The visual factors grain inspectors use to estimate falling number and vomitoxin in wheat are never exact, but this year there’s even more variation than usual, says Norm Woodbeck, manager, agri operations with Intertek Commodities Services, a private grain-grading company.
“This has driven the industry to do a lot of testing (for the toxin deoxynivalenol) to verify what they’ve got because they just can’t take a chance,” Woodbeck said in an interview Jan. 7.
There’s no quick elevator test for deoxynivalenol (DON), a toxin produced by fusarium head blight. But researchers have established a correlation between fusarium-damaged kernels (FDK) and DON levels. The percentage of fusarium damage affects the wheat’s grade.
“I think this year we’re seeing, for whatever reason, with the vomitoxin that the relationships aren’t there that we maybe saw in the past,” Woodbeck said.
Some wheat samples contain more DON than would be expected given the percentage of fusarium-damaged kernels and some less, he said.
Sometimes the culprit is the so-called “nugget effect” when one or several kernels of wheat in a 1,000-gram test are heavily laden with DON, said David Hatcher of the Canadian Grain Commission’s Grain Research Laboratory.
“The CGC — I can’t stress this enough — takes this very seriously because grain safety is paramount to both domestic and international sales,” Hatcher said in an interview Jan. 8. “We feel it’s critical to stay on top of this.”
The CGC is exploring ways to conduct a quick DON test grain buyers can use on the elevator driveway to replace the current system based on damaged kernels, he said.
Varying weather conditions and different types of fusarium head blight, a fungal disease, can all result in different levels of DON, Hatcher said.
Sprouting wheat produces the enzyme alpha amylase, which reduces dough elasticity undermining bread quality. Grain inspectors use the percentage of sprouted wheat kernels as a quick way to estimate the damage. A more reliable but time-consuming measure is falling number — the length of time, measured in seconds, it takes a plunger to drop through a slurry of water and flour in a test tube.
A higher falling number means the dough will have more elasticity and produce better bread.
Woodbeck said he’s seeing lower falling numbers in wheat that doesn’t appear to have any sprouting. He suspects, however, there’s “incipient sprouting.” That’s when the sprouting process has started but isn’t visible.
“Our falling numbers are excellent this year. There’s not a problem, but they are somewhat lower than last (crop) year, however,” Hatcher said. “But the numbers are well within the 10-year average and well within a good rating.
“Sprouting was not a problem this year in our CWRS (Canada Western Red Spring wheat).”
Last crop year CWRS wheat routinely had falling numbers of 425 to 450, while this year they generally range between 380 and 400, “which is still totally acceptable and is well within our normal experience for a No. 1 CWRS,” Hatcher said.
The critical thing for millers and processors is knowing how wheat is going to perform, Woodbeck said. Then they can adjust their equipment and processes accordingly.