cooking Cooking, cookery, or culinary arts is the art, science and craft of using heat to Outline of food preparation, prepare food for consumption. Cooking techniques and ingredients vary widely, from grilling food over an open fire to using electric ...

, a leavening agent () or raising agent, also called a leaven () or leavener, is any one of a number of substances used in

dough Dough is a thick, malleable, sometimes elastic paste made from grains or from leguminous or chestnut crops. Dough is typically made by mixing flour with a small amount of water or other liquid and sometimes includes yeast or other leavening ag ...

s and

batters Batter or batters may refer to: Common meanings * Batter (cooking), thin dough that can be easily poured into a pan * Batter (baseball), person whose turn it is to face the pitcher * Batter (cricket), a player who is currently batting * Batter ...

that cause a foaming action (gas bubbles) that lightens and softens the mixture. An alternative or supplement to leavening agents is mechanical action by which air is incorporated (i.e.

kneading In cooking (and more specifically baking), kneading is a process in the making of bread or dough, used to mix the ingredients and add strength to the final product. Its importance lies in the mixing of flour with water; when these two ingredient ...

). Leavening agents can be biological or synthetic

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

s. The gas produced is often

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

, or occasionally

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

. When a dough or batter is mixed, the

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...

in the flour and the water in the dough form a

matrix Matrix most commonly refers to: * ''The Matrix'' (franchise), an American media franchise ** ''The Matrix'', a 1999 science-fiction action film ** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...

(often supported further by

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s like

gluten Gluten is a structural protein naturally found in certain cereal grains. Although "gluten" often only refers to wheat proteins, in medical literature it refers to the combination of prolamin and glutelin proteins naturally occurring in all grain ...

polysaccharides Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with w ...

, such as

pentosan Pentosans are polymers composed of pentoses. In contrast to cellulose, which is composed of hexose (glucose) monomers, pentosans are derived from five-carbon sugars such as xylose. Pentosan-rich biomass is the precursor to furfural. The pentosan co ...

s or

xanthan gum Xanthan gum () is a polysaccharide with many industrial uses, including as a common food additive. It is an effective thickening agent, emulsifier, and stabilizer that prevents ingredients from separating. It can be produced from simple sugars u ...

). The starch then gelatinizes and sets, leaving gas bubbles that remain.

Biological leavening agents

* ''

Saccharomyces cerevisiae ''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungus microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been o ...

'' producing

found in: **

baker's yeast Baker's yeast is the common name for the strains of yeast commonly used in baking bread and other bakery products, serving as a leavening agent which causes the bread to rise (expand and become lighter and softer) by converting the fermentable ...

Beer barm Barm is the foam or scum formed on the top of a fermenting liquid, such as beer, wine, or feedstock for spirits or industrial ethanol distillation. It is used to leaven bread, or set up fermentation in a new batch of liquor. Barm, as a leaven, ha ...

(unpasteurised—live yeast) **

ginger beer Traditional ginger beer is a sweetened and carbonated, usually non-alcoholic beverage. Historically it was produced by the natural fermentation of prepared ginger spice, yeast and sugar. Current ginger beers are often manufactured rather than ...

kefir Kefir ( ; also spelled as kephir or kefier; ; ; ) is a fermented milk drink similar to a thin yogurt or ayran that is made from kefir grains, a specific type of mesophilic symbiotic culture. The drink originated in the North Caucasus, in pa ...

sourdough starter Sourdough or sourdough bread is a bread made by the fermentation of dough using wild lactobacillaceae and yeast. Lactic acid from fermentation imparts a sour taste and improves keeping qualities. History In the ''Encyclopedia of Food Microbio ...

* ''

Clostridium perfringens ''Clostridium perfringens'' (formerly known as ''C. welchii'', or ''Bacillus welchii'') is a Gram-positive, rod-shaped, anaerobic, spore-forming pathogenic bacterium of the genus '' Clostridium''. ''C. perfringens'' is ever-present in nature an ...

