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Longan

From Wikipedia, the free encyclopedia
This article is about the fruit and tree. For other uses, seeLong'an (disambiguation).For places in China, seeLongnanandLongyan.
Not to be confused withLoganberry.

Longan
Photograph of a broadly spreading tree
A branch bearing many light brown fruits
Longan fruit
Scientific classificationEdit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Sapindales
Family: Sapindaceae
Genus: Dimocarpus
Species:
D. longan
Binomial name
Dimocarpus longan
Synonyms[2]
  • Dimocarpus undulatusWight
  • Euphoria cinerea(Turcz.) Radlk.
  • Dimocarpus leichhardtiiS.T. Reynolds
  • Euphoria glabraBlume
  • Euphoria gracilisRadlk.
  • Euphoria leichhardtiiBenth.
  • Euphoria longan(Lour.) Steud.
  • Euphoria longanaLam.
  • Euphoria malaiensis(Griff.) Radlk.
  • Euphoria microcarpaRadlk.
  • Euphoria nephelioidesRadlk.
  • Euphoria verruculosaSalisb.
  • Nephelium longan(Lour.) Hook.
  • Nephelium longanaCambess.
Longan
"Longan" in Traditional (top) and Simplified (bottom) Chinese characters
Traditional ChineseLong nhãn
Simplified ChineseLong nhãn
Literal meaning'dragon eye'

Dimocarpus longan,commonly known as thelongan(/ˈlɒŋɑːnˈ/) anddragon's eye,is a tropical tree species that produces edible fruit.[3]It is one of the better-known tropical members of the soapberry familySapindaceae,to which thelycheeandrambutanalso belong.[3]The fruit of the longan is similar to that of the lychee, but less aromatic in taste.[4]It is native to tropical Asia and China.[5]

The longan (fromVietnameselong nhãn,[6]close toCantoneselùhng ngáahnLong nhãn,literally 'dragon eye'), is so named because it resembles an eyeball when its fruit is shelled (the black seed shows through the translucent flesh like apupilandiris). The seed is small, round and hard, and of an enamel-like, lacquered black. The fully ripened, freshly harvested fruit has a bark-like shell, thin, and firm, making the fruit easy to peel by squeezing the pulp out as if one were "cracking" a sunflower seed. When the shell has more moisture content and is more tender, the fruit becomes less convenient to shell. The tenderness of the shell varies due to either premature harvest, variety, weather conditions or storage conditions.

Subspecies[edit]

Plants of the World Online[7]lists:

  • D. longanvar.echinatusLeenhouts (Borneo, Philippines)
  • D. longanvar.longetiolatusLeenhouts (Viet Nam)
  • D. longansubsp.malesianusLeenh. (widespread SE Asia)
  • D. longanvar.obtusus(Pierre) Leenh. (Indo-China)

Tree description[edit]

Longan fruit with flesh, seed, and peel visible.

Depending upon climate and soil type the tree may grow to over 100 feet (30 m)[8]in height, but it typically stands 30–40 ft (9–12 m) in height and thecrownis round.[3][9]The trunk is 2.5 ft (0.8 m) thick[3]with corkybark.[9]The branches are long and thick, typically drooping.[3]

Theleavesare oblong and blunt-tipped, usually 4–8 inches (10–20 cm) long and 2 in (5 cm) wide.[3]The leaves arepinnatelycompounded and alternate.[9]There are 6 to 9 pairs of leaflets per leaf[9]and the upper surface is wavy and a dark, glossy-green.[3]

The longan tree produces light-yellowinflorescencesat the end of branches.[3]The inflorescence is commonly called apanicle;they can be 4–18 in (10–46 cm) long, and widely branched.[9]The smallflowershave 5 to 6sepalsandpetalsthat are brownish-yellow.[9]The flower has a two-lobedpistiland 8stamen.There are three flower types, distributed throughout the panicle;[3]staminate (functionally male), pistillate (functionally female), andhermaphroditicflowers.[9]Flowering occurs as a progression.[9]

The fruit are circular and about 1 in (2.5 cm) wide; they hang in drooping clusters. The peel is tan, thin, and leathery with tiny hairs.[9]The flesh is translucent, and theseedis large and black with a circular white spot at the base.[3][9]This gives the illusion of an eye.[3]The flesh has a musky, sweet taste, which can be compared to the flavor of lychee fruit.[3]

The longan tree is somewhat sensitive tofrost.Longan trees prefer sandy soil. While the species prefers temperatures that do not typically fall below 4.5 °C (40 °F), it can withstand brief temperature drops to about −2 °C (28 °F).[10]Longan trees prefer sandy soil with mild levels of acidity andorganic matter.[3]Longans usually bear fruit slightly later than lychees.[11]

Longan being peeled and eaten.

