When it comes to mushrooms that grow below ground, the king of them all is the species known as ’tuber melanosporum’, more commonly known as the black truffle, Périgord truffle or French black truffle. Irregular in shape, this expensive truffle looks not unlike a lump of coal. Yet, the black truffle is highly-prized by chefs for its intense aroma and taste, and it is used to flavour all manner of dishes.
Normally around 10 cm in size, the taste of black truffles fully develops only after they have been heated, and they impart a slight peppery, bitter flavour.
Black truffles typically grow at a depth of between 5 and 50 cm below ground, and specially trained dogs are used to sniff them out, as they contain a compound called dimethyl sulfide, which is what attracts the dogs.
As mentioned, black truffles are highly-prized, which is what makes them so expensive, and prices can reach over a thousand euros a kilo. This is particularly true these days, as production has dropped over the past few decades, falling to between 20 and 40 metric tonnes per year. By way of comparison, in 1937, France produced around 1,000 metric tonnes of black truffles.
In fact, France accounts for most of the world’s production of black truffles, at about 45%, followed by Spain (35%) and Italy (20%). In Spain, Aragon and Catalonia are both areas where there is a lot of truffle production.