Inactivation of Saccharomyces cerevisiae in solution by low-amperage electric treatment

Abstract

Aims: The objectives of this study were to investigate the potential application of a low-amperage direct electric current as a non-thermal process for inactivation of Saccharomyces cerevisiae.

Methods and results: Electric current was generated using a direct current power supply connected to a traditional electrochemical cell with two platinum electrodes immersed in conducting solution containing a population of S. cerevisiae. This treatment provoked inactivation of the yeast cells. The microbial destruction illustrated by D-values calculated from survival curves was shown to be proportional to the current amperage (i) (D varies from 1547 min to 140 min when i varies from 0.1 to 1 A, respectively). The efficacy of the treatment was shown to be better at pH < 7. Statistical analysis showed no significant effect (P > 0.05) of ionic strength on yeast lethality induced by electrolysis.

Conclusions: The lethal effect of the electric treatment on S. cerevisiae in phosphate buffer was shown to be due to neither ohmic heating nor toxic hydrogen peroxide. A synergistic effect of temperature and electrolysis was observed when the temperature became lethal for the yeast.

Significance and impact of the study: The method described for yeast lethality induced by electrolysis has potential for soft sterilization, particularly when combined with the synergistic effect of moderate heat.