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''Castanea sativa'', the sweet chestnut, Spanish chestnut or just chestnut, is a
species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
of tree in the family
Fagaceae The Fagaceae are a family of flowering plants that includes beeches, chestnuts and oaks, and comprises eight genera with about 927 species. Fagaceae in temperate regions are mostly deciduous, whereas in the tropics, many species occur as evergre ...
, native to Southern Europe and
Asia Minor Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The ...
, and widely cultivated throughout the temperate world. A substantial, long-lived
deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, a ...
tree, it produces an edible seed, the chestnut, which has been used in cooking since ancient times.


Description

''C. sativa'' attains a height of with a trunk often in diameter. Around 20 trees are recorded with diameters over including one in diameter at breast height. A famous ancient tree known as the
Hundred Horse Chestnut The Hundred-Horse Chestnut ( it, Castagno dei Cento Cavalli; scn, Castagnu dî Centu Cavaddi) is the largest and oldest known chestnut tree in the world. Located on Linguaglossa road in Sant'Alfio, on the eastern slope of Mount Etna in Sicily. ...
in Sicily was historically recorded at in diameter (although it has split into multiple trunks above ground). The bark often has a net-shaped (retiform) pattern with deep furrows or fissures running spirally in both directions up the trunk. The trunk is mostly straight with branching starting at low heights. The oblong-lanceolate, boldly toothed
leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
are long and broad. The
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...
s of both sexes are borne in long, upright
catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind- pollinated ( anemophilous) but sometimes insect-pollinated (as in '' Salix''). They contain many, usually unisexual flowers, arra ...
s, the male flowers in the upper part and female flowers in the lower part. In the Northern Hemisphere, they appear in late June to July, and by autumn, the female flowers develop into spiny cupules containing 3–7 brownish
nuts Nut often refers to: * Nut (fruit), fruit composed of a hard shell and a seed, or a collective noun for dry and edible fruits or seeds * Nut (hardware), fastener used with a bolt Nut or Nuts may also refer to: Arts, entertainment, and media Com ...
that are shed during October. The female flowers eventually form a spiky sheath that deters predators from the seed.
Kew Gardens Kew Gardens is a botanical garden, botanic garden in southwest London that houses the "largest and most diverse botany, botanical and mycology, mycological collections in the world". Founded in 1840, from the exotic garden at Kew Park, its li ...
- Rhizotron & Xstrata Treetop Walkway
''Castanea sativa''
/ref> The sweet chestnut is naturally self incompatible, meaning that the plant cannot pollinate itself, making cross-pollination necessary. Some cultivars only produce one large seed per cupule, while others produce up to three seeds. The nut itself is composed of two skins: an external, shiny brown part, and an internal skin adhering to the fruit. Inside, there is an edible, creamy-white part developed from the
cotyledon A cotyledon (; ; ; , gen. (), ) is a significant part of the embryo within the seed of a plant, and is defined as "the embryonic leaf in seed-bearing plants, one or more of which are the first to appear from a germinating seed." The num ...
s. Sweet chestnut trees live to an age of 500 to 600 years. In cultivation they may even grow as old as 1,000 years or more.


Taxonomy

The tree is to be distinguished from the horse chestnut ''
Aesculus hippocastanum ''Aesculus hippocastanum'', the horse chestnut, is a species of flowering plant in the maple, soapberry and lychee family Sapindaceae. It is a large, deciduous, synoecious (hermaphroditic-flowered) tree. It is also called horse-chestnut, Europe ...
'', to which it is only distantly related. The horse chestnut bears similar looking seeds (conkers) in a similar seed case, which are not palatable to humans. Other
common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contra ...
s include "Spanish chestnut", or "marron" (French for "chestnut"). The generic name ''Castanea'' is the old
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
name for the plant species, while the
specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
''sativa'' means "cultivated by humans". Some selected varieties are smaller and more compact in growth yielding earlier in life with different ripening time: the Marigoule, the Marisol and the Maraval.


