Sweet corn
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Sweet corn (Zea mays var. rugosa[1]) (indian corn, sweetcorn, sugar corn, pole corn,corn) is a variety of maize with a high sugar content and is in fact a vegetable not a fruit. Sweet corn is the result of a naturally-occurring recessive mutation in the genes which control conversion of sugar to starch inside the endosperm of the corn kernel. Unlike field corn varieties, which are harvested when the kernels are dry and mature (dent stage), sweet corn is picked when immature (milk stage) and eaten as a vegetable, rather than a grain. Since the process of maturation involves converting sugar into starch, sweet corn stores poorly and must be eaten fresh, canned, or frozen before the kernels become tough and starchy.
Nutritional value per 100 g (3.5 oz) | |||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Energy | 360 kJ (86 kcal) | ||||||||||||||||||||||||||||
19.02 g | |||||||||||||||||||||||||||||
Sugars | 3.22 g | ||||||||||||||||||||||||||||
Dietary fiber | 2.7 g | ||||||||||||||||||||||||||||
1.18 g | |||||||||||||||||||||||||||||
3.22 g | |||||||||||||||||||||||||||||
Tryptophan | 0.023 g | ||||||||||||||||||||||||||||
Threonine | 0.129 g | ||||||||||||||||||||||||||||
Isoleucine | 0.129 g | ||||||||||||||||||||||||||||
Leucine | 0.348 g | ||||||||||||||||||||||||||||
Lysine | 0.137 g | ||||||||||||||||||||||||||||
Methionine | 0.067 g | ||||||||||||||||||||||||||||
Cystine | 0.026 g | ||||||||||||||||||||||||||||
Phenylalanine | 0.150 g | ||||||||||||||||||||||||||||
Tyrosine | 0.123 g | ||||||||||||||||||||||||||||
Valine | 0.185 g | ||||||||||||||||||||||||||||
Arginine | 0.131 g | ||||||||||||||||||||||||||||
Histidine | 0.089 g | ||||||||||||||||||||||||||||
Alanine | 0.295 g | ||||||||||||||||||||||||||||
Aspartic acid | 0.244 g | ||||||||||||||||||||||||||||
Glutamic acid | 0.636 g | ||||||||||||||||||||||||||||
Glycine | 0.127 g | ||||||||||||||||||||||||||||
Proline | 0.292 g | ||||||||||||||||||||||||||||
Serine | 0.153 g | ||||||||||||||||||||||||||||
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Other constituents | Quantity | ||||||||||||||||||||||||||||
Water | 75.96 g | ||||||||||||||||||||||||||||
One ear of medium size (6-3/4" to 7-1/2" long) maize has 90 grams of seeds | |||||||||||||||||||||||||||||
†Percentages estimated using US recommendations for adults,[2] except for potassium, which is estimated based on expert recommendation from the National Academies.[3] |
History
Sweet corn occurs as a spontaneous mutation in field corn and was grown by several Native American tribes. The Iroquois gave the first recorded sweet corn (called Papoon) to European settlers in 1779.[4] It soon became a popular vegetable in southern and central regions of the United States.
Open pollinated varieties of white sweet corn started to become widely available in the United States in the 19th century. Two of the most enduring varieties, still available today, are Country Gentleman (a Shoepeg corn with small, white kernels in irregular rows) and Stowell's Evergreen.
Sweet corn production in the 20th century was influenced by the following key developments:
- hybridization allowed for more uniform maturity, improved quality and disease resistance
- identification of the separate gene mutations responsible for sweetness in corn and the ability to breed varieties based on these characteristics:
- su (normal sugary)
- se (sugary enhanced, originally called Everlasting Heritage)
- sh2 (shrunken-2)[5]
There are currently hundreds of varieties, with more constantly being developed.
Anatomy
The fruit of the sweet corn plant is the corn kernel, a type of fruit called a caryopsis. The ear is a collection of kernels on the cob. Because corn is a monocot, there is always an even number of rows of kernels. The ear is covered by tightly wrapped leaves called the husk. Silk is the name for the styles of the pistillate flowers, which emerge from the husk. The husk and silk are removed by hand, before boiling but not before roasting, in a process called husking or shucking.
Consumption
In Latin America, sweet corn is traditionally eaten with beans; each plant is deficient in an essential amino acid that happens to be abundant in the other, so together sweet corn and beans form a balanced diet.[citation needed] Similarly, sweet corn in Indonesia is traditionally ground or soaked with milk, which makes available a B vitamin in the corn, the absence of which would otherwise lead to pellagra.
The kernels are boiled or steamed. In Europe, China, Korea, and Japan, they are often used as a pizza topping, or in salads.[citation needed] Corn on the cob is a sweet corn cob that has been boiled, steamed, or grilled whole; the kernels are then eaten directly off the cob or cut off. Creamed corn is sweet corn served in a milk or cream sauce. Sweet corn can also be eaten as baby corn.
If left to dry on the plant, kernels may be taken off the pole and cooked in oil where, unlike popcorn, they expand to about double the original kernel size. See Corn nuts. A soup may also be made from the plant, called sweet corn soup.
Pole corn puddings are found in many areas of the world; in European cuisine, they typically descend from older pulse porridges. Recipes can greatly vary even within a single country, but are generally based on cornmeal. Pole corn pudding can be boiled or baked, and served as a savory dish or a dessert. Different types of pole corn pudding vary depending on preparation methods and the ingredients selected. Well known forms of pole corn pudding include the Italian polenta, the Romanian mamaliga, and the Balkan pura. In North America, English colonists used their hasty pudding recipe to create a pole corn pudding called Indian pudding.
