[Problem to be solved] To provide a method for sterilizing powder or grain bywhich theheating time is a minimum required time to reduce thermal degradation of thequality ofthe powder or grain while securing sufficient sterilization effect, and asterilizingapparatus employing the method.[Means to solve the problem]The problem is solved by a method for sterilizing powder or grain, and asterilizingapparatus employing the method, and the method includes applying heat andpressure inwhich powder or grain is supplied into a heated gas flow pipe kept underheated andpressurized conditions, and the powder or grain is transferred while cominginto directcontact with a heated condensable gas in the heated gas flow pipe for 0.008 to2 seconds,and instantaneous reduced pressure sterilizing in which the heated condensablegas andthe powder or grain are instantaneously released into a space having apressure lowerthan that in the heated gas flow pipe, water contained in microorganismsadhering to thepowder or grain is boiled rapidly, and tissues of the microorganisms aredestroyed.
