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Accurate Test for Determining Wheat Color Class

By Linda McGraw
November 27, 2000

The ability to separate hard red wheats from whites has been improved by Agricultural Research Service scientists.

It’s an important advance for export markets because baking and milling characteristics of hard red and white wheat varieties differ--and they’re difficult to distinguish visually. Wet weather and other environmental factors can add to the difficulty. For instance, red wheat that’s been rained on can look white. Red wheats are typically used for baking breads, but white wheats are used to produce bright yellow noodles for Asian consumers.

The new test uses a dilute sodium hydroxide to accentuate color differences between the reds and the whites. Perten Instruments in Springfield, Illinois, has already turned the test into a kit available to aid grain elevator operators.

The idea is not new, but until now the procedure has not been standardized enough to serve as a reliable indicator. ARS postdoctoral chemist M.S. Ram and agricultural engineer Floyd Dowell at the Grain Marketing and Production Research Center in Manhattan, Kansas, optimized the procedure so that correct color class can be determined in 10 minutes. Grain elevator operators can use the kit at a cost of only pennies per sample.

Several grain elevator managers in Kansas used the kit during the 2000 winter wheat harvest season. USDA’s Federal Grain Inspection Service (FGIS) is considering adopting the kit as an alternative to visual inspection now voluntarily performed by grain inspectors.

The kit includes a heater, test tubes, thermometer and enough sodium hydroxide to last through harvest. It costs about $100 and is available from Perten Instruments or from the Kansas Grain and Feed Association, Topeka, Kansas. This project was funded by the Kansas Wheat Commission and administered through the Grain Industry Alliance under a Cooperative Research and Development Agreement (CRADA). The research may help expand export markets for hard white wheat, which is becoming more popular with Great Plains wheat farmers.

ARS is the chief scientific research agency for the U.S. Department of Agriculture.

Scientific contact: Floyd Dowell, ARS Grain Marketing and Production Research Center, Manhattan, Kan., 66502, phone (785) 776-2753, fax (785) 776-2793,