Effects of Processing and Temperature on Imidacloprid Residues in Chrysanthemum morifolium

Effects of processing and temperature on the residual content of imidacloprid in Chrysanthemum morifolium were investigated. As indicated by the level of the pesticide residues in commercial C. morifolium products on the market, the common field spraying practice on the plants seemed acceptable for meeting the food safety requirement. For this study, at various processing stages the imidacloprid concentrations in the dried chrysanthemum buds and flowers were reduced by 6.36% and 8.71%, respectively, during blanching; 3.99% and 4.48%, respectively, during thermal dehydration; and, 13.18% and 29.60%, respectively, during ambient temperature drying. It showed that imidacloprid was largely dissipated from the products by drying under ambient conditions. Evaporation apparently raised the relative imidacloprid concentration in the finished products. Under high temperatures, the rate of imidacloprid reduction in a thermal dehydration was greater than that of an ambient drying suggesting the possibility of pesticide degradation by heat.