Electrical conductivities of three vegetable and two meat samples were determined by subjecting them to a constant voltage power supply in a static ohmic heating device. Conductivities of vegetable samples were increased by soaking them in salt solutions, while soaking in water resulted in reduced conductivity due to leaching of electrolytes. Conductivities under ohmic heating conditions increased linearly with temperature. When field strengths were decreased, the conductivity‐temperature curve gradually became nonlinear, and under conventional heating conditions, a sharp transition was observed.

A device was developed to determine the electrical conductivities of foods under ohmic or conventional heating conditions. Orange and tomato juices (serum and various solids contents) were tested in the device. the electrical conductivity of juices increased with temperature and decreased with solids content. the temperature dependence of conductivity was linear, both under conventional and ohmic heating. Experiments on suspensions of carrot juice solids, and polystyrene spheres in sodium phosphate solution showed an increase in electrical conductivity of the suspension with decreasing particle size.

Understanding of the ohmic heating of liquid‐particle mixtures requires preliminary study and model development within a static heater. A mathematical (3D finite element) model was developed for prediction of temperatures of mixtures of liquids and multiple particles within a static heater. Experiments were conducted using cubic potato particles within sodium phosphate solutions, for various particle sizes, orientations, concentrations, and liquid conductivities. the mathematical model was found to yield satisfactory prediction of experimental trends. Critical parameters affecting the relative heating rates of particles and liquid were the conductivities of the two phases, and the volume fraction of each phase. Ohmic heating appears most promising with high‐solids concentration mixtures.

Suspensions of yeast cell (zygo Saccharomyces bailii) in a phosphate buffer solution were subjected to conventional (hot water) and ohmic (electric current) heating under identical temperature histories. Experiments were also conducted with cells of Escherichia coli to compare the lethal effect of combination of sublethal electrical preteatment and conventional heating with conventional heating. The kinetic parameters (D,Z,K and E(a)) were determined for both organisms during different treatments. There was no significant difference in the death rate of yeast cells during conventional and ohmic heating at the voltage range used in this study. Results of electrical pretreatment and conventional heating on E. coli indicated differences under certain conditions when compared with pure conventional heating. Thus it is concluded that microbial death during ohmic heating was due primarily to thermal effects with no significant effect of electric current per se. Sublethal electrical pretreatment appears to offer potential for increased bacterial inactivation in certain cases.

The effect of high pressure treatments at various temperature combinations on the inactivation of Clostridium botulinum type E spores of strains, Alaska and Beluga in phosphate buffer (0.067 M, pH 7.0) was investigated. No reduction of spores was observed at any pressurization (Maximum = 827 MPa) for temperatures below 35C. At pressurization of 827 MPa for 5 min, log unit reduction of spores increased as temperatures increased from 35 to 55C. An increase in the processing time from 5 to 10 min at a combination of high pressure (827 MPa) and low temperature (40C) resulted in a 5‐log reduction of Alaska spores. About 5‐log reductions for strains Alaska and Beluga occurred at 50 and 55C, respectively, after processing at pressures of 827 MPa for 5 min.