Tuber melanosporum
Fruiting body of Tuber melanosporum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Pezizomycetes
Order: Pezizales
Family: Tuberaceae
Genus: Tuber
Species:
T. melanosporum
Binomial name
Tuber melanosporum
Vittad. 1831
Tuber melanosporum
View the Mycomorphbox template that generates the following list
Glebal hymenium
Hymenium attachment is not applicable
Lacks a stipe
Ecology is mycorrhizal
Edibility is choice

Tuber melanosporum, called the black truffle, Périgord truffle or French black truffle,[1] is a species of truffle native to Southern Europe. It is one of the most expensive edible fungi in the world. In 2013, the truffle cost between 1,000 and 2,000 euros per kilogram.

Description

The round, dark brown fruiting bodies (ascocarps) have a black-brown skin with small pyramidal cusps.[2] They have a strong, aromatic smell and normally reach a size of up to 10 centimetres (4 inches).[3] Some may be significantly larger, such as a black truffle found in 2012 in Dordogne with a mass of 1.277 kilograms (2.82 pounds).[4]

Their flesh is initially white, then dark. It is permeated by white veins, which turn brown with age.[5] The spores are elliptical and measure about 22–55 µm by 20–35 µm.[3] They are dark brown and covered with large spikes.

In the Northern Hemisphere, the fruiting bodies develop from April to June and are harvested from November to March.[6]

Until 2010, all truffle species were thought to be homothallic, that is, capable of sexual reproduction from a single organism. Subsequent research indicated that black truffles are heterothallic; that is, sexual reproduction requires contact between the mycelia of different mating types.[7] If mycelia of different mating types surround a tree, eventually, one type becomes predominant.

Aroma

The fruiting bodies of the black truffle exude a scent reminiscent of undergrowth, strawberries, wet earth, or dried fruit with a hint of cocoa. Their taste, which fully develops after the truffles are heated, is slightly peppery and bitter.[8] If stored at room temperature, the aromatic compounds dissipate, while storage around the freezing point (0°C) leads to an increased synthesis of these compounds.

The volatile compounds that contribute to the aroma and are developed by the fruiting bodies include 2-methyl-1-butanol, isoamyl alcohol, 2-methylbutyraldehyde, and 3-methylbutyraldehyde, as well as traces of sulfur compounds.[8][9] One of these, dimethyl sulfide, is what attracts truffle dogs, truffle hogs and truffle flies to the fruiting bodies.[10] Several species of yeast, which produce part of the aromatic compounds, have been isolated from Tuber melanosporum and Tuber magnatum.[11]

Chemistry

The genome of the black truffle was published in 2010.[12] It contains 125 million base pairs, 58% of the genome consists of transposable elements, and the genome contains only 7,500 identified protein-encoding genes. During symbiosis, genes involved in the decomposition of plant cell walls and lipids are induced. This indicates that black truffles decompose the cell walls of their host plants at the beginning of the symbiosis.

Truffles contain the endocannabinoid anandamide (AEA) and the major metabolic enzymes of the endocannabinoid system (ECS). The AEA content increases in the late stages of truffles’ development. AEA and ECS metabolic enzymes may have evolved earlier than endocannabinoid-binding receptors, and AEA might be an ancient attractant to truffle-eating animals, which are well-equipped with endocannabinoid-binding receptors.[13]

Similar species

Black truffle, cut

The black truffle is morphologically very similar to the commercially less valuable Chinese truffle (Tuber indicum). To avoid fraud or misidentifications in commerce, a RFLP genetic test has been developed to distinguish the two species.[14] Externally, they can be distinguished by their skin, which is smoother and dark red or dark brown in the Chinese truffle. Two other similar truffle species are the summer truffle (Tuber aestivum) and the winter truffle (Tuber brumale), whose flesh is of a lighter color.

Taxonomy

Italian naturalist Carlo Vittadini described the black truffle in 1831.

Ecology

Development and phenology

Black truffles suppress the growth of plants around their symbiont, creating the impression of a burnt area.

