Impact of Pulsed Electric Fields on the Dehydration and Physical Properties of Apple and Potato Slices

Abstract

The effect of pulsed electric fields (PEF) on drying and some physical properties of apple and potato was evaluated. Pulsed electric field intensities from 0.75 to 1.5 kV/cm with pulse duration within 100 and 300 μs were studied. The number of pulses applied was up to 120. Measurement of porosity and density were conducted using a mercury porosimeter. The drying process was carried out in a convective air oven at 70°C. The compressive strength of apples was reduced between 21 and 47% after treatment. The results show potential advantage for PEF enhanced juice extraction from the tissues even at moderate PEF treatment. PEF treatment increased porosity and particle density but decreased bulk density. Treating the apple samples with PEF resulted in generation of more pores of sizes in the order of cell wall thickness. Thus electric field application affected not only cell membranes but also cell wall integrity. PEF treatment enhanced drying rates of potato samples. Diffusion coefficients of PEF pretreated potato samples increased by up to 40%.