Boletus edulis

"Cep" redirects here. For other uses, see Cep (disambiguation).

Boletus edulis
In the northern Apennine Mountains, Abetina Reale forest, Italy
Conservation status
Least Concern  (IUCN 3.1)<ref name=iucn>Template:Cite iucn</ref>
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Basidiomycota
Class:	Agaricomycetes
Order:	Boletales
Family:	Boletaceae
Genus:	Boletus
Species:	B. edulis
Binomial name
Boletus edulis Bull. (1782)
Synonyms<ref name="urlMycoBank: Boletus edulis">"Boletus edulis Bull. 1782". MycoBank. International Mycological Association. Retrieved 2010-10-21.</ref>
Ceriomyces crassus Battarra (1775) Boletus solidus Sowerby (1809) Leccinum edule (Bull.) Gray (1821) Dictyopus edulis (Bull.) Forq. (1890)

Boletus edulis Mycological characteristics
	Pores on hymenium
	Cap is convex
	Hymenium is adnate
	Stipe is bare
	Spore print is brown
	Ecology is mycorrhizal
	Edibility is choice

Template:Stack end Boletus edulis (English: cep, penny bun, porcino) is a basidiomycete fungus, and the type species of the genus Boletus. It is prized as an edible mushroom.

The fungus produces spore-bearing fruit bodies above ground in summer and autumn. The fruit body has a large brown cap which on occasion can reach Template:Convert, rarely Template:Convert in diameter and Template:Convert in weight. Like other boletes, it has tubes extending downward from the underside of the cap, rather than gills; spores escape at maturity through the tube openings, or pores. The pore surface of the B. edulis fruit body is whitish when young, but ages to a greenish-yellow. The stout stipe, or stem, is white or yellowish in colour, up to Template:Convert, rarely Template:Convert tall and Template:Convert thick, and partially covered with a raised network pattern, or reticulations.

The fungus grows in deciduous and coniferous forests and tree plantations, forming symbiotic ectomycorrhizal associations with living trees by enveloping the tree's underground roots with sheaths of fungal tissue. Widely distributed in the Northern Hemisphere across Eurasia and North America, it does not occur naturally in the Southern Hemisphere, although it has been introduced to southern Africa, Australia, New Zealand, and Brazil. Several closely related European mushrooms formerly thought to be varieties or forms of B. edulis have been shown using molecular phylogenetic analysis to be distinct species, and others previously classed as separate species are conspecific with this species. The western North American species commonly known as the California king bolete (Boletus edulis var. grandedulis) is a large, darker-coloured variant first formally identified in 2007.

B. edulis is held in high regard in many cuisines, and is commonly prepared and eaten in soups, pasta, or risotto. The mushroom is low in fat and digestible carbohydrates, and high in protein, vitamins, minerals and dietary fibre. Although it is sold commercially, it is very difficult to cultivate. Available fresh in autumn throughout Europe and Russia, it is most often dried, packaged, and distributed worldwide. It keeps its flavour after drying, and it is then reconstituted and used in cooking. B. edulis is also one of the few fungi sold pickled.

Taxonomy

Pierre Bulliard first described B. edulis in 1782.

Boletus edulis was first described in 1782 by the French botanist Pierre Bulliard and still bears its original name.<ref>Template:Cite book</ref> The starting date of fungal taxonomy had been set as January 1, 1821, to coincide with the date of the works of the 'father of mycology', Swedish naturalist Elias Magnus Fries, which meant the name required sanction by Fries (indicated in the name by a colon) to be considered valid, as Bulliard's work preceded this date. It was thus written Boletus edulis Bull.:Fr. A 1987 revision of the International Code of Botanical Nomenclature set the starting date at May 1, 1753, the date of publication of Linnaeus' work, the Species Plantarum.<ref>Template:Cite book</ref> Hence, the name no longer requires the ratification of Fries' authority. Early alternate names include Boletus solidus by English naturalist James Sowerby in 1809,<ref>Template:Cite book This entire work is available in Commons here, but the reference is to plate 419 with textual description on page 697. Sowerby described the same modern species as B. edulis on plate 111 (description on page 57).</ref> and Gray's Leccinum edule.<ref>Template:Cite book</ref> Gray's transfer of the species to Leccinum was later determined to be inconsistent with the rules of botanical nomenclature, and he apparently was unfamiliar with the earlier works of Fries when he published his arrangement of bolete species.<ref>Šutara J. (1985). "Leccinum and the question of superfluous names (Fungi: Boletaceae)". Taxon. 34 (4): 678–86. doi:10.2307/1222214. JSTOR 1222214.</ref>

Boletus edulis is the type species of the genus Boletus. In Rolf Singer's classification of the Agaricales mushrooms, it is also the type species of section Boletus, a grouping of about 30 related boletes united by several characteristics: a mild-tasting, white flesh that does not change colour when exposed to air; a smooth to distinctly raised, netted pattern over at least the uppermost portion of the stem; a yellow-brown or olive-brown spore print; white tubes that later become yellowish then greenish, which initially appear to be stuffed with cotton; and cystidia that are not strongly coloured.<ref name=Singer1986>Template:Cite book</ref><ref>Template:Cite book</ref> Molecular analysis published in 1997 established that the bolete mushrooms are all derived from a common ancestor, and established the Boletales as an order separate from the Agaricales.<ref>Binder M, Besl H, Bresinsky A (1997). "Agaricales oder Boletales? Molekularbiologische Befunde zur Zuordnung einiger umstrittener Taxa". Zeitschrift für Mykologie. 63: 189–196.</ref>

The generic name is derived from the Latin term bōlētus "mushroom", which was borrowed in turn from the Ancient Greek βωλίτης, "terrestrial fungus".<ref>Template:Cite book</ref> Ultimately, this last word derives from bōlos/βῶλος "lump", "clod", and, metaphorically, "mushroom".<ref name="Liddell 1980">Template:Cite book</ref> The βωλίτης of Galen, like the boletus of Latin writers like Martial, Seneca and Petronius,<ref>Peter Howell, A Commentary on Book One of the Epigrams of Martial, The Athlone Press, 1980 p.152-3. Howell doubts the identification, and mentions the view advanced by Augusta A. Imholtz Jr., 'Fungi and piace- names, thè origin of boletus,' in AJP Vol.98, 1977 pp.71f., that the Latin word may derive from the Spanish town Boletum, modern-day Boltaña, south of the Pyrenees, which is still famous for its mushrooms.</ref> is often identified as the much prized Amanita caesarea.<ref name = "Ramsbottom53">Template:Cite book</ref> The specific epithet edulis in Latin means "eatable" or "edible".<ref>Template:Cite book</ref>

