Thursday, June 9, 2011

Would Corn by Any Other Name Taste as Sweet?

Nothing is quite like sinking your teeth into this year’s first ears of sweet corn.

Tim Reinbott, superintendent for the University of Missouri Bradford Research and Extension Center, admits that sometimes he doesn’t even get out of the field before succumbing to that tempting first bite.  “Some varieties are so good that I’ll eat four ears right off the plant without even cooking them,” he said. “If you ask people what their favorite sweet corn is, many will say Peaches and Cream because that was one of the first bicolor varieties that tasted really good, but actually there are hundreds of sweet corn varieties out there.”

Reinbott wants farmers and consumers to realize all the options available. Each year he plans a sweet corn tasting event where more than 150 people get acquainted with new genetic hybrids as well as old corn mainstays.

“We ask people to rate corn types from 1 to 5,” he said. “Last year we found popular varieties like Peaches and Cream came in at 2.5, varieties like Bodacious and Incredible you often see at farmers markets came in around 3.8, but newer varieties like Honey Select and Vision – which are heterozygous with supersweet and tender genes in them – get 4.6s and 4.7s.”

Sugar and starch
Juicy, delicious goodness starts with selecting and planting the right varieties of corn.  Farmers and backyard gardeners have to wade through a lot of choices, and new varieties continue to enter the picture. But it might be hard to find some of the best varieties at your local store.

“In the case of seed racks in hardware stores, those varieties are selected according to historical records of what varieties sell, so you are going to see varieties of corn and tomatoes that might be decades old,” said David Trinklein, an MU Extension horticulturist.  He suggests looking for newer varieties online through vegetable seed retailers if you can’t find them locally.

To enhance the flavor of corn, researchers developed hybrids in the early 1900s with an enhanced sugar-inducing gene, which they called “su.” In the 1950s they came out with the sugary enhanced gene (se), followed by shrunken-2 (sh2), also known as supersweet.

“The supersweet has four to 10 times the amount of sugar of regular varieties, with the idea that if it sits on the grocery store shelf for a week it still will be sweeter,” said Trinklein, “The problem is that supersweet isn’t as visually appealing and the kernels are slightly chewy with a shriveled kind of look.”

To take advantage of the best traits of different varieties, researchers developed “synergistic” and “augmented” varieties. Synergistic corn ears contain 25 percent su genes, 25 percent se and 50 percent sh2 genes to balance sweetness, look and field performance. Augmented varieties combine sh2 kernels with a few su and se kernels sprinkled throughout an ear. These typically score at the top of taste tests.

Some recent varieties, such as Attribute, also integrate a Bt gene, much like in field corn. That gene acts as an insecticide, protecting the plant from European corn borer, cutworm and corn earworm.

Much of the drive to develop sweeter varieties has to do with what happens after the corn is harvested.

“As soon as the corn is picked, the sugars start to convert into starch,” Trinklein said. “You have these old stories about having a pot of water boiling on the stove and you send someone with fast foot speed to the field to pick the corn, and as they run back to the kitchen they shuck it because when they drop it into the boiling water it stops the conversion of sugars to starch.”

Some newer hybrids convert sugar to starch much more slowly and also have more sugar in them, so they preserve the corn’s sweet taste for a few days longer.

Making your sweet corn plot grow
While tomatoes rank at the top in popularity, corn has a place in many vegetable gardens. Compared to tomatoes, corn is one of the easier vegetables is to grow. With tomato plants, gardeners might have to deal with a number of different blights and wilts, but there aren’t many diseases that affect sweet corn, Trinklein said.

Sow corn in a furrow about one inch deep, spacing rows 30-42 inches apart. Once they sprout, thin your rows to get one plant every 8-10 inches. Since sweet corn is wind-pollinated, plant in blocks several rows wide instead of making one long row. Because you are truly eating the offspring of corn with each ear, separating varieties keeps each one true to its flavor.

“In the case of sweet corn you are eating the product of pollination and fertilization, so it does make a difference what the male parent is in regards to the taste of sweet corn,” Trinklein said.

Corn needs 1-2 inches of water per week. This becomes more important when the corn tassels. After corn silks and is pollinated, the kernels start to fill and if water is scarce, ears won’t be juicy.

For multiple harvests, plant a few rows then allow 10 days between each subsequent planting. Three or four plantings will give you corn up to the first fall frost.  Typically corn is ready to be eaten 22-24 days after silking, but the exact number of days depends heavily on how hot it is.

“Sweet corn is rated according to days to harvest, but there’s a big difference between 75 days in southern Florida and northern Minnesota,” Trinklein said. “Temperature influences maturity and commercial growers use ‘heat units’ instead of days to predict ripening. In July it might only take four days to accumulate the same number of heat units that might take 8-10 days to accumulate in the cooler month of May.”

Those ears are still a few months off, but Reinbott hopes producers broaden their taste horizons.  “The whole idea is to educate the public and farmers that there really is something different out there besides Peaches and Cream or Bodacious,” he said.

Click here for results of Bradford Farm’s last two years of sweet corn variety tasting.

For more information on sweet corn:
"Sweet Corn" (from the Missouri Master Gardener Core Manual)
MU Extension vegetable planting calendar
Popular varieties
Variety, Maturity, Color,  Comments

Bodacious, 75 days, yellow, high yielding; good seedling vigor

Frisky, 69 bicolor, early with great flavor; excellent early vigor
Gold Nugget, 75 days, yellow, superior holding ability; gaining popularity

Jackpot, 80 days, bicolor, excellent quality; good disease tolerance

Incredible, 85 days, yellow, leading market-garden variety; great flavor

Peaches and Cream, 85 days, bicolor, excellent flavor; tender kernels

Silver King, 85 days, white, sweeter version of the popular Silver Queen

Sugar Baby, 65 days, bicolor, very early; tolerant of cool soil; very sweet

Tender Treat, 95 days, yellow, slow conversion starch to sugar; tall stalks

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