Inactivation of Saccharomyces cerevisiae by CO2 Microbubbles at a Lower Pressure and Near Ambient Temperature

Abstract

The ability of CO2 microbubbles (MB-CO2) to inactivate Saccharomyces cerevisiae suspended in a physiological saline solution at a pressure lower than 2.0 MPa was investigated. A 6-log reduction in the S. cerevisiae population was induced by MB-CO2 at 40C and 2.0 MPa after a 50 min treatment in a physiological saline solution with 5.0% ethanol, and a 3-log reduction was induced by low-pressurized CO2 under the same conditions. Furthermore, the ability of MB-CO2 to inactivate S. cerevisiae increased concomitant with increasing the CO2 feeding rate, pressure, temperature, and ethanol concentration in a physiological saline solution. Additionally, the decimal reduction time (D value) in the inactivation of S. cerevisiae by the MB-CO2 treatment might depend on the saturation value of the dissolved CO2 concentration in the solution. These results suggested that MB-CO2 treatment could inactivate S. cerevisiae in a low-concentration ethanol solution at 40C to 45C and at a pressure of 1.0 to 2.0 MPa.