Assessment of microwave energy for disinfestation of grain

Infestation of grain by insects is widely controlled by the use of insecticides. Use of contact insecticides results in chemical residues left in the food which may have adverse effects on humans. Also insects develop resistance to both contact insecticides and fumigants. Microwave disinfestation offers an alternate way to disinfest grain. Microwaves are electromagnetic waves with frequencies ranging from 300 MHz to 300 GHz. The use of microwaves for killing insects is based on the dielectric heating of insects present in grain, which is a relatively poor conductor of electricity. There is a possibility of selective heating of insects in grain because of a significant difference in dielectric constants between grain and insects. The major advantage of using microwave energy is that no chemical residues are left in the food and insects are unlikely to develop resistance to this treatment. Principle of microwave disinfestation, experimental results from previous studies and the advantages of using microwaves for disinfestation of grain are discussed.