Black truffles grow at a depth of 5 cm (2 in) to 50 cm (20 in) as ectomycorrhizae, preferably in loose calcareous soil,[15] close to the roots of their plant symbionts. These include holm oaks, French oaks, hazel, cherry and other deciduous trees.[3] The symbiosis of holm oak saplings and black truffles has been shown to improve photosynthesis and root growth in the plant.[16]

Black truffles suppress the growth of plants around their symbiont, creating the impression of a burnt (brûlé) area around it. They do so by parasitizing the roots of other plants, which may lead to necrosis of the root bark and the death of the parasitized plant.[17] Moreover, part of the scent emitted by the truffles may limit the growth of other plants through oxidative stress.[18]

Reproduction

Boars and the larvae of the truffle fly (Suillia tuberiperda), which eat the fruiting bodies, aid in the distribution of the species by excreting the indigestible spores. Their excrement likely also serves to fertilize the spores. Black truffles are sometimes found together with winter truffles, which aid the growth of black truffles in wet soils.[19]

Distribution and habitat

The natural habitat of the black truffle includes various regions in Spain, France, Italy, and Croatia. These are presumably the areas where the host plants found refuge during the last Ice Age. In these areas, the search for black truffles and their cultivation is a tradition going back more than 200 years. Truffles are still collected manually in a traditional way in large areas of natural forests. For example, the county of Alto Maestrazgo (province of Castellón, Spain) has an ideal ground with suitable conditions for cultivating truffles. Albocàsser, Atzaneta, Culla, and Morella are just some of the villages in this region where one can find black truffles in large amounts.[20]

Climate change has increasingly affected this form of recollection, and since 2010, a significant drop in productivity has occurred in naturally producing forests.

Cultivation

To improve production, planters must ensure that neighboring trees harbor mycelia of different mating types, such as by inoculating new saplings with a mycelium of a particular type.

Cultivated areas are increasingly popular, and in central Spain, several thousands of hectares are dedicated to truffle cultivation (the Mecca of the black truffle being in Sarrión, Teruel province in the Aragon region). Some experiments have also been conducted in burnt areas, with promising results, as legally, no need to ask for a land-use change exists when planting truffles, as it can be considered (EU-28) as forest land.[21]

Black truffles are now also cultivated in Australia, New Zealand, Chile,[22] North America, Argentina, South Africa,[15][23] and Wales.[24] Cultivation involves the planting of, for example, hazel trees whose roots are inoculated with truffle mycelium. The first fruiting bodies can be harvested about 4-10 years after planting the trees.[25]

France accounts for around 45% of the world's production of black truffles, Spain 35%, and Italy 20%. Smaller amounts are produced in the United States, South Africa, Slovenia, Croatia, and the Australian states of Tasmania and Western Australia. In 2005, black truffles were found in Serbia.[26] About 80% of the French production comes from southeast France: upper Provence (départements of Vaucluse and Alpes-de-Haute-Provence), part of Dauphiné (département of Drôme), and part of Languedoc (département of Gard). About 20% of the production comes from southwest France: Quercy (département of Lot) and Périgord. The largest truffle market in France (and probably also in the world) is at Richerenches in Vaucluse. The largest truffle market in southwest France is at Lalbenque in Quercy. These markets are busiest in January when the black truffles have their highest perfume.

Production has considerably diminished during the 21st century, dropping to around 20 metric tonnes per year, with peaks of about 46 tonnes in the best years. By comparison, in 1937, France produced about 1,000 metric tonnes of black truffles.

The following table shows the production in the EU of T. melanosporum in Spain, France, and Italy. Production data are in metric tonnes and country weights in percentage and come from the Groupe Européen Truffe et Trufficulture, an association of the leading European producers.

YearsSpainFranceItalyEU % of average yearSpain vs EUFrance vs EUItaly vs EU
1990/1991301755283583310
1991/1992102053556295714
1992/199323313579040545
1993/19949222335227676
1994/199541230467392665
1995/199620192564102313039
1996/199725502095151265321
1997/1998803024134213602218
1998/199971442540285616
1999/200035401085135414712
2000/20016354457113789
2001/2002201554063503813
2002/200340352095151423721
2003/20047962235324127
2004/20052227105994374617
2005/2006141583759384122
2006/20072028105892344817
2007/2008252685994424414
2008/200914582092146156322
2009/201093284978186516
2010/20111837,21267,2107275518
2011/201214,542,3864,8103226512
2012/20131538,22073,2116205227
2013/2014455030125198364024

As the data show, France has been the leading producer of black truffles in the last decade and a half but is rapidly challenged by Spain, where regions have made use of the EU-funded Rural Development Programme to subsidise cultivated plantations.[27] This is particularly visible in the Teruel province of the Aragón region, where the black truffle represents the first and main economic activity (in GDP and employment), especially since 2010-2011 when many plantations opened under the last Rural Development Programme 2000-2006 came into production phase.[28]

Uses

With a price of about 1,000 to 2,000 euros per kilogram, black truffles are the second-most expensive truffles after white truffles and one of the most sought-after edible mushrooms in the world.[6]

In cooking, black truffles are used to refine the taste of meat, fish, soups, cheeses, and risotto. Unlike white truffles, the aroma of black truffles does not diminish when they are heated but becomes more intense.[29] They are most commonly shaved into or on top of a dish raw or infused with high-quality olive oil or butter. [30]