Common names

Common names for B. edulis vary by region. The standard Italian name, porcino (pl. porcini), means porcine;<ref>"porcino in Vocabolario – Treccani". www.treccani.it.</ref> fungo porcino, in Italian, echoes the term suilli, literally "hog mushrooms", a term used by the Ancient Romans<ref>Pliny, Natural History, Bk. 16, 11, 31: "Such is the multiplicity of products in addition to the acorn that are borne by hard-oaks; but they also produce edible fungi (boletos) and hog mushrooms (suillos)." Pliny, Natural History, 10 vols., tr. H. Rackham, Harvard University Press/Heinemann, (1945) 1968, vol. 4, pp. 408–409.</ref> and still in use in southern Italian terms for this species.<ref>Neapolitan sillo, and Calabrian sillu/siddu. See Glauco Sanga, Gherardo Ortalli, Nature knowledge: ethnoscience, cognition, and utility, Berghahn Books, 2003 p. 78.</ref> The derivation has been ascribed to the resemblance of young fruit bodies to piglets, or to the fondness pigs have for eating them.<ref name="Carluccio03">Carluccio, pp. 36–38.</ref> It is also known as "king bolete".<ref name=Zeitl76>Template:Cite book</ref> The English penny bun refers to its rounded brownish shape. The German name Steinpilz (stone mushroom) refers to the species' firm flesh.<ref>Template:Cite book (online Template:Webarchive)</ref> In Austria, it is called Herrenpilz, the "noble mushroom",<ref name = "Carluccio03"/> while in Mexico, the Spanish name is panza, meaning "belly".<ref>Jarvis MC, Miller AM, Sheahan J, Ploetz K, Ploetz J, Watson RR, Ruiz MP, Villapan CA, Alvarado JG, Ramirez AL, Orr B (2004). "Edible wild mushrooms of the Cofre de Perote region, Veracruz, Mexico: An ethnomycological study of common names and uses". Economic Botany. 58 (Suppl. S): S111 – S115. doi:10.1663/0013-0001(2004)58[S111:EWMOTC]2.0.CO;2. S2CID 27729532.</ref> Another Spanish name, rodellon, means "small round boulder", while the Dutch name eekhoorntjesbrood means "squirrel's bread".<ref name=Schalkwijk-Barendsen1991>Template:Cite book</ref> Russian names are belyy grib (ru:белый гриб; "white mushroom" as opposed to less valuable "black mushrooms") and borovik (ru:боровик; from bor—"pine forest"). The vernacular name cep is derived from the Catalan cep or its French name cèpe, although the latter is a generic term applying to several related species. In France, it is more fully cèpe de Bordeaux, derived from the Gascon cep "trunk" for its fat stalk,<ref>Template:Cite book</ref> ultimately from the Latin cippus "stake".<ref>Template:Cite encyclopedia</ref> Ceppatello, ceppatello buono, ceppatello bianco, giallo leonato, ghezzo, and moreccio are names from Italian dialects,<ref>Template:Cite book</ref><ref>Template:Cite book</ref> and ciurenys or surenys is another term in Catalan.<ref>Template:Cite book</ref> The French-born King Charles XIV John popularised B. edulis in Sweden after 1818,<ref>Template:Cite book</ref> and is honoured in the local vernacular name Karljohanssvamp, as well as the Danish name Karl Johan svamp. The monarch cultivated the fungus about his residence, Rosersberg Palace.<ref>Template:Cite book</ref> The Finnish name is herkkutatti, from herkku 'delicacy', and tatti, 'bolete'.Template:Cn

Description

Cross-section showing white flesh, broad stem, and spore tubes on the underside of the cap

The cap of this mushroom is Template:Convert broad at maturity. Slightly sticky to touch, it is convex in shape when young and flattens with age. The colour is generally reddish-brown fading to white in areas near the margin, and continues to darken as it matures. The stipe, or stem, is Template:Convert in height, and up to Template:Convert thick—rather large in comparison to the cap;<ref name=Kozikowski1996/> it is club-shaped, or bulges out in the middle. It is finely reticulate on the upper portion, but smooth or irregularly ridged on the lower part. The under surface of the cap is made of thin tubes, the site of spore production; they are Template:Convert deep, and whitish in colour when young, but mature to a greenish-yellow.<ref name=Grund1976/> The angular pores, which do not stain when bruised, are small—roughly 2 to 3 pores per millimetre.<ref name=Tylutki1987II>Template:Cite book</ref> In youth, the pores are white and appear as if stuffed with cotton (which are actually mycelia); as they age, they change colour to yellow and later to brown. The spore print is olive brown. The flesh of the fruit body is white, thick and firm when young, but becomes somewhat spongy with age. When bruised or cut, it either does not change colour, or turns a very light brown or light red.<ref name=Wang1995/> Fully mature specimens can weigh about Template:Convert; a huge specimen collected on the Isle of Skye, Scotland, in 1995 bore a cap of Template:Convert, with a stipe Template:Convert in height and Template:Convert wide, and weighed Template:Convert.<ref name=Kozikowski1996>Kozikowski GR. (1996). "Foray Report from Skye". Mycologist. 10 (4): 183–84. doi:10.1016/S0269-915X(96)80022-X.</ref> A similarly sized specimen found in Poland in 2013 made international news.<ref>"Giant mushroom found in Poland". BBC News.</ref>

Stem shape can range from club-shaped to centrally bulbous

Boletus edulis is considered one of the safest wild mushrooms to pick for the table, as few poisonous species closely resemble it, and those that do may be easily distinguished by careful examination.<ref name = "Carluccio03"/> The most similar poisonous mushroom may be the devil's bolete (Rubroboletus satanas), which has a similar shape, but has a red stem and stains blue on bruising.<ref name="Carluccio03" /> It is often confused with the very bitter and unpalatable Tylopilus felleus, but can be distinguished by the reticulation on the stalk; in porcini, it is a whitish, net-like pattern on a brownish stalk, whereas it is a dark pattern on white in the latter. Porcini have whitish pores while the other has pink. If in doubt, tasting a tiny bit of flesh will yield a bitter taste.<ref name = "Carluccio03"/> It can also resemble the "bolete-like" Gyroporus castaneus, which is generally smaller, and has a browner stem. Boletus huronensis, an uncommon mushroom of northeastern North America, is another recognized look-alike known to cause severe gastrointestinal disorders.<ref>Bill Bakaitis (2019). "Boletus huronensis: Comments on its toxicity with diagnostic images of its field characteristics and staining reactions". North American Mycological Association.</ref>

The spores are elliptical to spindle-shaped, with dimensions of 12–17 by 5–7 μm. The basidia, the spore-bearing cells, are produced in a layer lining the tubes, and arrange themselves so their ends are facing the center of the tube; this layer of cells is known technically as a hymenium. The basidia are thin-walled, mostly attached to four spores, and measure 25–30 by 8–10 μm. Another cell type present in the hymenium is the cystidia, larger sterile cells that protrude beyond the basidia into the lumen of the hymenium, and act as air traps, regulating humidity.<ref>Template:Cite book</ref> B. edulis has pleurocystidia (cystidia located on the face of a pore) that are thin-walled, roughly spindle-shaped to ventricose, and measure 30–45 by 7–10 μm; the "stuffed" feature of the hymenium is caused by cheilocystidia—cells found on the edges of the pores.<ref name=Grund1976>Template:Cite book</ref> The hyphae of B. edulis do not have clamp connections.<ref name=Tylutki1987II/>

Related species

B. edulis var. grandedulis

B. regineus

Several similar brownish-coloured species are sometimes considered subspecies or forms of this mushroom. In Europe, in addition to B. edulis (or cèpe de Bordeaux), the most popular are:

• Cèpe bronzé ("dark cep"; Boletus aereus), much rarer than B. edulis, is more highly regarded by gourmets, and consequently more expensive. Usually smaller than B. edulis, it is also distinctively darker in colour.<ref name = "Carluccio03"/> It is especially suited to drying.<ref name=Zeitl76/>
• Cèpe des pins ("pine tree cep"; Boletus pinophilus or Boletus pinicola) grows among pine trees. Rarer than B. edulis, it is less appreciated by gourmets than the two other kinds of porcini, but remains a mushroom rated above most others.<ref name=Zeitl76/>
• Cèpe d'été ("summer cep"; Boletus reticulatus), also less common and found earlier.<ref name = "Carluccio03"/>

