Effect of storage condition and time on the odor of malathion-treated wheat

Wheat samples treated with premium grade malathion or technical grade malathion were submitted to two different types of sensory panels who were used to discriminate between the odor of treated and untreated wheat.Unselected panelists had difficulty distinguishing treated from untreated grain. Eight panelists selected for their ability to detect insecticide odors in wheat found there was no change in the odor difference between protectant-treated and untreated wheat during 8 weeks storage. However, grain protectant odor seemed somewhat more difficult to detect when the wheat was stored in open containers.A technical grade malathion odor was more obvious in wheat than the premium grade malathion, though the odor of the technical grade malathion decreased markedly over time especially when the treated grain was stored in open containers. In fact, when storage in open containers was used, the patterns of numbers of correct triangular discriminations and ratings of odor difference between treated and untreated wheat were similar for both formulations. A statistically significant proportion of panelists, selected or unselected, never considered the premium grade malathion odor obnoxious.