Cyperus esculentus (also called chufa, tiger nut, atadwe, yellow nutsedge, and earth almond) is a crop of the sedge family widespread across much of the world. It is found in most of the Eastern Hemisphere, including Southern Europe, Africa and Madagascar, as well as the Middle East and the Indian subcontinent. C. esculentus is cultivated for its edible tubers, called earth almonds or tiger nuts, as a snack food and for the preparation of horchata de chufa, a sweet, milk-like beverage.
Cyperus esculentus can be found wild, as a weed, or as a crop. It is an invasive species outside its native range, and is readily transported accidentally to become invasive. In many countries, C. esculentus is considered a weed. It is often found in wet soils such as rice paddies and peanut farms as well as well-irrigated lawns and golf courses during warm weather.
C. esculentus was one of the oldest cultivated plants in prehistoric and Ancient Egypt, where it was an important food. Roots of wild chufa have been found at Wadi Kubbaniya, north of Aswan, dating to around 16,000 BC. Dry tubers also appear later in tombs of the Predynastic period, around 3000 BC. During that time, C. esculentus tubers were consumed either boiled in beer, roasted, or as sweets made of ground tubers with honey. The tubers were also used medicinally, taken orally, as an ointment, or as an enema, and used in fumigants to sweeten the smell of homes or clothing. Chufa continued to be an important source of food in the Dynastic period, and cultivation of the plant remained exclusively in Egypt. The tomb of the vizier Rekhmire from the 15th century BCE, shows peasants preparing and measuring tiger nuts. The modern name for tiger nuts in Egypt is حب العزيز (Hab el Aziz = grains of Al-Aziz) named after the Fatimid ruler who was reputedly fond of it.
Cyperus esculentus is an annual or perennial plant, growing to 90 cm (3 ft) tall, with solitary stems growing from a tuber. The plant is reproduced by seeds, creeping rhizomes, and tubers. Due to its clonal nature, C. esculentus can take advantage of soil disturbances caused by anthropogenic or natural forces. The stems are triangular in section and bear slender leaves 3–10 millimetres (1⁄8–3⁄8 in) wide. The spikelets of the plant are distinctive, with a cluster of flat, oval seeds surrounded by four hanging, leaf-like bracts positioned 90 degrees from each other. They are 5 to 30 millimetres (1⁄4 to 1+1⁄8 in) long and linear to narrowly elliptic with pointed tips and 8 to 35 florets. The color varies from straw-colored to gold-brown. They can produce up to 2420 seeds per plant. The plant foliage is very tough and fibrous and is often mistaken for a grass. The roots are an extensive and complex system of fine, fibrous roots and scaly rhizomes with small, hard, spherical tubers and basal bulbs attached.
The tubers are 0.3–1.9 cm (1⁄8–3⁄4 in) in diameter and the colors vary between yellow, brown, and black. One plant can produce several hundred to several thousand tubers during a single growing season. With cool temperatures, the foliage, roots, rhizomes, and basal bulbs die, but the tubers survive and resprout the following spring when soil temperatures remain above 6 °C (43 °F). They can resprout up to several years later. When the tubers germinate, many rhizomes are initiated and end in a basal bulb near the soil surface. These basal bulbs initiate the stems and leaves above ground, and fibrous roots underground. C. esculentus is wind pollinated and requires cross pollination as it is self–incompatible.
C. esculentus is a highly invasive species in Oceania, Mexico, some regions of the United States, and the Caribbean, mainly by seed dispersion. It is readily transported internationally, and is adaptable to re-establish in varied climate and soil environments. In Japan, it is an exotic clonal weed favorable to establish in wet habitats.
Cyperus esculentus cultivation requires a mild climate. Low temperature, shade, and light intensity can inhibit flowering. Tuber initiation is inhibited by high levels of nitrogen, long photoperiods, and high levels of gibberellic acid. Flower initiation occurs under photoperiods of 12 to 14 hours per day.