The wild longan population have been decimated considerably by large-scale logging in the past, and the species used to be listed asVulnerableon theIUCN Red List.If left alone, longan tree stumps will resprout and the listing was upgraded toNear Threatenedin 1998. Recent field data are inadequate for a contemporary IUCN assessment.[1]

History[edit]

The longan is believed to originate from the mountain range betweenMyanmarand southern China. Other reported origins include Indonesia, India,Sri Lanka,upper Myanmar,north Thailand,Kampuchea(more commonly known as Cambodia), northVietnamandNew Guinea.[12]

Its earliest record of existence draws back to theHan dynastyin 200 BC. The emperor had demanded lychee and longan trees to be planted in his palace gardens inShaanxi,but the plants failed. Four hundred years later, longan trees flourished in other parts of China likeFujianandGuangdong,where longan production soon became an industry.[13]

Later on, due to immigration and the growing demand for nostalgic foods, the longan tree was officially introduced to Australia in the mid-1800s, Thailand in the late-1800s, and Hawaii and Florida in the 1900s. The warm, sandy-soiled conditions allowed for the easy growth of longan trees. This jump-started the longan industry in these locations.[13]

Despite its long success in China, the longan is considered to be a relatively new fruit to the world. It has only been acknowledged outside of China in the last 250 years.[13]The first European acknowledgment of the fruit was recorded byJoao de Loureiro,a Portuguese Jesuit botanist, in 1790. The first entry resides in his collection of works,Flora Cochinchinensis.[6][4]

Currently, longan crops are grown in southern China,Taiwan,northern Thailand, Malaysia, Indonesia, Cambodia, Laos, Vietnam, India, Sri Lanka,Philippines,Australia, the United States, andMauritius.[12]It is also grown inBangladesh.[14]

Uses[edit]

Culinary[edit]

The fruit is sweet, juicy, and succulent in superior agricultural varieties. The seed and the peel are not consumed. Apart from being eaten raw like other fruits, longan fruit is also often used in Asian soups, snacks, desserts, andsweet-and-sourfoods, either fresh or dried, and sometimes preserved and canned in syrup. The taste is different from lychees; while longan has a drier sweetness similar to dates, lychees are often messily juicy with a more tropical, grape-like sour sweetness.

Dried longan are often used inChinese cuisineand Chinese sweet dessert soups. InChinese food therapyandherbal medicine,it is believed to have an effect on relaxation.[15]In contrast with the fresh fruit, which is juicy and white, the flesh of dried longans is dark brown to almost black.

Once fermented, it can be made intolongan wine.

Nutrition[edit]

Longans, raw
A peeled longan fruit
Nutritional value per 100 g (3.5 oz)
Energy251 kJ (60 kcal)
15.14 g
Sugarsn/a
Dietary fiber1.1 g
0.1 g
1.31 g
Threonine0.034 g
Isoleucine0.026 g
Leucine0.054 g
Lysine0.046 g
Methionine0.013 g
Phenylalanine0.030 g
Tyrosine0.025 g
Valine0.058 g
Arginine0.035 g
Histidine0.012 g
Alanine0.157 g
Aspartic acid0.126 g
Glutamic acid0.209 g
Glycine0.042 g
Proline0.042 g
Serine0.048 g
VitaminsQuantity
%DV†
Thiamine (B1)
3%
0.031 mg
Riboflavin (B2)
11%
0.14 mg
Niacin (B3)
2%
0.3 mg
Vitamin C
93%
84 mg
MineralsQuantity
%DV†
Calcium
0%
1 mg
Iron
1%
0.13 mg
Magnesium
2%
10 mg
Manganese
2%
0.052 mg
Phosphorus
2%
21 mg
Potassium
9%
266 mg
Sodium
0%
0 mg
Zinc
0%
0.05 mg
Other constituentsQuantity
Water83 g
Link to USDA Database entry
†Percentages estimated usingUS recommendationsfor adults,[16]except for potassium, which is estimated based on expert recommendation fromthe National Academies.[17]

Raw longan fruit is 83% water, 15%carbohydrates,1%protein,and contains negligible fat. In a 100 gram reference amount, raw longan supplies 60caloriesof food energy, 101% of theDaily Value(DV) ofvitamin C,12% DV ofriboflavin,and no othermicronutrientsin appreciable quantities.

