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New Instrument Helps in Determining Wheat Quality

By Linda McGraw
October 15, 1997

An automated system to identify wheat classes, characteristics and defects--including kernels damaged by diseases such as karnal bunt or scab--could help grain inspectors verify whether wheat is suitable for export. The first commercial prototype of the system is being demonstrated this week at the annual meeting of the American Association of Cereal Chemists, held in San Diego, Calif., October 12-15.

Karnal bunt is a wheat fungus recently found in areas of the southwest U.S. If samples of wheat contain "bunted kernels"--those infected with karnal bunt-- countries without the disease may not import the infected wheat. So it's critical that uninfected wheat can be certified free of karnal bunt.

Currently, bulk wheat samples are visually examined for bunted kernels. But grain inspectors would need to check only a few wheat kernels with a new instrument designed by Agricultural Research Service scientists and engineers with Perten Instruments North America, Springfield, Ill. The instrument detects either common or karnal bunt and sorts suspect kernels. A positive result would signal the inspector to verify visually whether the suspect kernel is infected with karnal bunt.

In preliminary tests at ARS' Grain Marketing and Production Research Center in Manhattan, Kan., the instrument correctly identified 93 percent of all bunted kernels.

The instrument combines near-infrared technology with an automated system to detect wheat quality in single wheat kernels. It uses an ARS-patented single kernel characterization system and a diode-array spectrometer made by Perten Instruments. Each wheat kernel has a unique physical composition, as shown by light being absorbed differently at various wavelengths. An integrated fiber optic system allows rapid analysis of two kernels per second.

ARS originally designed the system to separate hard and soft wheat classes. In addition to hardness and disease damage, the new instrument measures moisture, protein, color class, and hidden insects in wheat kernels.

Scientific contact: Floyd E. Dowell, ARS U.S. Grain Marketing Research Center, Manhattan, Kan., phone (785) 776-2726 or 2753, fax 776-2792,