Molecular phylogenetic analyses have proven these three are all distinctive and separate species;<ref>Vizzini A, Mello A, Ghignone S, Sechi C, Ruiu P, Bonfante P (2008). "Boletus edulis complex: from phylogenetic relationships to specific primers". Pagine di Micologia (30): 49–52. ISSN 1122-8911.</ref> other taxa formerly believed to be unique species or subspecies, such as B. betulicola, B. chippewaensis, B. persoonii, B. quercicola and B. venturii, are now known to be part of a B. edulis species complex with a wide morphological, ecological and geographic range,<ref>Beugelsdijk DCM; van der Linde S; Zuccarello GC; den Bakker; Draisma SGA; Noordeloos ME. (2008). "A phylogenetic study of Boletus section Boletus in Europe". Persoonia. 20 (1): 1–7. doi:10.3767/003158508X283692. PMC 2865352. PMID 20467482.</ref><ref name=dent10>Dentinger BT, Ammirati JF, Both EE, Desjardin DE, Halling RE, Henkel TW, Moreau PA, Nagasawa E, Soytong K, Taylor AF, Watling R, Moncalvo JM, McLaughlin DJ (2010). "Molecular phylogenetics of porcini mushrooms (Boletus section Boletus)" (PDF). Molecular Phylogenetics and Evolution. 57 (3): 1276–1292. doi:10.1016/j.ympev.2010.10.004. PMID 20970511. Archived from the original (PDF) on 2013-05-23.</ref> and that the genetic variability in this complex is low.<ref>Beugelsdijk DC, van der Linde S, Zuccarello GC, den Bakker HC, Draisma SG, Noordeloos ME (2008). "A phylogenetic study of Boletus section Boletus in Europe". Persoonia. 20: 1–7. doi:10.3767/003158508X283692. PMC 2865352. PMID 20467482.</ref> Similar molecular technology has been developed to rapidly and accurately identify B. edulis and other commercially important fungi.<ref>Mello A, Ghignone S, Vizzini A, Sechi C, Ruiu P, Bonfante P (2006). "ITS primers for the identification of marketable boletes". Journal of Biotechnology. 121 (3): 318–29. doi:10.1016/j.jbiotec.2005.08.022. PMID 16213623.</ref><ref>Lian B, Zang JP, Hou WG, Yuan S, Smith DL (2008). "PCR-based sensitive detection of the edible fungus Boletus edulis from rDNA ITS sequences". Electronic Journal of Biotechnology. 11 (3): 1–8. doi:10.2225/vol11-issue3-fulltext-4 (inactive 2024-11-10). hdl:1807/48975. ISSN 0717-3458.{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)</ref>

Three divergent lineages found in Yunnan province in China that are commonly marketed and sold as B. edulis (and are actually more closely related to B. aereus) were described in 2013 as B. bainiugan, B. meiweiniuganjun and B. shiyong.<ref name="Dentinger 2013">Dentinger B (12 October 2013). "Nomenclatural novelties" (PDF). Index Fungorum (29): 1. ISSN 2049-2375.</ref><ref name="Dentinger 2014">Dentinger B, Suz LM (2014). "What's for dinner? Undescribed species of porcini in a commercial packet". PeerJ. 2 (2:e570): e570. doi:10.7717/peerj.570. PMC 4179395. PMID 25279259.</ref> The classification has since been updated and expanded. All lineages are still members of Boletus sect. Boletus, the sensu sticto "porcini clade" of the genus.<ref name=Cui2016>Cui, Yang-Yang; Feng, Bang; Wu, Gang; Xu, Jianping; Yang, Zhu L. (November 2016). "Porcini mushrooms (Boletus sect. Boletus) from China" (PDF). Fungal Diversity. 81 (1): 189–212. doi:10.1007/s13225-015-0336-7. S2CID 12866685.</ref>

B. rex-veris

Western North America has several species closely related to B. edulis. The white king bolete (Boletus barrowsii), found in parts of Colorado, New Mexico, Arizona, and California (and possibly elsewhere), is named after its discoverer Chuck Barrows.<ref>Volk T. (August 2004). "Boletus barrowsii, Chuck Barrows' bolete". Tom Volk's Fungus of the Month. Department of Biology, University of Wisconsin-La Crosse. Archived from the original on 2008-10-03. Retrieved 2008-09-23.</ref> It is lighter in colour than B. edulis, having a cream-coloured cap with pink tones;<ref name=Miller2006>Template:Cite book</ref> often mycorrhizal with Ponderosa pine, it tends to grow in areas where there is less rainfall. Some find its flavour as good as if not better than B. edulis.<ref name=Evenson>Template:Cite book</ref> The California king bolete (Boletus edulis var. grandedulis) can reach massive proportions, and is distinguished from B. edulis by a mature pore surface that is brown to slightly reddish. The cap colour appears to be affected by the amount of light received during its development, and may range from white in young specimens grown under thick canopy, to dark-brown, red-brown or yellow brown in those specimens receiving more light.<ref name=eb1>Arora D. (2008). "California porcini: three new taxa, observations on their harvest, and the tragedy of no commons" (PDF). Economic Botany. 62 (3): 356–75. doi:10.1007/s12231-008-9050-7. S2CID 23176365. Archived from the original (PDF) on 2012-03-12. Retrieved 2009-11-04.</ref> The queen bolete (Boletus regineus), formerly considered a variety of B. aereus, is also a choice edible. It is generally smaller than B. edulis, and unlike that species, is typically found in mixed forests.<ref name="urlCalifornia Fungi: Boletus regineus">Wood M, Stevens F. "California Fungi: Boletus regineus". MykoWeb. Retrieved 2009-11-02.</ref> The spring king bolete (Boletus rex-veris), formerly considered a variety of B. edulis or B. pinophilus, is found throughout western North America. In contrast to B. edulis, B. rex-veris tends to fruit in clusters, and, as its common name suggests, appears in the spring.<ref name="urlCalifornia Fungi: Boletus rex-veris">Wood M, Stevens F. "California Fungi: Boletus rex-veris". MykoWeb. Retrieved 2009-11-03.</ref> B. fibrillosus is edible but considered inferior in taste.<ref>Template:Cite book</ref>

Habitat and distribution

In Lithuania

The fruit bodies of Boletus edulis can grow singly or in small clusters of two or three specimens. The mushroom's habitat consists of areas dominated by pine (Pinus spp.), spruce (Picea spp.), hemlock (Tsuga spp.) and fir (Abies spp.) trees, although other hosts include chestnut, chinquapin, beech, Keteleeria spp., Lithocarpus spp., and oak. In California, porcini have been collected in a variety of forests, such as coastal forests, dry interior oak forests and savannas and interior high-elevation montane mixed forests,<ref name=Hall1998/> to an altitude of Template:Convert.<ref name=Hall2003>Template:Cite book</ref> In northwestern Spain, they are common in scrublands dominated by the rock rose species Cistus ladanifer and Halimium lasianthum.<ref>Oria-de-Rueda J, Martin-Pinto P, Olaizola J (2008). "Bolete productivity of cistaceous scrublands in northwestern Spain". Economic Botany. 62 (3): 323–30. doi:10.1007/s12231-008-9031-x. S2CID 20095996.</ref> In the Midi region of south-west France, they are especially favoured and locally called cèpe de Bordeaux after the town from which they are traded to the north and abroad.<ref>Template:Cite book</ref>