Tubers can develop in soil depths around 30 cm (1-foot), but most occur in the top or upper part. They tolerate many adverse soil conditions including periods of drought and flooding and survive soil temperatures around −5 °C (23 °F). They grow best on sandy, moist soils at a pH between 5.0 – 7.5. The densest populations of C. esculentus are often found in low-lying wetlands. They do not tolerate salinity.
C. esculentus is cultivated in Nigeria, United States, Guatemala, Mexico, Chile, Brazil, Lebanon, Syria, Jordan, Saudi Arabia, Oman, Iran, Iraq, Pakistan, India, Yemen, Morocco, Ivory Coast, Sudan, South Sudan, Gambia, Guinea Bissau, Ghana, Niger, Burkina Faso, Togo, Benin, Cameroon, and Mali, where they are used primarily as animal feed or as a side dish, but in Hispanic countries they are used mainly to make horchata, a sweet, milk-like beverage.
Chufa is normally planted on previously tilled flat soils with ridges to facilitate irrigation. Seeds are planted manually on these ridges, which are approximately 60 cm (2.0 ft) apart. Distances between seeds may vary from 15 to 20 cm (6 to 8 in) and seeding depth is around 8 cm (3 in). A typical seeding rate for chufa is about 120 kg of tubers/ha (107 lbs/acre).
They are planted between April and May and must be irrigated every week until they are harvested in November and December. Tubers develop about 6 – 8 weeks after seedling emergence and grow quickly during July and August. The maturing is around 90 – 110 days. The average yield can approach between 10 and 19 t/ha.
Harvest and drying process
Harvest usually occurs in November or December and the leaves are scorched during the harvest. With a combine harvester, the tiger nut is pulled out of the ground. Immediately after harvesting, the tiger nuts are washed with water in order to remove sand and small stones. The drying occurs usually in the sun and can take up to three months. The temperatures and humidity levels have to be monitored very carefully during this period. The tiger nuts have to be turned every day to ensure uniform drying. The drying process ensures a longer shelf life. This prevents rot or other bacterial infections, securing quality and high nutrition levels. Disadvantages in the drying process are shrinkage, skin wrinkles and hard nut texture.
Tiger nut loses a considerable amount of water during drying and storage. The starch content of the tiger nut tubers decreases and the reducing sugar (invert sugar) content increases during storage. Tiger nut can be stored dry and rehydrated by soaking without losing the crisp texture. Soaking is often done overnight. Dried tiger nuts have a hard texture and soaking is indispensable to render them edible with ease and to ensure acceptable sensory quality.
According to the Consejo Regulador de Chufa de Valencia (Regulating Council for Valencia's Tiger Nuts), the nutritional composition/100 ml of the Spanish beverage horchata de chufas is as follows: energy content around 66 kcal, proteins around 0.5 g, carbohydrates over 10 g with starch at least 1.9 g, fats at least 2 g.
Dried tiger nut has a smooth, tender, sweet, and nutty taste. It can be consumed raw, roasted, dried, baked or as tiger nut milk or oil.
In Spain, the drink now known as horchata de chufa (also sometimes called horchata de chufas or, in West African countries such as Nigeria and Mali, kunnu aya) is the original form of horchata.[dubious ] It is made from soaked, ground and sweetened tiger nuts mixed with sugar and water. According to researchers at the University of Ilorin, kunnu made from tiger nuts is an inexpensive source of protein. It remains popular in Spain, where a regulating council exists to ensure the quality and traceability of the product in relation to the designation of origin. There it is served ice-cold as a natural refreshment in the summer, often served with fartons. Horchata de chufa is also used instead of dairy milk by the lactose-intolerant. The majority of the Spanish tiger nut crop is utilised in the production of horchata de chufa. Alboraya is the most important production centre.
The tubers are edible raw or cooked. They have a slightly sweet, nutty flavour, compared to the more bitter-tasting tuber of the related Cyperus rotundus (purple nutsedge). They are quite hard and are generally soaked in water before they can be eaten, making them much softer and giving them a better texture. They are a popular snack in West Africa. The tubers can also be dried and ground into flour.
