Truffle

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Black truffle (Tuber melanosporum) Truffe noire du Perigord.jpg
Black truffle (Tuber melanosporum)
White truffles from San Miniato White truffles from San Miniato.jpg
White truffles from San Miniato
Black truffles from San Miniato Black truffles, San Miniato.jpg
Black truffles from San Miniato

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. [1] These genera belong to the class Pezizomycetes and the Pezizales order. Several truffle-like basidiomycetes are excluded from Pezizales, including Rhizopogon and Glomus. Truffles are ectomycorrhizal fungi, so are usually found in close association with tree roots. Spore dispersal is accomplished through fungivores, animals that eat fungi. [2] These fungi have significant ecological roles in nutrient cycling and drought tolerance.

Contents

Some of the truffle species are highly prized as food. French gastronome Jean Anthelme Brillat-Savarin called truffles "the diamond of the kitchen". [3] Edible truffles are used in Italian, French [4] and numerous other national haute cuisines . Truffles are cultivated and harvested from natural environments.

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) [5] and later in writings of Theophrastus in the 4th 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. [6]

Rome and Thracia in the Classical period identified three kinds of truffles: Tuber melanosporum , T. magnificus , and T. magnatum . The Romans 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. [6] 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. Because Ancient Roman cuisine used many spices and flavorings, the terfez may have been appropriate 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. [7]

Renaissance and modernity

During the Renaissance, truffles regained popularity in Europe and were honoured at the court of King Francis I of France. They were popular in Parisian markets in the 1780s, imported seasonally from truffle grounds, where peasants had long enjoyed them. Brillat-Savarin (1825) noted that they were so expensive, they appeared only at the dinner tables of great nobles and kept women. They were sometimes served with turkey.

Cultivation

Statue of Joseph Talon in Saint-Saturnin-les-Apt Joseph Talon.JPG
Statue of Joseph Talon in Saint-Saturnin-lès-Apt
Planted truffle groves near Beaumont-du-Ventoux Beaumont - truffieres.jpg
Planted truffle groves near Beaumont-du-Ventoux

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. [3]

Truffles can in fact be cultivated. [8] As early as 1808, attempts to cultivate truffles, known in French as trufficulture, were successful. 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. [9] [10] 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. [11]

A truffle market in Carpentras, France Truffle Market in Carpentras.jpg
A truffle market in Carpentras, France

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, 75,000 hectares (190,000 acres) of truffle-producing trees had been planted.

In the 20th century, 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. Between the two world wars, the truffle groves planted in the 19th century stopped being productive. (The average lifecycle 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.[ citation needed ] Today, they are a rare delicacy reserved for the rich, or used on very special occasions.

In the 1970s, new attempts for mass production of truffles were started to make up for the decline in wild truffles. About 80% of the truffles now produced in France come from specially planted truffle groves.[ citation needed ] Investments in cultivated plantations are underway in many parts of the world using controlled irrigation for regular and resilient production. [12] [13] Truffle-growing areas exist in numerous countries.[ citation needed ]

A critical phase of the cultivation is the quality control of the mycorrhizal plants. Between 7 and 10 years are needed for the truffles to develop their mycorrhizal network, and only after that the host-plants come into production. 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. [14] 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.

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. [15]

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. [16]

In 1999, the first Australian truffles were harvested in Tasmania, [17] 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.

Truffle production has expanded into the colder regions of Victoria, New South Wales and Western Australia. [18] In 2014, over 5,000 kilograms (11,000 pounds) of truffles were harvested by Truffle Hill, Manjimup, Western Australia.

In June 2014, A grower harvested Australia's largest truffle from their property at Robertson, in the Southern Highlands of New South Wales. It was a French black perigord fungus weighing in at 1.1172 kg (2 lb 7+716 oz) and was valued at over $2,000 per kilogram [19]

United States

Tom Michaels, owner of Tennessee Truffle, began producing Périgord truffles commercially in 2007. [20] 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, essentially driving him out of business. [21] 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 [22] Likewise, Ian Purkayastha of Regalis Foods has set up a small farm in Fayetteville, Arkansas. [23] [24]

Nancy Rosborough of Mycorrhiza Biotech in Gibsonville, North Carolina reported that their 2021 harvests are outstanding, producing as much as an estimated 200 pounds of bianchetto, or "whitish" truffles on one plot. [25]