Distribution and habitat

The species is native to Southern Europe and
Asia Minor Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The ...
. It is found across the
Mediterranean region In biogeography, the Mediterranean Basin (; also known as the Mediterranean Region or sometimes Mediterranea) is the region of lands around the Mediterranean Sea that have mostly a Mediterranean climate, with mild to cool, rainy winters and ...
, from the
Caspian Sea The Caspian Sea is the world's largest inland body of water, often described as the List of lakes by area, world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad s ...
to the
Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth#Surface, Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Afr ...
. It is thought to have survived the last ice age in several refuges in Southern Europe, on the southern coast of the
Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, ...
with a main centre on the southern slope of the
Caucasus The Caucasus () or Caucasia (), is a region between the Black Sea and the Caspian Sea, mainly comprising Armenia, Azerbaijan, Georgia (country), Georgia, and parts of Southern Russia. The Caucasus Mountains, including the Greater Caucasus range ...
and in the region of north-western Syria, possibly extending into
Lebanon Lebanon ( , ar, لُبْنَان, translit=lubnān, ), officially the Republic of Lebanon () or the Lebanese Republic, is a country in Western Asia. It is located between Syria to Lebanon–Syria border, the north and east and Israel to Blue ...
. The species is widely distributed throughout Europe, where in 2004 ''C. sativa'' was grown on of forest, of which were mainly cultivated for wood and for fruit production.
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
,
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan ar ...
, southern Switzerland,
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = '' Plus ultra'' ( Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , ...
,
Portugal Portugal, officially the Portuguese Republic, In recognized minority languages of Portugal: :* mwl, República Pertuesa is a country located on the Iberian Peninsula, in Southwestern Europe, and whose territory also includes the Macaronesian ...
and
Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders wit ...
are countries with a strong sweet chestnut tradition, with trees cultivated intensively in coppices and orchards. Countries like
England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...
,
Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = "Lijepa naša domovino"("Our Beautiful Homeland") , image_map = , map_caption = , capit ...
,
Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...
and
Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to t ...
only have a partially developed sweet chestnut tradition due to geography or history. Nevertheless, centuries-old specimens may be found in Great Britain today. Examples can be seen particularly in the London Boroughs of Islington and Camden. In other European countries, ''C. sativa'' has only been introduced recently, for example in
Slovakia Slovakia (; sk, Slovensko ), officially the Slovak Republic ( sk, Slovenská republika, links=no ), is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the ...
or the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
. The tree requires a mild climate and adequate moisture for good growth and a good nut harvest. Its year-growth (but not the rest of the tree) is sensitive to late spring and early autumn frosts; it is also intolerant of lime. Under forest conditions, it will tolerate moderate shade well. It can live to more than 2,000 years of age in natural conditions, such as the Hundred Horse Chestnut near
Mount Etna Mount Etna, or simply Etna ( it, Etna or ; scn, Muncibbeḍḍu or ; la, Aetna; grc, Αἴτνα and ), is an active stratovolcano on the east coast of Sicily, Italy, in the Metropolitan City of Catania, between the cities of Messina a ...
in eastern Sicily.


Ecology

The leaves provide food for some animals, including Lepidoptera such as the
case-bearer __NOTOC__ The Coleophoridae are a family of small moths, belonging to the huge superfamily Gelechioidea. Collectively known as case-bearers, casebearing moths or case moths, this family is represented on all continents, but the majority are foun ...
moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of ...
'' Coleophora anatipennella'' and North American rose chafer ''
Macrodactylus subspinosus ''Macrodactylus subspinosus'' is a North American beetle of the family Scarabaeidae. The members of this genus are known as "Rose chafers", not to be confused with the European "Rose chafer", '' Cetonia aurata''. ''M. subspinosus'' occurs from ...
''. The two major fungal pathogens of the sweet chestnut are the
chestnut blight The pathogenic fungus ''Cryphonectria parasitica'' (formerly ''Endothia parasitica'') is a member of the Ascomycota (sac fungi). This necrotrophic fungus is native to East Asia and South East Asia and was introduced into Europe and North America ...
(''Cryphonectria parasitica'') and the ink disease caused by '' Phytophthora cambivora'' and ''
Phytophthora cinnamomi ''Phytophthora cinnamomi'' is a soil-borne water mould that produces an infection which causes a condition in plants variously called " root rot", "dieback", or (in certain ''Castanea'' species), "ink disease". The plant pathogen is one of the w ...
''. In North America as well as in Southern Europe C''ryphonectria parasitica'' destroyed most of the chestnut population in the 20th century. With biological control, the population of the sweet chestnut is not threatened anymore by the chestnut blight and is regenerating. Ink disease is infesting trees mostly in humid soils, with the mycelium invading the root and resulting in wilting of the leaf. Absence of fruit formation leads to die back of the
petal Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corolla''. Petals are usuall ...
. The ink disease is named after the black exudates at the base of the trunk. Nowadays there are cultivars that are resistant to the ink disease. ''Phytophthora cambivora'' caused serious damage in Asia and the US, and it still continues to destroy new plantations in Europe. Another serious pest which is difficult to control is the gall wasp ('' Dryocosmus kuriphylus'') which was recently introduced in Southern Europe, originating in Asia.


