Microwave dielectric properties of foods and some other substances

Abstract

Abstract: Without the dipolar properties of water at microwave frequencies, there would be no life on earth, and certainly no microwave food heating. The microwave oven frequency of 2450 MHz was chosen rather arbitrarily 60 years ago and is indeed optimal for the purpose. But even a quite small ionic content causes a comparable absorption of microwaves to that of water. With the increased use of microwave modelling, accurate dielectric and thermal data for foods are becoming more important. The binding of water in various components is accounted for in mixture formulae, including semi-frozen foods. The limits of use for dielectric data for homogenised samples (MUTs) for computations of the ‘effective’ microwave permittivity are also dealt with. Finally, microwave data for some food container materials are given.