SPOILER ALERT
BY EMILY R. JOHNSON • PHOTO COURTESY OF CGC
The invisible fungal mycotoxin ochratoxin-A, or OTA, can spoil grain under high moisture and temperature conditions. Though it develops exclusively in stored wheat, oats, barley and other grains, OTA is produced by Penicillium verrucosum, a naturally occurring soil fungus. It is a known carcinogen when concentrated and causes kidney damage and other serious health effects when consumed by humans and animals. When pigs consume OTA in feed, humans who ingest the pork can be exposed to the toxin. It can also greatly damage poultry health, but beef and dairy products are at low risk, as OTA is detoxified by rumen enzymes.
International grain exports may be tested for OTA. Global buyers, including China, Indonesia and the European Union, have set maximum limits as low as five parts per billion. The presence of the mycotoxin in cereal exports could put Canada’s reputation as a high-quality grain producer at risk, said Krista Zuzak. She is the director of crop protection and production at Cereals Canada and trade and cereals technical lead for Keep It Clean. “In Canada, we are very export dependent when it comes to our grain,” she said. “Having excess mycotoxins present in our grains that exceed those limits could harm that reputation.”
A shipment found to have an unacceptable OTA concentration can be rejected. Product recalls may result if contaminated grain makes its way further along the supply chain. Canada and the U.S. have not set OTA regulations for international grain shipments. While it is rare for Canadian grain shipments to exceed limits set by global customers, farmers are essential in upholding Canada’s reputation for quality grain through their grain management practices. “The good reputation of Canadian grain is built upon several things, including consistency, quality, functionality and safety, as well as the knowledge and support of the grain value chain,” said Sheryl Tittlemier, research scientist and manager of the Canadian Grain Commission’s (CGC) Trace Organics and Trace Elements program.
Chandra Singh, director of the Lethbridge Polytechnic Advanced Post-Harvest Technology Centre, advises farmers to apply best practices. “Aeration is key to management of OTA in the bin,” he said. “Some years farmers have bumper crops and fill their bins to the top. Dead zones with no aeration are at high risk for OTA.” Singh recommends grain be kept cool, between zero and five degrees, and to watch for condensation on bin walls and other indicators of high moisture. Hot spots in the bin may be the first indicators of fungal activity. OTA can’t be detected visually, though it may be accompanied by mold. “If you see signs of fungus infestation, or if mold develops, the issue needs to be taken seriously,” said Singh.
Monitoring becomes increasingly important the longer grain is stored. CGC data indicate OTA is more frequently detected in late summer and early fall when grain that has been kept under improper storage conditions for an extended period goes to market. “Grain that’s been in the bin a year or more moves out of the bin and is exported,” said Tittlemier. According to the CGC, 70 per cent of exports exhibit no measurable quantity of OTA. When detected, it is generally at very low concentrations. “Everyone along the grain value chain in Canada understands the need to uphold its reputation,” added Tittlemier. She stressed that although OTA detections in exported grain are not increasing year-over-year, farmers must remain vigilant and maintain good storage conditions. To learn more about OTA, visit keepitclean.ca.
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