Cultivation[edit]

Growth[edit]

Longan, like its sister fruit lychee, thrives in humid areas or places with high rainfall, and can grow on most types of soil that does not induce issues with water drainage.[18]Ample temperatures are also instrumental in longan growth: while longan can resist small stretches of cool temperatures, they can be damaged or killed in longer stretches of temperatures as high as −2 degrees Celsius. Younger plants tend to be more vulnerable to the cold than those more mature.[18][19]

Harvest[edit]

During harvest, pickers must climb ladders to carefully remove branches of fruit from longan trees. Longan fruit remain fresher if still attached to the branch, so efforts are made to prevent the fruit from detaching too early. Mechanical picking would damage the delicate skin of the fruit, so the preferred method is to harvest by hand. Knives and scissors are the most commonly used tools.[20]

Fruit is picked early in the day to minimize water loss and to prevent high heat exposure, which would be damaging. The fruit is then placed into either plastic crates or bamboo baskets and taken to packaging houses, where the fruit undergo a series of checks for quality. The packaging houses are well-ventilated and shaded to prevent further decay. The process of checking and sorting are performed by workers instead of machinery. Any fruit that is split, under-ripe, or decaying is disposed of. The remaining healthy fruit is then prepared and shipped to markets.[21]

Many companies add preservatives to canned longan. Regulations control the preserving process. The only known preservative added to canned longan issulfur dioxide,to prevent discoloration.[21]Fresh longan that is shipped worldwide is exposed to sulfurfumigation.Tests have shown that sulfur residues remain on the fruit skin, branches, and leaves for a few weeks. This violates many countries' limits on fumigation residue, and efforts have been made to reduce this amount.[21]

Distribution[edit]

Longan is found commonly in most of Asia, primarily in mainland China, Taiwan, Vietnam and Thailand. China, the main longan-producing country in the world, produced about 1.9 million metric tons (2.1 million short tons) of longan in 2015–2017, accounting for 70% of the world's longan production and more than 50% of the world's longan plots.[22]Vietnam and Thailand produced around 500 and 980 thousand metric tons (550 and 1,080 thousand short tons), respectively.[23]Like Vietnam, Thailand's economy relies heavily on the cultivation and shipments of longan as well as lychee. This increase in the production of longan reflects recent interest in exotic fruits in other parts of the world. However, the majority of the demand comes from Asian communities in North America, Europe and Australia.[21]

Yield[edit]

While longan yields average out to 2 to 5 tonnes per hectare, there have been observed yields of up to 19.5 tonnes per ha in Israel.[24]

Advancements in selective breeding have allowed scientists to find a strain of longan containing a "high proportion of aborted seeds" at the end of a thirty-year breeding program in 2001.[25]Studies in 2015 that aimed to aid longan breeding efforts discovered that −20 degrees Celsius is the optimal temperature for long-term storage of longan pollen, a key ingredient in enabling longan breeding programs.[26]

Diseases[edit]

Plant based diseases can affect both longan fruits and their trees, and the severity of these diseases can range from harmless cosmetic damage to rendering to the fruit inedible.

The most prevalent disease among longan plants is theWitch's broom,which can be found in all major longan-producing Asian territories, including China, Thailand, and Vietnam.[27]Witch's Broomworks by deforming longan skin, and at times by causing the plant to prematurely drop its fruit, similar to thePhytophthora palmivora.[28]

Another common disease that longan trees can carry is the aptly namedLongan Decline,which is largely prevalent in Thailand, with reports finding that it could affect up to 40% of longan trees alone.[29]Affected trees are more vulnerable to common tree pests and algae, and often bear low-quality fruit unworthy of yield.[29]

Algal spotis another plant disease that can affect longan plants and trees. Common among tropical fruits, the disease mainly takes form as red-orange algae that can appear on a fruit-bearing tree's leaves or branches.[30]Algal spoton longan plants, like many other tropical fruits, is caused byCephaleuros virescens.[31]

An oomycete disease that causesblighton leaves and foliage of a plant and affects the related lychee,Phytophthora palmivora,can also appear on both longan plants and fruit,[32]particularly in the Thailand region. When affecting longan, it can create brown spots on the fruit in an erratic fashion, and can also cause longan to drop prematurely from the plant. Early symptoms can also include a darknecrosison the plant itself.[33]

Stem-end rot is a disease common amongst litchi and longan, and causes browning and rot on the stem of the fruit. Longan also suffer from various decay-accelerating fungi.[29]

An oomycete disease that affects the related lychee,Phytophthoralitchii,also afflictsD. longan.[32]

Gallery[edit]

