Bicarbonate of soda (US: baking soda) is an alkaline powder used to soften water for cooking vegetables which helps them to retain their colour during cooking. It is also a principal ingredient in leavening agents. It gives off carbon dioxide when it comes into contact with an acid, such as lemon, sour milk or cream of tartare, causing it to release bubbles of air into the mixture. It should be added just when you wish the mixture to start rising as the activity starts immediately.
