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Keywords:

  • high voltage;
  • spore;
  • electric pulse;
  • sterilization;
  • Bacillus

ABSTRACT

Electric field strengths (E) from 20 to 50 kV/cm with pulse numbers ranging from 15 to 50 were applied to Bacillus spore suspensions in 0.10 to 0.15% NaCl solution. The lowest count of viable spores, expressed as the logarithmic ratio of initial count before treatment to surviving spores (log(No/N) geqslant R: gt-or-equal, slanted 3.425 and 5 at 25°C) was obtained at 50 kV/cm with 30 and 50 pulses for B. subtilis and B. cereus, respectively. The log(No/N) increased with increased treatment temperature or increased time gap between pulses. Spores were unable to repair damage even after 1 mo.