Microwave Applications in Food Industries

Microwave heating is a process of heating technique, where heating causes the electric field to polarize the charges in the material by two mechanisms namely polarization and conduction. Microwave frequencies have very short wave lengths (33.3 cm at 900 MHz, 12.2 cm at 2450 MHz). This process is based on the ability of a particular substance to absorb microwave energy and effectively convert the electromagnetic energy to heat. Due to mechanical oscillation, the frictional forces within the molecules cause heat to be de veloped due to the motion of dipoles. Microwave heating includes induction, radio frequency, direct resistance or infra-red heating. Microwaves have many advantages in food processing such as drying, tempering, blanching, cooking, pasteurization, sterilization, and baking. When compared with convectional heating methods, microwave heating has considerable advantages, high reliability, especially with regard to energy efficiency, most efficient in drying within the falling rate period, puffing of a material in case of doughnuts by internal pressure. During microwave heating, heat is transferred from the surface of food to the interior by convection and conduction. By using microwave heating processing of chunks of meat, sardines, and skinless frankfurters can be done. Microwave bread pasteurization is one of the processes which enhances the destruction of micro organisms and heat liable spores during cooling, slicing, and packaging operation. The present study involves microwave applications in different food processing operations.