Chemical leavening was conceived as an alternative to yeast leavening and long sourdough preparations. Back in the 19th century, the limited knowledge of microbiology and the sensitivity of yeast cells to handling and atmospheric conditions made it difficult for bakers to consistently produce high-quality batches of bread. Further complications such as the absence of commercial refrigeration and hygiene practices made it impossible to properly maintain fresh yeast.
In 1856, chemist Eben Norton Horsford patented the first modern baking powder.2 Horsford originally extracted monocalcium phosphate by boiling animal bones. The monocalcium phosphate acted as an acid that combined with baking soda to create a reaction producing C02. By the 1880s, Horsford’s company switched to mining the monocalcium phosphate to lower costs.2 He placed the two ingredients together in one container, adding cornstarch to soak up moisture, which prevented the ingredients from reacting prematurely.2 The company he created became known as Rumford.
Baking powder has the following nutritional panel:3
Baking powder, when hydrated, will aerate the dough or batter. The aeration provides a light, porous cell structure and fine grain. Also a texture with desirable appearance, along with palatability, to baked goods.1
Commonly used leavening acids in baking powder are MCP, SAPP, SALP, SAS, and tartaric acid. These may be used individually or in combination. MCP is fast-reacting so it is often combined with a slower-acting leavening acid, like SAPP, SALP, or SAS. An example reaction is shown below:
NaHCO3 + H+ = Na+ + CO2 + H2O
Sodium bicarbonate + Acid = Sodium + Carbon Dioxide + Water
Baking powder is classified according to its reaction rate:4
- Fast-acting: systems such as sodium bicarbonate-monocalcium phosphate monohydrate react quickly during mixing, hydration and floor time standing as well.
- Slow-acting: typically use a combination of sodium bicarbonate and sodium pyrophosphate where gas evolution is triggered by high baking temperatures.
- Double-acting: consist of a mixture of sodium aluminium sulfate (SAS) and monocalcium phosphate (MCP). Typical applications of double-acting leavening include products that are baked at home such as biscuits, pancakes and waffles. In addition to their effect on gas expansion and subsequent volume building, chemical leavening affects cake’s pH, crumb texture and color.
Fillers are used in addition to the active components to make the ingredient shelf-stable. The most common filler is corn starch. Corn starch may be augmented with calcium carbonate, calcium sulfate, calcium lactate, or calcium silicate.4 Fillers perform a two-fold function:
- Stabilize the product by keeping the active ingredients apart, thereby preventing premature reaction, in case moisture should find access to the powder4
- Standardize the strength of the powder4
It’s production begins with the raw ingredients.
The process is as follows:5
- Sodium carbonate is produced using the Solvay ammonia process. Ammonia and carbon dioxide are passed through a saltwater solution in an absorption tower. This results in a compound called ammonium bicarbonate, which reacts with the salt to produce sodium bicarbonate crystals and ammonium chloride.
- Bicarbonate crystals are filtered out by centrifuges and washed to remove residual chloride. The material is heated and reacted with carbon dioxide to produce sodium carbonate.
- Sodium carbonate is then dissolved, carbonated, and cooled, which results in crystallized sodium bicarbonate.
- Tartaric acid is made using potassium hydrogen tartrate, which is a waste product from wine-making.
- Tartaric acid and sodium bicarbonate are blended and cornstarch is added. Industrial mixers combine the powders into a single, homogeneous blend.
This chemical leavener may be single- or double-acting. Double-acting is more common and means that the it contains a combination of leavening acids that will release gas during the mixing and again during baking. There are a variety of on the market, allowing for use in a wide range of applications. Things to consider when choosing a baking powder are reaction time, single- vs. double-acting in relation to the processing time, and baking temperature/time for the product. It will also impact the finished product’s pH.
When creating a recipe, the formula ratio is 1 to 1 ¼ teaspoon of baking powder per 1 cup flour.6 Using too much will result in a bitter-tasting product, large bubbles, and surface blistering. Using too little will result in tough dense crumb with little volume.
Although baking powder has a shelf life of 24 months from date of manufacture it may lose efficacy within 6 months of opening.6 A quick test can determine the potency. Stir 1 teaspoon into 1/3 cup of hot water.6 If bubbles appear, it is fine to use. You can make your own baking powder by combining 15ml/1 tbsp bicarbonate of soda with 30ml/2 tbsp cream of tartar.6
Bases and acids used for chemical leavening:
- Sodium bicarbonate
- Ammonium bicarbonate
- Potassium bicarbonate
- Potassium acid tartrate (cream of tartar)
- Monocalcium phosphate (MCP)
- Sodium acid pyrophosphate (SAPP)
- Sodium aluminum phosphate (SALP)
- Dicalcium phosphate dihydrate
- Sodium aluminum sulfate
- Glucono delta-lactone (GDL)
- Fumaric acid
- Combination of an acid, base and a proper vehicle or diluting agent.
- Commercial presentations include cream of tartar, baking soda or monocalcium phosphate, and corn-starch or corn flour to control moisture and delay acid-base premature reactions.
Creating a leavening reaction
When creating a leavening reaction it is crucial to know the neutralizing value to avoid an unbalance in the formula. The neutralizing value (NV) is defined as the parts (by weight) of baking soda necessary to release all the carbon dioxide by 100 parts (by weight) of a leavening acid. For example, in the case of baking soda (sodium bicarbonate, NaHCO3), NV is expressed as:
NV = g of NaHCO3 neutralized by 100 g leavening acid
CFR Title 21 Sec. 182.1 lists baking powder as generally recognized as safe (GRAS) when used in accordance with good manufacturing practices.7
- Chung, F.H.Y. “Bakery Processes, Chemical Leavening Agents.” Wiley Online Library. John Wiley & Sons, Inc., 4 December 2000. http://onlinelibrary.wiley.com/doi/10.1002/0471238961.0308051303082114.a01/abstract. Accessed 22 August 2017.
- Panko, B. “The Great Uprising: How a Powder Revolutionized Baking.” Smithsonian.com. Smithsonian Institution, 20 June 2017. www.smithsonianmag.com/science-nature/great-uprising-how-powder-revolutionized-baking-180963772/. Accessed 22 August 2017.
- “Calories in baking powder.” Baking Powder Nutrition Facts, Baking Powder Calories, Nutritional Information. Under Armour. www.myfitnesspal.com/nutrition-facts-calories/baking-powder. Accessed 22 August 2017.
- Pyler, E.J. Baking Science & Technology. 3rd ed., vol. 2, Sosland, 1988. 931-933.
- “Baking Powder.” How Products Are Made. www.madehow.com/Volume-6/Baking-Powder.html. Accessed 22 August 2017
- “Baking Powder.” What’s Cooking America. 15 December 2016. https://whatscookingamerica.net/Q-A/BakingPowder.htm Accessed 22 August 2017.
- US Food and Drug Administration. “CFR – Code of Federal Regulations 21CFR182.1.” 1 April 2016. www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=182.1. Accessed 18 August 2017.