Cultivation


Cultivation forms

Three different cultivation systems for the sweet chestnut can be distinguished: * ''
Coppicing Coppicing is a traditional method of woodland management which exploits the capacity of many species of trees to put out new shoots from their stump or roots if cut down. In a coppiced wood, which is called a copse, young tree stems are repeated ...
'': Mainly for wood extraction. Standard conditions yield 15 m3 wood per ha and year. * ''
Selve Selve Automobilwerke AG was a car maker located in Hameln (near Hannover, Germany). After World War I, the ''Northern German Automobile Works'' (), which made the Colibri car and the Sperber, was absorbed by the Selve firm, which was already pro ...
'': Fruit production from grafted trees. The trees have a short tribe and a big crown. Trees have a high density and the ground between the trees is often used as pasture. * ''High forest:'' Wood and fruit production. This cultivation form is less intensive with a yield of 4–12 dt/ha and replacement of trees every 50–80 years. The trees grow from seeds and build a dense canopy. The field management is dependent on the cultivation system. While cleaning the soil from the leaves and pruning is the norm, the use of fertilizer, irrigation and pesticides is less common and reserved for more intensive cultivation.


Requirements

The sweet chestnut tree grows well on
limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...
-free, deeply weathered soil. The optimal pH value of the soil is between 4.5 and 6, and the tree cannot tolerate soil compaction. The tolerance to wet ground and to clay-rich soils is very low. It is a heat-loving tree which needs a long vegetation period. The optimal average temperature is between 8 °C and 15 °C and in January the temperature should preferably not be below -1 °C but it may tolerate temperatures as low as -15 °C. Low temperature in autumn can damage the fruit. The maximal altitude is strongly dependent on the climate. In general, the climate should be similar to
viticulture Viticulture (from the Latin word for ''vine'') or winegrowing (wine growing) is the cultivation and harvesting of grapes. It is a branch of the science of horticulture. While the native territory of ''Vitis vinifera'', the common grape vine, ran ...
. Optimal precipitation is between . Before planting, seeds must be stratified at 2-3 °C so germination can start 30–40 days later. After a year, the young trees are being transplanted.


Harvest

A tree grown from seed may take 20 years or more before it bears fruits, but a grafted cultivar such as 'Marron de Lyon' or 'Paragon' may start production within five years of being planted. Both cultivars bear fruits with a single large kernel, rather than the usual two to four smaller kernels. The fruit yield per tree is usually between , but can get as high as 300 kg. Harvest time is between middle of September and middle of November. There are three harvesting techniques: * By hand: The sweet chestnuts are harvested by rake or broom, with a harvest speed of 5 to 30 kg every hour depending on the soil relief. Also, the capsule makes the harvest more complicated and even painful for the worker. * By hand with nets: This technique is less time-consuming and protects the fruits from injuries. However, setting up the nets is work intensive. * Mechanical: The fruits are collected with a machine that works similarly to a vacuum cleaner. Doing so is time-saving and economical, but it's possible that some fruits get injured, and a big initial investment is needed. Furthermore, a visual sorting is not possible. The total world chestnut harvest was 1.17 million tons in 2006, but only 151,000 tons were ''C. sativa.''


Post-harvest treatment

The most widespread treatment before storage is water curing, a process in which the sweet chestnuts are immersed in water for nine days. The aim of this practice is to limit the main storage problems threatening the sweet chestnut: fungi development and the presence of insect worms. As an alternative to water curing, hot water treatment is also commercially used. After water treatment, the sweet chestnuts are stored in a controlled environment with high carbon dioxide concentrations. In contrast to a cold storage system, where the fruits are stored at low temperatures in untreated air, the controlled environment method avoids flesh hardening which negatively impacts the processability of the product.