In Northern Nigeria, it is called aya and it is usually eaten fresh. It is sometimes dried and later rehydrated and eaten. Also a snack is made by toasting the nuts and sugar coating it is popular among the Hausa children of Northern Nigeria. Also, a drink known as kunun aya is made by processing the nuts with dates and later sieved and served chilled.
In Egypt, tiger nuts are known by the name Hab el-Aziz and after softening it by soaking in water, it is sold on hand carts as a street food. Its popularity was depicted in movies, such as the song named after it: Hab el Aziz.
Flour of roasted tiger nut is sometimes added to biscuits and other bakery products as well as in making oil, soap, and starch extracts. It is also used for the production of nougat, jam, beer, and as a flavoring agent in ice cream and in the preparation of kunnu (a local beverage in Nigeria). Kunnu is a nonalcoholic beverage prepared mainly from cereals (such as millet or sorghum) by heating and mixing with spices (dandelion, alligator pepper, ginger, licorice) and sugar. To make up for the poor nutritional value of kunnu prepared from cereals, tiger nut was found to be a good substitute for cereal grains. Tiger nut oil can be used naturally with salads or for deep frying. It is considered to be a high quality oil. Tiger nut “milk” has been tried as an alternative source of milk in fermented products, such as yogurt production, and other fermented products common in some African countries and can thus be useful replacing milk in the diet of people intolerant to lactose to a certain extent.
Since the tubers of C. esculentus contain 20-36% oil, it has been suggested as potential oil crop for the production of biodiesel. One study found that chufa produced 1.5 metric tonnes of oil per hectare (174 gallons/acre) based on a tuber yield of 5.67 t/ha and an oil content of 26.4%. A similar 6-year study found tuber yields ranging from 4.02 to 6.75 t/ha, with an average oil content of 26.5% and an average oil yield of 1.47 t/ha. The oil of the tuber was found to contain 18% saturated (palmitic acid and stearic acid) and 82% unsaturated (oleic acid and linoleic acid) fatty acids.
The boiled nuts are used in the UK as a bait for carp. The nuts have to be prepared in a prescribed manner to prevent harm to the fish. The nuts are soaked in water for 24 hours, and then boiled for 20 minutes or longer until fully expanded. Some anglers then leave the boiled nuts to ferment for 24–48 hours, which can enhance their effectiveness. If the nuts are not properly prepared, they can be toxic to carp. This was originally thought to have been the cause of death of Benson, a large, well-known female carp weighing 54 lb (24 kg) found floating dead in a fishing lake, with a bag of unprepared tiger nuts lying nearby, empty, on the bank. An examination of the fish by a taxidermist concluded tiger nut poisoning was not the cause of death, but rather the fish had died naturally.
Compatibility with other crops
C. esculentus is extremely difficult to remove completely once established. This is due to the plant having a stratified and layered root system, with tubers and roots being interconnected to a depth of 36 cm or more. The tubers are connected by fragile roots that are prone to snapping when pulled, making the root system difficult to remove intact. Intermediate rhizomes can potentially reach a length of 60 cm. The plant can quickly regenerate if a single tuber is left in place. By competing for light, water and nutrients it can reduce the vigour of neighbouring plants. It can develop into a dense colony. Patch boundaries can increase by more than one meter per year. Tubers and seed disperse with agricultural activities, soil movement or by water and wind. They are often known as a contaminant in crop seeds. When plants are small they are hard to distinguish from other weeds such as Dactylis glomerata and Elytrigia repens. Thus it is hard to discover in an early stage and therefore hard to counteract. Once it is detected, mechanical removal, hand removal, grazing, damping, and herbicides can be used to inhibit C. esculentus.
Similar native or non-native species that can confuse identification
- Sedges (Cyperus) have grass-like leaves and resemble each other in the appearance. They can mainly be distinguished from grasses by their triangular stems.
- Purple nutsedge (C. rotundus) is another weedy sedge that is similar to the yellow nutsedge (C. esculentus). These two sedges are difficult to distinguish from each other and can be found growing on the same site. Some differences are the purple spikelets and the tubers formed by C. rotundus are often multiple instead of just one at the tip. In addition the tubers have a bitter taste instead of the mild almond-like flavour of C. esculentus.