Boletus edulis has a cosmopolitan distribution, concentrated in cool-temperate to subtropical regions.<ref name=Hall1998/> It is common in Europe—from northern Scandinavia, south to the extremities of Greece and Italy—and North America, where its southern range extends as far south as Mexico.<ref name=Wang1995>Wang Y, Sinclair L, Hall IR, Cole AL (1995). "Boletus edulis sensu lato: a new record for New Zealand" (PDF). New Zealand Journal of Crop and Horticultural Science. 23 (2): 227–31. doi:10.1080/01140671.1995.9513892. Retrieved 2009-12-06.</ref> It is well known from the Borgotaro area of Parma, Italy, and has PGI status there. The European distribution extends north to Scandinavia and south to southern Italy and Morocco.<ref name=Hall1998>Hall IR, Lyon AJ, Wang Y, Sinclair L (1998). "Ectomycorrhizal fungi with edible fruiting bodies 2. Boletus edulis". Economic Botany. 52 (1): 44–56. doi:10.1007/BF02861294. S2CID 20934023.</ref> In North America, it can be found from May to October inland<ref>"Seasonal Chart for Edible Mushrooms". Central Oregon Mushroom Club. Archived from the original on 2024-03-31. Retrieved 2024-03-31.</ref> and August to January on the West Coast.<ref name="audu">Template:Cite book</ref> In China, the mushroom can be found from the northeastern Heilongjiang to the Yunnan–Guizhou Plateau and Tibet.<ref name=Wang1995/> It has been recorded growing under Pinus and Tsuga in Sagarmatha National Park in Nepal,<ref>Giri A, Rana P (2007). "Some Higher Fungi from Sagarmatha National Park (SNP) and its adjoining areas, Nepal". Scientific World. 5 (5): 67–74. doi:10.3126/sw.v5i5.2659.</ref> as well as in the Indian forests of Arunachal Pradesh.<ref>Adhikary RK, Baruah P, Kalita P, Bordoloi D (1999). "Edible mushrooms growing in forests of Arunachal Pradesh". Advances in Horticulture and Forestry. 6: 119–23.</ref> In West Asia, the species has been reported from the northwest forests of Iran.<ref>Asef MR. (2008). "Macrofungi of Arasbaran 2. Boletes (families Boletaceae and Suillaceae)" (PDF). Rostaniha (in العربية). 9 (2): 210–29.</ref>

Cultivation

Some steps have been made towards cultivating Boletus edulis,<ref name="Wang2014">Wang, Yun; Chen, Ying Long (2014), Solaiman, Zakaria M.; Abbott, Lynette K.; Varma, Ajit (eds.), "Recent Advances in Cultivation of Edible Mycorrhizal Mushrooms", Mycorrhizal Fungi: Use in Sustainable Agriculture and Land Restoration, vol. 41, Berlin, Heidelberg: Springer Berlin Heidelberg, p. 384, doi:10.1007/978-3-662-45370-4_23, ISBN 978-3-662-45369-8, retrieved 2022-10-03</ref> including mycorrhization of rockrose shrubs enhanced by helper bacteria.<ref name="Mediavilla2015">Mediavilla, Olaya; Olaizola, Jaime; Santos-del-Blanco, Luis; Oria-de-Rueda, Juan Andrés; Martín-Pinto, Pablo (2015-07-26). "Mycorrhization between Cistus ladanifer L. and Boletus edulis Bull is enhanced by the mycorrhiza helper bacteria Pseudomonas fluorescens Migula" (PDF). Mycorrhiza. 26 (2): 161–168. doi:10.1007/s00572-015-0657-0. ISSN 0940-6360. PMID 26208816. S2CID 8967720.</ref>

Non-native introductions

Boletus edulis grows in some areas where it is not believed to be indigenous. It is often found underneath oak and silver birch in Hagley Park in central Christchurch, New Zealand, where it is likely to have been introduced,<ref>Orlovich D, Stringer A, Yun W, Hall I, Prime G, Danell E, Weden C, Bulman S (2004). "Boletus edulis Bull. Ex Fries in New Zealand". Australasian Mycological Society Newsletter. 1 (1): 6.</ref> probably on the roots of container-grown beech, birch, and oak in the mid-19th century—around the time exotic trees began to be planted in the Christchurch area.<ref name=Wang1995/> Similarly, it has been collected in Adelaide Hills region of Australia in association with three species of introduced trees.<ref name="Catcheside 2011">Catcheside PS, Catcheside DE (2011). "Boletus edulis (Boletaceae), a new record for Australia". Journal of the Adelaide Botanic Garden. 25: 5–10. Archived from the original (PDF) on 2014-05-17.</ref> It has been growing plentifully in association with pine forests in the southern KwaZulu-Natal Midlands in South Africa for more than 50 years and is believed to have been introduced with the import of pine trees.<ref>Eicker A. (1990). "Commercial mushroom production in South Africa". Bulletin (418). Pretoria: Department of Agricultural Development.</ref><ref>Marais LJ, Kotzé JM (1977). "Notes on ectotrophic mycorrhizae of Pinus patula in South Africa". South African Forestry Journal. 100: 61–71. doi:10.1080/00382167.1977.9629436.</ref> It also grows in pine plantations in neighboring Zimbabwe.<ref name=Masuka1996/>

Ecology

B. edulis is ectomycorrhizal and may co-occur with Pinus radiata

and Amanita muscaria.

Fruit body production

Italian folklore holds that porcini sprout up at the time of the new moon;<ref name = "Carluccio03"/> research studies have tried to investigate more scientifically the factors that influence the production of fruit bodies. Although fruit bodies may appear any time from summer to autumn (June to November in the UK), their growth is known to be triggered by rainfall during warm periods of weather followed by frequent autumn rain with a drop in soil temperature.<ref name=Hall1998/> Above average rainfall may result in the rapid appearance of large numbers of boletes, in what is known in some circles as a "bolete year".<ref name=Nilper>Template:Cite book</ref> A 2004 field study indicated that fruit body production is enhanced by an open and sunny wood habitat,<ref>Salerni E, Perini C (2004). "Experimental study for increasing productivity of Boletus edulis s.l. in Italy". Forest Ecology and Management. 201 (2–3): 161–70. doi:10.1016/j.foreco.2004.06.027.</ref> corroborating an earlier observation made in a Zimbabwean study;<ref name=Masuka1996>Masuka AJ. (1996). "Dynamics of mushroom (Boletus edulis) production in pine plantations in Zimbabwe". Journal of Applied Science in Southern Africa. 2 (2): 69–76. doi:10.4314/jassa.v2i2.16877.</ref> removal of the litter layer on the forest floor appeared to have a negative effect on fruit body production, but previous studies reported contradictory results.<ref>Baar J, Ter Braak CJ (1996). "Ectomycorrhizal sporocarp occurrence as affected by manipulation of litter and humus layers in Scots pine stands of different age". Applied Soil Ecology. 4 (1): 61–73. doi:10.1016/0929-1393(96)00097-2.</ref><ref>Baar J, de Vries FW (1995). "Effects of manipulation of litter and humus layer on ectomycorrhizal colonization potential in Scots pine stands of different age". Mycorrhiza. 5 (4): 267–72. doi:10.1007/BF00204960. S2CID 32618842.</ref> A Lithuanian study conducted in 2001 concluded that the maximal daily growth rate of the cap (about 21 mm or 0.8 in) occurred when the relative air humidity was the greatest, and the fruit bodies ceased growing when the air humidity dropped below 40%. Factors most likely to inhibit the appearance of fruit bodies included prolonged drought, inadequate air and soil humidity, sudden decreases of night air temperatures, and the appearance of the first frost.<ref>Kasparavicius, J. (2001). "Influence of climatic conditions on the growth of fruit bodies of Boletus edulis". Botanica Lithuanica. 7 (1): 73–78. ISSN 1392-1665.</ref> Plots facing north tend to produce more mushrooms compared to equivalent plots facing south.<ref>Martín-Pinto P, Vaquerizo H, Peñalver F, Olaizola J, Oria-de-Rueda J (2006). "Early effects of a wildfire on the diversity and production of fungal communities in Mediterranean vegetation types dominated by Cistus ladanifer and Pinus pinaster in Spain". Forest Ecology and Management. 225 (1–3): 296–305. doi:10.1016/j.foreco.2006.01.006.</ref>