Cultivars

The ornamental cultivar ''C. sativa'' 'Albomarginata' has gained the
Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr (No ...
's
Award of Garden Merit The Award of Garden Merit (AGM) is a long-established annual award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. History The Award of Garden Merit ...
.


French origin

* Bouche de Betizac *
Maraval Maraval is one of the northern suburbs of Trinidad's capital, Port of Spain, a valley in northern Trinidad in Trinidad and Tobago. It is situated at the bottom of the hills of Paramin and located east of the Diego Martin valley to which it is co ...
*
Marigoule Marigoule is the name of a french hybrid of chestnut (synonym M.15 or CA 15), cross between a European chestnut (Castanea sativa) and Japanese (Castanea crenata). In 1986, it originated from a Migoule orchard in Ussac in Corrèze. Marigoule (a cont ...
* Marsol * Precoce Migoule


American origin

* Colossal * Labor Day


Uses

The species is widely cultivated for its edible seeds (also called nuts) and for its wood. Sweet chestnut has been listed as one of the 38 substances used to prepare
Bach flower remedies Bach flower remedies (BFRs) are solutions of brandy and water—the water containing extreme dilutions of flower material developed by Edward Bach, an English homeopath, in the 1930s. Bach claimed that the dew found on flower petals retains t ...
, a kind of
alternative medicine Alternative medicine is any practice that aims to achieve the healing effects of medicine despite lacking biological plausibility, testability, repeatability, or evidence from clinical trials. Complementary medicine (CM), complementary and ...
promoted for its supposed effect on health. However, according to
Cancer Research UK Cancer Research UK (CRUK) is the world's largest independent cancer research organization. It is registered as a charity in the United Kingdom and Isle of Man, and was formed on 4 February 2002 by the merger of The Cancer Research Campaign and t ...
, "there is no scientific evidence to prove that flower remedies can control, cure or prevent any type of disease, including cancer".


Food

The species' large genetic diversity and different
cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...
s are exploited for uses such as flour, boiling, roasting, drying, and sweets. The raw nuts, though edible, have a skin which is astringent and unpleasant to eat when still moist; after drying for a time the thin skin loses its astringency but is still better removed to reach the white fruit underneath. Cooking dry in an oven or fire normally helps remove this skin. Chestnuts are traditionally roasted in their tough brown husks after removing the spiny cupules in which they grow on the tree, the husks being peeled off and discarded and the hot chestnuts dipped in salt before eating them. Roast chestnuts are traditionally sold in streets, markets and fairs by street vendors with mobile or static
brazier A brazier () is a container used to burn charcoal or other solid fuel for cooking, heating or cultural rituals. It often takes the form of a metal box or bowl with feet. Its elevation helps circulate air, feeding oxygen to the fire. Braziers h ...
s. The skin of raw peeled chestnuts can be relatively easily removed by quickly blanching the nuts after scoring them by a cross slit at the tufted end. Once cooked, chestnuts acquire a sweet flavour and a floury texture similar to the sweet potato. The cooked nuts can be used for stuffing poultry, as a vegetable or in nut roasts. They can also be used in confections, puddings, desserts and cakes. They are used for flour, bread making, a cereal substitute, coffee substitute, a thickener in soups and other cookery uses, as well as for fattening stock. A sugar can be extracted from them. The Corsican variety of
polenta Polenta (, ) is a dish of boiled cornmeal that was historically made from other grains. The dish comes from Italy. It may be served as a hot porridge, or it may be allowed to cool and solidify into a loaf that can be baked, fried, or grilled. ...
(called ''pulenta'') is made with sweet chestnut flour. A local variety of Corsican beer also uses chestnuts. The product is sold as a sweetened paste mixed with vanilla, , sweetened or unsweetened as chestnut purée or ''purée de marron'', and candied chestnuts as ''marrons glacés''. In Switzerland, it is often served as ''Vermicelles''. Roman soldiers were given chestnut porridge before going into battle. Leaf infusions are used in respiratory diseases and are a popular remedy for whooping cough. A hair shampoo can be made from infusing leaves and fruit husks. Caldarroste, geröstete Kastanien, roasted Chestnuts.jpg, Roasted chestnuts Kestaneci chestnut vendor.jpg, Street vendors in
Istanbul Istanbul ( , ; tr, İstanbul ), formerly known as Constantinople ( grc-gre, Κωνσταντινούπολις; la, Constantinopolis), is the List of largest cities and towns in Turkey, largest city in Turkey, serving as the country's economic, ...
Marrons glacés.jpg, Marrons glacés Crema di castagne o confettura di marroni.jpg, Farine de châtaigne corse.jpg, ( AOC)


