Keep July 4 cookouts sweet with fresh-picked corn

COLUMBIA, Mo.—Nothing says summer like biting into delectable, juicy sweet corn at a Fourth of July cookout. Whether boiled in a pot or charred over an open grill, savoring freshly picked sweet corn embodies the patriotic spirit of a midsummer celebration before fireworks light up the night sky.

The term “freshly picked” is used since sweet corn connoisseurs know that the greater the delay between harvest and consumption, the less sweet the corn will taste, said University of Missouri Extension horticulturist David Trinklein.

There is sound science behind this observation, Trinklein said. From the moment an ear of sweet corn is harvested, the sugar in its kernels starts converting into starch. At room temperature, up to 50% of the sweet corn's sugar can turn to starch within the first 24 hours due to enzymatic activity.

Accordingly, sweet corn picked far away, shipped great distances and allowed to sit on the produce counter for days can’t match the quality of freshly picked sweet corn. People who have not had the pleasure of eating fresh sweet corn do not know how tasty it can be, Trinklein said.

Sweet corn (Zea mays var. saccharata) is a mutant strain of corn that accumulates about twice as much sugar in its endosperm (storage tissue) than does field corn. Native Americans developed the original strains of sweet corn centuries before European colonization.

The first known mention of a sweet corn variety was in 1779, when European settlers documented a variety called “Papoon,” which was developed by the Iroquois. They grew it alongside beans and squash in a sustainable companion planting system called the “Three Sisters.”

Early varieties of sweet corn were sweet because of a sugar-inducing gene, su1. By the late 19th and early 20th centuries, commercial breeders began hybridizing the plant to improve its sweetness. Several new mutants have been identified in recent years that improve upon the su1 gene. These include the se1 (sugary enhanced) and sh2 (super sweet) genes.

The se1 varieties, also referred to as Everlasting Heritage (EH), have considerably more sugar than the su1 varieties. Sugar is still converted to starch once the corn is harvested, but because se1 varieties have more sugar to begin with, they remain sweet several days longer. Consumed immediately after being harvested, se1 varieties offer unparalleled flavor, Trinklein said.

The sh2 varieties have several advantages over su1 and se1 varieties. In addition to being three times sweeter than su1 sweet corn, the conversion of sugar to starch in sh2 sweet corn is negligible. The shortcoming of sh2 varieties is their somewhat chewy kernels.

Synergistic hybrids (SY or HSE) are the newest type of sweet corn. These varieties have about 75% of their kernels as sugary enhanced (se1) sweet corn and 25% as super sweet (sh2). Synergistic types contain more sugar than regular se1 types and have excellent shelf life along with good kernel texture.

Since the endosperm of seed results from the genetic influence of both parents, se1 and sh2 varieties must be prevented from cross-pollinating with other varieties for best eating quality. This can be accomplished by staggering planting dates by at least 14 days or separating plantings by 250 feet or more, Trinklein said.

For more information, refer to the MU Extension publication Growing Sweet Corn in Missouri.