Durum wheat kernel size and its impacts on milling quality

Canada is a global leading exporter of durum wheat, and Canada Western Amber Durum (CWAD) wheat is the second largest wheat class produced in Canada. CWAD is highly sought after by end-use buyers because eligible varieties have superior milling quality with high semolina yield and low ash content. They’re also high in yellow pigment and protein contents with strong gluten properties.

The Grain Research Laboratory’s Bread Wheat and Durum research team studied different durum varieties and kernel sizes to better understand the factors affecting milling quality. They found that the kernel size of durum wheat, which can be impacted by growing conditions like drought, is effective at predicting milling quality at times when test weight failed to differentiate and protect quality expectations.

Small kernels showed much greater variability in test weight than medium and large kernels. The research team suggests monitoring kernel size distribution, in addition to test weight, when there is a greater chance that small kernels can be present.

Semolina and total milling yields also reduced gradually when they saw a decrease in kernel size from large to medium kernels. With small kernels (those passing through a no. 6 slotted sieve), they saw a drastic decrease in milling yields and an increase in ash content. Increased ash content can significantly affect the end-use performance and product colour.

Their research highlights the important role of intrinsic kernel properties in durum milling. They observed that medium-sized kernels from varieties with superior milling quality had higher milling yield than large kernels of inferior milling quality. Further research is needed to explore the underlying factors that contribute to the varietal difference in milling quality of durum wheat.