Constituents

''Castanea sativa'' is considered as having very interesting nutritional characteristics. The fruit contains significant amounts of a wide range of valuable nutrients. In the past, its characteristic and nutritional components gave sweet chestnut an important role in human nutrition due to its beneficial health effects. Sweet chestnut is also appreciated in a
gluten-free diet A gluten-free diet (GFD) is a nutritional plan that strictly excludes gluten, which is a mixture of proteins found in wheat (and all of its species and hybrids, such as spelt, kamut, and triticale), as well as barley, rye, and oats. The inclu ...
. Furthermore, this characteristic is valuable in cases of celiac diseases as well as reducing coronary heart diseases and cancer rates. Various composition and health studies have shown its big potential as a food ingredient and
functional food A functional food is a food claimed to have an additional (often one related to health promotion or disease prevention) by adding new ingredients or more of existing ingredients. The term may also apply to traits purposely bred into existing ed ...
. The fat content is very low and is dominated for the most part by unsaturated fatty acids. Sweet chestnut is a good source for
starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...
; chestnuts of all varieties generally contain about the same amount of starch. The energy value per 100 g (3.5 oz) of ''C. sativa'' amounts to 891 kJ (213 kcal). ''C. sativa'' is characterized by high moisture content which ranges from 41% to 59% and a considerable level of starch (≈40 g 100 g−1 dry matter). Regarding mineral content, the chestnut provides a good source for
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish ...
,
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
,
magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...
,
manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy u ...
and
potassium Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosp ...
. Its sugar content ranges from 14% to 20% dry weight depending on the cultivar; which is very important, since the sensory appeal of sweet chestnut is correlated with its sugar content. However, high sugar amounts seem to have a negative impact on the fiber content. Generally,
glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, usi ...
content in European chestnuts is very low and ranges from zero to traces. Instead,
fructose Fructose, or fruit sugar, is a ketonic simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorb ...
is mostly responsible for the sweet taste.


Effect of processing

Sweet chestnut is suited for human nutrition. Most sweet chestnut is consumed in processed form, which has an impact on the nutrient composition. Its naturally high concentration of
organic acid An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are ...
s is a key factor influencing the organoleptic characteristics of fruits and vegetables, namely flavor. Organic acids are thought to play an important role against diseases as an
antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricants ...
. Heat appears to be the most influencing factor when it comes to decreasing the organic acid content. However, even after heating sweet chestnuts, antioxidant activity remains relatively high. On the other hand, the consumer must consider that roasting, boiling or frying has a big impact on the nutritional profile of chestnut. Vitamin C significantly decreases between 25 and 54% when boiled and 2–77 % when roasted. Nevertheless, roasted or boiled chestnuts may still be a solid vitamin C source, since 100 gram still represent about 20% of the recommended daily dietary intake. The sugar content is also affected by the high temperatures. Four processes are decisive for the degrading process of sugar while cooking:
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...
of starch to oligosaccharide and monosaccharide, decomposition of sucrose to glucose and fructose,
caramelization Caramelization is a process of browning of sugar used extensively in cooking for the resulting sweet nutty flavor and brown color. The brown colors are produced by three groups of polymers: caramelans (C24H36O18), caramelens (C36H50O25), and ...
of sugars and degradation of sugars. Organic acids are also affected by high temperatures: their content decreases about 50% after frying, and 15% after boiling. Responsible for the aromatic characteristics of cooked chestnuts is the effect of degradation of saccharides, proteins and lipids, the caramelization of saccharides and the
maillard reaction The Maillard reaction ( ; ) is a chemical reaction between amino acids and reducing sugars that gives browned food its distinctive flavor. Seared steaks, fried dumplings, cookies and other kinds of biscuits, breads, toasted marshmallows, and m ...
that is reducing sugar and amino acids.


