EVALUATION OF A HIGH-SPEED COLOR SORTER FOR SEGREGATION OF RED AND WHITE WHEAT

Authors: Pasikatan, Melchor; Dowell, Floyd

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2002
Publication Date: 1/1/2003
Citation: Pasikatan, M.C., Dowell, F.E. 2003. Evaluation of a high-speed color sorter for segregation of red and white wheat. Applied Engineering in Agriculture. 19(1):71-76.

Interpretive Summary: The color class of wheat is related to its end use, and thus its market price. A rapid means of segregating red from white wheat may help sellers receive premiums offered by the market for pure white wheat lots and avoid the disincentive for wheat of mixed classes. Wheat breeders also need color class sorting to ensure the purity of their breeding lines. They need an automatic means of purifying white wheat samples to replace the manual method of removing white wheat from hundreds of early generation populations which can contain >98% red kernels. A commercial high-speed color sorter that used either red or green filter was evaluated for sorting wheat blends. Common varieties of white and red wheat were mixed to form 10 wheat blends with 95% white and 5% red wheat by mass. When a wheat blend was passed once through the sorter, at least 15% of the total wheat mass needed to be rejected in order to reject most of the red wheat. This rejection would leave <1% red wheat in the portion accepted by the sorter for blends where red and white wheat had considerable color contrast. For blends where the color contrast between red and white wheat was substantial-to-negligible, reduction of red wheat in the accept portion to <1% would require rejection of 20-25% wheat mass in a single pass through the sorter. The same results could also be achieved by a second pass of accept portion through the sorter rejecting 15% mass on the first pass and 10-15% mass on the second pass. The red filter detected and thus rejected more red wheat than the green filter.

Technical Abstract: A high-speed color sorter has the potential to help wheat breeders purify their white wheat breeding lines and white wheat exporters to meet purity requirements of end users. For this reason, a color sorter was evaluated for sorting mixed red and white wheat. Single-pass sorting procedures, which rejected 15, 20, and 25% of the wheat mass, were studied using red and green filters for 10 wheat blends from common cultivars of hard white and hard red winter wheat. Wheat blends contained 95% white and 5% red wheat. Percent red and white wheat in the accept and reject portions were determined by soaking in sodium hydroxide. For wheat blends with white wheat of consistent color that contrasted considerably with the red wheat contaminant, the amount of red wheat in the accept portion could be reduced to <1% when 15% of the wheat mass was rejected. This reduction could be achieved for most other blends when rejecting 20-25% of the mass or through re-sorting the accept portion. The red filter resulted in more red kernels rejected than the green filter.