'' producing

found in

salt-rising bread Salt-rising (or salt-risen) bread is a dense white bread that is traditional in the Appalachian Mountains, leavened by naturally occurring ''Clostridium perfringens'' and other bacteria rather than by yeast. Salt-rising bread is made from wheat f ...

Chemical leavening agents

Chemical leavens are mixtures or compounds that release gases when they react with each other, with moisture, or with heat. Most are based on a combination of acid (usually a low molecular weight organic acid) and a

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...

bicarbonate In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula . Bicarbonate serves a crucial biochemic ...

. After they act, these compounds leave behind a chemical salt. Chemical leavens are used in

quick bread Quick bread is any bread leavened with a chemical leavening agent rather than a biological one like yeast or sourdough starter. An advantage of quick breads is their ability to be prepared quickly and reliably, without requiring the time-consumi ...

s and

cake Cake is a flour confection made from flour, sugar, and other ingredients, and is usually baked. In their oldest forms, cakes were modifications of bread, but cakes now cover a wide range of preparations that can be simple or elaborate, ...

s, as well as

cookie A cookie is a baked or cooked snack or dessert that is typically small, flat and sweet. It usually contains flour, sugar, egg, and some type of oil, fat, or butter. It may include other ingredients such as raisins, oats, chocolate chips, n ...

s and numerous other applications where a long biological

fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...

is impractical or undesirable.

History

Chemical leavening using

pearl ash Potash () includes various mined and manufactured salts that contain potassium in water-soluble form.

as a leavening agent was mentioned by

Amelia Simmons Amelia Simmons is an American writer noted for publishing the '' American Cookery''. This cookbook is considered an important text that provided insights into the language and culinary practices of former colonists, helping shape American identit ...

in her ''

American Cookery ''American Cookery'', by Amelia Simmons, is the first known cookbook written by an American, published in Hartford, Connecticut, in 1796. Until then, the cookbooks printed and used in the Thirteen Colonies were British. Its full title is: '' ...

'', published in 1796. Since chemical expertise is required to create a functional chemical leaven without producing off-flavors from the chemical precursors involved, such substances are often mixed into premeasured combinations for maximum results. These are generally referred to as

baking powder Baking powder is a dry chemical leavening agent, a mixture of a carbonate or bicarbonate and a weak acid. The base and acid are prevented from reacting prematurely by the inclusion of a buffer such as cornstarch. Baking powder is used to increase ...

s. Sour milk and carbonates were used in the 1800s. The breakthrough in chemical leavening agents occurred in the 1930s with the introduction of

monocalcium phosphate Monocalcium phosphate is an inorganic compound with the chemical formula Ca(H2PO4)2 ("AMCP" or "CMP-A" for anhydrous monocalcium phosphate). It is commonly found as the monohydrate ("MCP" or "MCP-M"), Ca(H2PO4)2·H2O. Both salts are colourless sol ...

s . Other leavening agents developed include sodium aluminium sulfate ,

disodium pyrophosphate Disodium pyrophosphate or sodium acid pyrophosphate (SAPP) is an inorganic compound consisting of sodium cations and pyrophosphate anion. It is a white, water-soluble solid that serves as a buffering and chelating agent, with many applications i ...

, and

sodium aluminium phosphate Sodium aluminium phosphate (SAlP) describes the inorganic compounds consisting of sodium salts of aluminium phosphates. The most common SAlP has the formulas NaH14Al3(PO4)8·4H2O and Na3H15Al2(PO4)8.Klaus Schrödter, Gerhard Bettermann, Thomas St ...

s . These compounds combine with sodium bicarbonate to give

in a predictable manner.

Other leavens

Steam Steam is a substance containing water in the gas phase, and sometimes also an aerosol of liquid water droplets, or air. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization ...

and

air The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...

are used as leavening agents when they expand upon heating. To take advantage of this style of leavening, the baking must be done at high enough temperatures to flash the water to steam, with a batter that is capable of holding the steam in until set. This effect is typically used in

popover A popover is a light roll made from an egg batter similar to that of Yorkshire pudding, typically baked in muffin tins or dedicated popover pans, which have straight-walled sides rather than angled. Popovers may be served either as a sweet, t ...