Wood

This tree responds very well to
coppicing Coppicing is a traditional method of woodland management which exploits the capacity of many species of trees to put out new shoots from their stump or roots if cut down. In a coppiced wood, which is called a copse, young tree stems are repeated ...
, which is still practised in Britain, and produces a good crop of
tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner ...
-rich wood every 12 to 30 years, depending on intended use and local growth rate. The tannin renders the young growing wood durable and weather resistant for outdoor use, thus suitable for posts, fencing or stakes. Oleg Polunin. ''Trees and Bushes of Britain and Europe''. Ed Paladin, 1973, pp. 51, 188 and 195). The wood is of light colour, hard and strong. It is used to make furniture, barrels (sometimes used to age
balsamic vinegar Balsamic vinegar ( it, aceto balsamico) is a very dark, concentrated and intensely flavoured vinegar originating in Modena, Italy, made wholly or partially from grape must: freshly crushed grape juice with all the skins, seeds and stems. The ...
), and roof beams notably in southern Europe (for example in houses of the
Alpujarra The Alpujarra (, Arabic: ''al-bussarat'') is a natural and historical region in Andalusia, Spain, on the south slopes of the Sierra Nevada and the adjacent valley. The average elevation is above sea level. It extends over two provinces, G ...
, Spain, in southern France and elsewhere). The timber has a density of 560 kg per cubic meter,Chestnut
. Niche Timbers. Accessed 19-08-2009.
and due to its durability in ground contact is often used for external purposes such as fencing. It is also a good fuel, though not favoured for open fires as it tends to spit. Tannin is found in the following proportions on a 10% moisture basis:
bark Bark may refer to: * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Places * Bark, Germany * Bark, Warmian-Masurian Voivodeship, Poland Arts, ...
(6.8%), wood (13.4%), seed husks (10 - 13%). The leaves also contain tannin.