References

  1. ↑ There are several common names for the species in the popular literature. For example, the Field Guide to North American Truffles (Trappe, Evans & Trappe, 2007) refers to it as the "French black"; Taming the Truffle (Hall, Brown, Zambonelli, 2007) calls it the "black Périgord truffle" (but lists it under the scientific name in the index); The Book of Fungi (Roberts & Evans, 2011) calls it the "black truffle"; and the European field guide Mushrooms (Laessoe & Lincoff, 2002) calls it simply the "Perigord truffle."
  2. ↑ Gerhardt, Ewald (2011). Der große BLV-Pilzführer für unterwegs. Munich. p. 662. ISBN 978-3-8354-0644-5.{{cite book}}: CS1 maint: location missing publisher (link)
  3. 1 2 3 Laux, Hans E. (2010). Der große Kosmos-Pilzführer. Alle Speisepilze mit ihren giftigen Doppelgängern. Stuttgart: Kosmos. p. 688. ISBN 978-3-440-12408-6.
  4. ↑ "1,3 Kilo schwerer Trüffel in Dordogne gefunden". ORF. 15 January 2012. Retrieved 27 July 2013.
  5. ↑ Cetto, Bruno (1988). Täublinge, Milchlinge, Boviste, Morcheln, Becherlinge u.a. Enzyklopädie der Pilze. Vol. 4. Munich: BLV. p. 477. ISBN 978-3-405-13477-8.
  6. 1 2 "Schwarze Trüffel". Huettenhilfe.de. Retrieved 27 July 2013.
  7. ↑ Andrea Rubini; Beatrice Belfiori; Claudia Riccioni; Sergio Arcioni; Francis Martin; Francesco Paolocci (2011), "Tuber melanosporum: mating type distribution in a natural plantation and dynamics of strains of different mating types on the roots of nursery-inoculated host plants", New Phytologist (in German), vol. 189, no. 3, pp. 723–735, doi:10.1111/j.1469-8137.2010.03493.x, PMID 20964691
  8. 1 2 Franco Bellesia; Adriano Pinetti; Alberto Bianchi; Bruno Tirillini (1998), "The volatile organic compounds of black truffle (Tuber melanosporum Vitt.) from Middle Italy", Flavour and Fragrance Journal (in German), vol. 13, no. 1, pp. 56–58, doi:10.1002/(SICI)1099-1026(199801/02)13:1<56::AID-FFJ692>3.0.CO;2-X
  9. ↑ Laura Culleré; Vicente Ferreira; Berenger Chevret; María E. Venturini; Ana C. Sánchez-Gimeno; Domingo Blanco (2010), "Characterisation of aroma active compounds in black truffles (Tuber melanosporum) and summer truffles (Tuber aestivum) by gas chromatography–olfactometry", Food Chemistry (in German), vol. 122, no. 1, pp. 300–306, doi:10.1016/j.foodchem.2010.02.024
  10. ↑ T. Talou; A. Gaset; M. Delmas; M. Kulifaj; C. Montant (1990), "Dimethyl sulphide: the secret for black truffle hunting by animals?", Mycological Research (in German), vol. 94, no. 2, pp. 277–278, doi:10.1016/S0953-7562(09)80630-8
  11. ↑ Pietro Buzzini u. a. (2005), "Production of volatile organic compounds (VOCs) by yeasts isolated from the ascocarps of black (Tuber melanosporum Vitt.) and white (Tuber magnatum Pico) truffles", Archives of Microbiology (in German), vol. 184, no. 3, pp. 187–193, doi:10.1007/s00203-005-0043-y, PMID 16187098, S2CID 9395930
  12. ↑ Francis Martin u. a. (2010), "Périgord black truffle genome uncovers evolutionary origins and mechanisms of symbiosis", Nature (in German), vol. 464, no. 7291, pp. 1033–1038, Bibcode:2010Natur.464.1033M, doi:10.1038/nature08867, PMID 20348908
  13. ↑ Pacioni, Giovanni; Rapino, Cinzia; Zarivi, Osvaldo; Falconi, Anastasia; Leonardi, Marco; Battista, Natalia; Colafarina, Sabrina; Sergi, Manuel; Bonfigli, Antonella (1 February 2015). "Truffles contain endocannabinoid metabolic enzymes and anandamide". Phytochemistry. 110: 104–110. Bibcode:2015PChem.110..104P. doi:10.1016/j.phytochem.2014.11.012. PMID 25433633.
  14. ↑ Francesco Paolocci; Andrea Rubini; Bruno Granetti; Sergio Arcioni (1997), "Typing Tuber melanosporum and Chinese black truffle species by molecular markers", FEMS Microbiology Letters (in German), vol. 153, no. 2, pp. 255–260, doi:10.1111/j.1574-6968.1997.tb12582.x, PMID 9271850
