Most commercially-available baking powders are made up of an alkaline component (typically
baking soda), one or more
acid salts, and an inert starch (
cornstarch in most cases, though potato starch may also be used). Baking soda is the source of the carbon dioxide,
[3] and the acid-base reaction is more accurately described as an acid-activated decomposition of baking soda, which can be generically represented as
[4]
NaHCO3 + H+ → Na+ + CO2 + H2O The inert starch serves several functions in baking powder. Primarily it is used to absorb moisture, and thus prolong shelf life by keeping the powder's alkaline and acidic components from reacting prematurely. A dry powder also flows and mixes more easily. Finally, the added bulk allows for more accurate measurements.
[5]
The acid in a baking powder can be either fast-acting or slow-acting.
[6] A fast-acting acid reacts in a wet mixture with baking soda at room temperature, and a slow-acting acid will not react until heated in an oven. Baking powders that contain both fast- and slow-acting acids are
double acting; those that contain only one acid are
single acting. By providing a second rise in the oven, double-acting baking powders increase the reliability of baked goods by rendering the time elapsed between mixing and baking less critical, and this is the type most widely available to consumers today. Common low-temperature
acid salts include
cream of tartar and
monocalcium phosphate. High-temperature acid salts include
sodium aluminum sulfate,
sodium aluminum phosphate, and
sodium acid pyrophosphate[7
From:
http://en.wikipedia.org/wiki/Baking_powder
Still would not use it. There are plenty of other sources of P, that do not work so good for biscuits.