Drying corn at too high a temperature can damage starch and make it difficult to extract, but research at the University of Illinois suggests that certain corn hybrids might be more resistant to high temperatures.

"So it looks like resistance to high temperature may well be a genetically controlled trait," said Steven Eckhoff, University of Illinois agricultural and biological engineer. This means hybrids might be developed that can be dried at high temperatures--a clear economic advantage for producers.

"As a producer, I want to dry my corn at as high a temperature as I'm allowed to use," Eckhoff said. "The higher I can dry at, the faster my throughput is, the lower my cost.

"I call drying temperature the wild card in terms of grain quality," he added. "You can do everything else right, but your work can be destroyed in an instant with too high of a drying temperature."

The goal of Eckhoff's research is to determine the magnitude of the effect of drying temperature on starch extractability, and to determine if sensitivity to drying temperature varies by hybrid. Eckhoff chose 12 hybrids in cooperation with researchers at Pioneer's Champaign Research Center for his study.

Moisture content of the corn plays an equally important part in this process, so corn harvested at 35 percent and 22 percent moisture content was dried at temperatures of 230 F and 77 F.

"We found that the responses were different for different hybrids," he said.

Starch yield loss was highest when corn with high moisture content was dried at high temperatures. But the loss ranged from 4.6 percent to 12.7 percent, depending upon the hybrid.

Although drying corn with low moisture content at low temperatures proved best for starch extractability, when certain hybrids with low moisture content were dried at both high and low temperatures, starch extractability was comparable.

This research shows promise for developing hybrids that can be dried at higher temperatures. The next step is to look at the effect of drying at multiple (15-25) locations to determine how much this characteristic is influenced by environment and how much is genetics. But coordinating such a large study poses its share of logistics problems, said Eckhoff.

"You have one shot at drying every year," he explained. "You want to bring in samples from multiple locations and you have to have enough dryers to dry them all down about the same time. Coordinating that is almost impossible."

So Eckhoff set out to make an inexpensive dryer that could be used on location at farms and test fields. He attached a standard funnel to the barrel of a commercial heat gun using black pipe. A mesh screen, stretched across the top of the funnel, holds several layers of corn. A thermocouple is placed directly below the corn and is attached to a data recorder, to read and record the temperature.

After trying several heat guns, he found one that had a fairly sensitive temperature control. Researchers were able to keep the temperature stable and use it for sample preparation.

"It still needs to be worked on, but it's not bad," said Eckhoff. "And it gave us samples of 600 to 700 grams, which was plenty for the starch yield testing we needed to do."

The system certainly paid off in terms of results. "We think this research shows there is potential to produce high yielding hybrids that have high starch extractability at a high drying temperature," Eckhoff concluded. "That would be the best of all worlds."

Author: Leanne Lucas