As of 2022, markets for the Appalachian truffle (Tuber canaliculatum) are expanding, and it was deemed "America's next food craze" by Outside magazine. [26]

Etymology

The origin of the word "truffle" is from the Tamazight language in North Africa,[ citation needed ] where the truffle is native to the Atlas Mountains.[ citation needed ] In Moroccan Tamazight, the "truffle" is called tireffas, which comes from the verb youfess, meaning "to bury," referring to how deeply rooted truffles are under the soil.[ citation needed ]

Other sources also attribute "truffle" to originate from the Latin term tūber, meaning "swelling" or "lump", which became tufer. However, the Tamazight term predates the Latin term,[ citation needed ] and is phonologically closer to the various European terms used today: Danish trøffel, Dutch truffel, English truffle, French truffe, German Trüffel, Greek τρούφα trúfa, Italian tartufo, Polish trufla, Romanian trufă, Spanish trufa, and Swedish tryffel. Additionally, in Moroccan Arabic, the term used is tirfa (ترفة).

The German word Kartoffel ("potato") is derived from the Italian term for truffle because of superficial similarities. [27] In Portuguese, the words trufa and túbera are synonyms, the latter closer to the Latin term.

Phylogeny

Evolution of subterranean fruiting bodies from above-ground mushrooms. Truffle Evolution.jpg
Evolution of subterranean fruiting bodies from above-ground mushrooms.

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. [28] Within the order Pezizales, subterranean fungi evolved independently at least fifteen times. [28] Contained within Pezizales are the families Tuberaceae, Pezizaceae, Pyronematacae, and Morchellaceae. All of these families contain lineages of subterranean or truffle fungi. [1]

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. [29] Molecular clockwork has suggested the evolution of ectomycorrhizal fungi occurred approximately 130 million years ago. [30]

The evolution of subterranean fruiting bodies has arisen numerous times within the Ascomycota, Basidiomycota, and Glomeromycota. [1] 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. [31]

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. [31]

The phylogeny and biogeography of the genus Tuber was investigated in 2008 [32] 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. [33]

The truffle habit has evolved independently among several basidiomycete genera. [34] [35] [36] 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. [34] Studies have suggested that selection for subterranean fruiting bodies among ascomycetes and basidiomycetes occurred in water-limited environments. [31] [34]

Species

Black

Black Perigord truffle, cross-section Tuber brumale - Vue sur la tranche coupee.jpg
Black Périgord truffle, cross-section

The black truffle or black Périgord truffle (Tuber melanosporum), the second-most commercially valuable species, is named after the Périgord region in France. [37] Black truffles associate with oaks, hazelnut, cherry, and other deciduous trees and are harvested in late autumn and winter. [37] [38] The genome sequence of the black truffle was published in March 2010. [39]

Summer or burgundy

Summer truffles in a shop in Rome Black.summer.truffle.arp.jpg
Summer truffles in a shop in Rome

The black summer truffle (Tuber aestivum) is found across Europe and is prized for its culinary value. [40] Burgundy truffles (designated Tuber uncinatum , but the same species) are harvested in autumn until December and have aromatic flesh of a darker colour. These associate with various trees and shrubs. [40]

White

A white truffle washed and with a corner cut to show the interior. Truffle washed and cut.jpg
A white truffle washed and with a corner cut to show the interior.

Tuber magnatum, the high-value white truffle or trifola d'Alba Madonna ("Truffle of the Madonna from Alba" in Italian) is found mainly in the Langhe and Montferrat areas [41] of the Piedmont region in northern Italy, and most famously, in the countryside around the cities of Alba and Asti. [42] A large percentage of Italy's white truffles also come from Molise.

Whitish

The "whitish truffle" (Tuber borchii) is a similar species native to Tuscany, Abruzzo, Romagna, Umbria, the Marche, and Molise. It is reportedly not as aromatic as those from Piedmont, although those from Città di Castello are said to come quite close. [38]

Other Tuber

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 Leucangium carthusianum , Oregon black truffle; Tuber gibbosum , Oregon spring white truffle; and Tuber oregonense , the Oregon winter white truffle. Kalapuya brunnea , the Oregon brown truffle, has also been commercially harvested and is of culinary note.

