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Sweet corn ( Zea mays convar. saccharata var. rugosa), also called sweetcorn, sugar corn and pole corn, is a variety of maize grown for human consumption with a relatively high sugar content.
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. Sweet corn is picked when still immature (the milk stage) and prepared and eaten as a vegetable, unlike field corn, which is harvested when the kernels are dry and mature (dent stage). Since the process of maturation involves converting sugar to starch, sweet corn stores poorly and must be eaten fresh, Canning, or frozen, before the kernels become tough and starchy.
It is one of the six major types of corn, the others being dent corn, flint corn, pod corn, popcorn, and flour corn.Linda Campbell Franklin, "Corn," in Andrew F. Smith (ed.), The Oxford Encyclopedia of Food and Drink in America. 2nd ed. Oxford: Oxford University Press, 2013 (pp. 551–558), p. 553.
Open pollination of white sweet corn started to become widely available in the United States in the 19th century. Two of the most enduring cultivars, still available today, are 'Country Gentleman' (a Shoepeg corn with small kernels in irregular rows) and 'Stowell's Evergreen'.
Sweet corn production in the 20th century was influenced by the following key developments:
There are dozens of sweet corn cultivars.
In Malaysia, there exists a variety unique to the Cameron Highlands named "pearl corn". The kernels are glossy white, resembling pearls, and can be eaten raw off the cob, although they are often boiled in water and salt.
In the Philippines, boiled sweet corn kernels are served hot with margarine and Powdered cheese as an inexpensive snack sold by street vendors.
Similarly, sweet corn in Indonesia is traditionally ground or soaked with milk, which makes available the B vitamins niacin in the corn, the absence of which would otherwise lead to pellagra. Cheese and condensed milk are added to sweet corn in the snack jasuke, short for jagung susu keju.
In Brazil, a combination of ground sweet corn and milk is also the basis of various well-known dishes, such as pamonha and the pudding-like dessert curau, while sweet corn eaten directly off the cob tends to be served with butter.
In Europe and Asia sweet corn is often used as a pizza topping or in salads. Corn on the cob is a sweet corn cob that has been boiled, steamed, or grilled whole; the kernels are then cut off and eaten or eaten directly off the cob. Creamed corn is sweet corn served in a milk or cream sauce. Sweet corn can also be eaten as baby corn. Corn soup can be made adding water, butter and flour, with salt and pepper for seasoning.
In the United States, sweet corn is eaten as a steamed vegetable or on the cob, and is usually served with butter and salt. It can be found in Tex-Mex cooking in chili, tacos, and salads. Corn mixed and cooked with lima beans is one form of succotash. Sweet corn is one of the most popular vegetables in the United States, being most popular in the southern and central regions of the country, and can be purchased either fresh, canned, or frozen. Sweet corn ranks among the top ten vegetables in value and per capita consumption.
Sucrose represents 60% of the sugars in cooked yellow sweet corn (table). According to the Ontario government agency, Foodland Ontario, the sugar content of traditional corn is about 9-16%, compared to 14-44% in sweet varieties of corn.
Supersweet corn are cultivars of sweet corn which produce higher than normal levels of sugar developed by University of Illinois at Urbana–Champaign professor John Laughnan. He was investigating two specific in sweet corn, one of which, the sh2 mutation (, a Glucose-1-phosphate adenylyltransferase), caused the corn to shrivel when dry. After further investigation, Laughnan discovered that the endosperm of sh2 sweet corn kernels store less starch and from 4 to 10 times more sugar than normal su sweet 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 1980s. The popularity 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. Breeding has resolved the germination rate issue, but it is still generally true that sh2 corn is less juicy than their su counterparts. sh2-i ("shrunken2-intermediate") cultivars under development exploits a different mutation on the same gene to create varieties that are both juicy and sweet.
The third gene mutation to be discovered is the se (or se1) for "sugary enhanced" allele, responsible for so-called "Everlasting Heritage" cultivars, such as 'Kandy Korn'. Cultivars with the se alleles have a longer storage life and contain 12–20% sugar. The gene for Se1 has been located.
All of the alleles responsible for sweet corn are recessive, so it must be isolated from other corn, such as field corn and popcorn, 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 do not need to be isolated from each other. However supersweet cultivars containing the sh2 allele must be grown in isolation from other cultivars 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 cultivars incorporating multiple gene types:
Cultivars
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 cultivars are best when cooked within 30 minutes of harvest. Despite their short storage life, many open-pollinated cultivars such as 'Golden Bantam' remain popular for home gardeners and specialty markets or are marketed as . Although less sweet, they are often described as more tender and flavorful than hybrids.
Genetics
Early cultivars, including those used by Native Americans, were the result of the mutant su ("sugary") or su1 () allele of an isoamylase.
Often seed producers of the sy and augmented sh2 types will use brand names or trademarks to distinguish these cultivars instead of mentioning the genetics behind them. Generally these brands or trademarks will offer a choice of white, bi-color and yellow cultivars which otherwise have very similar characteristics.
Genetically modified corn
Genetically modified sweet corn is available to commercial growers to resist certain insects or herbicides, or both. Such transgenic varieties are not available to home or small acreage growers due to protocols that must be followed in their production.
See also
External links
Categories: Maize, Vegetables, Crops Originating From Indigenous Americans, Crops Originating From North America, Crops Originating From The United States, Grasses Of Mexico, Grasses Of North America, Grasses Of The United States, Agriculture In Mesoamerica, Cuisine Of The Northeastern United States, Symbols Of Illinois
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