Growers should play it safe and not surpass recommended drying temperatures because it can be difficult to tell if grain has been damaged from overheating.
“If you have too high a temperature and the grain is exposed to it for too long you will not necessarily see it. The only way you will pick that up is on a functional test, said Dr. Dave Hatcher, a research scientist in the Canadian Grain Commission.
He said when cereals and oilseeds are heated above the recommended temperatures there is a denaturation of the existing proteins that are responsible for the end product’s quality.
With wheat, the end user will struggle to produce quality product such as noodles and bread if the wheat is overheated in the drying process.
“What gives wheat the unique capability to make dough that rises and then you bake in the oven, is these key gluten proteins. Inappropriate heating during drying cause these to be denatured and they won’t be able to hold the gas or form the viscoelastic properties that are essential to hold back the (carbon dioxide) that is formed by the yeast to cause the bread to rise,” Hatcher said.
Oxidation can occur in canola if it is overheated during drying, which can also affects its end uses.
With canola “you can have oxidation of the oils which are not desirable, you can have potential impact on the fatty acids, and denaturation of the proteins,” Hatcher said.
“The end user is expecting oil that has certain characteristics, and if it doesn’t fall within those characteristics that they want, because it’s oxidized or denaturation, it can have a problem. There can also be some discolouration and therefore causing other problems,” Hatcher said.
He said there is a grading standard for grains damaged from overheating during the drying process, and that if there is clear evidence of damage, growers can lose more than one grade for their grain.
“My major concern is that in their haste to dry down, they think that high temperatures are better in shorter periods of time. But inadvertently they can damage the crop and potentially get less at the gate when they go to sell it,” Hatcher said.
“It’s better to go with the appropriate temperature. I guess it will take longer but it won’t denature the key proteins. Or potentially oxidize some other important components in the grains or oilseeds.”
A temperature chart for drying specific crops is available at on the CGC website.