramella, president of the Olive Oil Masters' Corporation of Italy, trying to unravel the extras in extra-virgin.
Stretching out on all sides are the stands of 244 leading oil producers, bathed in the greenish light that reflects off thousands of bottles of the precious fluid, great plates of ciabatta chunks drizzled with it and row upon row of little samples, poured into small plastic tumblers for passers-by to try. At a wine tasting, spitting out is in order, but here protocol demands that you sip and swallow one viscous, mouth-coating example after another - a prospect that makes me feel slightly green myself. Talk about being well oiled!
But it's the perfect opportunity to learn how to judge good olive oil - a handy skill, now that Ireland is embracing the Mediterranean diet with Latin fervour. We still consume only the teeniest dribble compared to the Italians, who absorb 12 litres per head per year - a far greater quantity of olive oil than we can manage of wine. But the graph is climbing steeply, with Irish consumption 10 times greater than it was 10 years ago, when olive oil was still something dispensed meagrely on a teaspoon into children's ears. The strange thing is that despite this huge overall increase, sales of the best stuff, extra-virgin, haven't risen much - a sign, perhaps, that its merits and complexities aren't widely understood.
Dr Zaramella produces a proper tasting glass, rather like a night-light holder with a round inside, pours in half an inch of oil and, cupping it in his hand, rolls it about with a wide, circular movement. This is a vital warm-up process. No aromas will be released until it reaches the magic level of 28s0] C. Then in with the nose. As with wine, aromas are more revealing than taste alone. A long and vigorous sniff should expose any defects - such as rancidity, mould, vinegariness, metallic off-notes or an earthiness which - yuk - can denote worms. "Keep your eyes closed for two seconds and concentrate as you smell," suggests the doctor, who must know what he is talking about: one of his oils, Fior del Colle, carried off the Golden Lion award for the best oil in the delicately fruity category at this year's Sol, while his Mirum won the punchier class two years ago.
Then a sip, rolled around to coat the inside of the mouth entirely, and a sharp intake of air to bring the flavours more vividly alive. "There are three characteristics to check - fruitiness, pepperiness and bitterness. A good oil must have all of these in harmony." As with wine, the aftertaste is an important yardstick of quality: the longer it lingers and the more pleasant its sensations, the better the oil. In fact, it is the aftertaste as much as the aromas that oil tasters consider when searching for flavour descriptors. Apples, tomatoes, artichokes, nuts, melon, grass . . . these are some of the things you may think of when scrutinising your extra-virgin. Contrary to what you might expect, the colour - even that glorious dark green - is of no significance. What else did I learn from the oil master? We may think we're doing pretty well to have a bottle of top-quality unguent in the cupboard, but it's not enough: we should apparently have three - light for fish, fruity for salads and more peppery, even slightly bitter, to contrast with sweet-flavoured vegetables. The earlier the olives are harvested, the more delicate the oil and the lower the level of oleic acid, which must be under 1 per cent to qualify for the extra-virgin tag.
Unfiltered oil is best, since filtration increases the risk of rancidity through oxidation. But unfiltered oils don't necessarily look cloudy. Opacity is simply the sign of a very fresh young oil that hasn't had time to settle down. Freshness is vital, by the way (a fact overlooked by too many Irish retailers). Your extra-virgin will be extra disappointing unless you store it away from the light and consume it greedily within 18 months of the bottling date - if there is one that is decipherable. The best book in English on olive oils, according to Dr Zaramella, is The Olive Oil Companion by Judy Ridgeway (Little Brown, £15), a guide so highly rated that, in translation, it is used as a bible by Italian producers. Alas, the British edition has just gone out of print and there are no plans for another edition, so any oil obsessive happening upon a copy would be well advised to snap it up.
You'll also need to keep a sharp eye out for the oils themselves, as new types are appearing all the time on the shelves of Irish supermarkets, delis and wine shops. Many retailers now offer a choice of at least half a dozen extra-virgins - but I've yet to see a range to rival that of Terroirs in Donnybrook, with about three dozen highly rated oils around Christmas and not less than two dozen examples during the rest of the year.
Do the style and quality of the extra-virgins that come our way vary as dramatically as the prices? Do you get what you pay for, or is it all marketing hype? The four hot chefs you see pictured above were persuaded to assemble in the Rhino Room at Cooke's for a blind tasting of Italian extra-virgin oils - the most expensive, from single estates, costing five times as much as the cheapest blends.
Extra-Virgins Put To The Test
Filippo Berio Cold Pressed, Special Selection. Widely available, 750ml £6.39. The classiest oil in the big-selling Berio range. Our chefs found it pleasantly fruity if not particularly mind-blowing. "A neutral oil that you can play with," said Kevin Thornton. Michael Martin thought it rather too heavy and cloying to use as a dressing but fine for cooking.
St Michael Tuscan. Marks & Spencer, 500ml £4.59. Another pretty straightforward example with a strong, peppery character suddenly emerging in mid-palate, then fading fast. "Not bad as an all-rounder," said Ben Gorman - but the consensus was that this was less appealing than the Filippo Berio special selection at around the same price.
Selvapiana. Karwig Wines, Carrigaline, 500ml £10. A lukewarm reception for this Tuscan from an estate whose wine bottles are more exciting. Weighty looking and a rich, dark green, it offered relatively little in terms of aromas or flavours, considering the price. Kevin Thornton felt it might be good for marinades. Michael Martin thought he might anoint warm lentils with it.
Ornellaia. Terroirs Donnybrook, 750ml £15. Excitement at last! From Marchese Lodovico Antinori's highly acclaimed wine estate, a terrifically assertive oil with enticing ripe fruit aromas and punchy flavours - black pepper with a hint of smoke - persisting all the way through a lingering finish. "A lovely sweet smell, a good fruity tang and plenty of pepper," said John Cooke. Top marks from three of our four tasters, and it was my favourite, too. Francoise Gilley of Terroirs, who has snapped up Ireland's entire allocation, confesses to sneaking a bottle home as a treat "any time I feel a bit low".
Badia a Coltibuono. Findlaters Harcourt St, Grapes of Mirth Rathmines, Terroirs Donnybrook, Fahys Ballina, 500ml about £10.50. Thornton: "Much too peppery. It opens every taste bud and then destroys it." Cooke: "Very viscous, very spicy, not at all pleasant." Martin: "Very acidic and fiery - like raw rocket leaves." Gorman: "It dries your throat up so much you choke on it." Sorry, Coltibuono, an oil I've bought for years and always enjoyed.
Frescobaldi Laudemio. Terroirs Donnybrook, 500ml £19.50; also Cooke's Food Hall, Castle Market, and a few other outlets. The famous Tuscan in the perfume-style bottle (well hidden from the panel as it's such a giveaway) lived up to its lofty reputation. It was Kevin Thornton's favourite and the No 2 choice of the other chefs, after the Ornellaia. "It's subtle," said Thornton. "The flavours emerge gently and linger gently. A great salad oil." "I'd love to use it with a touch of honey or sugar to dress oven-roast root vegetables," said Michael Martin. Of all the oils, this was the most distinctively olive-like in character, reminding everyone of a big plate of fat olives with herbs. The swish bottle and box make it an elegant present - but at a price.