Treatment of potato tissue by pulsed electric fields with time-variable strength: Theoretical and experimental analysis

• Treatment of potato by pulse electric fields (PEF) was studied.
• Different strategies of treatment with time-variable electric field strength E were studied.
• PEF experiments with disk-shaped and compressed sliced potato samples were done.
• Predictions of theory were compared with the data of experiments.
• Optimized PEF protocols with time-variable E were discussed.

This work discusses efficiency of pulsed electric field (PEF) treatment of cellular material with time-variable electric field strength, E. The potato was selected as a model tissue. Computer model, based on electroporation theory, was developed to simulate different strategies of E value changes. In the experimental part of this work, the PEF treatment was applied to disk-shaped and sliced samples using a laboratory compression chamber, equipped with a PEF-treatment system. The experiments were done using PEF generator that provided pulses of near-rectangular shape, the pulse duration was ti = 1000 μs, the value of E was varied within 200 and 800 V/cm, and the total time of PEF treatment, tPEF, was varied within 0 and 0.1 s. The electrical conductivity disintegration index, Z, was used for characterization of the PEF-induced damage of potato tissue. Both theory and experiment predicted the minimum power consumption Wo at the optimal value of Eo ≈ 400 V/cm. The computer simulation predicted that application of protocols with time-variable electric fields would allow optimization of PEF treatment with initial electric field Ei deviating from the optimal value Eo. PEF experiments revealed that exponential increase of E values can be useful at small initial electric field strengths, E < Eo, as far as it allows significant improvement of PEF-treatment efficiency. The PEF experiments with pressing of potato slices have shown that PEF treatment before pressing was more efficient than treatment during the pressing, and the specific energy consumption for the both samples was approximately the same (W ≈ 7.5 kJ/kg).