Simulation and experimental investigation of food material breakage using pulsed electric field treatment

We consider the simplified dielectric breakage model used for simulation of the kinetics of food material breakage under pulsed electric field (PEF) treatment. The model is based on an effective media approximation, which includes equations with the same morphology parameters as in percolation theory. The probability of a whole cell breakage by a pulse of t(i) duration is estimated on the basis of electroporation theory. We account for the bridging effect resulting from the deviations of the local conductivity near the selected cell from the average effective media conductivity. The most important feature of the proposed model is the existence of the jamming behaviour occurring sometimes in experimental observations of the biological tissue breakage. The different transitions corresponding to the jamming steps are identified. Experimental results were obtained for thin apple slices treated with electric pulses at field strengths E = 0.2-2.2 kV cm(-1), pulse durations t(i) = 10-100 mu s, pulse repetition times t = 10-100 ms and the number of pulses n = 1-100 000. The model gives results consistent in general with the experimental observations. We discuss the correlation between the degree of food material destruction, field strength, time of PEF treatment and power consumption. (C) 2000 Elsevier Science Ltd. All rights reserved.