The pecan truffle (Tuber lyonii) [43] syn. texense [44] 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". [45] Although pecan farmers used to find them along with pecans and discard them, considering them a nuisance, they sell for about $160 a pound and have been used in some gourmet restaurants. [46]

Beyond Tuber

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. Pisolithus tinctorius , which was historically eaten in parts of Germany, is sometimes called "Bohemian truffle". [6]

Geopora spp. are important ectomycorrhizal partners of trees in woodlands and forests throughout the world. [1] Pinus edulis, a widespread pine species of the Southwest US, is dependent on Geopora for nutrient and water acquisition in arid environments. [47] Like other truffle fungi, Geopora produces subterranean sporocarps as a means of sexual reproduction. [47] Geopora cooperi , also known as pine truffle or fuzzy truffle, is an edible species of this genus. [1]

Rhizopogon truffle. Rhizopogon rubescens.jpg
Rhizopogon truffle.

Rhizopogon spp. are ectomycorrhizal members of the Basidiomycota and the order Boletales, a group of fungi that typically form mushrooms. [48] Like their ascomycete counterparts, these fungi are capable of creating truffle-like fruiting bodies. [48] Rhizopogon spp. are ecologically important in coniferous forests where they associate with various pines, firs, and Douglas fir. [49] In addition to their ecological importance, these fungi hold economic value, as well. Rhizopogon spp. are commonly used to inoculate coniferous seedlings in nurseries and during reforestation. [48]

Hysterangium spp. are ectomycorrhizal members of the Basidiomycota and the order Hysterangiales that form sporocarps similar to true truffles. [50] These fungi form mycelial mats of vegetative hyphae that may cover 25-40% of the forest floor in Douglas fir forests, thereby contributing to a significant portion of the biomass present in soils. [50] Like other ectomycorrhizal fungi, Hysterangium spp. play a role in nutrient exchange in the nitrogen cycle by accessing nitrogen unavailable to host plants and by acting as nitrogen sinks in forests. [49]

Glomus spp. are arbuscular mycorrhizae of the phylum Glomeromycota within the order Glomerales. [31] Members of this genus have low host specificity, associating with a variety of plants including hardwoods, forbs, shrubs, and grasses. [31] These fungi commonly occur throughout the Northern Hemisphere. [31]

Members of the genus Elaphomyces are commonly mistaken for truffles.

Ecology

The mycelia of truffles form symbiotic, mycorrhizal relationships with the roots of several tree species including beech, birch, hazel, hornbeam, oak, pine, and poplar. [51] Mutualistic ectomycorrhizal fungi such as truffles provide valuable nutrients to plants in exchange for carbohydrates. [52] Ectomycorrhizal fungi lack the ability to survive in the soil without their plant hosts. [28] In fact, many of these fungi have lost the enzymes necessary for obtaining carbon through other means. For example, truffle fungi have lost their ability to degrade the cell walls of plants, limiting their capacity to decompose plant litter. [28] Plant hosts can also be dependent on their associated truffle fungi. Geopora, Peziza, and Tuber spp. are vital in the establishment of oak communities. [53]

Tuber species prefer argillaceous or calcareous soils that are well drained and neutral or alkaline. [54] [55] [56] Tuber truffles fruit throughout the year, depending on the species, and can be found buried between the leaf litter and the soil. The majority of fungal biomass is found in the humus and litter layers of soil. [49]

The lifecycle of the order Pezizales in Ascomycota Pezizales, Ascomycota Life Cycle.jpg
The lifecycle of the order Pezizales in Ascomycota

Most truffle fungi produce both asexual spores (mitospores or conidia) and sexual spores (meiospores or ascospores/basidiospores). [57] Conidia can be produced more readily and with less energy than ascospores and can disperse during disturbance events. Production of ascospores is energy intensive because the fungus must allocate resources to the production of large sporocarps. [57] Ascospores are borne within sac-like structures called asci, which are contained within the sporocarp.

