The present invention relates to a method for preparing a foaming beverage powder, the method comprising: providing a porous beverage powder; heating the porous beverage powder to a temperature below its glass transition temperature in a gas-containing atmosphere; increasing 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; and then 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.