Truffles are held in high esteem in French cooking.

• White truffles are generally served uncooked and shaved over steaming buttered pasta or salads. White or black paper-thin truffle slices may be inserted in meats, under the skins of roasted fowl, in foie gras preparations, in pâtés, or in stuffings. Because of their high price and their pungent taste, truffles are used sparingly.
• Black truffles are far less pungent and more refined than their white cousins.

The Midi - Southern France - has the sweet limestone soils and dry hot weather that truffles need to grow. In 1900 truffles were used by most people, and on many occasions. Nowadays, they are a rare delicacy reserved for the rich, or used on special occasions.

Looking for truffles in open ground is almost always carried out with specially trained pigs or dogs. Pigs were the used extensively in the past - and still in the popular imagination - but nowadays farmers prefer to use dogs, which do not eat the truffles. Both pigs and dogs have keen senses of smell, but while dog's must be trained to the scent of truffles, female pigs or sows need no training . A compound within the truffle resembles a sex pheromone of boars - to which the sow is naturally attracted. It is possible that the attraction that sows have towards these fungi prompted their discovery by early human populations.

Truffles are generally found under certain trees - they live symbiotically with the trees' root system. Symbiotes of the truffle include oaks, holm oaks, hornbeam, hazelnut trees and colurna. The average life cycle of a truffle-producing tree is around 30 years

The truffle is a fungus that grows underground. It forms in Spring between April and June. When it is born it has the form of a tiny cup ( stade apothécioïde ), of which the edges will close up and form the Tuber. The interior of the Tuber will grow veines stériles then veines fertiles. This whole autonomous ensemble is the gleba (body) of the truffle, coloured white, and covered with a skin ornamented with small warts or scales which, as well as protecting the tuber, contributes to its respiration and nutrition.

After a period of inactivity, the hot periods in July ( thermal stress ) and the storms in August ( or irrigation ), will set off the growing cycle. If the amount of water and heat are optimal, the nearly finished size will be attained at the beginning of September . Inside the gleba, the number of of asques ( sacks containing the spores ) will increase. First hyalines (nearly transparent the spores, which represent the seed of the fungus, will little by little brown during the melanisation process, which will end by the acquisition of aroma and the maturity of the fungus

The zones of production of Tuber melansporum are between 4O and 47 degrees of latitude North. This species needs a temperate climate with well marked seasons. During its maturing phase it freezes underground at -7° C. The ideal climate for truffles is:

• Winter with nights at -5°, and days between 1O° et 14°C
• Spring with alternating periods of damp and heat.
• Hot Summer interrupted by thunderstorms, especially between August 1 and 15.
• An Autumn which is not too wet.

Tuber melanosporum is a resistant truffle, both against drought and flood, but it is vulnerable during its growing cycle to shortage and excess of water, either of which can be fatal.

If truffles are not harvested, they will degrade and rot, releasing asques which will set free spores. The cycle will continue with the germination of a number of spores, liberating of "hyphes" (or primary mycélium ) likely to infect the rootlets of a host tree by giving birth to new mycorrhizes.

Contrary to popular legend, truffles can be cultivated. As early as 1808, there were successful attempts to cultivate them, known in French as trufficulture.

People had long observed that truffles were growing among the roots of certain trees, oak trees in particular, and scientific research has established that truffles live in symbiosis with the host tree. In 1808, Joseph Talon, from Apt in southern France, had the idea of sowing acorns collected at the foot of oak trees known to host truffles in their root system. The experiment was successful. Years later, truffles were found in the soil around the oak trees grown from those acorns. In 1847, Auguste Rousseau of Carpentras planted 7 hectares (17 acres) of oak trees again from acorns found on the soil around truffle-producing oak trees, and he subsequently obtained large harvests of truffles. He received a prize at the 1855 World's Fair in Paris.

These successful attempts were met with enthusiasm in southern France. In the late 19th century, an epidemic of phylloxera destroyed most of the vineyards in southern France. Another epidemic destroyed most of the silkworms in the area, rendering the fields of mulberry trees useless. Large tracts of land were set free for the cultivation of truffles and thousands of truffle-producing trees were planted. Production reached peaks of hundreds of tonnes at the end of the 19th century. In 1890 there were 750 km² (185,000 acres) of truffle-producing trees.

In the 20th century, with the growing industrialisation of France and the subsequent rural exodus, many of these truffle fields (champs truffiers or truffières) returned to wilderness. The First World War also dealt a serious blow to the French countryside, killing 20% or more of the male working force. As a consequence, newly acquired techniques of trufficulture were largely lost. Between the two world wars, the truffle fields planted in the 19th century stopped being productive. After 1945 the production of truffles plummeted, and the prices consequently rocketed.

In the last 30 years, new attempts for a mass production of truffles have been made. Eighty percent of the truffles now produced in France come from specially planted truffle-fields. Production has yet to recover its 1900's peaks. The countryside in southern France is largely depopulated, with a lot of the lands in the hands of the descendants of the farmers. These descendants live in towns and cities and feel mostly unconcerned by the countryside. Local farmers are also opposed to a return of mass production, which would decrease the price of truffles. However, prospects for a mass production are immense. It is currently estimated that the world market could absorb 50 times more truffles than France currently produces. There are now truffle-growing areas in Spain, Sweden, New Zealand and Australia.

The Tuber Aestivum summer truffle is harvested from May until December, while two lesser-used truffles include the Tuber Macrosporum black truffle and the Tuber Mesentericum scorzone truffle.

Soils for truffles

It is clear that T. mélanosporum can prosper in certain types of chalky or lime soils, in a fairly wide range, however.
mélanosporum is found in the limey gréseux of Maestrich ( Ste Alvère-24 ), as on the Turonn chalks (crétacé sup.-37), as in the recent calcareous alluvions fluviatiles ( Carpentras ). Section of a truffle-bearing soil.

Soil analyses on these different sites known to be good producer show constant factors in physical characteristics, structure, water retaining capacity balanced elements ( clay, lime, sand ), drainage capacity.

Among the chemical characteristics, it can be noticed that there are slight variations of PH ( water ), of C/N and of exchangeable CaO and a possibly of wide variation in phosphorus, potassium, organic matter. If the physical characteristics can changed little, the chemical attributes can be compensated for easily.

Ecology of truffles

The life and death of the roots in the soil take part in its permanent transformation. The living roots enter the cycle of organic matter and help improve the fertility of of the environment necessary for the development of the fungus. The mésofauna will do its indispensable work of chopping up, digestion, aeration and nutrition where the mélanosporum will prosper.