Because truffle fungi produce their sexual fruiting bodies under ground, spores cannot be spread by wind and water. Therefore, nearly all truffles depend on mycophagous animal vectors for spore dispersal. [1] This is analogous to the dispersal of seeds in fruit of angiosperms. When the ascospores are fully developed, the truffle begin to exude volatile compounds that serve to attract animal vectors. [1] For successful dispersal, these spores must survive passage through the digestive tracts of animals. Ascospores have thick walls composed of chitin to help them endure the environment of animal guts. [57]

Animal vectors include birds, deer, and rodents such as voles, squirrels, and chipmunks. [1] [53] [58] Many species of trees, such as Quercus garryana , are dependent on the dispersal of sporocarps to inoculate isolated individuals. For example, the acorns of Q. garryana may be carried to new territory that lacks the necessary mycorrhizal fungi for establishment. [53]

Some mycophagous animals depend on truffles as their dominant food source. Flying squirrels, Glaucomys sabrinus , of North America play a role in a three-way symbiosis with truffles and their associated plants. [1] G. sabrinus is particularly adapted to finding truffles using its refined sense of smell, visual clues, and long-term memory of prosperous populations of truffles. [1] This intimacy between animals and truffles indirectly influences the success of mycorrhizal plant species.

After ascospores are dispersed, they remain dormant until germination is initiated by exudates excreted from host plant roots. [59] Following germination, hyphae form and seek out the roots of host plants. Arriving at roots, hyphae begin to form a mantle or sheath on the outer surface of root tips. Hyphae then enter the root cortex intercellularly to form the Hartig net for nutrient exchange. Hyphae can spread to other root tips colonizing the entire root system of the host. [59] Over time, the truffle fungus accumulates sufficient resources to form fruiting bodies. [59] [53] Rate of growth is correlated with increasing photosynthetic rates in the spring as trees leaf out. [53]

Nutrient exchange

Truffle fungi receive carbohydrates from their host plants, and provide them with valuable micro- and macronutrients. Plant macronutrients include potassium, phosphorus, nitrogen, and sulfur, whereas micronutrients include iron, copper, zinc, and chloride. [52] In truffle fungi, as in all ectomycorrhizae, the majority of nutrient exchange occurs in the Hartig net, the intercellular hyphal network between plant root cells. A unique feature of ectomycorrhizal fungi is the formation of the mantle on outer surface of fine roots. [52]

Truffles have been suggested to co-locate with the orchid species Epipactis helleborine and Cephalanthera damasonium , [60] though this is not always the case.

Nutrient cycling

Truffle fungi are ecologically important in nutrient cycling. Plants obtain nutrients via their fine roots. Mycorrhizal fungi are much smaller than fine roots, so have a higher surface area and a greater ability to explore soils for nutrients. Acquisition of nutrients includes the uptake of phosphorus, nitrate or ammonium, iron, magnesium, and other ions. [52] Many ectomycorrhizal fungi form fungal mats in the upper layers of soils surrounding host plants. These mats have significantly higher concentrations of carbon and fixed nitrogen than surrounding soils. [61] Because these mats are nitrogen sinks, leaching of nutrients is reduced. [49]

Mycelial mats can also help maintain the structure of soils by holding organic matter in place and preventing erosion. [31] Often, these networks of mycelium provide support for smaller organisms in the soil, such as bacteria and microscopic arthropods. Bacteria feed on the exudates released by mycelium and colonize soil surrounding them. [62] Microscopic arthropods such as mites feed directly on mycelium and release valuable nutrients for the uptake of other organisms. [63] Thus, truffle fungi, along with other ectomycorrhizal fungi, facilitate a complex system of nutrient exchange between plants, animals, and microbes.

Importance in arid-land ecosystems

Plant community structure is often affected by the availability of compatible mycorrhizal fungi. [64] [65] In arid-land ecosystems, these fungi become essential for the survival of their host plants by enhancing ability to withstand drought. [66] A foundation species in arid-land ecosystems of the Southwest United States is Pinus edulis , commonly known as pinyon pine. P. edulis associates with the subterranean fungi Geopora and Rhizopogon. [67]

As global temperatures rise, so does the occurrence of severe droughts detrimentally affecting the survival of arid-land plants. This variability in climate has increased the mortality of P. edulis. [68] Therefore, the availability of compatible mycorrhizal inoculum can greatly affect the successful establishment of P. edulis seedlings. [67] Associated ectomycorrhizal fungi will likely play a significant role in the survival of P. edulis with continuing global climate change.[ citation needed ]

Extraction

A trained truffle hunting pig in Gignac, Lot, France Cochon truffier.JPG
A trained truffle hunting pig in Gignac, Lot, France
A trained truffle hunting dog in Mons, Var, France Dog smelling for truffles in Mons, Var.jpg
A trained truffle hunting dog in Mons, Var, France
Comparison of truffle dog and hog
Truffle dogTruffle hog
Keen sense of smellKeen sense of smell
Must be trainedInnate ability to sniff out truffles
Easier to controlTendency to eat truffles once found

