Dielectric Behavior of a Semi-Solid Food at Low, Intermediate and High Moisture Contents

Publisher Website
Google Scholar
Abstract
The dielectric behavior of a semi-solid food was essentially predicted at 3 GHz, 25°C, for a range of moisture contents and water activities, by an electrophysical model for two-phase heterogeneous mixtures based on lumped-circuit analysis. The model involved an active aqueous ionic phase and an inert solids phase whose properties were estimated from proximate analysis data. A critical level of water activity was seen for activation of conductive loss mechanisms which appeared to be related to the availability of water in mobile forms. This is seen to involve ionization of salts below saturation levels and salts bound to food solids at low moisture contents. Observed dielectric behavior was primarily associated with water and ion activities and is believed to result from the ionization and subsequent dilution of aqueous ions as moisture contents were increased by sorbing samples at progressively higher water activities. The state of wafer in semi-solid foods is seen in terms of relative mobilities which appear to be related to the kinetics of microbial growth and biochemical reactions of foods in prolonged storage at low and intermediate moisture contents. Results of this and previous work suggest that bound water relaxations are negligible at microwave frequencies.

This publication has 1 reference indexed in Scilit: