Milk thermization by pulsed electric fields (PEF) and electrically induced heat

Whole milk was processed using selected combinations of pulsed electric fields (PEF) and thermal treatments to inactivate Listeria innocua. Electric field intensities of 30 and 40 kV/cm were applied at selected number of pulses (1-30) and temperatures (20-72 degrees C) for less than 10 s. A maximum microbial reduction of 4.3 log cycles was achieved using 10, 17.5, 20 and 25 pulses, when processing milk at 30 kV/cm and initial temperatures of 43, 33, 23 and 13 degrees C, respectively. Around 4.3 log cycles of L innocua was observed when treating milk at 40 kV/cm using 3, 10, 12.5, 15, and 20 pulses and 53, 33, 23, 15, and 3 degrees C, respectively. Milk treated with 40 kV/cm of electric field intensity, few pulses, and initial temperature close to 55 degrees C showed the best balance between L innocua inactivation and energy-consumption. An energy expenditure of around 244 J/mL was achieved, which can be further reduced to 44 J/mL using a thermal regeneration system. (C) 2010 Elsevier Ltd. All rights reserved.