We revealed previously that the effect of microbial inactivation with supercritical CO2 depended on the concentration of CO2 dissolved in the solution.Micro-and nano-bubbles (tiny bubbles with diameters of less than 50 μ m) are abundantly dissolved in the solution.Therefore,we devised an instrument with micro-and nano-bubbled CO2 under pressure less than 2.0 MPa (MNB-CO2) for the purpose of inactivating microorganisms in food at near room temperature.