Potassium acid carbonate.
Potassium bicarbonate is well known as both a raising agent and leavening agent in baking. The carbon dioxide bubbles help to lighten the texture of the sponge. Potassium bicarbonate is frequently added to various different types of drinks. Some brands of bottled water use potassium bicarbonate in order to improve the taste, whilst in club soda it is used to reduce the effect of effervescence in the liquid, which can often cause an excess number of bubbles and too much fizzing. Potassium bicarbonate also helps to preserve colour in food.