A method based on the electrical conductivity measurements is proposed to estimate the characteristic damage time (tau) of a food material in pulsed-electric fields (PEF). Empirical dependencies of tau versus electric field intensity E are obtained for apple, carrot and potato tissues. The generalized electroporation theory accounting for the sphericity of biological cells and distribution of their geometric sizes gives a credible description of the experimentally observed dependencies tau(E). An optimal electric field intensity E-opt that corresponds to minimum of power consumption at maximum of material disintegration is estimated theoretically and experimentally. For investigated tissue materials, the experimentally estimated value of E-opt is approximately 400 V cm(-1). The energy consumption during the PEF treatment at E-opt approximate to 400 V cm(-1) decreases in the next order: apple --> carrot --> potato. (C) 2002 Elsevier Science Ltd. All rights reserved.