Cell Permeabilisation, Microstructure and Quality of Dehydrated Apple Slices Treated with Pulsed Electric Field During Blanching

Effect of pulsed electric field as a blanching pretreatment on cell permeabilisation, microstructure and quality of dehydrated apple slices was studied. Apple slices were pulsed electric field pretreated (1.0 kV/cm, 1.5 kV/cm, and 2.0 kV/cm using 25 and 75 pulses) at a temperature of 60 °C and 80 °C in water followed by dehydration at 60 °C in a cabinet dryer. Cell disintegration index was found to increase significantly (p<0.05) with increase in the electric field strength, number of pulses and blanching temperature and thereby reducing the drying time. The dehydrated slices showed lower hardness and higher lightness (L*) values for the samples treated at higher electric field strength for longer durations. Scanning electron microscopic studies of samples revealed better retention of cellular integrity when pre-treated at a low level of PEF (1.0 kV/cm using 25 pulses) and blanched at low temperature (60 °C). However, the samples treated to a level of 1.5 kV/cm and 75 pulses of PEF with subsequent blanching temperature 80 °C was found to yield optimum cell permeabilisation. The study suggests that PEF can be used as an effective blanching pretreatment for achieve good quality dehydrated apple slices in less drying time.