Wheat disinfestation using microwave energy

A pilot-scale industrial microwave system operating at 2.45 GHz was used to determine the mortality of three common species of stored-grain insects, namely Tribolium castaneum, Cryptolestes ferrugineus, and Sitophilus granarius. Wheat samples (50 g each) at 14%, 16%, and 18% moisture content (wet basis) were infested with 5, 10, or 15 insects. The infested samples were then exposed to microwave energy at four different power levels 250, 300, 400, and 500 W for two exposure times of 28 and 56 s. Complete kill of adults of all three species and of post-embryonic stages of T. castaneum was achieved at 500 W with an exposure time of 28 s. There was a significant difference in the mortality of T. castaneum and C. ferrugineus adults at 14% and 16% moisture content (m.c.) wheat but there was no significant difference in the mortality at 16% and 18% m.c. Mortality of insects increased with either power or exposure time or both. Germination of wheat kernels was lower after treatment with microwave energy. Milling and baking tests were done for the samples at which 100% mortality was obtained. There was no significant difference in the quality of grain protein, flour protein, flour yield, flour ash, and loaf volume of wheat treated with microwave energy.