Mycorrhizal associations

Boletus edulis is mycorrhizal—it is in a mutualistic relationship with the roots of plants (hosts), in which the fungus exchanges nitrogen and other nutrients extracted from the environment for fixed carbon from the host. Other benefits for the plant are evident: in the case of the Chinese chestnut, the formation of mycorrhizae with B. edulis increases the ability of plant seedlings to resist water stress, and increases leaf succulence, leaf area, and water-holding ability.<ref>Quan L, Lei ZP (2000). "A study on effect of ectomycorrhizae on promoting Castanea mollissima resistance to drought and its mechanism". Forest Research (in 中文). 13 (3): 249–56. ISSN 1001-1498.</ref> The fungus forms a sheath of tissue around terminal, nutrient-absorbing root tips, often inducing a high degree of branching in the tips of the host, and penetrating into the root tissue, forming, to some mycologists, the defining feature of ectomycorrhizal relationships, a hartig net.<ref name="ReferenceA">Smith, Sally; Read, David. Mycorrhizal Symbiosis. Academic press, 1996</ref> The ectomycorrhizal fungi are then able to exchange nutrients with the plant, effectively expanding the root system of the host plant to the furthest reaches of the symbiont fungi.<ref name="ReferenceA"/> Compatible hosts may belong to multiple families of vascular plants that are widely distributed throughout the Northern Hemisphere; according to one 1995 estimate, there are at least 30 host plant species distributed over more than 15 genera.<ref name=Wang1995/> Examples of mycorrhizal associates include Chinese red pine,<ref>Fu SC, Tan Q, Chen MJ, Shang XD, Cai LY, Zhang MY (2009). "Mycorrhizal synthesis involving Boletus edulis and Pinus massoniana". Acta Edulis Fungi. 16 (1): 31–41. ISSN 1005-9873.</ref> Mexican weeping pine,<ref>Gross E, Thomazini-Casagrande LI, Caetano FH (1998). "A scanning electron microscopy study of ectomycorrhizae on Pinus patula Schiede and Deppe". Naturalia (Rio Claro). 23 (1): 93–101. ISSN 0101-1944.</ref> Scots pine, Norway spruce,<ref>Ceruti A, Tozzi M, Reitano G (1987–88). "Micorrize di sintesi tra Boletus edulis, Pinus sylvestris e Picea excelsa" [Mycorrhizal synthesis between Boletus edulis, Pinus sylvestris and Picea excelsa]. Allionia (Turin) (in italiano). 28: 117–24. ISSN 0065-6429.</ref> Coast Douglas-fir,<ref>Gobl F. (1977). "Mycorrhiza in Austrian Douglas fir stands". Centralblatt für das Gesamte Forstwesen (in Deutsch). 94 (4): 185–94. ISSN 0379-5292.</ref> mountain pine,<ref>Froidevaux L, Amiet R (1975). "Ecto mycorrhizae endo mycorrhizae of Pinus mugo plus Boletus edulis ssp edulis and Pinus cembra plus Suillus variegatus formed in pure culture". European Journal of Forest Pathology. 5 (1): 57–61. doi:10.1111/j.1439-0329.1975.tb00935.x. ISSN 0300-1237.</ref> and Virginia pine.<ref>Vozzo JA, Hackskaylo E (1961). "Mycorrhizal fungi on Pinus virginiana". Mycologia. 53 (5): 538–39. doi:10.2307/3756310. JSTOR 3756310.</ref> The fungus has also been shown to associate with gum rockrose, a pioneer early stage shrub that is adapted for growth in degraded areas, such as burned forests.<ref name=Agueda2008/> These and other rockrose species are ecologically important as fungal reservoirs, maintaining an inoculum of mycorrhizal fungi for trees that appear later in the forest regrowth cycle.<ref>Águeda B, Parladé J, de Miguel AM, Martínez-Peña F (2006). "Characterization and identification of field ectomycorrhizae of Boletus edulis and Cistus ladanifer". Mycologia. 98 (1): 23–30. doi:10.3852/mycologia.98.1.23. hdl:10171/18758. PMID 16800301.</ref>

The mushroom has been noted to often co-occur with Amanita muscaria or A. rubescens, although it is unclear whether this is due to a biological association between the species, or because of similarities in growing season, habitat, and ecological requirements.<ref name=Hall1998/> An association has also been reported between B. edulis and Amanita excelsa on Pinus radiata ectomycorrhizae in New Zealand, suggesting that other fungi may influence the life cycle of porcini.<ref>Hall IR, Wang Y, Amicucci A (2003). "Cultivation of edible ectomycorrhizal mushrooms". Trends in Biotechnology. 21 (10): 433–38. doi:10.1016/S0167-7799(03)00204-X. PMID 14512229.</ref> A 2007 field study revealed little correlation between the abundance of fruit bodies and presence of its mycelia below ground, even when soil samples were taken from directly beneath the mushroom; the study concluded that the triggers leading to formation of mycorrhizae and production of the fruit bodies were more complex.<ref>Peintner U, Iotti M, Klotz P, Bonuso E, Zambonelli A (2007). "Soil fungal communities in a Castanea sativa (chestnut) forest producing large quantities of Boletus edulis sensu lato (porcini): where is the mycelium of porcini?". Environmental Microbiology. 9 (4): 880–89. doi:10.1111/j.1462-2920.2006.01208.x. PMID 17359260.</ref>

Heavy-metal contamination

Boletus edulis is known to be able to tolerate and even thrive on soil that is contaminated with toxic heavy metals, such as soil that might be found near metal smelters. The mushroom's resistance to heavy-metal toxicity is conferred by a biochemical called a phytochelatin—an oligopeptide whose production is induced after exposure to metal.<ref>Collin-Hansen C, Pedersen SA, Andersen RA, Steinnes E (2007). "First report of phytochelatins in a mushroom: induction of phytochelatins by metal exposure in Boletus edulis". Mycologia. 99 (2): 161–74. doi:10.3852/mycologia.99.2.161. PMID 17682769.</ref> Phytochelatins are chelating agents, capable of forming multiple bonds with the metal; in this state, the metal cannot normally react with other elements or ions and is stored in a detoxified form in the mushroom tissue.Template:Cn

Pests and predators

The fruit bodies of B. edulis can be infected by the parasitic mould-like fungus Hypomyces chrysospermus, known as the bolete eater, which manifests itself as a white, yellow, or reddish-brown cottony layer over the surface of the mushroom.<ref name="urlHypomyces chrysospermus (MushroomExpert.Com)">Kuo M. "Hypomyces chrysospermus". MushroomExpert.Com. Retrieved 2009-11-02.</ref> Some reported cases of stomach ache following consumption of dried porcini have been attributed to the presence of this mould on the fruit bodies.<ref>Lunghini D, Onofri S, Zucconi L (1984). "Some cases of intoxication probably caused by Sepedonium spp. infecting fruiting-bodies of some species of Boletus". Micologia Italiana (in italiano). 13 (1): 1/37–1/38. ISSN 0390-0460.</ref> The mushroom is also used as a food source by several species of mushroom flies,<ref name=Hall1998/> as well as other insects and their larvae.<ref>Template:Cite book</ref> An unidentified species of virus was reported to have infected specimens found in the Netherlands and in Italy; fruit bodies affected by the virus had relatively thick stems and small or no caps, leading to the name "little-cap disease".<ref>Huttinga H, Wichers HJ, Dieleman van Zaayen A (1975). "Filamentous and polyhedral virus-like particle in Boletus edulis". Netherlands Journal of Plant Pathology. 81 (3): 102–106. doi:10.1007/BF01999860. S2CID 35794592.</ref><ref>Pisi A, Bellardi ME, Bernicchia A (1988). "Virus-like particles in Boletus edulis Bull. ex Fr. in Italy" (PDF). Phytopathologia Mediterranea. 27 (2): 115–18. ISSN 0031-9465. Retrieved 2009-11-03.</ref>

