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Keywords:

  • cell size;
  • disintegration index;
  • electrical conductivity;
  • plant tissues;
  • power consumption;
  • pulsed electric fields

Abstract:  Efficiency of pulsed electric field (PEF) induced permeabilization at 293 K in selected fruit and vegetable plant tissues (apple, potato, carrot, courgette, orange, and banana) at electric field strength (E) of 400 V·cm−1, 1000 V·cm−1 and pulse duration (tp) of 1000 μs was studied experimentally. The mean cell radius (〈r〉) was within 30 to 60 μm, and the ratio of electrical conductivities of the intact and damaged tissues (σid) was within 0.07 to 0.79 for the studied tissues. Electroporation theory predicts higher damage for tissue with larger cells; however, the direct correlation between PEF damage efficiency and size of cell was not always observed. To explain this anomaly, a theoretical Monte Carlo model was developed and checked for parameters typical for potato tissue. The model showed a strong dependence of PEF damage efficiency and power consumption (W) on σid ratio. The optimum value of electric field strength (Eopt) was an increasing function of σid, and plant tissues with high σid ratio (σid≈ 1) required application of a rather strong field (for example, Eopt≈ 3000 V·cm−1 for σid≈ 0.8). However, the PEF treatment at a lower field (E≈ 400 V·cm−1) allowed regulation of the selectivity of damage of cells in dependence of their size. A good qualitative correspondence between experimental data and simulation results were observed.