  • Longan (Dimocarpus longan) tree leaves
    Longan (Dimocarpus longan) tree leaves
  • Longan tree lower trunk
    Longan tree lower trunk
  • The longan was described in Joao de Loureiro's work, Flora Cochinchinensis, published in 1790
    The longan was described in Joao de Loureiro's work,Flora Cochinchinensis,published in 1790
  • Longan (Dimocarpus longan) baby fruits and leaves
    Longan (Dimocarpus longan) baby fruits and leaves

See also[edit]

References[edit]

  1. ^abBarstow, M. (2022)."Dimocarpus longan".IUCN Red List of Threatened Species.2022:e.T32399A67808402.Retrieved29 January2023.
  2. ^ab"Dimocarpus longan".World Checklist of Selected Plant Families.Royal Botanic Gardens, Kew.Retrieved5 September2016– viaThe Plant List.Note that this website has been superseded byWorld Flora Online
  3. ^abcdefghijklmMorton, Julia F. (1987).Longan; In: Fruits of Warm Climates.W. Lafayette, IN, USA: NewCrop, Center for New Crops and Plant Products, Department of Horticulture and Landscape Architecture, Purdue University. pp. 259–262.
  4. ^abPham, V.T.; Herrero, M. (2016)."Fruiting pattern in longan, Dimocarpus longan: from pollination to aril development"(PDF).Annals of Applied Biology.169(3): 357–368.doi:10.1111/aab.12306.hdl:10261/135703.
  5. ^"Dimocarpus longan".Germplasm Resources Information Network.Agricultural Research Service,United States Department of Agriculture.Retrieved11 December2017.
  6. ^abLoureiro, J. de (1790).Flora Cochinchinensis(in Latin). Vol. I. Lisbon: Ulyssipone.
  7. ^"Dimocarpus longan Lour. | Plants of the World Online | Kew Science".Plants of the World Online.
  8. ^Crane, Jonathan H.; Balerdi, Carlos F.; Sargent, Steven A.; Maguire, Ian (November 1978)."Longan Growing in the Florida Home Landscape".University of Florida(2016 ed.).Retrieved4 April2017.
  9. ^abcdefghijCrane, Jonathan; Balerdi, Carlos; Sarge, Steven; Maguire, Ian (2015)."Longan Growing in the Florida Home Landscape".IFAS University of Florida.Retrieved5 April2017.
  10. ^Herbst, S. & R. (2009).The Deluxe Food Lover's Companion.Barron's Educational Series – via Credo Reference.
  11. ^Jiang, Yueming; Zhang, Zhaoqi (November 2002). "Postharvest biology and handling of longan fruit (Dimocarpus longan Lour.)".Postharvest Biology and Technology.26(3): 241–252.doi:10.1016/s0925-5214(02)00047-9.
  12. ^abLim, T.K. (2013). "Dimocarpus longan subsp. longan var. longan".Edible Medicinal And Non-Medicinal Plants: Volume 6, Fruits.Springer Science & Business Media. pp. 18–29.ISBN978-94-007-5628-1.
  13. ^abcMenzel, C.; Waite, G.K.; Mitra, S.K. (2005).Litchi and Longan: Botany, Production and Uses.CAB International.ISBN9781845930226– via ProQuest ebrary.
  14. ^Khatun, MM; Karim, MR; Molla, MM; Khatun, MM; Rahman, MJ (2012)."Study on the physico-chemical characteristics of longan (Euphoria longana) germplasm".Bangladesh Journal of Agricultural Research.37(3): 441–447.doi:10.3329/bjar.v37i3.12087.ISSN0258-7122.
  15. ^Teeguarden, Ron."Tonic Herbs That Every Qigong Practioner [sic] Should Know, Part 2 ".Qi Journal.
  16. ^United States Food and Drug Administration(2024)."Daily Value on the Nutrition and Supplement Facts Labels".FDA.Archivedfrom the original on 27 March 2024.Retrieved28 March2024.
  17. ^National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Food and Nutrition Board; Committee to Review the Dietary Reference Intakes for Sodium and Potassium (2019). Oria, Maria; Harrison, Meghan; Stallings, Virginia A. (eds.).Dietary Reference Intakes for Sodium and Potassium.The National Academies Collection: Reports funded by National Institutes of Health. Washington, DC: National Academies Press (US).ISBN978-0-309-48834-1.PMID30844154.Archivedfrom the original on 9 May 2024.Retrieved21 June2024.
