From: http://www.wisegeek.org/what-are-truffles.htm
Often called the diamond of the culinary world, a truffle
is a rare, edible mushroom that is considered to be a delicacy due to
its intense aroma and characteristic flavor. They have a firm texture
and are most often shaven on top of food before serving, although they
can also be used to infuse flavor into dishes. Though there are
hundreds of different species, only some — mostly those found in the
genus Tuber — are considered delicacies. Truffles grow
underground in symbiotic relationships with trees and are difficult to
find; as a result, they are usually harvested in the wild by trained
hogs and dogs.
The French black or Périgord truffle, Tuber melanosporum, is prized for its aromatic and fruity qualities. When fresh, it has a brown-black exterior with white veins on the inside. It ranges in size from a pea to an orange, and weighs up to 2.2 pounds (1 kg). These truffles are found in the Périgord region of southwestern France.
Types
Truffles are usually classified mainly based on their appearance, smell, and taste. Found in a variety of regions around the world, many are commonly known by their location rather than their technical name. Their value varies depending on their rarity and specific aromatic qualities; the rarest are the most expensive food in the world.The French black or Périgord truffle, Tuber melanosporum, is prized for its aromatic and fruity qualities. When fresh, it has a brown-black exterior with white veins on the inside. It ranges in size from a pea to an orange, and weighs up to 2.2 pounds (1 kg). These truffles are found in the Périgord region of southwestern France.
The very rare Italian white or Piedmont truffle, Tuber magnatum,
has the strongest smell of all truffles. At its freshest, it has a
smooth, dirty beige surface that ages to a brown. It ranges from walnut-
to apple-size, weighing up to 1 pound (0.45 kg). Found in primarily in
the Piedmont region in north-west Italy, its aroma and flavor decrease
approximately one to two weeks after harvest.
Other notable varieties include the Oregon white truffle, the Chinese truffle, and the summer truffle. The two varieties of the Oregon white — Tuber oregonese and Tuber gibbosum — are white when immature and develop into an orange-brown and a pale olive-brown, respectively, at maturity. The brown Chinese varieties — Tuber sinense and Tuber indicum — are found in South China and are often harvested before they have fully matured, making them less expensive and more readily available. Found in France, Italy, and Spain, the summer truffle — Tuber aestivum — is the most common truffle, and exhibits a more delicate aroma.
As cooking dissipates their flavor, truffles are most often served raw. They can be sliced, scraped, or grated on top of ready-to-serve dishes, sauces, or soups. They also pair well with fattier foods, such as cheeses, butters, oils, and eggs.
Infusing flavor into foods creates another use for the truffle. Thin slices of the fungus inserted just under the skin allows meats to readily absorb the flavor. Only small amounts are needed to make truffle butter, as the aroma will flavor the entire batch. It should be noted that, while they can be added to olive oil to infuse their flavor, most "truffle oil" doesn't actually contain any truffles.
Truffle hunting is a lucrative business when they are in season, from fall through spring. In North America, raking back the soil and searching by sight is the usual method for harvesting. In Europe, hunters use truffle hogs and specially-trained dogs to sniff them out. The female truffle hogs become alert to the scent of the mature truffle because it is similar to the pheromones of the male hog's saliva. The sow is difficult to hold back, however, and will readily eat the expensive delicacy if allowed to do so.
For this reason, many hunters have begun to use truffle dogs, with the Lagotto Romagnolo being the only breed specifically recognized for this trait as of 2009. Though they lack the innate ability of the hog to detect the scent, dogs can be specially trained to do so. The advantage comes when the truffle is located, as the dog is much less likely to eat it.
Other notable varieties include the Oregon white truffle, the Chinese truffle, and the summer truffle. The two varieties of the Oregon white — Tuber oregonese and Tuber gibbosum — are white when immature and develop into an orange-brown and a pale olive-brown, respectively, at maturity. The brown Chinese varieties — Tuber sinense and Tuber indicum — are found in South China and are often harvested before they have fully matured, making them less expensive and more readily available. Found in France, Italy, and Spain, the summer truffle — Tuber aestivum — is the most common truffle, and exhibits a more delicate aroma.
Culinary Use
Truffles must be carefully handled to preserve their aroma and flavor. They should be cleaned of any dirt or debris, washed with water, and dried with a paper towel. To develop their aroma after being harvested, they should be placed in an air-tight container lined with paper towels and stored in the refrigerator for approximately three days. They can be stored in a glass jar for several months, but should never be dried as this will cause them to lose their pungency.As cooking dissipates their flavor, truffles are most often served raw. They can be sliced, scraped, or grated on top of ready-to-serve dishes, sauces, or soups. They also pair well with fattier foods, such as cheeses, butters, oils, and eggs.
Infusing flavor into foods creates another use for the truffle. Thin slices of the fungus inserted just under the skin allows meats to readily absorb the flavor. Only small amounts are needed to make truffle butter, as the aroma will flavor the entire batch. It should be noted that, while they can be added to olive oil to infuse their flavor, most "truffle oil" doesn't actually contain any truffles.
Harvesting and Hunting
Found approximately 1 foot (30 cm) under the ground, the vegetative part of the fungi — the mycelia — forms a symbiotic relationship with the roots of a variety of species of trees. Since they grow underground, truffles rely on animals to eat them and scatter their spores in order to reproduce. The strong odor of the mature truffle is what allows animals to locate them.Truffle hunting is a lucrative business when they are in season, from fall through spring. In North America, raking back the soil and searching by sight is the usual method for harvesting. In Europe, hunters use truffle hogs and specially-trained dogs to sniff them out. The female truffle hogs become alert to the scent of the mature truffle because it is similar to the pheromones of the male hog's saliva. The sow is difficult to hold back, however, and will readily eat the expensive delicacy if allowed to do so.
For this reason, many hunters have begun to use truffle dogs, with the Lagotto Romagnolo being the only breed specifically recognized for this trait as of 2009. Though they lack the innate ability of the hog to detect the scent, dogs can be specially trained to do so. The advantage comes when the truffle is located, as the dog is much less likely to eat it.
