Acidic salts are often used in foods as part of leavening agents. In this context, the acid salts are referred to as "leavening acids." Common leavening acids include cream of tartar and monocalcium phosphate.
An acidic salt can be mixed with an alkali salt (such as sodium bicarbonate or baking soda) to create baking powders which release carbon dioxide. Leavening agents can be slow-acting (e.g. sodium aluminum phosphate) which react when heated, or fast-acting (e.g., cream of tartar) which react immediately at low temperatures. Double-acting baking powders contain both slow- and fast-acting leavening agents and react at low and high temperatures to provide leavening rising throughout the baking process.
Disodium phosphate, , is used in foods and monosodium phosphate, , is used in animal feed, toothpaste and evaporated milk.