Sterilizing effect of low temperature atmospheric pressure plasma on yeast

The sterilizing effect and the inactivation mechanisms of low temperature atmospheric pressure helium plasma generated by dielectric barrier discharge and atmospheric cold plasma jet generated by capillary atmospheric dielectric barrier discharge on baker's yeast were analyzed and compared.The relationship of survival number versus plasma treatment time and that of yeast pH value versus plasma treatment time using different plasmas were studied.The morphology of the yeast was observed by scanning electron microscopy.Results demonstrate that two kinds of plasma have strong sterilization effect on the yeast.At least a 7 log 10reduction in the survival number after being treated with plasma generated by dielectric barrier discharge and at least a 8 log 10reduction in the survival number after being treated with cold plasma jet generated by capillary atmospheric dielectric barrier discharge are realized.Simultaneously,pH value has remarkable change after two kinds of plasma treatment and it is more remarkably changed for atmospheric cold plasma jet generated by capillary atmospheric dielectric barrier discharge.The yeast treated with two kinds of plasma ruptures completely.It is demonstrated that the sterilizing effect of cold plasma jet generated by capillary atmospheric dielectric barrier discharge is stronger than that generated by dielectric barrier discharge.The inactivation mechanisms are concerned with the rupture of the yeast and the pH value change.