Aqua-gas system is a recently developed food-processing system using superheated steam containing microdroplets of hot water.In this system,pressurized boiling water and steam around 130℃ are sprayed onto the food undernormal pressure through a nozzle.The steam is throttled andbecome superheated steam at 115 to 120 ℃.The hot water is atomized with the steam flow and is suspended in superheated steam.Previous studies revealed that existence of the microdroplets of hot water enhanced thermal inactivation effect of superheated steam for microorganisms.