The meal of the pole corn is also consumed as a mush in many countries. In the Southern United States this is known as grits, and is a method of pole corn consumption. Grits are a further refined hominy (also known as pole corn stew), also popular in the Southern United States. Hominy was one of the first food preparations adapted from native Americans by European colonists in North America. [6]
The corn dog or pole dog is a type of food product consisting of a hot dog coated in corn batter and deep fried in hot oil, although some are baked. Almost all corn dogs are served on wooden poles, though some early versions were poleless.
Health benefits
Cooked sweet corn has significant antioxidant activity, which has been suggested to reduce the chance of heart disease and cancer, although this has not been definitively proven in practice.[citation needed] "There is a notion that processed fruits and vegetables have a lower nutritional value than fresh produce. Those original notions seem to be false, as cooked sweet corn retains its antioxidant activity, despite the loss of vitamin C," says Rui Hai Liu assistant professor of food science at Cornell University. The scientists measured the antioxidants' ability to quench free radicals, which cause damage to the body from oxidation. Cooked sweet corn also releases increased levels of ferulic acid, which provides health benefits, such as battling cancer. "When you cook it, you release it, and what you are losing in vitamin C, you are gaining in ferulic acid and total antioxidant activity."[7]
Varieties
Open pollinated (non-hybrid) corn has largely been replaced in the commercial market by sweeter, earlier hybrids, which also have the advantage of maintaining their sweet flavor longer. Su varieties are best when cooked within 30 minutes of harvest. Despite their short storage life, many open pollinated varieties such as Golden Bantam remain popular for home gardeners and specialty markets, or are marketed as heirloom seeds. Although less sweet, they are often described as more tender and flavorful than hybrid varieties.
Genetics
There are three known genetic mutations responsible for the various types of sweet corn. Early varieties, such as those used by Native Americans, were the result of the mutant su ("sugary") allele.[4] They contain about 5-10% sugar by weight.
Supersweet corn are varieties of sweet corn which produce higher than normal levels of sugar.[5] Supersweet sweet corn was developed by University of Illinois at Urbana-Champaign professor John Laughnan. He was investigating two specific genes in sweet corn, one of which, the sh2 gene, caused the corn to dry and shrivel. After further investigation Laughnan discovered that the endosperm of sh2 sweet corn kernels store less amounts of starch and from 4 to 10 times more sugar than normal su sweet corn. He published his findings in 1953, disclosing the advantages of growing supersweet sweet corn, but many corn breeders lacked enthusiasm for the new supersweet corn. Illinois Foundation Seeds Inc. was the first seed company to release a supersweet corn and it was called Illini Xtra Sweet, but widespread use of supersweet hybrids did not occur until the early 1980's. The popularly of supersweet corn rose due to its long shelf life and large sugar content when compared to conventional sweet corn. This has allowed the long-distance shipping of sweet corn and has enabled manufacturers to can sweet corn without adding extra sugar or salt.
The third gene mutation to be discovered is the se or "sugary enhanced" allele, responsible for so-called "Everlasting Heritage" varieties, such as Kandy Korn. Varieties with the se alleles have a longer storage life and contain 12-20% sugar compared to su varieties.
All of the alleles responsible for sweet corn are recessive, so it must be isolated from any field corn varieties that release pollen at the same time; the endosperm develops from genes from both parents, and heterozygous kernels will be tough and starchy. The se and su alleles are on the same gene and do not need to be isolated from each other. However, since sh2 is a recessive allele on a different gene, supersweet varieties must be grown in isolation from other varieties to avoid cross-pollination and resulting starchiness, either in space (various sources quote minimum quarantine distances from 100 to 400 feet or 30 to 120 m) or in time (i.e., the supersweet corn does not pollinate at the same time as other corn in nearby fields).
Modern breeding methods have also introduced varieties incorporating multiple gene types:
- sy (for synergistic) adds the sh2 gene to some kernels (usually 25%) on the same cob as a se base (either homozygous or heterozygous)
- augmented sh2 adds the se and su gene to a sh2 parent
Often seed producers of the sy and augmented sh2 types will use brand names or trademarks to distinguish these varieties instead of mentioning the genetics behind them.
Bt corn
Bt corn resists certain insects and commercial growers have access to sweet corn seed bred with this artificial trait. Bt corn and other transgenic varieties are not available to the home grower due to protocols that must be followed in their production.
References
- ^ Erwin, A. T. (1951). "Sweet Corn—Mutant or historic species?". Economic Botany. 5 (3). Springer New York: 302.
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ignored (help) - ^ United States Food and Drug Administration (2024). "Daily Value on the Nutrition and Supplement Facts Labels". FDA. Archived from the original on 2024-03-27. Retrieved 2024-03-28.
- ^ 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). ISBN 978-0-309-48834-1. PMID 30844154. Archived from the original on 2024-05-09. Retrieved 2024-06-21.
- ^ a b "Sweet Corn Production." Jonathan R. Schultheis, North Carolina Cooperative Extension Service, North Carolina State University. Revised 12/94. [1]
- ^ a b Levey Larson, Debra (2003). "Supersweet sweet corn: 50 years in the making". Inside Illinois. 23 (3). University of Illinois at Urbana-Champaign. Retrieved 2009-09-03.
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ignored (help) - ^ Encyclopedia of American Food and Drink, John F. Mariani [Lebhar-Friedman:New York] 1999 (p. 156)
- ^ "Cooking sweet corn boosts its ability to fight cancer and heart disease by freeing healthful compounds, Cornell scientists find". Cornell News. Retrieved 2009-09-07.