- "Cyperus esculentus L. — The Plant List". www.theplantlist.org.
- "Chufa Information". Seed World. Retrieved 2020-04-29.
- Chen, Angus (April 27, 2016). "Loathed By Farmers, Loved By Ancients: The Strange History of Tiger Nuts". NPR. Retrieved January 5, 2021.
- "Is Atadwe (Tiger Nuts) Good for You? Health Benefits of Tiger Nuts". GhanaStar. 2015-11-15. Retrieved 2020-04-29.
- "Yellow nutsedge". University of Maryland Extension. Retrieved January 5, 2021.
- "Chufa (Earth Almond)". Chest of Books. Retrieved January 5, 2021.
- Sánchez‐Zapata, Elena; Fernández‐López, Juana; Pérez‐Alvarez, José Angel (2012-07-01). "Tiger Nut (Cyperus esculentus) Commercialization: Health Aspects, Composition, Properties, and Food Applications". Comprehensive Reviews in Food Science and Food Safety. 11 (4): 366–377. doi:10.1111/j.1541-4337.2012.00190.x. ISSN 1541-4337.
- "World Checklist of Selected Plant Families: Royal Botanic Gardens, Kew". Kew Science. Retrieved January 5, 2021.
- "Biota of North America Program, 2013 county distribution map".
- Altervista Flora Italiana, Zigolo dolce, Yellow Nutsedge, Cyperus esculentus L. includes photographs plus distribution maps for Europe and North America
- "Cyperus esculentus (yellow nutsedge)". CABI. 19 November 2018. Retrieved 31 October 2019.
- Sánchez-Zapata, E; Fernández-López, J; Angel Pérez-Alvarez, J (2012). "Tiger Nut (Cyperus esculentus) Commercialization: Health Aspects, Composition, Properties, and Food Applications". Comprehensive Reviews in Food Science and Food Safety. 11 (4): 366–77. doi:10.1111/j.1541-4337.2012.00190.x.
- Macho, Gabriele A. (2014-01-08). "Baboon Feeding Ecology Informs the Dietary Niche of Paranthropus boisei". PLOS ONE. 9 (1): e84942. Bibcode:2014PLoSO...984942M. doi:10.1371/journal.pone.0084942. ISSN 1932-6203. PMC 3885648. PMID 24416315.
- Sanderson, Helen (2005). Prance, Ghillean; Nesbitt, Mark (eds.). The Cultural History of Plants. Routledge. p. 74. ISBN 0415927463.
- Moshe, N (1992). "A Sweetmeat Plant, a Perfume Plant and their Weedy Relatives: A Chapter in the History of C. Esculentus L. and C. Rotundus L.". Economic Botany. 46: 64–71. doi:10.1007/bf02985255. S2CID 37815353.
- Defelice, MS (2002). "Yellow Nutsedge: Cyperus esculentus L. — Snack Food of the Gods1". Weed Technology. 16 (4): 901–7. doi:10.1614/0890-037x(2002)016[0901:yncels]2.0.co;2.
- Daniel Zohary and Maria Hopf, Domestication of plants in the Old World, third edition (Oxford: University Press, 2000), p. 198
- "Loathed By Farmers, Loved By Ancients: The Strange History Of Tiger Nuts". NPR.
- "Hab' el Aziz".
- Stoller, E.W. (1981). Yellow Nut Sedge: A Menace in the Corn Belt (No. 1642). US Department of Agriculture, Agricultural Research Service.
- Renne, Ian J.; Tracy, Benjamin F. (2006-08-30). "Disturbance persistence in managed grasslands: shifts in aboveground community structure and the weed seed bank". Plant Ecology. 190 (1): 71–80. doi:10.1007/s11258-006-9191-7. ISSN 1385-0237. S2CID 45148808.
- Oldfield, Callie A.; Evans, Jonathan P. (2016-03-01). "Twelve years of repeated wild hog activity promotes population maintenance of an invasive clonal plant in a coastal dune ecosystem". Ecology and Evolution. 6 (8): 2569–2578. doi:10.1002/ece3.2045. ISSN 2045-7758. PMC 4834338. PMID 27110354.
