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Subjective? Not exactly

Western Canada’s wheat-grading system is probably more objective than you think

For 40 years Western Canada’s grain industry has dreamed about the black box — an affordable machine that would take a handful of wheat and quickly and accurately spit out its end-use quality on the elevator driveway.

Like flying cars and cellulosic ethanol, it’s just around the corner, but never arrives.

The black box is seldom raised now, but the Western Canadian Wheat Growers Association (WCWGA) and Alberta Wheat Commission are calling for an “objective” wheat-grading system, especially for falling number, a measure of bread-making quality, and determining levels of the mycotoxin deoxynivalenol (DON).

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But by calling for a more “objective” testing the WCWGA seems to be implying the current system is “subjective.”

The CGC says it will use instrument testing if practical, but adds the current system is not only objective, but able to take into account degrading factors no machine currently can.

And even though inspectors aren’t testing grain, the grades assigned based on appearance, are connected to previous and ongoing testing by the CGC’s Grain Research Laboratory.

“We always tie it back to the science,” CGC inspection specialist Usman Mohammad told a grain-grading school organized by the Manitoba Wheat & Barley and Manitoba Canola Growers associations here Dec. 7.

For example

Asked for an example, Moham­mad said: “A test has shown that light and moderate mildew, there is no impact on end use, so we can literally increase the amount of heavy mildew into a sample (without lowering the grade).”

The CGC’s Western Grains Standards Committee (WGSC), which represents the grain supply chain, including farmers, recommended the change for mildew in 2016.

Similar tests are done on other degrading factors affecting milling and baking functionality such as frost/heat stress, midge damage and hard vitreous kernels.

To assist CGC and grain elevator inspectors alike with visually grading, the CGC prepares samples of wheat displaying specific degrading factors.

“Elevators should have these for comparison purposes,” Mohammad said. “They shouldn’t be applying a grade if they don’t have these tools.

“Even the most seasoned inspectors will use the tools.

“That is why we create them — to have consistency across the country — everybody is comparing it against the exact same tool.”

It takes four years of training to be a CGC grain inspector, he said.

Mildew is one of many degrading factors. It’s caused by fungi under high moisture conditions in standing mature wheat, giving kernels a grey appearance.

“It’s not a health concern,” Can­­adian International Grains Institute (Cigi) technician Robyn Makowski told the meeting. “It doesn’t produce any toxins, but it can… decrease your flour yields. But the main issue is that it affects the esthetics of the flour and the end products that are made with it.”

Nuances important

Even if a machine could assess mildew, it couldn’t distinguish nuances around severity or frequency, Mohammad said. For example, most kernels in a sample might have a light amount of mildew, but on almost every kernel. Another sample might have a high amount of mildew, but only on a small percentage of kernels.

“That’s where with inspectors, your knowledge and experience comes in,” he said.

Frost and heat stress cause similar damage in wheat. The impact of both hinges on wheat maturity, the temperature and how long it was very hot or cold, Makowski said.

“The big thing is the decreased baking performance and decreased handling properties,” she said.

Harder kernels are damaged more when milled. Some damage is needed for water absorption, but too much can result in too much absorption making dough sticky and difficult to handle, she said.

Fusarium head blight is a fungal disease, and unlike mildew, can cause mycotoxins (DON). Tolerances vary among countries.

The disease can also produce thin, chalky kernels, which have a negative effect on wheat protein, starch, test weight and milling and baking, she said.

Falling down

Sprouting, which is sometimes accompanied by mildew, affects alpha amylase, an enzyme in wheat that converts starches to sugars. It also results in too much carbon dioxide in the bread-making process, producing holes inside the bread, Makowski said.

Extra sugars can also caramelize resulting in white bread turning brown.

To measure the potential impact of higher levels of alpha amylase, flour and water are mixed in a slurry and the time it takes for a plunger to drop through it is measured. That’s the falling number. The faster the plunger falls, the poorer the bread-making quality is.

The minimum falling number is 250 seconds.

“Unfortunately if we have sprout damage and low falling numbers there’s not much that can be done,” Makowski said. We can try to blend it out but a very small amount of sprouted sample can ruin the whole batch.

“Unfortunately when we have sprout damage it is difficult to work with it.”

About the author

Reporter

Allan Dawson

Allan Dawson is a reporter with the Manitoba Co-operator based near Miami, Man. Covering agriculture since 1980, Dawson has spent most of his career with the Co-operator except for several years with Farmers’ Independent Weekly and before that a Morden-Winkler area radio station.

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