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.