Because truffles are subterranean, they are often located with the help of an animal possessing a refined sense of smell. Traditionally, pigs have been used for the extraction of truffles. [69] Both the female pig's natural truffle-seeking and her intent to eat the truffle were thought to be due to a compound within the truffle similar to androstenol, the sex pheromone of boar saliva, to which the sow is keenly attracted. Studies in 1990 demonstrated that the compound actively recognized by both truffle pigs and dogs is dimethyl sulfide. [69]

In Italy, the use of the pig to hunt truffles has been prohibited since 1985 because of damage caused by animals to truffle mycelia during the digging that dropped the production rate of the area for some years. An alternative to truffle pigs are dogs. Dogs pose an advantage in that they do not have a strong desire to eat truffles, so can be trained to locate sporocarps without digging them up. Pigs attempt to dig up truffles. [69]

Fly species of the genus Suilla can also detect the volatile compounds associated with subterranean fruiting bodies. These flies lay their eggs above truffles to provide food for their young. At ground level, Suilla flies can be seen flying above truffles. [69]

Volatile constituents

External video
Nuvola apps kaboodle.svg “The Chemistry of Truffles, the Most Expensive Food in the World”, Sarah Everts, CEN Online

The volatile constituents responsible for the natural aroma of truffles are released by the mycelia or fruiting bodies, 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, lifecycle, or location, they include:

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. [72] As of 2010, the volatile profiles of seven black and six white truffle species have been studied. [73]

Culinary use

Shaved Perigold truffle with pasta at Spago in Las Vegas, Nevada. Shaved black truffles with pasta - Spago Las Vegas - March 2022 - Sarah Stierch.jpg
Shaved Perigold truffle with pasta at Spago in Las Vegas, Nevada.

Because of their high price [74] and their strong aroma, truffles are used sparingly. Supplies can be found commercially as unadulterated fresh produce or preserved, typically in a light brine.

Their chemical compounds infuse well with fats such as butter, cream, cheeses, avocados, and coconut cream.

As the volatile aromas dissipate quicker when heated, truffles are generally served raw and shaved over warm, simple foods where their flavor will be highlighted, such as buttered pasta or eggs. Thin truffle slices may be inserted into meats, under the skins of roasted fowl, in foie gras preparations, in pâtés , or in stuffings. Some specialty cheeses contain truffles, as well. Truffles are also used for producing truffle salt and truffle honey.

While chefs once peeled 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 the valuable ingredient. Some restaurants stamp out circular discs of truffle flesh and use the skins for sauces.

Truffle oil (olive oil with Tuber melanosporum). Truffle olive oil with Tuber melanosporum.JPG
Truffle oil (olive oil with Tuber melanosporum).

Oil

Truffle oil is used as a lower-cost and convenient substitute for truffles, to provide flavouring, or to enhance the flavour and aroma of truffles in cooking. Some products called "truffle oils" contain no truffles, or include pieces of inexpensive, unprized truffle varietals, which have no culinary value, simply for show. [75] The vast majority is oil that has been artificially flavoured using a synthetic agent such as 2,4-dithiapentane. [75]

The scientific name is included on the ingredient list of truffle oils infused with natural truffles.

Vodka

Because more aromatic molecules in truffles are soluble in alcohol, it can be used to carry a more complex and accurate truffle flavour than oil without the need for synthetic flavourings. Many commercial producers use 2,4-dithiapentane regardless, as it has become the dominant flavor most consumers, unexposed to fresh truffles but familiar with oils, associate with them. Because most Western nations do not have ingredient labeling requirements for spirits, consumers often do not know if artificial flavorings have been used. [76] It is used as a spirit in its own right, a cocktail mix or a food flavoring. [77]

See also

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Suillus luteus is a bolete fungus, and the type species of the genus Suillus. A common fungus native to Eurasia, from the British Isles to Korea, it has been introduced widely elsewhere, including North and South America, southern Africa, Australia and New Zealand. Commonly referred to as slippery jack or sticky bun in English-speaking countries, its names refer to the brown cap, which is characteristically slimy in wet conditions. The fungus, initially described as Boletus luteus by Carl Linnaeus in 1753, is now classified in a different family as well as genus. Suillus luteus is edible, though not as highly regarded as other bolete mushrooms, and is commonly prepared and eaten in soups, stews or fried dishes. The slime coating, however, may cause indigestion if not removed before eating.

