| Chinese water chestnut | |
|---|---|
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| Illustrationc. 1880[1] | |
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| Corms of chinese water chestnut | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Clade: | Commelinids |
| Order: | Poales |
| Family: | Cyperaceae |
| Genus: | Eleocharis |
| Species: | E. dulcis |
| Binomial name | |
| Eleocharis dulcis | |
| Synonyms | |
| |
| Eleocharis dulcis | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Traditional Chinese | 荸薺 | ||||||||||
| Simplified Chinese | 荸荠 | ||||||||||
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| Cantonese name | |||||||||||
| Traditional Chinese | 馬蹄 | ||||||||||
| Simplified Chinese | 马蹄 | ||||||||||
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| Nutritional value per 100 g (3.5 oz) | |||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Energy | 406 kJ (97 kcal) | ||||||||||||||||||||||||||||||||||||||||||||||
23.94 g | |||||||||||||||||||||||||||||||||||||||||||||||
| Sugars | 4.8 g | ||||||||||||||||||||||||||||||||||||||||||||||
| Dietary fiber | 3 g | ||||||||||||||||||||||||||||||||||||||||||||||
0.1 g | |||||||||||||||||||||||||||||||||||||||||||||||
1.4 g | |||||||||||||||||||||||||||||||||||||||||||||||
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| Other constituents | Quantity | ||||||||||||||||||||||||||||||||||||||||||||||
| Water | 73.5 g | ||||||||||||||||||||||||||||||||||||||||||||||
| †Percentages estimated usingUS recommendations for adults,[3] except for potassium, which is estimated based on expert recommendation from theNational Academies.[4] | |||||||||||||||||||||||||||||||||||||||||||||||
Eleocharis dulcis, theChinese water chestnut or water chestnut, is a grass-likesedge native toAsia, tropicalAfrica, andOceania. It is grown in many countries for its ediblecorms, but if eaten uncooked, the surface of the plants may transmitfasciolopsiasis.
Thewater caltrop, which also is referred to by the same name, is unrelated and often confused with the water chestnut.
The water chestnut is not anut but rather anaquatic vegetable that grows inmarshes, under water, or in mud. It has stem-like, tubular green leaves that grow to about 1.5 m (5 ft).
The plant is native toAsia, tropicalAfrica, andOceania.[5]
In the dry season of theNorthern Territory inAustralia,magpie geese eat the bulbs of water chestnuts, allowing them to put on fat for the wet season and ensuring they are ready for breeding. In the wet season, water chestnut leaves are used to build their floating nests.[6]
The crop can be cultivated inpaddies, 2–7.5 m (7–25 ft) wide by up to 100 m (330 ft) long to allow for mechanization,[7] or in ahydroponic culture.[8] As it is an aquatic plant, it should always be submerged in approximately 10 cm (4 in) of water.[9] The crop needs continuously high soil temperatures, ideally 14–15.5 °C (57–60 °F).[9] At 13.6 °C (56.5 °F), the corms begin to sprout.[7] Soil is ideally asandy loam withpH 6.5 to 7.2.[10] The plant produces two types of subterraneanrhizomes. Under long-daylength conditions, rhizomes grow horizontally and then turn upwards forming daughter plants. Under short-daylength conditions, the rhizomes grow downward and produce acorm at the tip.[9][7] Thephotoperiod also significantly influences how fast the corms grow. Corms begin to develop much more slowly if the photoperiod exceeds 12 hours.[11] The corms are also the propagating material.[7] Alternatively, transplants can be used.[8] Machinery, such as tractor-mounted vegetable planters, can be used for plantation.[7]
Nitrogen addition is beneficial for corm production, applying a dose before planting and another dose when corms begin to enlarge.[7] To further improve nutrient levels, potassium and phosphorus mineralfertilizers can be used before planting, where theN:P:K uptake ratio is1:0.5:1.75.[7] Also organicmulch, especially mushroom compost, shows good results.[7]
