The invention relates to a method for extracting the gluten contained in a sample using an ethanol aqueous solution in the presence of a composition containing a disulphur group reducer and a decoupling agent, in a buffer having a pH of between 7 and 8. The inventive method can be used to extract quantitatively the gluten contained in a heat-processed or non-heat processed food sample before the quantification of the gluten by ELISA. The method is suitable for food analyses, in particular, for foodstuffs intended for celiac sufferers.