<i>Rhizopogon</i> Genus of fungi

Rhizopogon is a genus of ectomycorrhizal Basidiomycetes in the family Rhizopogonaceae. Species form hypogeous sporocarps commonly referred to as "false truffles". The general morphological characters of Rhizopogon sporocarps are a simplex or duplex peridium surrounding a loculate gleba that lacks a columnella. Basidiospores are produced upon basidia that are borne within the fungal hymenium that coats the interior surface of gleba locules. The peridium is often adorned with thick mycelial cords, also known as rhizomorphs, that attach the sporocarp to the surrounding substrate. The scientific name Rhizopogon is Greek for 'root' (Rhiz-) 'beard' (-pogon) and this name was given in reference to the rhizomorphs found on sporocarps of many species.

Sporocarp (fungi) Fungal structure on which spore-producing structures are borne

The sporocarp of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cycle, while the rest of the life cycle is characterized by vegetative mycelial growth and asexual spore production.

<i>Sarcosphaera</i> Genus of fungi

Sarcosphaera is a fungal genus within the Pezizaceae family. It is a monotypic genus, containing the single species Sarcosphaera coronaria, commonly known as the pink crown, the violet crown-cup, or the violet star cup. It is a whitish or grayish cup fungus, distinguished by the manner in which the cup splits into lobes from the top downward. It is commonly found in the mountains in coniferous woods under humus on the forest floor, and often appears after the snow melts in late spring and early summer. The fungus is widespread, and has been collected in Europe, Israel and the Asian part of Turkey, North Africa, and North America. In Europe, it is considered a threatened species in 14 countries. Although several taxa have been described as Sarcosphaera species since the introduction of the genus in 1869, most lack modern descriptions, have been transferred to the related genus Peziza, or are considered synonymous with S. coronaria.

Fevansia is a fungal genus in the family Albatrellaceae. A monotypic genus, it contains the single rare truffle-like species Fevansia aurantiaca, found in old-growth forests of Oregon. The name Fevansia honors Frank Evans of the North American Truffling Society, who collected the holotype specimen. Aurantiaca is Latin for "pale orange", referring to the color of the peridium.

<i>Suillus quiescens</i> Species of fungus

Suillus quiescens is a pored mushroom of the genus Suillus in the family Suillaceae. First collected in 2002 on Santa Cruz Island off the coast of California, in association with Bishop Pine, the species was scientifically described and named in 2010. In addition to its distribution in coastal California, it was also found forming ectomycorrhizae with the roots of pine seedlings in the eastern Sierra Nevada, coastal Oregon, and the southern Cascade Mountains. It resembles Suillus brevipes, but can be distinguished from that species by its paler-colored immature cap and by the tiny colored glands on the stipe that darken with age.

Gasteroid fungi Group of fungi

The gasteroid fungi are a group of fungi in the Basidiomycota. Species were formerly placed in the obsolete class Gasteromycetes Fr., or the equally obsolete order Gasteromycetales Rea, because they produce spores inside their basidiocarps rather than on an outer surface. However, the class is polyphyletic, as such species—which include puffballs, earthstars, stinkhorns, and false truffles—are not closely related to each other. Because they are often studied as a group, it has been convenient to retain the informal (non-taxonomic) name of "gasteroid fungi".

False truffle Type of fungus with underground fruiting bodies resembling truffles

A false truffle or a hymenogastrale is any species of fungus that has underground fruiting bodies that produce basidiocarps resembling the true truffles of genus Tuber. While rodents such as squirrels eat a wide variety of false truffle species, many are considered toxic or otherwise inedible by humans and only a few are sought after as food.

<i>Geopora cooperi</i> Species of fungus

Geopora cooperi, commonly known as the pine truffle or the fuzzy truffle, is a species of fungus in the family Pyronemataceae. It has a fuzzy brown outer surface and an inner surface of whitish, convoluted folds of tissue. Widely distributed in the Northern Hemisphere, the species has been recorded from Asia, Europe, and North America.

