Bakers Journal

Technical Talk: April 2015

April 16, 2015
By Dr. John Michaelides

Leavening Lowdown

Bakers have plenty of options when it comes to aerating dough and batter.

Many baked goods require aeration of dough or batter, which is achieved via leavening agents. Aeration makes the structure of the dough and batter light and fairly porous, which translates into the crumb characteristics of the finished baked good products. In the process of baking, porosity of the batter is important because it improves volume, tenderness and cell structure of the crumb.

Leavening occurs via the production of carbon dioxide by yeast during the fermentation process, or by the release of carbon dioxide through the reaction of chemical leavening agents. Leavening can also be achieved via mechanical aeration – such as mixing and creaming – as well as the water vapour that forms during the heat of baking.

The most common chemical leavening agents used in cake products consist of the combination of sodium bicarbonate or, as it’s commonly called, baking soda, as well as various acidic agents. Sodium bicarbonate is the most commonly used source of carbon dioxide because it’s non-toxic, relatively cheap and easy to handle.


Different leavening acids are available for bakers to combine with baking soda and use in their formulations. Premixed baking powders, which are more convenient, are also available, but they are restricted in their application.

There are three basic types of baking powders: fast acting, slow acting and double acting. Fast-acting powders release most of the carbon dioxide in a few minutes after coming into contact with water, so the batter must be processed quickly to avoid loss of volume. Slow-acting baking powders do not release any carbon dioxide until they are exposed to the heat of the baking. Double-acting baking powders react partially at low temperatures, releasing some carbon dioxide, and complete the reaction during exposure to baking temperatures. Double-acting baking powders are often used in commercial cake baking because they perform a uniform regulated action resulting in good cake characteristics.

Baking powders contain the reactive compounds of baking soda and leavening acids, as well as other inert compounds such as corn starch, calcium carbonate, calcium sulfate, calcium lactate, etc. These inert compounds keep the reactive compound apart to prevent premature reaction and standardize powder strength.

Another common source of carbon dioxide that can be used as a leavening agent is ammonium bicarbonate (NH4HCO3). When ammonium bicarbonate is heated it releases carbon dioxide and ammonia. Its use, however, is restricted to some dry cookies and crackers, because in any products that contain moisture the ammonia will be retained and the baked goods will be inedible.

Bakers can use a complete premixed baking powder or combine sodium bicarbonate with a leavening acid. There are eight types of leavening acids to choose from, depending on the application required.

Anhydrous monocalcium phosphate (AMCP) is a fairly stable ingredient protected from ambient moisture by a coating of potassium and aluminum phosphates. It is slow reacting with only about 15 per cent of carbon dioxide released at the mixing stage.

Dicalcium phosphate dehydrate (DCP) has a very slow reactive rate and it only reacts with sodium bicarbonate when the temperature of the batter reaches 60 C.

Glucono-delta-lactone (GDL) reacts slowly to release gluconic acid, which in turn reacts with sodium bicarbonate to release carbon dioxide. It may leave a bitter aftertaste in the product, but is suggested to reduce fat absorption in doughnuts.

Monocalcium phosphate (MCP) is a very fast-reacting leavening acid releasing most carbon dioxide (60-70 per cent) by the end of the mixing stage with the remainder being released during baking. Its action results in batters with high viscosity and high volume.  

Potassium acid tartrate (cream of tartar) is one of the fastest reacting leavening acids with about 70 per cent released within the first two minutes. For this reason its use is very limited.

Sodium acid pyrophosphate (SAPP) comes in different grades with different reaction rates from very slow to slow. Very slow SAPP grades are used in cake doughnuts because they require partial leavening action during the frying period in order to achieve buoyancy without full expansion. Cake doughnuts usually require a number of different fast- and slow-reacting acids.

Sodium aluminum phosphate (SALP) is one of the most commonly used leavening acids in double acting systems. It releases carbon dioxide fast during the baking stage, does not contribute to flavour changes and provides strong fine close texture with the added benefit of reducing tunnel formation in cakes.

Sodium aluminum sulfate (SAS) is a very slow acting acid with practically no reaction at room temperature. SAS is used in special applications such as chocolate cake where it contributes to a characteristic colour and in English muffins where it is responsible for the large gas holes due to the quick release of the carbon dioxide when the English muffins are heated on a grill.

For more information, or fee-for-service help with food technical and processing issues and needs, contact Dr. John Michaelides at John Michaelides Consulting at 519-743-8956 or, or at Bioenterprise by calling 519-821-2960. Bioenterprise is a company made up of experienced professionals who coach and mentor emerging agri-technology companies from planning to start-up to profitability and beyond.

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