Electrical conductivity of particle–fluid mixtures in ohmic heating: Measurement and simulation

The electrical conductivity (EC) of food systems is a key parameter of the ohmic heating process. Ohmic heating experiments were conducted using a Teflon cylindrical cell. Electrical conductivity values were evaluated for the ohmic processing (25–125 °C) of blanched, 2-cm cubic particles (carrot, potato, radish, beef muscle, pork muscle and commercial ham) dispersed in carrier fluid (5% w/w starch–water solution with 0.15–1.5% w/w salt concentrations). Assuming an analogy between thermal conductivity (TC) and EC five existing TC theoretical models (series, parallel, two forms of Maxwell–Eucken models and effective medium theory) were applied and evaluated for EC of various solid–fluid structural systems. Parallel and Series models are not practically applicable in real food system, however they can indicate the useful limit values of highest and lowest EC among all two-phase structures. The first Maxwell–Eucken model, which describes solid particles dispersed in continuous liquid, showed the best agreement between predicted EC values and experimental data. This model provided a useful and relatively simple new approach to predict the effective EC for mixtures of different types of solid food particles immersed in liquid food.