COLOR AND CONDUCTIVITY CHANGES IN APPLE AND POTATO SLICES SUBJECTED TO PULSED ELECTRIC FIELD TREATMENTS

The impact of pulsed electric fields (PEF) on color and electrical conductivities of apple and potato slices was studied. Cylindrical shaped apple and potato slices were used in the study. Pulse widths of 100, 200, and 300 µs; and electric field strengths of 0.75 and 1.5 kV/cm were applied to the slices. The number of pulses applied for apple samples were 1, 5, 30 and 60, whereas 1, 5, 30 and 120 pulses were used for potatoes. Variation in relative conductivity (defined as the ratio of electrical conductivities measured after a given number of pulses and that measured after the first pulse) depended on the applied electric field strength and the number of pulses delivered. Relative conductivity of samples increased exponentially with increasing number of pulses and approached an apparent saturation level. PEF treatments also induced color changes in the treated samples. Increasing electric field intensity from 0.75 to 1.5 kV/cm accelerated discoloration process.