A truffle is the fruiting body of a subterranean ascomycete fungus, predominantly one of the many species of the genus Tuber. In addition to Tuber, many other genera of fungi are classified as truffles including Geopora, Peziza, Choiromyces, Leucangium, and over a hundred others. These genera belong to the class Pezizomycetes and the Pezizales order. There are several truffle-like basidiomycetes excluded from Pezizales including Rhizopogon and Glomus. Truffles are ectomycorrhizal fungi and are therefore usually found in close association with tree roots. Spore dispersal is accomplished through fungivores, animals that eat fungi. These fungi have significant ecological roles in nutrient cycling and drought tolerance.
Some of the truffle species are highly prized as food. French gourmet Jean Anthelme Brillat-Savarin called truffles “the diamond of the kitchen”. Edible truffles are held in high esteem in French, Italian, Ottoman, Middle Eastern and Spanish cuisine, as well as in international haute cuisine. Truffles are cultivated agriculturally and are also harvested from natural habitats.
The first mention of truffles appears in the inscriptions of the neo-Sumerians regarding their Amorite enemy’s eating habits (Third Dynasty of Ur, 20th century BCE) and later in writings of Theophrastus in the fourth century BCE. In classical times, their origins were a mystery that challenged many; Plutarch and others thought them to be the result of lightning, warmth and water in the soil, while Juvenal thought thunder and rain to be instrumental in their origin. Cicero deemed them children of the earth, while Dioscorides thought they were tuberous roots.
Rome and Thracia in the Classical period produced three kinds of truffles: the Tuber melanosporum, the Tuber magnificanus and the Tuber magnatum. The Romans, however, did not use these and instead used a variety of fungus called Terfez, also sometimes called a “desert truffle.” Terfez used in Rome came from Lesbos, Carthage, and especially Libya, where the coastal climate was less dry in ancient times. Their substance is pale, tinged with rose. Unlike truffles, terfez have little inherent flavour. The Romans used the terfez as a carrier of flavour, because the terfez tend to absorb surrounding flavours. Indeed, Ancient Roman cuisine used many spices and flavourings, and terfez were perfect in that context.
Truffles were rarely used during the Middle Ages. Truffle hunting is mentioned by Bartolomeo Platina, the papal historian, in 1481, when he recorded that the sows of Notza were without equal in hunting truffles, but they should be muzzled to prevent them from eating the prize.
During the Renaissance, truffles regained popularity in Europe and were honoured at the court of King Francis I of France. However, it was not until the 17th century that Western (and in particular French) cuisine abandoned “heavy” oriental spices, and rediscovered the natural flavour of foodstuffs. Truffles were very popular in Parisian markets in the 1780s. They were imported seasonally from truffle grounds, where peasants had long enjoyed their secret. Brillat-Savarin (1825) noted characteristically that they were so expensive they appeared only at the dinner tables of great nobles and kept women. A great delicacy was a truffled turkey.
Truffles long eluded techniques of domestication, as Jean-Anthelme Brillat-Savarin (1825) noted:
The most learned men have sought to ascertain the secret, and fancied they discovered the seed. Their promises, however, were vain, and no planting was ever followed by a harvest. This perhaps is all right, for as one of the great values of truffles is their dearness, perhaps they would be less highly esteemed if they were cheaper.
However, truffles can be cultivated. As early as 1808, there were successful attempts to cultivate truffles, known in French as trufficulture. People had long observed that truffles were growing among the roots of certain trees, and in 1808, Joseph Talon, from Apt (département of Vaucluse) in southern France, had the idea of transplanting some seedlings that he had collected at the foot of oak trees known to host truffles in their root system.
For discovering how to cultivate truffles, some sources now give priority to Pierre II Mauléon (1744–1831) of Loudun (in western France), who began to cultivate truffles around 1790. Mauléon saw an “obvious symbiosis” between the oak tree, the rocky soil and the truffle, and attempted to reproduce such an environment by taking acorns from trees known to have produced truffles, and sowing them in chalky soil. His experiment was successful, with truffles being found in the soil around the newly grown oak trees years later. In 1847, Auguste Rousseau of Carpentras (in Vaucluse) 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.
Truffle market in Carpentras
These successful attempts were met with enthusiasm in southern France, which possessed the sweet limestone soils and dry, hot weather that truffles need to grow. In the late 19th century, an epidemic of phylloxera destroyed many of the vineyards in southern France. Another epidemic killed most of the silkworms there, too, making the fields of mulberry trees useless. Thus, large tracts of land were set free for the cultivation of truffles. Thousands of truffle-producing trees were planted, and production reached peaks of hundreds of tonnes at the end of the 19th century. In 1890, there were 75,000 hectares (190,000 acres) of truffle-producing trees.
In the 20th century, however, with the growing industrialization 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 lost. Also, between the two world wars, the truffle groves planted in the 19th century stopped being productive. (The average life cycle of a truffle-producing tree is 30 years.) Consequently, after 1945, the production of truffles plummeted, and the prices have risen dramatically. In 1900, truffles were used by most people, and on many occasions. Today, they are a rare delicacy reserved for the rich, or used on very special occasions.
In the last 30 years,[when?] new attempts for mass production of truffles have been started. Eighty percent of the truffles now produced in France come from specially planted truffle groves. Nonetheless, production has yet to recover its 1900s peaks. Local farmers are sometimes opposed to a return of mass production, which would possibly decrease the price of truffles (though it is commonly stated that demand is 10 times higher than supply). In exchange there are heavy investments in cultivated plantations underway in many parts of the world. Thanks to controlled irrigation, regular and resilient production is indeed possible. There are now truffle-growing areas in the United Kingdom, United States, Spain, Italy, Sweden, New Zealand, Australia, Chile and South Africa.
