Sterilization of Yakju(Rice Wine) on a Serial Multiple Electrode Pulsed Electric Field Treatment System

Yakju(rice wine) was sterilized with high-voltage square-wave pulses of duration at various electric field strengths and frequencies on a serial multiple electrode pulsed electric field(PEF) treatment system consisted of 7 electrodes connected in series. The initial microbial counts of Yakju were CFU/mL for total aerobes, CFU/mL for lactic acid bacteria and CFU/mL for yeasts. The sterilization of microorganisms in Yakju was a first order reaction and the sterilization effect increased as the field strength and the frequency increased. The and the decreased with the electric field strength. Yeast showed lower than bacteria. Lactic acid bacteria showed lower than general aerobic bacteria under the electric field strength below 30 kV/cm, but higher ones under that above 40 kV/cm. The of general aerobic bacteria, lactic acid bacteria and yeast in Yakju were 39.4, 49.3 and 47.6 kV/cm, respectively. The PEF sterilization resulted in less changes in color and sensory properties than heat sterilization, and the PEF treated Yakju showed superior quality to the heat treated one. The commercial sterilization of Yakju was accomplished with 2-cycle treatment on the tested serial PEF treatment system.