It can be concluded that the electrical conductivity of fruit purees is strongly dependent on temperature and dependent on ionic concentration and pulp content. The electrical conductivity of the fruit purees increased with temperature rise, linearly. The rate of change of temperature for the apricot puree was higher than the peach puree at all voltage gradients applied. Bubbling occurred above 60 C especially at higher voltage gradients. The selection of inert electrode coatings, the use of high frequency power and the prevention of air bubbles in the sample could avoid the occurrence of the bubbles. The mathematical models taking the system performance coefficients into account can be used to predict accurately the ohmic heating times of fruit purees. The determination of electrical conductivity changes and system performance coefficients during ohmic heating are important in the design of ohmic heaters.