The invention relates to methods for producing flavor stable beverages. The methods involve reducing the level of one or more amino acids, and in particular the level of methionine. The level of amino acids may be reduced by a number of different methods, for example by increasing the level of acid or base and removal of said acid or base by Reverse Electro-Enhanced Dialysis. The level of amino acids may also be reduced by treatment with an oxidizing agent, such as H2O2. The invention also comprises combinations of such methods.