History

Pollen data indicates that the first spreading of ''C. sativa'' due to human activity started around 2100–2050 B.C. in
Anatolia Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The r ...
, northeastern
Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders wit ...
and southeastern
Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Mac ...
. Compared to other crops, the sweet chestnut was probably of relatively minor importance and distributed very heterogeneously throughout these regions. The first charcoal remains of sweet chestnut only date from around 850–950 B.C., making it very difficult to infer a precise origin history. A newer but more reliable source are the literary works of Ancient Greece, with the richest being
Theophrastus Theophrastus (; grc-gre, Θεόφραστος ; c. 371c. 287 BC), a Greek philosopher and the successor to Aristotle in the Peripatetic school. He was a native of Eresos in Lesbos.Gavin Hardy and Laurence Totelin, ''Ancient Botany'', Routle ...
's ''Historia plantarum'', written in the third century B.C. Theophrastus focuses mainly on the use of sweet chestnut wood as timber and charcoal, only mentioning the use of the fruit once when commenting on the digestive difficulties it causes, but praising its nourishing quality. Several Greek authors wrote about medicinal properties of the sweet chestnut, specifically as a remedy against lacerations of the lips and of the oesophagus. Similar to the introduction of grape vine and olive cultivation to the Latin world, ''C. sativa'' is thought to have been introduced during the colonisation of the Italian peninsula by the Greeks. Further clues pointing to this theory can be found in the work of
Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic ...
, who mentions only Greek colonies in connection with sweet chestnut cultivation. Today's phylogenetic map of the sweet chestnut, while not fully understood, shows greater genetic similarity between Italian and western Anatolian ''C. sativa'' trees compared to eastern Anatolian specimen, reinforcing these findings. Nonetheless, until the end of the pre-Christian era, the spread and use of the chestnut in Italy remained limited. Carbonised sweet chestnuts were found in a Roman villa at
Torre Annunziata Torre Annunziata (; nap, Torr'Annunziata) is a city and commune in the Metropolitan City of Naples, region of Campania in Italy. It is located on the Gulf of Naples at the foot of Mount Vesuvius. History The city was destroyed in the Vesuvius ...
near
Naples Naples (; it, Napoli ; nap, Napule ), from grc, Νεάπολις, Neápolis, lit=new city. is the regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 909,048 within the city's adminis ...
, destroyed by the eruption of Mount Vesuvius in A.D. 79. Clues in art and literature indicate a dislike of the sweet chestnut by the Roman aristocracy. Like Theophrastus, Latin authors are sceptical of the sweet chestnut as a fruit, and Pliny the Elder even goes as far as admiring how well nature has hidden this fruit of apparently so little value. In the beginning of the Christian era, people probably started to realize the value and versatility of sweet chestnut wood, leading to a slow spread of the cultivation of ''C. sativa'' trees, a theory that is supported by pollen data and literary sources, as well as the increased use of sweet chestnut wood as poles and in supporting structures, wood works and pier building between A.D. 100 and 600. Increasing sweet chestnut pollen appearances in Switzerland,
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan ar ...
,
Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...
and the
Iberian peninsula The Iberian Peninsula (), ** * Aragonese and Occitan: ''Peninsula Iberica'' ** ** * french: Péninsule Ibérique * mwl, Península Eibérica * eu, Iberiar penintsula also known as Iberia, is a peninsula in southwestern Europe, defi ...
in the first century A.D. suggests the spreading of cultivated sweet chestnut trees by the Romans. Contrary to that notion, other scientists found no indication of the Romans spreading ''C. sativa'' before the fifth century. While the husks of sweet chestnuts, dated to the third or early fourth century, have been identified from the bottom of a Roman well at Great Holts Farm, in Boreham in
Essex Essex () is a county in the East of England. One of the home counties, it borders Suffolk and Cambridgeshire to the north, the North Sea to the east, Hertfordshire to the west, Kent across the estuary of the River Thames to the south, and G ...
, England; this deposit includes remains of other exotic food plants and provides no evidence that any of them originated locally. No other evidence of sweet chestnut in Roman Britain has been confirmed.Sweet Chestnut (''Castanea sativa'' Mill.) in Britain: Re-assessment of its Status as a Roman Archaeophyte. R. Jarman, Z. Hazell, G. Campbell, J. Webb and F. M. Chambers. Britannia 50 (2019), 49-74 doi:10.1017/S0068113X19000011 Indeed, no centre of sweet chestnut cultivation outside the Italian peninsula in Roman times has been detected. Widespread use of chestnut in western Europe started in the early Middle Ages and flourished in the late Middle Ages. In the mid-seventh-century Lombard laws, a composition of one solidi is set for felling a chestnut tree (or, also, hazel, pear or apple) belonging to another person (''
Edictum Rothari The ''Edictum Rothari'' (lit. ''Edict of Rothari''; also ''Edictus Rothari'' or ''Edictum Rotharis'') was the first written compilation of Lombard law, codified and promulgated on 22 November 643 by King Rothari in Pavia by a gairethinx, an assem ...
'', No. 301, 643 AD). Since the beginning of the 20th century, due to depopulation of the countryside and the abandonment of the sweet chestnut as a staple food as well as the spread of chestnut blight and ink disease, ''C. sativa'' cultivation has dramatically decreased. Nowadays, sweet chestnut production is sometimes seen at a turning point again, because the development of high-value sweet chestnut products combined with changing needs of an urban society is leading to a revival in ''C. sativa'' cultivation.


See also

* American chestnut * Chinese chestnut * Japanese chestnut


References

* Rushforth, K. (1999). ''Trees of Britain and Europe''. HarperCollins .
Fao.org
''Castanea sativa''


External links

* *
U.C. Davis, California: ''Castanea sativa'' in horticulture

Plants for a Future database: ''Castanea sativa''

''Castanea sativa''
- distribution map, genetic conservation units and related resources.
European Forest Genetic Resources Programme European Forest Genetic Resources Programme (EUFORGEN) is an international network that supports the conservation and sustainable use of forest genetic resources in Europe. The programme’s tasks include to coordinate and promote ''in situ'' and ...
(EUFORGEN) {{Authority control
sativa Sativa, sativus, and sativum are Latin botanical adjectives meaning '' cultivated''. It is often associated botanically with plants that promote good health and used to designate certain seed-grown domestic crops. Usage ''Sativa'' (ending in -a) ...
Edible nuts and seeds Flora of Western Asia Flora of Europe Flora of Greece Flora of Italy Medicinal plants of Asia Medicinal plants of Europe Trees of Mediterranean climate Garden plants of Asia Garden plants of Europe Ornamental trees Flora of Montenegro Fruit trees Taxa named by Philip Miller