The present invention relates to a method for preparing a foaming beverage powder, the method comprising:providing a porous beverage powderheating the porous beverage powder to a temperature below its glass transition temperature in a gas-containing atmosphereincreasing the pressure of the gas-containing atmosphere to thereby raise the temperature of the porous beverage powder to a temperature above its glass transition temperature andthen decreasing the pressure of the gas-containing atmosphere to thereby lower the temperature of the porous beverage powder to a temperature below its glass transition temperature.