Leavening can also be produced using microorganisms (e.g. yeast and/or sourdough bacteria) or chemical agents (baking powder, or ammonium bicarbonate). The resulting CO2 gas, along with water vapor and entrapped air expand during baking, causing the dough or batter to rise.
The concept of leavening agents is as old as bread itself. Recorded evidence of leavened bread extends as far back as the ancient Egyptians and biblical times.
The first leavening agents involved the production of carbon dioxide gas from natural fermentation reactions carried out by wild yeasts and lactic acid bacteria. It was not until the 19th century that knowledge of chemicals first influenced the development of leavening agents, i.e. sodium bicarbonate and acid phosphates, that were later used in sweet baked goods.
In addition to gas production and baked product volume increase, leavening agents perform additional functions, such as:
- pH control (e.g. baking powder residual soda)
- Flavor enhancement (salt production from neutralization reaction)
- Crust color improvement (slightly alkaline pH promotes Maillard browning reactions)
Leavening function can develop from many sources:
- Baker’s yeast → pure culture propagation, biomass growth and downstream processing
- Chemical leaveners (non-organic) → industrial production of food phosphates
- Organic acids → industrial fermentation and downstream processing for acid concentration
- Steam → naturally produced during thermal processing thanks to water heating and vapor formation
Nutrition and health
Leavening agents do not perform a nutritional function in baked goods nor are they intended to enhance the nutritional value of the finished product. Given their nature, some leavening agents, like leavening acids, assume an extra addition of salts and sodium.
Sodium is widely known for its contribution to blood pressure rise in humans. This is why most suppliers of chemical leaveners are now searching for non-sodium-containing baking powders, such as SAPP and baking soda, with alternative acids or bases which are free of Na element.
Types of leavening agents used in the bakery industry:
- Chemical leavening
- Bases and carbon-containing substances
- Ammonium bicarbonate (NH4HCO3)
- Ammonium carbonate ((NH4)2CO3)
- Baking soda (sodium bicarbonate, NaHCO3)
- Potassium bicarbonate (KHCO3)
- Sodium acid pyrophosphate (SAPP)
- Sodium aluminum sulfate (SAS)
- Sodium aluminum phosphate (SALP)
- Organic acids (citric, tartaric)
- Dicalcium phosphate dihydrate (DPD)
- Dimagnesium phosphate
- Glucono delta lactone (GDL)
- Monocalcium phosphate (MCP)
- Biochemical (biological) leavening
- Baker’s yeast (Saccharomyces cerevisiae)
- Pure lactic acid bacteria (LAB) cultures
- Yeast-preferments (biga, poolish, sponge)
- Mechanical leavening (air incorporation or entrapment as micro- and macroscopic gas bubbles)
- Egg whites beating
- Sugar / solid fat Mixing (creaming)
- Steam leavening
- Virtually all bakery products
The following table summarizes the basic regulation status of some leavening agents:1,2,3
- National Archives, Code of Federal Regulations, Title 21 Chapter I Subchapter B Part 182 SUBSTANCES GENERALLY RECOGNIZED AS SAFE, https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-182, Accessed 23 October 2021.
- National Archives, Code of Federal Regulations, Title 21 Chapter I Subchapter B Part 184 DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE, https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-184, Accessed 23 October 2021.
- National Archives, Code of Federal Regulations, Title 21 Chapter I Subchapter B Part 172 FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION, https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-172, Accessed 23 October 2021.