Truffle

Black Périgord truffle

A truffle is the fruiting body of a subterranean Ascomycete fungus, predominantly one of the many species of the genus Tuber. Some of the truffle species are highly prized as food. French gourmet Jean Anthelme Brillat-Savarin called truffles "the diamond of the kitchen".^[1] Edible truffles are held in high esteem in French, Georgian, Greek, Italian, Croatian, Middle Eastern and Spanish cooking, as well as in international haute cuisine. Truffles are ectomycorrhizal fungi and are therefore usually found in close association with the roots of trees. Spore dispersal is accomplished through fungivores, animals that eat fungi.

Etymology

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: Italian tartufo, French truffe, Spanish trufa, Danish trøffel, German Trüffel, Swedish tryffel, Dutch truffel, Polish trufla, Croatian tartuf / тартуф. In Portuguese, the words trufa and túbera are synonyms, the latter closer to the Latin term. The German word Kartoffel ("potato") is derived from the Italian term for truffle because of superficial similarities.^[2]

Biology

The mycelia of truffles form symbiotic, mycorrhizal relationships with the roots of several tree species including beech, poplar, oak, birch, hornbeam, hazel, and pine.^[3][4] They prefer argillaceous or calcareous soils that are well drained and neutral or alkaline.^[5][6] Truffles fruit throughout the year, depending on the species and can be found buried between the leaf litter and the soil.

Phylogeny

The phylogeny and biogeography of truffles was investigated in 2008^[7] using internal transcribed spacers (ITS) of nuclear DNA with five major clades (Aestivum, Excavatum, Rufum, Melanosporum and Puberulum); this was later improved and expanded in 2010 using large subunits (LSU) of mitochondrial DNA to nine major clades. 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.^[8]

Types

White truffle

White truffle washed and cut

The "white truffle" or "trifola d'Alba Madonna" (Tuber magnatum) is found mainly in the Langhe and Montferrat areas^[9] of the Piedmont region in northern Italy and, most famously, in the countryside around the cities of Alba and Asti;^[10] in Italy it can also be found in Molise, Abruzzo, and in the hills around San Miniato, in Tuscany. It is also found on the Istria peninsula, in Croatia in the Motovun forest along the Mirna river,^[11] and in Slovenia along the Dragonja and Rizana river,^[12] as well as in the Drome area in France. Growing symbiotically with oak, hazel, poplar and beech and fruiting in autumn, they can reach 12 cm (5 in) diameter and 500 g, though are usually much smaller. The flesh is pale cream or brown with white marbling.^[13] Italian white truffles are very highly esteemed (illustration, left) and are the most valuable on the market: The white truffle market in Alba is busiest in the months of October and November when the Fiera del Tartufo (truffle fair) takes place. In 2001, the Tuber magnatum truffles sold for between $1000–$2200 per pound ($2000–$4500 per kg);^[14] as of December 2009 they were being sold at $14,203.50 per kilogram.

In 1999, Giancarlo Zigante and his dog Diana found one of the largest truffles in the world near Buje, Croatia. The truffle weighed 1.31 kilograms (2 lb 14 oz) and has entered the Guinness Book of Records.^[15]

The record price paid for a single white truffle was set in December 2007, when Macau casino owner Stanley Ho paid $330,000 (£165,000) for a specimen weighing 1.5 kilograms (3.3 lb), discovered by Luciano Savini and his dog Rocco. One of the largest truffles found in decades, it was unearthed near Pisa, Italy, and sold at an auction held simultaneously in Macau, Hong Kong, and Florence.^[16] This record was then matched on November 27, 2010 when Ho again paid $330,000 for a pair of white truffles, including one weighing nearly a kilogram.

