Types of Sweet Corn
Most of the corn sold fresh, canned or frozen in grocery stores is actually sweet corn, a sugary mutation of the common field corn first domesticated in the Americans more than 5,000 years ago. There are more than 200 cultivars and hybrids of sweet corn. Sweet corn kernels can be white, yellow or bi-colored. Different types of sweet corn have varying sugar levels, which affect the texture, flavor and shelf-life of the kernels.
History
Field corn, also known as dent corn, originated in the Americas from a wild grass. Sweet corn arose from field corn by a genetic mutation discovered in Pennsylvania during the 1700s, according to the United States Department of Agriculture (Resources 3). While field corn contains approximately 4 percent sugar in the milky stage--the tender-kernel stage at which corn is picked for eating--standard sweet corn can contain 6 percent sugar or more (Resources 2). Field corn is still used for animal feed and processed foods like popcorn, corn syrup and cornmeal, but sweet corn now dominates the fresh market.
Significance
Sugar in corn is eventually converted into starch, causing kernels to become tougher and less palatable over time. The more sugar in a kernel, the longer it will take to break down, making sweet corn easier to ship and store than other varieties. Super sweet varieties developed in the 1990s stay good twice as long as earlier corn--approximately 10 days. Demand for sweeter varieties, as well as more availability, increased the value of sweet corn crops by 81 percent between the late 1980s and late 1990s (Resources 3).
Types
There are three main types of sweet corn: normal sugary, sugary-enhanced and super sweet. Normal sweet corn and the slightly more sucrose-rich sugar-enhanced sweet corn are the most common types sold at grocery stores and farmers' markets. Both normal and sugary-enhanced kernels have a sweet flavor and creamy texture. Super sweet corn kernels carry the highest level of complex sugars, two to three times the amount in normal sweet corn, according to the University of Minnesota extension (Resources 1). These higher levels of sucrose take longer to break down, making super sweet varieties ideal for shipping. On the downside, they have a texture that can be more crunchy than creamy.
Color
Though sweetness is related to sugar, not color, it has been noted that different regions of the U.S. favor different colors of sweet corn kernels. Florida buyers purchase more yellow corn, while Californians are partial to whites (Resources 3). Different varieties of sweet corn also grow better depending on the climate in a region. Yellow corn does have a nutritional advantage over white corn; yellow kernels are considered a good source of Vitamin A, while white kernels do not contain a significant amount of the vitamin.
Storage and Cooking
Sweet corn is best eaten the day it is harvested, but since that's often not realistic, you can preserve all types of sweet corn for two to three days by refrigerating cobs in their husks immediately after picking or purchasing. Remove husks just before cooking. Sweet corn can be boiled, steamed or grilled and, depending on personal taste, is usually flavorful enough to be eaten without butter.
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