A critical phase of the cultivation is the quality control of the mycorrhizal plants. It takes between 7 and 10 years for the truffles to develop their mycorrhizal network, and only after that the host-plants come into production. Both a complete soil analysis to avoid contamination by other dominant fungus and a very strict control of the formation of mycorrhizae are necessary to ensure the success of a plantation. Total investment per hectare for an irrigated and barrier-sealed plantation (against wild boars) can cost up to €10,000. Considering the level of initial investment and the maturity delay, farmers who have not taken care of both soil conditions and seedling conditions are at high risk of failure.
In New Zealand and Australia
The first black truffles (Tuber melanosporum) to be produced in the Southern Hemisphere were harvested in Gisborne, New Zealand, in 1993.
In 1999, the first Australian truffles were harvested in Tasmania, the result of eight years of work. Trees were inoculated with the truffle fungus in the hope of creating a local truffle industry. Their success and the value of the resulting truffles has encouraged a small industry to develop. A Western Australian venture, The Truffle and Wine Company, had its first harvest in 2004, and in 2005 they unearthed a 1-kg (2.2-lb) truffle. In 2008, an estimated 600 kilograms (1,300 lb) of truffles were removed from the rich ground of Manjimup. Each year, the company has expanded its production, moving into the colder regions of Victoria and New South Wales.
In June 2010, Tasmanian growers harvested Australia’s largest truffle from their property at Myrtle Bank, near Launceston. It weighed in at 1.084 kilograms (2 lb 6.2 oz) and was valued at about A$1,500 per kg.
New Zealand’s first burgundy truffle was found in July 2012 at a Waipara truffle farm. It weighed 330 g and was found by the farm owner’s beagle.
In the United States
While there have been some notable successes in truffle farming in the United States in the recent past, and farmers have planted trees that may produce large harvests in the near future, all current harvests are small scale.
Tom Michaels, owner of Tennessee Truffle, began producing Périgord truffles commercially in 2007. At its peak in the 2008-2009 season, his farm produced about 200 pounds of truffles, but Eastern filbert blight almost entirely wiped out his hazel trees by 2013 and production dropped tenfold, essentially driving him out of business. Eastern filbert blight similarly destroyed the orchards of other once promising commercial farmers such as Tom Leonard, also in East Tennessee, and Garland Truffles in North Carolina. Newer farmers such as New World Truffieres clients Pat Long in Oregon and Paul Beckman in Idaho, or Nancy Rosborough of Mycorrhiza Biotech in Gibsonville, NC, are still in the early stages and waiting for their harvests to increase in size.
The origin of the word truffle appears to be the Latin term tūber, meaning “swelling” or “lump”, which became tufer- and gave rise to the various European terms: Danish trøffel, Dutch truffel, English truffle, French truffe, German Trüffel, Greek τρούφα trúfa, Italian tartufo, Polish trufla, Romanian trufă, Spanish trufa, and Swedish tryffel.
The German word Kartoffel (“potato”) is derived from the Italian term for truffle because of superficial similarities. In Portuguese, the words trufa and túbera are synonyms, the latter closer to the Latin term.
Phylogeny and species
Phylogenetic analysis has demonstrated the convergent evolution of the ectomycorrhizal trophic mode in diverse fungi. The subphylum, Pezizomycotina, containing the order Pezizales, is approximately 400 million years old. Within the order Pezizales, subterranean fungi evolved independently at least fifteen times. Contained within Pezizales are the families Tuberaceae, Pezizaceae, Pyronematacae, and Morchellaceae. All of these families contain lineages of subterranean or truffle fungi. The oldest ectomycorrhizal fossil is from the Eocene about 50 million years ago. This indicates that the soft bodies of ectomycorrhizal fungi do not easily fossilize. Molecular clockwork has suggested the evolution of ectomycorrhizal fungi occurred approximately 130 million years ago.
The evolution of subterranean fruiting bodies has arisen numerous times within the Ascomycota, Basidiomycota, and Glomeromycota. For example, the genera Rhizopogon and Hysterangium of Basidiomycota both form subterranean fruiting bodies and play similar ecological roles as truffle forming ascomycetes. The ancestors of the Ascomycota genera Geopora, Tuber, and Leucangium originated in Laurasia during the Paleozoic era. Phylogenetic evidence suggests that the majority of subterranean fruiting bodies evolved from above-ground mushrooms. Over time mushroom stipes and caps were reduced, and caps began to enclose reproductive tissue. The dispersal of sexual spores then shifted from wind and rain to utilizing animals.
The phylogeny and biogeography of the genus Tuber was investigated in 2008 using internal transcribed spacers (ITS) of nuclear DNA and revealed five major clades (Aestivum, Excavatum, Rufum, Melanosporum and Puberulum); this was later improved and expanded in 2010 to nine major clades using large subunits (LSU) of mitochondrial DNA. The Magnatum and Macrosporum clades were distinguished as distinct from the Aestivum clade. The Gibbosum clade was resolved as distinct from all other clades, and the Spinoreticulatum clade was separated from the Rufum clade.
The truffle habit has evolved independently among several basidiomycete genera. Phylogenetic analysis has revealed that basidiomycete subterranean fruiting bodies, like their ascomycete counterparts, evolved from above ground mushrooms. For example, it is likely that Rhizopogon species arose from an ancestor shared with Suillus, a mushroom forming genus. Studies have suggested that selection for subterranean fruiting bodies among ascomycetes and basidiomycetes occurred in water-limited environments.