Once the corms turn dark brown, they should be harvested.[7] If left in the soil after this point in time, corms will get sweeter, however shelf life will decline.[7] The corms can be harvested using a modified gladiolus corm harvester once the paddy is drained.[8] Alternatively, a "water-suction harvester" can be used without the need to drain the paddy.[7] The corms have to be washed after harvest and brushed once they are dry.[8]
The per plant yield was described at 2.3 kg (5 lb 1 oz) per season (fresh matter).[12] In China, yields are reported between 20–40 t/ha (9–18 short ton/acre),[9] while in the United States a range between 47–85 t/ha (21–38 short ton/acre) has been mentioned.[12]
The harvested corms are best stored at 4 °C (39 °F). At this temperature, transpiration and thus weight loss are minimized.[7] This will also delaysprouting and minimize deterioration resulting from small injuries.[7] Corms should not be stored at temperatures above 13.6 °C (56.5 °F) as otherwise the corms will begin to sprout.[7] If the corms need to be stored longer term, they can also be kept in ableach solution of 1000 ppm.[13]
Chinese water chestnut is usually not very prone to pests;[8] nevertheless, some animals and fungi may attack the plant:Water fowl may damage the stems and corms, especially when plants are young.[7] Similarly,rodents and grazing animals pose a threat to the Chinese water chestnut, which may be discouraged by keeping the paddy inundated.[7]Caddisfly larvae (Trichoptera) and other leaf-eatingcaterpillars also feed on the stems. However, unless complete defoliation below the waterline occurs, the plants can normally tolerate this damage.[7] Plant hoppers (Fulgoridae) andscale insects feed on plant sap and may cause subsequent death.[7] Other pests include thenematodesDitylenchus andDolichodorus heterocephalus.[9] Fungal species can also attack the Chinese water chestnut. In warmer climates, arust is caused byUromyces,[7] andCylindrosporium eleocharidis causes stemblight.[14]
If eaten uncooked, the surface of the plants may transmitfasciolopsiasis.[15]
Raw water chestnuts are 74% water, 24%carbohydrates, 1%protein, and contain very littlefat. In a 100-gram reference amount, raw water chestnuts supply 410 kilojoules (97 kcal) of food energy, are rich (20% or more of theDaily Value, DV) invitamin B6 (25% DV), and contain moderate amounts of otherB vitamins,manganese, andpotassium (10% to 17% DV).
Raw water chestnuts are edible,[16] and are slightly sweet and crunchy. The small, rounded corms have a crisp, white flesh and may be eaten raw, slightly boiled, or grilled, and often arepickled ortinned.[citation needed] Boiled water chestnuts have a firm and slightly crunchy texture, with a mild and slightly nutty flavor that may easily be overpowered by seasonings or sauces with which the water chestnut is served or cooked. They may be combined withbamboo shoots,coriander,ginger,sesame oil, andsnow peas. Steamed orsauteed vegetable dishes may contain water chestnuts, such as noodle or rice recipes.[17] They may also be added to minced-meat fillings and dishes, such as Cantonesedim sum-stylesteamed meatballs, to add a crunchy texture.[18] The Thai dessertthapthim krop, with water chestnuts as its main ingredient, was named one of the world's best 50 desserts in 2019 byCNN Travel.[19]
The corms are a popular ingredient inChinese cuisine, in which they are most often eaten raw, sometimes sweetened. They also may be ground into aflour form used for makingwater chestnut cake, which is common as part ofdim sum cuisine. They are unusual among vegetables for remaining crisp even after being cooked or canned, because theircell walls are cross-linked and strengthened by certainphenolic compounds, such as oligomers offerulic acid.[20] This property is shared by other vegetables that remain crisp in this manner, including thetiger nut,lotus root andspurge nettle root.[21] The corms contain the antibiotic agentpuchiin,[9][22] which is stable to high temperature.[23]
Apart from the edible corms, the leaves can be used for cattlefeed,mulch orcompost.[12]