- ^ USGS Weeds in the West project: Status of introduced Plants in Southern Arizona Parks, Factsheets for Cyperus esculentus L., 2003, Tucson, Arizona
- Stoller, E. W.; Wax, L. M. (1973-01-01). "Yellow Nutsedge Shoot Emergence and Tuber Longevity". Weed Science. 21 (1): 76–81. doi:10.1017/S004317450003174X. JSTOR 4042258.
- Ross, Merrill A.; Lembi, Carole A. (2008). Applied Weed Science (3 ed.). Prentice Hall. p. 322. ISBN 978-0135028148.
- N. Pascual-Seva, et al., Furrow-irrigated chufa crops in Valencia (Spain) Spanish Journal of Agricultural Research 2013 11(1), 258-267. http://revistas.inia.es/index.php/sjar/article/view/3385/1803
- Pascual-Seva, N., San Bautista, A., López Galarza, S., Maroto, J.V. and Pascual, B. 2012. Yield and Irrigation Water Use Efficiency for Ridge - and Bed - cultivated Chufa (Cyperus Esculentus L. var. Sativus Boeck). Acta Hort. (ISHS) 936:125-132
- Reid WS, Hergert GB, Fagan WE, 1972. Development of a Prototype mechanical Harvester for Chufa (Cyperus esculentus L. var sativus Boek). Canadian Agricultural Engineering 14.
- Tigernuts Traders, S.L., Tigernuts Oil, 2012, http://www.tigernut.com
- Coşkuner, Yalçın; Ercan, Recai; Karababa, Erşan; Nazlıcan, Ahmet Nedim (2002). "Physical and chemical properties of chufa (Cyperus esculentus L) tubers grown in the Çukurova region of Turkey". Journal of the Science of Food and Agriculture. 82 (6): 625–631. doi:10.1002/jsfa.1091.
- "Consejo Regulador de Chufa de Valencia". Chufadevalencia.org. 2002-12-31. Retrieved 2012-06-05.
- Roselló-Soto, Elena; Poojary, Mahesha M.; Barba, Francisco J.; Koubaa, Mohamed; Lorenzo, Jose M.; Mañes, Jordi; Moltó, Juan Carlos (2018). "Thermal and non-thermal preservation techniques of tiger nuts' beverage "horchata de chufa". Implications for food safety, nutritional and quality properties". Food Research International. 105: 945–951. doi:10.1016/j.foodres.2017.12.014. ISSN 0963-9969. PMID 29433293.
- Angier, Bradford (1974). Field Guide to Edible Wild Plants. Harrisburg, PA: Stackpole Books. p. 58. ISBN 0-8117-0616-8. OCLC 799792.
- Elias, Thomas S.; Dykeman, Peter A. (2009) . Edible Wild Plants: A North American Field Guide to Over 200 Natural Foods. New York: Sterling. p. 130. ISBN 978-1-4027-6715-9. OCLC 244766414.
- Zhang, He Yuan; Hanna, Milford A; Ali, Yusuf; Nan, Lu (1996). "Yellow nut-sedge tuber oil as a fuel". Industrial Crops and Products. 5 (3): 177–181. doi:10.1016/0926-6690(96)89446-5.
- Makareviciene, Violeta; Gumbyte, Milda; Yunik, Anatolii; Kalenska, Svitlana; Kalenskii, Viktor; Rachmetov, Dzhamal; Sendzikiene, Egle (2013). "Opportunities for the use of chufa sedge in biodiesel production". Industrial Crops and Products. 50: 633–637. doi:10.1016/j.indcrop.2013.08.036. ISSN 0926-6690.
- Bilali et al., "Exploring Serbian consumers’ attitude toward ethical values of organic, fair-trade and typical/traditional products" The Fifth International Scientific Conference, Rural Development 2011, Proceedings, Volume 5, Book 1, p. 337.
- Bailey, John (5 August 2009). "The extraordinary life and suspicious death of Benson the giant carp". The Guardian. Retrieved 21 March 2019.
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