Abstract
Dielectric constants of raw and gelatinized rice powder were measured as a function of water content at 9. 4 GHz. Both constants agreed well within the whole water content.
The state of water in rice powder was explained as follows.
1) Within 08%; ε′ is fairly small and nearly constant. All water molecules are bound.
2) Within 835%; ε′ changes in accordance with Bruggeman-Hanai theory for W/O emulsion. Free water molecules are dispersed in rice powder.
3) Within 4050%; ε′ and ε″ change sharply with change in water content. Interfacial polarization of dispersed water particles may disappear with increase in water content due to the formation of conducting paths.
4) Within 60100%; ε′ increases slowly as water content increases. Considering changes of the density of specimens in this range, rice powder would be dispersing in water like O/W type emulsion.
