Le grand fromage: why Vieux Boulogne is the world's smelliest cheese

To the uninitiated, it smells like the product of a cow's behind rather than its udders. A more sophisticated nose would compare it to wet earth, mushrooms, and a hint of rotting leaves.

To the uninitiated, it smells like the product of a cow's behind rather than its udders. A more sophisticated nose would compare it to wet earth, mushrooms, and a hint of rotting leaves.

They would agree, however, that Vieux Boulogne, a soft cheese from the northern French port of the same name, is one humdinger of a fromage.

A scientific exercise to measure the olfactory strength of different cheeses suggests that it could even be the smelliest on the planet. Vieux Boulogne achieves its special potency from having its rind washed in beer. It beat 14 other cheeses measured by Stephen White of Cranfield University using a human panel of testers and then by applying an "electronic nose" to the results.

It beat Epoisses de Bourgogne, a cheese so smelly it is banned from being eaten on public transport in France, Camembert, Munster and Roquefort. British Cheddar was rated the second mildest-smelling in the tests.

Nineteen students and staff at the university were given two hours to smell the cheeses. They were then asked to rank them in terms of strength.

According to Dr White, the panel concluded that those whose rinds were washed in beer, brandy or salt solution, were the most potent. "There was no obvious correlation between the age of the selected cheeses and smelliness, nor type of milk origin, although cow's milk cheeses did dominate the smell chart," he said. "Those that are at the top of the list really are pongers."

The powerful aroma of the winner is created by the interaction of bacteria in the beer with the milk enzymes of the rind. This creates micro-organisms that release volatile particles picked up by the nose.

For good measure, Dr White then applied his electronic nose, a device usually used to sniff for urinary infections or to diagnose tuberculosis. He found that the smelliest cheeses created a similar "fingerprint". He believes the device could be used by manufacturers to sniff out authentic cheeses from fake ones.

But those wishing to display the sort of gastronomic machismo that drives people to order the hottest curry on the menu, should beware. Vieux Boulogne is actually a "sheep in wolf's clothing". Its bite is altogether more demure than its bark, with the smell emanating from the rind rather than the cheese itself. It is described as a young, modern cheese best eaten at between seven and nine weeks old, and typically served with crusty bread and a beer.

Patricia Michelson, owner of the La Fromagerie cheese shops in London, provides the only outlet for the cheese in Britain, which sells for £10.99 a kilo. She warns that strength and taste are partly governed by perception.

"This should not be thought of as the smelliest cheese but one with a high potency and a forward pungency," Ms Michelson said yesterday. "On first impact it smells of a farmyard and many people's perception of a farmyard is one of poo. My perception would be wild mushrooms and earth, altogether more romantic. Simply because a cheese smells high, it doesn't mean it is off or even particularly strong."

The British cheese board is becoming an increasingly adventurous place. Epoisses de Bourgogne is sold in Sainsbury's, Tesco and Waitrose. Experts say cheeses should be selected according to the beverage with which they will be consumed. Beer is growing in popularity as an accompaniment, especially to those cheeses whose rind has been washed in beer. Professional cheese tasters enjoy a rich and varied vocabulary, employing descriptions akin to those used by their colleagues in the wine trade. Goats' cheeses are noted for their citrus flavours, fudginess and tang. Gruyères are often admired for their milkiness or nuttiness. Although France and Italy are considered world leaders in cheese-making, they have long operated a strict geographical quality control system, similar to the Appellation d'Origine Controllée and Denominazione di Origine Protetta methods used for wine.

Sally Clarke, of Fine Cheeses from France, which promotes cheese in the UK and commissioned the research, said: "Love it or loathe it, the sign of a fine cheese is often its characteristic smell as well as its flavour and texture, and we wanted to find out if France's reputation for producing smelly cheeses was true."

But the rest of Europe and the world is catching up. British Cheddar is among the finest, said Ms Michelson. Dutch aged goudas are highly prized, as are Greek fetas. Georgia is rapidly emerging on the world cheese map, while Peru's llama-milk cheeses have been generating excitement. All of which makes alarming news for those who believe cheese is best served with a chunk of pineapple on the end of a cocktail stick.

THE 15 MOST PUNGENT

1: Vieux Boulogne: Aromatic, earthy cow's milk cheese from Boulogne sur Mer, Pas de Calais, aged 7-9 weeks. Rind is washed with beer

2: Pont l'Evêque: Earthy cow's milk cheese from Normandy, aged 6 weeks. Rind is washed with brine

3: Camembert de Normandie: Nutty cow's milk cheese of Normandy, minimum age 21 days. Soft, bloomy rind

4: Munster: Spicy cow's milk cheese from Alsace Lorraine, north-east France, aged 3 weeks. Rind washed in brine

5: Brie de Meaux: Earthy, nutty cow's milk cheese from Ile de France, near Paris, aged 4-8 weeks. Soft, bloomy rind

6: Roquefort: Spicy and tangy sheep's milk cheese from Roquefort, near Toulouse, aged 3 months. Blue-mould cheese

7: Reblochon: Nutty, earthy cow's milk cheese from the Savoie region in France, aged for 3-4 weeks

8: Livarot: Fruity and earthy cow's milk cheese from Normandy, aged 90 days. Rind is washed with brine

9: Banon: Silky, tangy goat's milk cheese from Provence, aged 1-2 weeks and wrapped in chestnut leaves

10: Epoisses de Bourgogne (below) : Mellow and pungent cow's milk cheese from Burgundy, 4-6 weeks. Rind is washed with brandy

11: Parmesan: Gritty cow's milk cheese from Italy, aged 2 years

12: Raclette: Chewy, nutty cow's milk cheese from the French Alps, aged 2 months

13: Ossau Iraty: Fruity, earthy sheep's milk cheese from the Basque region in southern France, aged 3 months

14: Cheddar: Crumbly, nutty cow's milk cheese made across the UK, aged 6-24 months

15: Crottin de Chavignol: Fudgy, zesty goat's milk cheese from Chavignol near to Sancerre in the central region of France, aged for 0-6 months. Test was 4-6 weeks