Sodium Bicarbonate
What it does
Raising agent, acidity regulator.
How it's made
Manufactured (soda ash process).
Sodium bicarbonate — bicarbonate of soda or baking soda — is the classic raising agent, releasing carbon dioxide to make cakes, breads and biscuits rise. It is also used as an acidity regulator and is the alkaline partner in baking powders. It is the same substance used as a mild antacid.
It is made industrially, most famously by the Solvay process, in which salt (sodium chloride), ammonia and carbon dioxide are reacted in a brine solution; sodium bicarbonate is relatively insoluble and crystallises out, and it can also be produced by passing carbon dioxide through a solution of sodium carbonate.
The bicarbonate is filtered, washed and dried into a fine white powder. In baking it works by reacting with acid (from an added acid salt, or from ingredients like buttermilk or yoghurt) and with heat, releasing carbon dioxide bubbles that lift the mixture; this is why it is usually paired with an acid in recipes and baking powders.
Possible reactions
Generally safe; high sodium.