Effects of pulsed electric fields treatment on vacuum drying of potato tissue

Effects of pulsed electric fields (PEF) on vacuum drying of potato tissue were studied. PEF treatment was done using electric field strength of E = 600 V/cm and total treatment time of tPEF = 0.1 s to reach a high level of potato tissue disintegration. The vacuum drying was performed at sub-atmospheric pressure, p = 30 kPa (that corresponds to the boiling temperature of water ≈ 70 °C), and different temperatures, Td = 40, 50, 60 and 70 °C. The evolution of temperature inside the sample and moisture content were compared for the PEF treated and untreated samples. The dried samples were analyzed using scanning electron microscopy, textural, and capillary impregnation tests. At all drying temperatures the most significant part of free water was evaporated at relatively low temperatures inside samples (18-27 °C) and the effects of starch gelatinisation were excluded. The PEF treatment allowed noticeable decreasing of drying time (by 22-27% at Td = 40-70 °C). The significant effects of PEF on texture and microstructure of dried potato tissue were revealed.