Boletus edulis is a food source for animals such as the banana slug (Ariolimax columbianus),<ref>Keller HW, Snell KL (2002). "Feeding activities of slugs on Myxomycetes and macrofungi". Mycologia. 94 (5): 757–60. doi:10.2307/3761690. JSTOR 3761690. PMID 21156549.</ref> the long-haired grass mouse,<ref>Bozinovic F, Muñoz-Pedreros A (1995). "Nutritional ecology and digestive responses of an omnivorous-insectivorous rodent (Abrothrix longipilis) feeding on fungus". Physiological Zoology. 68 (3): 474–89. doi:10.1086/physzool.68.3.30163780. S2CID 87835970.</ref> the red squirrel,<ref>Grönwall O, Pehrson Å (1984). "Nutrient content in fungi as a primary food of the Red Squirrel Sciurus vulgaris L". Oecologia. 64 (2): 230–31. Bibcode:1984Oecol..64..230G. doi:10.1007/BF00376875. PMID 28312343. S2CID 28125328.</ref> and, as noted in one isolated report, the fox sparrow.<ref>Schiller AM, Larson KW (2006). "Fox Sparrow foraging on a king bolete mushroom". Northwestern Naturalist. 87 (3): 252. doi:10.1898/1051-1733(2006)87[252:FSFOAK]2.0.CO;2. ISSN 1051-1733. S2CID 86235892.</ref>

Culinary uses

A porcini mushroom and noodle soup served in a bread bowl at a Polish restaurant

A porcini mushroom sandwich in Stockholm, Sweden

Boletus edulis, as the species epithet edulis (Template:Langx) indicates, is an edible mushroom. Italian chef and restaurateur Antonio Carluccio has described it as representing "the wild mushroom par excellence", and hails it as the most rewarding of all fungi in the kitchen for its taste and versatility.<ref name = "Carluccio03"/> Considered a choice edible, particularly in France, Germany, Poland and Italy,<ref name=Zeitl76/> it was widely written about by the Roman writers Pliny the Elder and Martial, although ranked below the esteemed Amanita caesarea. When he was served suilliTemplate:Efn instead of boleti,<ref>Template:Cite book</ref> the disgruntled Martial wrote: Template:Blockquote

The flavour of porcini has been described as nutty and slightly meaty, with a smooth, creamy texture, and a distinctive aroma reminiscent of sourdough. Young, small porcini are most appreciated, as the large ones often harbour maggots (insect larvae), and become slimy, soft and less tasty with age. The fruit bodies are collected by holding the stipe near the base and twisting gently. Cutting the stipe with a knife may risk the part left behind rotting and the mycelium being destroyed. Peeling and washing are not recommended.<ref name="Carluccio03" /> The fruit bodies are highly perishable, due largely to the high water content (around 90%), the high level of enzyme activity, and the presence of a flora of microorganisms.<ref name=Jaworska2008>Jaworska G, Bernaś E (2008). "The effect of preliminary processing and period of storage on the quality of frozen Boletus edulis (Bull: Fr.) mushrooms". Food Chemistry. 113 (4): 936–43. doi:10.1016/j.foodchem.2008.08.023.</ref> Caution should be exercised when collecting specimens from potentially polluted or contaminated sites, as several studies have shown that the fruit bodies can bioaccumulate toxic heavy metals like mercury,<ref>Melgar MJ, Alonson J, Garcia MA (2009). "Mercury in edible mushrooms and underlying soil: Bioconcentration factors and toxicological risk". Science of the Total Environment. 407 (1): 5328–34. Bibcode:2009ScTEn.407.5328M. doi:10.1016/j.scitotenv.2009.07.001. PMID 19631362.</ref> cadmium,<ref>Collin-Hansen C, Yttri KE, Andersen RA, Berthelsen BO, Steinnes E (2002). "Mushrooms from two metal-contaminated areas in Norway: occurrence of metals and metallothionein-like proteins". Geochemistry: Exploration, Environment, Analysis. 2 (2): 121–30. Bibcode:2002GEEA....2..121C. doi:10.1144/1467-787302-015. S2CID 129662148.</ref> caesium and polonium.<ref>Collin-Hansen C, Andersen RA, Steinnes E (2005). "Molecular defense systems are expressed in the king bolete (Boletus edulis) growing near metal smelters". Mycologia. 97 (5): 973–83. doi:10.3852/mycologia.97.5.973. PMID 16596949.</ref><ref>Collin-Hansen C, Andersen RA, Steinnes E (2005). "Damage to DNA and lipids in Boletus edulis exposed to heavy metals". Mycological Research. 109 (12): 1386–96. doi:10.1017/S0953756205004016. PMID 16353638.</ref> Bioaccumulated metals or radioactive fission decay products are like chemical signatures: chemical and radiochemical analysis can be used to identify the origin of imported specimens,<ref>Marzano FN, Bracchi PG, Pizzetti P (2001). "Radioactive and conventional pollutants accumulated by edible mushrooms (Boletus sp.) are useful indicators of species origin". Environmental Research. 85 (3): 260–64. Bibcode:2001ER.....85..260M. doi:10.1006/enrs.2001.4233. PMID 11237515.</ref> and for long-term radioecological monitoring of polluted areas.<ref>Grodzinskaya AA, Berreck M, Haselwandter K, Wasser SP (2003). "Radiocesium contamination of wild-growing medicinal mushrooms in Ukraine". International Journal of Medicinal Mushrooms. 5 (1): 61–86. doi:10.1615/InterJMedicMush.v5.i1.90. ISSN 1521-9437.</ref>

Porcini are sold fresh in markets in summer and autumn in Europe and Russia, and dried or canned at other times of the year, and distributed worldwide to countries where they are not otherwise found.<ref name=Lamaison05>Template:Cite book</ref> They are eaten and enjoyed raw, sautéed with butter, ground into pasta, in soups, and in many other dishes. In France, they are used in recipes such as cèpes à la Bordelaise, cèpe frits and cèpe aux tomates.<ref>Ramsbottom J. (1947). "Some edible fungi". The British Medical Journal. 2 (4250): 304–305. doi:10.1136/bmj.2.4520.304. PMC 2055419. PMID 20257565.</ref> Porcini risotto is a traditional Italian autumn dish.<ref>Carluccio, p. 166.</ref> Porcini are a feature of many cuisines, including Provençal,<ref>Template:Cite book</ref> and Viennese.<ref>Template:Cite book</ref> In Thailand they are used in soups and consumed blanched in salads.<ref name=Solomon>Template:Cite book</ref> Porcini can also be frozen, either while raw or after cooking in butter. The colour, aroma, and taste of porcini deteriorate noticeably after being frozen for four months. Blanching (or soaking and blanching) as a processing step before freezing can extend the freezer life to 12 months.<ref name=Jaworska2008/> They are also one of the few species sold commercially as pickled mushrooms.<ref>Carluccio, p. 99.</ref>