  15. 1 2 C. C. Linde; H. Selmes (2012), "Genetic Diversity and Mating Type Distribution of Tuber melanosporum and Their Significance to Truffle Cultivation in Artificially Planted Truffiéres in Australia", Applied and Environmental Microbiology (in German), vol. 78, no. 18, pp. 6534–6539, Bibcode:2012ApEnM..78.6534L, doi:10.1128/AEM.01558-12, PMC 3426713, PMID 22773652
  16. ↑ Andrea Nardinia; Sebastiano Salleo; Melvin T. Tyree; Moreno Vertovec (2000), "Influence of the ectomycorrhizas formed by Tuber melanosporum Vitt. on hydraulic conductance and water relations of Quercus ilex L. seedlings" (PDF), Annals of Forest Science (in German), vol. 57, no. 4, pp. 305–312, doi:10.1051/forest:2000121
  17. ↑ I. Plattner; I.R. Hall (1995), "Parasitism of non-host plants by the mycorrhizal fungus Tuber melanosporum", Mycological Research (in German), vol. 99, no. 11, pp. 1367–1370, doi:10.1016/S0953-7562(09)81223-9
  18. ↑ Richard Splivallo; Mara Novero; Cinzia M Bertea; Simone Bossi; Paola Bonfante (2007), "Truffle volatiles inhibit growth and induce an oxidative burst in Arabidopsis thaliana", The New Phytologist (in German), vol. 175, no. 3, pp. 417–424, doi:10.1111/j.1469-8137.2007.02141.x, PMID 17635217
  19. ↑ M. Mamoun; J. M. Olivier (1993), "Competition between Tuber melanosporum and other ectomycorrhizal fungi under two irrigation regimes", Plant and Soil (in German), vol. 149, no. 2, pp. 211–218, doi:10.1007/BF00016611, S2CID 39143446
  20. ↑ "Spanish Truffle Recipes: Slow Food and the Truffle Season in Spain". Slow Living Mediterráneo. 9 February 2017. Retrieved 13 June 2017.
  21. ↑ Martinez de aragon, Juan; Fischer, Christine; Bonet, Jose-Antonio; olivera, Antoni; Oliach, Daniel; Colinas, Carlos (2012). "Economically profitable post-fire restoration with black truffle (Tuber melanosporum) producing plantations". New Forests. 43 (5–6): 615–630. doi:10.1007/s11056-012-9316-x. S2CID 17598889.
  22. ↑ "First exports of Chilean truffles set for 2013". Archived from the original on 5 January 2015. Retrieved 4 January 2015.
  23. ↑ Pieterse, Chelsea (16 June 2016). "Kokstad farmer finds first black truffle of season". The Witness. Archived from the original on 2 September 2021.
  24. ↑ Thomas, Paul; Büntgen, Ulf (2017). "First harvest of Périgord black truffle in the UK as a result of climate change". Climate Research. 74 (1): 67–70. Bibcode:2017ClRes..74...67T. doi:10.3354/cr01494. JSTOR 26394476. S2CID 135270279. Archived from the original on 2 September 2021.
  25. ↑ madrimasd. "New technique to grow black truffles". ScienceDaily, 23 Oct. 2012. Web. 5 Aug. 2013. Archived 2 September 2021 at archive.today.
  26. ↑ "KURIR". Arhiva.kurir-info.rs. Retrieved 16 June 2012.
  27. ↑ Bonet, Jose-Antonio; Fischer, Christine; Colinas, Carlos (2006). "Cultivation of black truffle to promote reforestation and land-use stability". Agronomy for Sustainable Development. 26 (1): 69–76. doi:10.1051/agro:2005059. hdl:10459.1/30348.
  28. ↑ Bonet, Jose-Antonio; Oliach, Daniel; Fischer, Christine; Martinez de Aragon, Juan; Colinas, Carlos (2009). "Cultivation Methods of the Black Truffle, the Most Profitable Mediterranean Non-Wood Forest Product; A State of the Art Review". Modelling, Valuing and Managing Mediterranean Forest Ecosystems for Non-Timber Goods and Services (57): 57–71.
  29. ↑ Jochim, Tobias. "Trüffel". Gourmetglobe.de. Retrieved 27 July 2013.
  30. ↑ Tita, Nicolo. "The Fresh Truffle Guide - How to Use Fresh Truffles, 7 November 2018. Retrieved on 27 January 2021.
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