Abstract
Pulsed electric field sterilization becomes getting popular technique for sterilizing liquid foods with normal temperature. However, its electrical energy efficiency, inactivation ratio of bacteria divided by input energy, has been low with using ordinary plate-to-plate type electrode system. The authors proposed a concentric electric field electrode configuration to raise energy efficiency. In the present study, the effect of operating conditions with varying design parameters of the sterilizer on the survivability of microorganism was studied experimentally. A spiral electrode sterilizer, which is two spiral wires that were connected to pulse source and ground, was the most efficient electrode system in our study. The survival ratios of Escherichia coli K-12 were decreased with increasing pulse peak voltage and capacitance value, however, they were dependent on the input electrical energy calculated by applied voltage and pulse forming capacitor. When 300 J/ml of electrical energy was applied, 10 -5 of survival ratio could be achieved without relating to the applied voltage and pulse forming capacitor. Electrical conductivity of the liquid greatly affected to the survival ratio where the sufficient inactivation was achieved less than 5 mS/cm.