Dried

A pile of dried porcini at the Borgotaro porcino festival in Italy

Boletus edulis is well suited to drying—its flavour intensifies, it is easily reconstituted, and its resulting texture is pleasant.<ref>Carluccio, p. 96.</ref> Reconstitution is done by soaking in hot, but not boiling, water for about twenty minutes; the water used is infused with the mushroom aroma and it too can be used in subsequent cooking. Dried porcini have more protein than most other commonly consumed vegetables, apart from soybeans. Some of their protein is indigestible, though digestibility is improved with cooking.<ref name=Arora86>Template:Cite book</ref>

Like other boletes, porcini can be dried by being strung separately on twine and hung close to the ceiling of a kitchen. Alternatively, the mushrooms can be dried by cleaning with a brush (washing is not recommended), and then placing them in a wicker basket or bamboo steamer on top of a boiler or hot water tank.<ref name=Carluccio97>Carluccio, p. 97.</ref> Another method is drying in an oven at Template:Convert for two to three hours, then increasing the temperature to Template:Convert until crisp or brittle.<ref>Template:Cite book</ref> Once dry, they must be kept in an airtight container.<ref name=Carluccio97/> Importantly for commercial production, porcini retain their flavour after industrial preparation in a pressure cooker or after canning or bottling, and are thus useful for manufacturers of soups or stews. The addition of a few pieces of dried porcino can significantly add to flavour, and they are a major ingredient of the pasta sauce known as carrettiera (carter's sauce).<ref>Template:Cite book</ref> The drying process is known to induce the formation of various volatile substances that contribute to the mushroom's aroma. Chemical analysis has shown that the odour of the dried mushroom is a complex mixture of 53 volatile compounds.<ref name="pmid19845295">Misharina TA, Muhutdinova SM, Zharikova GG, Terenina MB, Krikunova NI (2009). "The composition of volatile components of cepe (Boletus edulis) and oyster mushrooms (Pleurotus ostreatus)". Applied Biochemistry and Microbiology. 45 (2): 187–93. doi:10.1134/S0003683809020124. PMID 19382709. S2CID 21525680.</ref>

Commercial harvest

Porcini can vary considerably in size.

A 1998 estimate suggested that the total annual worldwide consumption of Boletus edulis and closely related species (B. aereus, B. pinophilus, and B. reticulatus) was between 20,000 and 100,000 tons.<ref name=Hall1998/> Approximately 2,700 tonnes (3,000 tons) were sold in France, Italy and Germany in 1988, according to official figures. The true amount consumed far exceeds this, as the official sales figures did not account for informal sales or consumption by collectors.<ref name=Hall2003/> They are widely exported and sold in dried form, reaching countries where they do not occur naturally, such as Australia and New Zealand. The autonomous community of Castile and León in Spain produces 7,700 tonnes (8,500 tons) annually.<ref name=Agueda2008>Agueda B, Parlade J, Fernandez-Toiran LM, Cisneros O, de Miguel AM, Modrego MP, Martinez-Pena F, Pera J (2008). "Mycorrhizal synthesis between Boletus edulis species complex and rockroses (Cistus sp.)". Mycorrhiza. 18 (8): 443–49. doi:10.1007/s00572-008-0192-3. PMID 18695982. S2CID 11233267.</ref> In autumn, the price of porcini in the Northern Hemisphere typically ranges between $20 and $80 per kilogram, although in New York in 1997 the wholesale price rose to more than $200 per kilogram due to scarcity.<ref name=Hall2003/>

In the vicinity of Borgotaro in the Province of Parma of northern Italy, the four species Boletus edulis, B. aereus, B. aestivalis and B. pinophilus have been recognised for their superior taste and officially termed Fungo di Borgotaro. Here these mushrooms have been collected for centuries and exported commercially. Owing to the globalisation of the mushroom trade most of the porcini commercially available in Italy or exported by Italy no longer originate there. Porcini and other mushrooms are also imported into Italy from various locations, especially China and eastern European countries; these are then often re-exported under the "Italian porcini" label.<ref>Sitta N, Floriani M (2008). "Nationalization and globalization trends in the wild mushroom commerce of Italy with emphasis on porcini (Boletus edulis and allied species)". Economic Botany. 62 (3): 307–22. doi:10.1007/s12231-008-9037-4. S2CID 44274570.</ref><ref name=Boa2004>Template:Cite book</ref>

In Italy the disconnect with local production has had an adverse effect on quality; for example in the 1990s some of the dried porcino mushrooms exported to Italy from China contained species of genus Tylopilus, which are rather similar in appearance and when dried are difficult for both mushroom labourers and mycologists alike to distinguish from Boletus. Tylopilus species typically have a very bitter taste, which is imparted to the flavour of the porcini with which they are mixed.<ref>Sitta N. (2000). "Presence of Tylopilus into dried "Porcini" mushrooms from China". Micologia Italiana (in italiano). 29 (1): 96–99. ISSN 0390-0460.</ref>

After the fall of the Iron Curtain and the subsequent reduction of economic and political barriers, central and eastern European countries with local mushroom harvesting traditions, such as Albania, Bulgaria, Macedonia, Romania, Serbia and Slovenia, developed into exporters of porcini, concentrating primarily on the Italian market.<ref name=Boa2004/> Porcini and other wild fungi from these countries are also destined for France, Germany and other western European markets, where demand for them exists but collection on a commercial scale does not.<ref name=Boa2004/> Picking B. edulis has become an annual seasonal income earner and pastime in countries like Bulgaria, especially for many Roma communities and the unemployed.<ref name=belogradchik>Focus Information Agency, Bulgaria. "По 1 тон гъби на ден се предават в изкупвателните пунктове в Белоградчик" [One ton of mushrooms a day are being submitted to purchasing stations in Belogradchik]. Belogradchik.info (in български). Archived from the original on 2011-07-21. Retrieved 2009-11-02.</ref> A lack of control of the harvest has led to heavy exploitation of the mushroom resource.<ref name=worldwildlife>Drumeva M, Gyosheva M. "The Macromycetes Fungi of Bulgaria". World Wildlife Fund. Retrieved 2009-11-27.</ref>

Like many other strictly mycorrhizal fungi, B. edulis has eluded cultivation attempts for years.<ref name=Arora86/><ref>Template:Cite book</ref><ref name="Wang2014" /> The results of some studies suggest that unknown components of the soil microflora might be required for B. edulis to establish a mycorrhizal relationship with the host plant.<ref>Veselkov IM. (1975). "Artificial propagation of Boletus edulis in forests". Растительньіе Ресурсы России. 11: 574–78.</ref><ref>Ceruti A, Tozzi M, Reitano G (1988). "Micorize di sintesi tra Boletus edulis, Pinus sylvestris e Picea excelsa". Allionia (Turin) (in italiano). 28: 117–24.</ref><ref>Template:Cite book</ref> Successful attempts at cultivating B. edulis have been made by Spanish scientists by mycorrhization of Cistus species,<ref name="Wang2014" /> with Pseudomonas fluorescens bacteria helping the mycorrhiza.<ref name="Mediavilla2015" />

