Potassium bicarbonate is coated with an anionic or amphoteric surfactant, which is preferably a metal soap, such as calcium stearate, to inhibit caking on storage, and premature loss of carbon dioxide when mixed with acidulant, e.g. in a baking powder or self-raising flour blend. Loss of carbon dioxide in the blend may be further inhibited by coating the acidulant with surfactant. Combination of surfactant coating with an inorganic anti-caking agent such as silicon dioxide gives synergistic protection against caking of the potassium bicarbonate. Preferably the bicarbonate has D50 of between 35 and 200µ and is free from particles greater than 400µ.