<i>Suillus collinitus</i> Species of fungus

Suillus collinitus is a pored mushroom of the genus Suillus in the family Suillaceae. It is an edible mushroom found in European pine forests. The mushroom has a reddish to chestnut-brown cap that reaches up to 11 cm (4.3 in) in diameter, and a yellow stem measuring up to 7 cm (2.8 in) tall by 1 to 2 cm thick. On the underside of the cap are small angular pores, initially bright yellow before turning greenish-brown with age. A characteristic feature that helps to distinguish it from similar Suillus species, such as S. granulatus, is the pinkish mycelia at the base of the stem.

<i>Tuber oregonense</i> Species of fungus

Tuber oregonense, commonly known as the Oregon white truffle, is a species of edible truffle in the genus Tuber. Described as new to science in 2010, the North American species is found on the western coast of the United States, from northern California to southern British Columbia west of the Cascade Range. A mycorrhizal fungus, it grows in a symbiotic association with Douglas fir. It overlaps in distribution with the closely related T. gibbosum, but they have different growing seasons: T. oregonense typically appears from October through March, while T. gibbosum grows from January to June. The fruit bodies of the fungus are roughly spherical to irregular in shape, and resemble small potatoes up to 5 cm (2 in) in diameter. Inside the truffle is the gleba, which is initially white before it becomes a marbled tan color. The large, often thick-walled, and strongly ornamented spores are produced in large spherical asci. The truffle is highly prized for its taste and aroma. Some individuals have claimed success in cultivating the truffles in Christmas tree farms.

<i>Kalapuya brunnea</i> Species of fungus

Kalapuya brunnea is a species of truffle in the monotypic fungal genus Kalapuya. The truffle occurs only in the Pacific Northwest region of the United States, in western Oregon and northern California. Known locally as the Oregon brown truffle, it was formerly thought to be an undescribed species of Leucangium until molecular analysis demonstrated that it was distinct from that genus. The truffle is reddish brown with a rough and warty outer skin, while the interior spore-producing gleba is initially whitish before developing greyish-brown mottling as it matures. Mature truffles have an odor resembling garlicky cheese, similar to mature Camembert. The species has been harvested for culinary purposes in Oregon.

Mycorrhizal network Underground hyphal networks that connect individual plants together

Mycorrhizal networks are underground hyphal networks created by mycorrhizal fungi that connect individual plants together and transfer water, carbon, nitrogen, and other nutrients and minerals.

Ectomycorrhiza Non-penetrative symbiotic association between a fungus and the roots of a vascular plant

An ectomycorrhiza is a form of symbiotic relationship that occurs between a fungal symbiont, or mycobiont, and the roots of various plant species. The mycobiont is often from the phyla Basidiomycota and Ascomycota, and more rarely from the Zygomycota. Ectomycorrhizas form on the roots of around 2% of plant species, usually woody plants, including species from the birch, dipterocarp, myrtle, beech, willow, pine and rose families. Research on ectomycorrhizas is increasingly important in areas such as ecosystem management and restoration, forestry and agriculture.

Tuber anniae is a species of truffle in the genus Tuber. The truffle is purported to be uncommon, but is primarily found in the United States Pacific Northwest. Recently the fruiting of closely related taxa have been found in the Baltic Rim countries, primarily forests dominated by Scots pine in eastern Finland.

<i>Tuber melanosporum</i> Black truffle

Tuber melanosporum, called the black truffle,Périgord truffle or French black truffle, is a species of truffle native to Southern Europe. It is one of the most expensive edible fungi in the world.

<i>Thelephora terrestris</i>

Thelephora terrestris is an inedible species of fungus in the Basidiomycota phylum. It is commonly known by the name Common Fiber Vase because of its circular and overlapping cap. As well, it has also been called the Earthfan fungus.

<i>Rhizopogon salebrosus</i> Species of fungus

Rhizopogon salebrosus is a mushroom species within the Rhizopogon sub-genus Amylopogon. R.salebrosus is a monotropoid mycorrhiza that is of vital importance to the ecology of conifer forests, especially in the Pacific Northwest region of North America. Although it is native to North America, R. salebrosus has been found in Europe and its range is generally limited to mountainous regions with sufficient precipitation. The mycoheterotrophic plant, Pterospora andromedea is often found in an obligate association with R. salebrosus in western parts of the U.S. Eastern populations of P. andromedea are typically symbiotic with another Rhizopogon sub species, R. kretzerae.

<i>Tuber borchii</i> Species of fungi

Tuber borchii, known as the whitish truffle or bianchetto truffle, is a small, common species of edible truffle excellent for use in cuisine.

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