Nutrition

Boletus edulis mushrooms are 9% carbohydrates, 3% fat, and 7% protein (table). Fresh mushrooms consist of over 80% moisture,<ref name=Ouzouni2006>Ouzouni PK, Riganakos KA (2006). "Nutritional value and metal content profile of Greek wild edible fungi". Acta Alimentaria. 36 (1): 99–110. doi:10.1556/AAlim.36.2007.1.11.</ref> although reported values tend to differ somewhat as moisture content can be affected by environmental temperature and relative humidity during growth and storage.<ref>Template:Cite book</ref> The carbohydrate component contains the monosaccharides glucose, mannitol and α,α-trehalose, the polysaccharide glycogen, and the water-insoluble structural polysaccharide chitin, which accounts for up to 80–90% of dry matter in mushroom cell walls. Chitin, hemicellulose, and pectin-like carbohydrates—all indigestible by humans—contribute to the high proportion of insoluble fibre in B. edulis.<ref name=Kalac2009>Kalač P. (2009). "Chemical composition and nutritional value of European species of wild growing mushrooms: a review". Food Chemistry. 113 (1): 9–16. doi:10.1016/j.foodchem.2008.07.077.</ref>

The total lipid, or crude fat, content makes up 3% of the dry matter of the mushroom. The proportion of fatty acids (expressed as a % of total fatty acids) are: linoleic acid 42%, oleic acid 36%, palmitic acid 10%, and stearic acid 3%.<ref>Pedneault K, Angers P, Gosselin A, Tweddell RJ (2006). "Fatty acid composition of lipids from mushrooms belonging to the family Boletaceae". Mycological Research. 110 (Pt 10): 1179–83. doi:10.1016/j.mycres.2006.05.006. PMID 16959482.</ref>

A comparative study of the amino acid composition of eleven Portuguese wild edible mushroom species showed Boletus edulis to have the highest total amino acid content.<ref name=Ribeiro2008b>Ribeiro B, Andrade PB, Silva BM, Baptista P, Seabra RM, Valento P (2008). "Comparative study on free amino acid composition of wild edible mushroom species". Journal of Agricultural and Food Chemistry. 56 (22): 10973–79. doi:10.1021/jf802076p. PMID 18942845.</ref><ref>Tsai SY, Tsai HL, Mau JL (2008). "Non-volatile taste components of Agaricus blazei, Agrocybe cylindracea and Boletus edulis". Food Chemistry. 107 (3): 977–83. doi:10.1016/j.foodchem.2007.07.080.</ref>

B. edulis mushrooms are rich in the dietary minerals, sodium, iron, calcium, and magnesium, with amounts varying according to the mushroom component and to soil composition in the geographic region of China where they were sampled.<ref name=Kalac2009/><ref name="Su">Su, Jiuyan; Zhang, Ji; Li, Jieqing; Li, Tao; Liu, Honggao; Wang, Yuanzhong (6 April 2018). "Determination of mineral contents of wild Boletus edulis mushroom and its edible safety assessment". Journal of Environmental Science and Health, Part B. 53 (7): 454–463. doi:10.1080/03601234.2018.1455361. ISSN 0360-1234. PMID 29624491. S2CID 4665228.</ref> They also have high content of B vitamins and tocopherols.<ref name="Jaworska">Jaworska, Grażyna; Pogoń, Krystyna; Skrzypczak, Aleksandra; Bernaś, Emilia (12 July 2015). "Composition and antioxidant properties of wild mushrooms Boletus edulis and Xerocomus badius prepared for consumption". Journal of Food Science and Technology. 52 (12): 7944–7953. doi:10.1007/s13197-015-1933-x. ISSN 0022-1155. PMC 4648917. PMID 26604366.</ref> B. edulis contains appreciable amounts of selenium, a trace mineral,<ref>Falandysz J. (2008). "Selenium in edible mushrooms". Journal of Environmental Science and Health, Part C. 26 (3): 256–99. doi:10.1080/10590500802350086. PMID 18781538. S2CID 205722725.</ref> although the bioavailability of mushroom-derived selenium is low.<ref>Mutanen M. (1986). "Bioavailability of selenium in mushrooms". International Journal for Vitamin and Nutrition Research. 56 (3): 297–301. PMID 3781756.</ref>

Phytochemicals and research

Phytochelatins give B. edulis resistance to toxic heavy metals like cadmium.

Boletus edulis fruit bodies contain diverse phytochemicals, including 500 mg of ergosterol per 100 g of dried mushroom,<ref name=Mattilla2002>Mattila P, Lampi AM, Ronkainen R, Toivo J, Piironen V (2002). "Sterol and vitamin D₂ contents in some wild and cultivated mushrooms". Food Chemistry. 76 (3): 293–98. doi:10.1016/S0308-8146(01)00275-8.</ref> and ergothioneine.<ref>Ey J, Schömig E, Taubert D (2007). "Dietary sources and antioxidant effects of ergothioneine". Journal of Agricultural and Food Chemistry. 55 (16): 6466–74. doi:10.1021/jf071328f. PMID 17616140.</ref> The fruit bodies contain numerous polyphenols, especially a high content of rosmarinic acid,<ref name="Vamanu">Vamanu, Emanuel; Nita, Sultana (2013). "Antioxidant capacity and the correlation with major phenolic compounds, anthocyanin, and tocopherol content in various extracts from the wild edible Boletus edulis mushroom". BioMed Research International. 2013: 1–11. doi:10.1155/2013/313905. ISSN 2314-6133. PMC 3591155. PMID 23509707.</ref> and organic acids (such as oxalic, citric, malic, succinic and fumaric acids),<ref>Shu-Yao T, Hui-Li T, Jeng-Leun Mau LW (2007). "Antioxidant properties of Agaricus blazei, Agrocybe cylindracea, and Boletus edulis". Food Science and Technology. 40 (8): 1392–1402. doi:10.1016/j.lwt.2006.10.001.</ref> and alkaloids.<ref>Ribeiroa B; Lopesa R; Andradea PB; Seabraa RM; Gonçalvesa, Baptistab P; Quelhasa I; Valentão P. (2008). "Comparative study of phytochemicals and antioxidant potential of wild edible mushroom caps and stipes" (PDF). Food Chemistry. 110 (1): 47–56. doi:10.1016/j.foodchem.2008.01.054. hdl:10198/4404. PMID 26050164.</ref>

Aroma

Aroma compounds giving B. edulis mushrooms their characteristic fragrance include some 100 components, such as esters and fatty acids.<ref name="csoka">Csóka, Mariann; Geosel, Andras; Amtmann, Maria; Korany, Kornel (2017). "Volatile Composition of Some Cultivated and Wild Culinary-Medicinal Mushrooms from Hungary". International Journal of Medicinal Mushrooms. 19 (5): 433–443. doi:10.1615/intjmedmushrooms.v19.i5.50. ISSN 1521-9437. PMID 28845772.</ref> In a study of aroma compounds, 1-octen-3-one was the most prevalent chemical detected in raw mushrooms, with pyrazines having increased aroma effect and elevated content after drying.<ref name="Zhang">Zhang, Huiying; Pu, Dandan; Sun, Baoguo; Ren, Fazheng; Zhang, Yuyu; Chen, Haitao (2018). "Characterization and comparison of key aroma compounds in raw and dry porcini mushroom ( Boletus edulis ) by aroma extract dilution analysis, quantitation and aroma recombination experiments". Food Chemistry. 258: 260–268. doi:10.1016/j.foodchem.2018.03.056. ISSN 0308-8146. PMID 29655732. S2CID 4890378.</ref>

In human culture

In 2023, with the signing of bill H.B. 92, Boletus edulis became the state mushroom of Utah.<ref>"H.B. 92 State Mushroom Designation". Utah.gov. Utah State Legislature. Retrieved 2 April 2025.</ref>

See also

• List of Boletus species
• List of North American boletes

References

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Citations

Cited texts

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