ARCHIVED - Harvest Science - Issue 2 The grain science and technology newsletter

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Durum safer because of variety development

For Canada's variety registration system to successfully meet the needs of producer, the grain industry and customers, it has to be flexible and responsive. One example was to adapt durum varieties to new safety limits for cadmium concentration.

Thriving market for Canadian durum

In the early 1990s, the Canadian durum industry was thriving with over 50 per cent world market share and exports of over 3 million metric tonnes a year. A significant part of this success was the industry's ability to meet the quality needs of international customers. This meant developing and growing varieties with qualities important to customers, such as higher protein content for pasta firmness and elevated yellow pigment concentration for good pasta colour. Varieties at the time, such as Kyle and AC Avonlea, did this successfully.

Measuring cadmium levels.
The Grain Research Laboratory tests cadmium levels in durum using an inductively coupled plasma–mass spectrometer (ICP-MS) to ensure levels meet customer requirements for grain safety.

Grain safety as important as quality

Despite all the success, the 1990s also brought a new awareness and focus on grain safety.

"Even though customers were satisfied with Canadian durum quality, the industry was concerned about potentially being shut out of important European markets due to concern about the levels of cadmium. It decided to take a proactive approach and focus on finding ways to lower cadmium in Canadian durum through plant breeding and set a mandatory limit for cadmium content for new variety registration," says Eugene Gawalko, retired Program Manager for Trace Elements.

Breeder, durum field.
Breeder inspects a new durum line grown in a co-operative trial.
Photo by Jim Downey, SeCan Association.

Safety concerns

Cadmium is a trace element that can be harmful to humans and animals. It can be found naturally in soil. Soils of North American wheat production areas contain elevated natural amounts of cadmium. Durum wheat normally accumulates more cadmium from soil than other commonly grown cereals.

Low cadmium limits proposed

Although cadmium was a general safety concern, there was little attention paid to its level in durum. Canada's variety registration system also did not have limits in place for cadmium. The situation changed when Codex Alimentarius, an international committee dedicated to protecting consumer health and ensuring fair food trade, considered setting a 200 parts per billion (ppb) limit for cadmium concentration in durum.

Challenged by limits

Gawalko says that even though this limit was only a proposal at the time, it created concern in the Canadian durum industry. If Codex Alimentarius set a standard for cadmium, it was expected that many countries would follow suit and set comparable limits.

"Canadian durum varieties at the time would not have met the proposed Codex limits of 200 parts per billion. This would have been a challenge and could have shut Canada out of markets such as the European Union," he says.

Research team assembled

Not prepared to let this happen, the grain industry took action by assembling a research team tasked with lowering cadmium levels in durum wheat to meet any potential limits set by Codex Alimentarius.

The team consisted of durum wheat breeders, experts in grain quality and trace elements at the Canadian Grain Commission, and marketers. Their collaborative work and research led to the identification of a single dominant gene that reduces cadmium levels by up to half. Incorporation of this gene reduces the cadmium in durum to levels well below proposed international limits. The Canadian Grain Commission started cadmium analysis for breeder lines in 1997.

New, safer varieties developed

Armed with this information, breeders developed new varieties with all the desirable agronomic and quality traits that also absorbed less cadmium from soil. Their work led to the registration of Strongfield in 2004. It was the first Canadian durum variety with reduced cadmium, and it is currently a dominant variety in Canadian durum wheat production.

Lower cadmium made a requirement

Plant breeders showed that it was possible to develop new varieties that absorb less cadmium without detrimental effects on agronomic and quality traits. As a result, the Canadian Grain Commission recommended that all new durum varieties considered for registration have a limit of 100 ppb for cadmium. The recommendation was made to the Prairie Grain Development Committee, a committee that advises the Canadian Food Inspection Agency on variety registration, and was accepted in 2005. All durum varieties registered since then have reduced cadmium.

Durum producers ready for cadmium limits

In 2005, after years of consideration, Codex Alimentarius implemented a limit of 200 parts per billion for cadmium in durum. Years of work on reducing cadmium meant that the durum industry in Canada was well prepared for the Codex limit and ahead of major competitors.

Improvements continue

As more low cadmium durum varieties become available and replace regular varieties, the cadmium levels in most Canadian durum export cargoes are well below the current Codex limit of 200 ppb. They are also low enough to meet cadmium limits of 150 ppb, a limit the European Union is currently considering for cereals, cereal products and oilseeds.

Dr. Bin Xiao Fu, Program Manager for Durum Wheat Research, says that the work on improving durum varieties continues.

"In anticipation of further tightening of cadmium level by the European Union in the long term, further reduction of cadmium concentration will better position Canadian durum in theis market in the future. Breeders continue to work on getting cadmium levels as low as possible. The variety registration system has shown it is flexible and responsive to customers' concerns about grain safety. It has set requirements that help guide breeders and protect markets for producers," he says.

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