  18. ^abPaull, R. E.; Duarte, O., eds. (2011).Tropical fruits, Volume 1.doi:10.1079/9781845936723.0000.ISBN9781845936723.
  19. ^Blancke, Rolf (17 March 2017).Tropical Fruits and Other Edible Plants of the World.doi:10.7591/9781501704284.ISBN9781501704284.
  20. ^Siddiq, Muhammad (2012).Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging.John Wiley & Sons – via Google Books.
  21. ^abcdMenzel, C.; Waite, G.K.; Mitra, S.K. (2005).Litchi and Longan: Botany, Production and Uses.CAB International.ISBN9781845930226– via ProQuest ebrary.
  22. ^Luo, Jun, Can-fang Zhou, and Zhong Wan. "Analysis on the development status of lychee industry in Guangdong province in 2010." Guangdong Agric Sci 4 (2011): 16-8.
  23. ^Altendorf, Sabine (July 2018)."MINOR TROPICAL FRUITS Mainstreaming a niche market"(PDF).FAO.Retrieved9 September2020.
  24. ^Lora, Jorge; Pham, Van The; Hormaza, José I. (2018), Al-Khayri, Jameel M.; Jain, Shri Mohan; Johnson, Dennis V. (eds.),"Genetics and Breeding of Fruit Crops in the Sapindaceae Family: Lychee (Litchi chinensis Sonn.) and Longan (Dimocarpus longan Lour.)",Advances in Plant Breeding Strategies: Fruits,Cham: Springer International Publishing, pp. 953–973,doi:10.1007/978-3-319-91944-7_23,ISBN978-3-319-91943-0,retrieved5 October2022
  25. ^Huang, J.S.; Xu, X.D.; Zheng, S.Q.; Xu, J.H. (August 2001)."Selection for Aborted-Seeded Longan Cultivars".Acta Horticulturae(558): 115–118.doi:10.17660/actahortic.2001.558.14.ISSN0567-7572.
  26. ^Pham, V.T.; Herrero, M.; Hormaza, J.I. (December 2015)."Effect of temperature on pollen germination and pollen tube growth in longan ( Dimocarpus longan Lour.)".Scientia Horticulturae.197:470–475.doi:10.1016/j.scienta.2015.10.007.hdl:10261/127752.ISSN0304-4238.
  27. ^Olesen, T.; Menzel, C. M.; Wiltshire, N.; McConchie, C. A. (2002)."Flowering and shoot elongation of lychee in eastern Australia".Australian Journal of Agricultural Research.53(8): 977.doi:10.1071/ar01179.ISSN0004-9409.
  28. ^So, Vera; Zee, S.-Y. (September 1972)."A New Virus of Longan (Euphoria longanaLam.) in Hong Kong ".PANS Pest Articles & News Summaries.18(3): 283–285.doi:10.1080/09670877209411804.ISSN0030-7793.
  29. ^abcMenzel, C. M.; Waite, G. K., eds. (2005).Litchi and longan: botany, production and uses.doi:10.1079/9780851996967.0000.ISBN9780851996967.
  30. ^Visarathanonth, N. (December 1990)."A Survey of Some Temperate Fruit Diseases in Thailand".Acta Horticulturae(279): 609–618.doi:10.17660/actahortic.1990.279.67.ISSN0567-7572.
  31. ^Bache, Bryon (December 1994)."Compendium of Tropical Fruit Diseases, by R. C. Ploetz G. A. Zentmyer, W. T. Nishijima, K. G. Rohrbach & H. D. Ohr. viii + 88 pp. St Paul, Minnesota: American Phytopathological Society (1994). £30.00 (US) $37.00 (elsewhere) (paper back) ISBN 0 582 89054 162 0".The Journal of Agricultural Science.123(3): 419–420.doi:10.1017/s0021859600070520.ISSN0021-8596.
  32. ^abWang, Yan; Tyler, Brett M.; Wang, Yuanchao (8 September 2019). "Defense and Counterdefense During Plant-Pathogenic Oomycete Infection".Annual Review of Microbiology.73(1).Annual Reviews:667–696.doi:10.1146/annurev-micro-020518-120022.ISSN0066-4227.PMID31226025.S2CID195259901.
  33. ^Sittigul, C.; Pota, S.; Visitpanich, J.; Nualbunruang, P.; Sookchaoy, K. (January 2005)."The Brown Spot Disease of Longan in Thailand".Acta Horticulturae(665): 389–394.doi:10.17660/actahortic.2005.665.48.ISSN0567-7572.

External links[edit]

Wikimedia Commons has media related toDimocarpus longan.
Wikispecieshas information related toDimocarpus longan.

Longan Production in Asia

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