In December 2014, a White Alba’s Truffle weighing in at 4.16 pounds or 1.89 kilos was unearthed in the Umbrian region of Italy by the Balestra Family of Sabatino. It was auctioned at Sotheby’s in New York.^[17] While some had expected it to sell for $1 million,^[18] it was sold for $61,000 to a Taiwanese buyer.^[19]

A variety of white truffle (Tuber magnatum pico) is found in other parts of northern and central Italy, but is as aromatic as those from Piedmont.^[13]

Whitish truffle

The "whitish truffle" (Tuber borchii) is a similar species found in Tuscany, Abruzzo, Romagna, Umbria, the Marche and Molise. It is not as aromatic as those from Piedmont, although those from Città di Castello come quite close.^[13]

Black truffle

Black Périgord Truffle, cut

The black truffle or black Périgord truffle (Tuber melanosporum), the second-most commercially valuable species, is named after the Périgord region in France and grows with oak and hazelnut trees. Black truffles are harvested in late autumn and winter.^[13] The genome sequence of the black truffle was published in March 2010.^[20]

Summer or burgundy truffle

The black summer truffle (Tuber aestivum) is found across Europe and is prized for its culinary value. Burgundy truffles (Tuber uncinatum) are harvested in autumn until December and have aromatic flesh of a darker colour.

Black summer truffle (in Italian: Tartufi Neri Estivi) in a shop window in Rome, Italy

Other species

A less common truffle is "garlic truffle" (Tuber macrosporum). In the U.S. Pacific Northwest, several species of truffle are harvested both recreationally and commercially, most notably, the "Oregon white truffles", Tuber oregonense and Tuber gibbosum, and Leucangium carthusianum.

The "pecan truffle" (Tuber lyonii)^[21] syn. texense^[22] is found in the Southern United States, usually associated with pecan trees. Chefs who have experimented with them agree "they are very good and have potential as a food commodity".^[23] Although pecan farmers used to find them along with pecans and discard them, considering them a nuisance, they sell for about $100 a pound and have been used in some gourmet restaurants.

Truffle-like species

The term "truffle" has been applied to several other genera of similar underground fungi. The genera Terfezia and Tirmania of the family Terfeziaceae are known as the "desert truffles" of Africa and the Middle East. "Hart's truffle" is a name for Elaphomycetaceae. Pisolithus tinctorius, which was historically eaten in parts of Germany, is sometimes called "Bohemian truffle".^[24]

History

Antiquity

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)^[25] 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.^[24]

Italy in the Classical period produced three kinds of truffles: the Tuber melanosporum, the Tuber magnificanus and the Tuber magnatum. The Romans, however, only used the terfez (Terfezia bouderi), a fungus of similar appearance, which the Romans called truffles, and which is sometimes called "desert truffle". Terfez used in Rome came from Lesbos, Carthage, and especially Libya, where the coastal climate was less dry in ancient times.^[24] Their substance is pale, tinged with rose. Unlike truffles, terfez have no taste of their own. The Romans used the terfez as a carrier of flavour, because the terfez have the property to absorb surrounding flavours. Indeed, Ancient Roman cuisine used many spices and flavours, and terfez were perfect in that context.

Middle Ages

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.^[26]

According to a hadith narrated by Saeed bin Zaid, Muhammad said that truffles are like manna and that water from truffles "heals eye diseases".^[27]

Renaissance and modern times

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.

Cultivation

Truffles long eluded techniques of domestication, as Jean-Anthelme Brillat-Savarin (1825) noted:

Mushroom and truffle output in 2005

Statue of Joseph Talon in Saint-Saturnin-lès-Apt

Planted truffle groves near Beaumont-du-Ventoux

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.^[1]

However, truffles can be cultivated.^[28] 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'd collected at the foot of oak trees known to host truffles in their root system.

Truffle market in Carpentras

The experiment was successful: Years later, truffles were found in the soil around the newly grown oak trees. 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.^[29]

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 destroyed 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, 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 opposed to a return of mass production, which would decrease the price of truffles. There are now truffle-growing areas in the United Kingdom, United States, Spain, Sweden, New Zealand, Australia, Chile and South Africa.

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.^[30]

In 1999, the first Australian truffles were harvested in Tasmania,^[31] 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 Wine and Truffle 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 Wine and Truffle Company has expanded its production, moving into the colder regions of Victoria and New South Wales.

In June 2010, Tasmanian growers Michael and Gwynneth Williams 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).^[32] Mrs. Williams told ABC Radio in Australia^[33] that it is 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 Rosie, the farm owner's beagle.^[34]

Extraction

Trained pig in Gignac, Lot, France

Trained dog in Mons, Var, France

The Lagotto Romagnolo is currently the only dog breed recognized for sniffing out truffles (although virtually any breed could be trained for this purpose).^[35]

The female pig's natural truffle-seeking, as well as her usual intent to eat the truffle, is due to a compound within the truffle similar to androstenol, the sex pheromone of boar saliva, to which the sow is keenly attracted.