Yorkshire pudding Yorkshire pudding is a baked pudding made from a batter of eggs, flour, and milk or water. A common British side dish, it is a versatile food that can be served in numerous ways depending on its ingredients, size, and the accompanying compone ...

s, and to a lesser extent in

tempura is a typical Japanese dish usually consisting of seafood, meat and vegetables that have been battered and deep fried. The dish was introduced by the Portuguese in Nagasaki through fritter-cooking techniques in the 16th century. The word ''tem ...

Mechanical leavening

Creaming is the process of beating sugar crystals and solid fat (typically

butter Butter is a dairy product made from the fat and protein components of churned cream. It is a semi-solid emulsion at room temperature, consisting of approximately 80% butterfat. It is used at room temperature as a spread, melted as a condiment ...

) together in a mixer. This integrates tiny air bubbles into the mixture, since the sugar crystals physically cut through the structure of the fat. Creamed mixtures are usually further leavened by a chemical leaven like baking soda. This is often used in

cookies A cookie is a baked or cooked snack or dessert that is typically small, flat and sweet. It usually contains flour, sugar, egg, and some type of oil, fat, or butter. It may include other ingredients such as raisins, oats, chocolate chips, nuts ...

. Using a

whisk A whisk is a cooking utensil which can be used to blend ingredients smooth or to incorporate air into a mixture, in a process known as '' whisking'' or ''whipping''. Most whisks consist of a long, narrow handle with a series of wire loops joi ...

on certain liquids, notably

cream Cream is a dairy product composed of the higher-fat layer skimmed from the top of milk before homogenization. In un-homogenized milk, the fat, which is less dense, eventually rises to the top. In the industrial production of cream, this process ...

egg white Egg white is the clear liquid (also called the albumen or the glair/glaire) contained within an egg. In chickens it is formed from the layers of secretions of the anterior section of the hen's oviduct during the passage of the egg. It forms arou ...

s, can also create foams through mechanical action. This is the method employed in the making of

sponge cake Sponge cake is a light cake made with egg whites, flour and sugar, sometimes leavened with baking powder. Some sponge cakes do not contain egg yolks, like angel food cake, but most of them do. Sponge cakes, leavened with beaten eggs, originated ...

s, where an egg protein matrix produced by vigorous whipping provides almost all the structure of the finished product. The

Chorleywood bread process The Chorleywood bread process (CBP) is a method of efficient dough production to make bread quickly, producing a soft, fluffy loaf. It was developed by Bill Collins, George Elton and Norman Chamberlain of the British Baking Industries Research As ...

uses a mix of biological and mechanical leavening to produce bread; while it is considered by food processors to be an effective way to deal with the soft wheat flours characteristic of British Isles agriculture, it is controversial due to a perceived lack of quality in the final product. The process has nevertheless been adapted by industrial bakers in other parts of the world.

References

External links

Wikibooks Wikibooks (previously called ''Wikimedia Free Textbook Project'' and ''Wikimedia-Textbooks'') is a wiki-based Wikimedia project hosted by the Wikimedia Foundation for the creation of free content digital textbooks and annotated texts that any ...

Cookbook A cookbook or cookery book is a kitchen reference containing recipes. Cookbooks may be general, or may specialize in a particular cuisine or category of food. Recipes in cookbooks are organized in various ways: by course (appetizer, first cour ...

has a recipe/module on ''

Leavening agent In cooking, a leavening agent () or raising agent, also called a leaven () or leavener, is any one of a number of substances used in doughs and batters that cause a foaming action (gas bubbles) that lightens and softens the mixture. An alterna ...

'' {{DEFAULTSORT:Leavening Agent Fermentation in food processing