Dimocarpus longan, commonly known as the longan (UK: //; US: //), is a tropical tree that produces edible fruit. It is one of the better-known tropical members of the soapberry family (Sapindaceae), to which the lychee also belongs. It is native to Southern Asia.
The longan (simplified Chinese: 龙眼; traditional Chinese: 龍眼; pinyin: lóngyǎn; 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 a pupil/iris). The seed is small, round and hard, and of an enamel-like, lacquered black. The fully ripened, freshly harvested shell is bark-like, thin, and firm, making the fruit easy to shell by squeezing the fruit out as if one is "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 transport/storage conditions. In China, it is also called guì yuán (桂圆), especially when dried.
The Dimocarpus longan tree is a medium-sized evergreen that can grow up to 6 to 7 metres (20 to 23 ft) in height. It is somewhat sensitive to frost. 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). Longans usually bear fruit slightly later than lychees.
The fruit is sweet, juicy and succulent in superior agricultural varieties and, apart from being eaten fresh, is also often used in Asian soups, snacks, desserts, and sweet-and-sour foods, either fresh or dried, sometimes canned with syrup. The taste is different from lychees; while longan have a drier sweetness, lychees are often messily juicy with a more tropical, sour sweetness.
The seed and the shell are not consumed.
Dried longan are often used in Chinese cuisine and Chinese sweet dessert soups. In Chinese food therapy and herbal medicine, it is believed to have an effect on relaxation. In contrast with the fresh fruit, which is juicy and white, the flesh of dried longans is dark brown to almost black. In Chinese medicine, the longan, much like the lychee, is thought to give internal "heat" (上火).
A peeled longan fruit
|Nutritional value per 100 g (3.5 oz)|
|Energy||251 kJ (60 kcal)|
|Dietary fiber||1.1 g|
|Aspartic acid||0.126 g|
|Glutamic acid||0.209 g|
Link to USDA Database entry
Vitamin B6/Folate values were unavailable
|Percentages are roughly approximated using US recommendations for adults.
Source: USDA Nutrient Database
|Wikimedia Commons has media related to Dimocarpus longan.|
Notes and references
- "The Plant List: A Working List of All Plant Species". Retrieved 14 February 2015.
- "USDA GRIN Taxonomy".
- Boning, Charles R. (2006). Florida's Best Fruiting Plants: Native and Exotic Trees, Shrubs, and Vines. Sarasota, Florida: Pineapple Press, Inc. p. 125.
- World Conservation Monitoring Centre (1998). Dimocarpus longan. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 9 May 2006.
- Manochai, P.; Sruamsiri, P.; Wiriya-alongkorn, W.; Naphrom, D.; Hegele, M.; Bangerth, F. (February 12, 2005). "Year around off season flower induction in longan (Dimocarpus longan, Lour.) trees by KClO3 applications: potentials and problems". Scientia Horticulturae. Department of Horticulture, Maejo University, Chiang Mai, Thailand; Department of Horticulture, Chiang Mai University, Chiang Mai, Thailand; Institute of Special Crops and Crop Physiology, University of Hohenheim, 70593 Stuttgart, Germany. 104 (4): 379–390. doi:10.1016/j.scienta.2005.01.004. Retrieved November 28, 2010.
- Yang B, Jiang YM, Shi J, Chen F, Ashraf M (2011). "Extraction and pharmacological properties of bioactive compounds from longan (Dimocarpus longan Lour.) fruit – A review". Food Research International. 44: 1837–1842. doi:10.1016/j.foodres.2010.10.019.