In Italy, the use of the pig to hunt truffles has been prohibited since 1985 because of damage caused by animals to truffle's mycelia during the digging that dropped the production rate of the area for some years.

Volatile constituents

The volatile constituents responsible for the natural aroma of truffles are released by the mycelia, fruiting body or derive from truffle-associated microbes. The chemical ecology of truffle volatiles is complex, interacting with plants, insects and mammals, which contribute to spore dispersal. Depending on the truffle species, life cycle or location, these are most notably:

• Sulfur volatiles, which occur in all truffle species, such as dimethyl mono- (DMS), di- (DMDS) and tri- (DMTS) sulfides, as well as 2-methyl-4,5-dihydrothiophene, characteristic of the white truffle T. borchii and bis(methylthio)methane occurring in all species but mostly characteristic of the white truffle T. magnatum. Some of the very aromatic white truffles are notably pungent, even irritating the eye when cut or sliced.
• Metabolites of non-sulfur amino acid constituents (simple and branched chain hydrocarbons) such as ethylene (produced by mycelia of white truffles affecting root architecture of host tree), as well as 2-methylbutanal, 2-methylpropanal and 2-phenylethanol (also common in baker’s yeast).
• Fatty acid-derived volatiles (C8-alcohols and aldehydes with a characteristic fungal odor, such as 1-octen-3-ol and 2-octenal). The former is derived from linoleic acid, and produced by mature white truffle T. borchii.

A number of truffle species and varieties are differentiated based on their relative contents or absence of sulfides, ethers or alcohols, respectively. The sweaty-musky aroma of truffles is similar to that of the pheromone androstenol that also occurs in humans.^[36] As of 2010, the volatile profiles of seven black and six white truffle species have been studied.^[37]

Culinary use

Truffle oil (olive oil with Tuber melanosporum).

Because of their high price^[38] and their pungent aroma, truffles are used sparingly. Supplies can be found commercially as unadulterated fresh produce or preserved, typically in a light brine.

White truffles are generally served raw, and shaved over steaming buttered pasta, salads, or fried eggs. White or black paper-thin truffle slices may be inserted into meats, under the skins of roasted fowl, in foie gras preparations, in pâtés, or in stuffings. Some speciality cheeses contain truffles, as well.

The flavor of black truffles is far less pungent and more refined than that of white truffles. Their strong flavor is often described as syrupy sweet. Black truffles also are used for producing truffle salt and truffle honey.

While in the past chefs used to peel truffles, in modern times, most restaurants brush the truffle carefully and shave it or dice it with the skin on so as to make the most of this valuable ingredient. A few restaurants in Switzerland still stamp out circular discs of truffle flesh and use the skins for sauces.

Truffle oil

Truffle oil is used as a lower-cost and convenient substitute for truffles, to provide flavoring, or to enhance the flavor and aroma of truffles in cooking. Most "truffle oil", however, does not contain any truffles.^[39] The vast majority is olive oil which has been artificially flavoured using a synthetic agent such as 2,4-dithiapentane.^[39]

Truffle vodka

The bulk of truffle oil on the market is made with a synthetic ingredient, as are many other truffle products. However, alcohol is now being used to carry the truffle flavour without the need for synthetic flavourings. The first truffle vodka, Black Moth Vodka, is a natural vodka infused with black Périgord truffles (Tuber melanosporum). Although primarily used as a spirit in its own right and mixed in a range of cocktails, truffle vodka is also used by various chefs to flavour dishes by evaporating the alcohol through cooking whilst retaining the truffle aroma.^[40]

See also

• Specialty foods

Notes

References

• Trappe, Matt; Evans, Frank; Trappe, James M. (2007). Field Guide to North American Truffles: Hunting, Identifying, and Enjoying the World's Most Prized Fungi. Natural History Series. Ten Speed Press. ISBN 9781580088626. 

• Nowak, Zachary (2015). Truffle: A Global History. The Edible Series. Reaktion. ISBN 978-1780234366. 

External links

Wikimedia Commons has media related to truffle.

• Website of the North American Truffling Society