The present invention relates to a process for preparing a formulation comprising an alkali metal salt selected from the group consisting of alkali metal bicarbonate salts, alkali metal carbonate salts, alkali metal sesquicarbonate salts and combinations thereof, wherein said process comprises the step of extruding a paste-like composition comprising a functionalizing agent and the metal salt. The invention furthermore relates to a formulation obtainable from said process and to the use of this formulation in various applications such as in plastic foaming or in food and feed leavening compositions.