Leavening agent
Encyclopedia
A leavening agent is any one of a number of substances used in dough
s and batters
that cause a foaming action which lightens and softens the finished product. The leavening agent incorporates gas bubbles into the dough—this may be air incorporated by mechanical means, but usually it is carbon dioxide
produced by biological agents, or by chemical agents reacting with moisture, heat, acidity, or other triggers. When a dough or batter is mixed, the starch
in the flour mixes with the water in the dough to form a matrix (often supported further by proteins like gluten
or other polysaccharides like pentosans or xanthan gum
), then gelatinizes
and "sets"; the holes left by the gas bubbles remain.
as part of their life cycle can be used to leaven products. Varieties of yeast
are most often used, particularly Saccharomyces
species (such as baker's yeast
, Saccharomyces cerevisiae
), though some recipes also rely on certain bacteria
. Yeast leaves behind waste byproducts (particularly ethanol
and some autolysis products) that contribute to the distinctive flavor of yeast breads. In the naturally leavened sourdough
breads, the flavor is further enhanced by various lactic acid bacteria
(Lactobacilli
) or acetic acid bacteria
(Acetobacter
).
Leavening with yeast is a process based on fermentation
, biologically changing the chemistry of the dough or batter as the yeast works. Unlike chemical leavening, which usually activates as soon as the water combines the acid and base chemicals, yeast leavening requires proofing
, which allows the yeast time to reproduce and consume carbohydrates in the flour. Yeast can unhydrate itself and then rehydrate itself later.
Yeast can also be used to make alcoholic beverage
s like beer
or wine
. The resulting cast-off yeast, known as barm
, can be used as a leavener and was probably ancestral to the use of modern pure-cultured yeast. Non-European cultures have used other by-products of making alcoholic beverages as leaveners, as in Ecuador: "In olden times when the sediment of chicha
called concho was used as a ferment, we had good bread; and now with better mills good quality bread has disappeared entirely."
While not as widely known, bacterial fermentation is sometimes used, occasionally providing a drastically changed flavor profile from a yeast fermentation; a well-known example is salt rising bread
, which uses a culture of the Clostridium perfringens
bacterium.
Some typical biological leaveners are:
s and cake
s, as well as cookie
s and numerous other applications where a long biological fermentation is impractical or undesirable.
Chemical leavening was first publicized by Amelia Simmons in her American Cookery, published in 1796, wherein she mentions the use of pearl ash as a leavening agent.
Since chemical expertise is required to create a functional chemical leaven without leaving behind 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
s.
Chemical leavening agents include:
is the process of beating sugar crystals and solid fat (typically butter
) 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 leavener. This is often used in cookies.
Using a whisk
on certain liquids, notably cream
or egg white
s, can also create foams through mechanical action. This is the method employed in the making of sponge cake
s, where an egg protein matrix produced by vigorous whipping provides almost all the structure of the finished product.
The Chorleywood Bread Process
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.
and air 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
s, Yorkshire pudding
s, and to a lesser extent in tempura
.
Nitrous oxide
is used as a propellant in aerosol whip cream cans. Large densities of N2O are dissolved in cream at high pressure. When expelled from the can, the nitrous oxide escapes emulsion instantly, creating a temporary foam in the butterfat matrix of the cream.
Dough
Dough is a paste made out of any cereals or leguminous crops by mixing flour with a small amount of water and/or other liquid. This process is a precursor to making a wide variety of foodstuffs, particularly breads and bread-based items , flatbreads, noodles, pastry, and similar items)...
s and batters
Batter (cooking)
Batter is a semi-liquid mixture of one or more flours combined with liquids such as water, milk or eggs used to prepare various foods. Often a leavening agent such as baking powder is included to aerate and fluff up the batter as it cooks, or the mixture may be naturally fermented for this purpose...
that cause a foaming action which lightens and softens the finished product. The leavening agent incorporates gas bubbles into the dough—this may be air incorporated by mechanical means, but usually it is carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
produced by biological agents, or by chemical agents reacting with moisture, heat, acidity, or other triggers. When a dough or batter is mixed, the starch
Starch
Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...
in the flour mixes with the water in the dough to form a matrix (often supported further by proteins like gluten
Gluten
Gluten is a protein composite found in foods processed from wheat and related grain species, including barley and rye...
or other polysaccharides like pentosans or xanthan gum
Xanthan gum
Xanthan gum is a polysaccharide, derived from the bacterial coat of Xanthomonas campestris, used as a food additive and rheology modifier, commonly used as a food thickening agent and a stabilizer...
), then gelatinizes
Starch gelatinization
Starch gelatinization is a process that breaks down the intermolecular bonds of starch molecules in the presence of water and heat, allowing the hydrogen bonding sites to engage more water. This irreversibly dissolves the starch granule...
and "sets"; the holes left by the gas bubbles remain.
Biological leaveners
Microorganisms that release carbon dioxideCarbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
as part of their life cycle can be used to leaven products. Varieties of yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
are most often used, particularly Saccharomyces
Saccharomyces
Saccharomyces is a genus in the kingdom of fungi that includes many species of yeast. Saccharomyces is from Greek σάκχαρ and μύκης and means sugar fungus. Many members of this genus are considered very important in food production. One example is Saccharomyces cerevisiae, which is used in making...
species (such as baker's yeast
Baker's yeast
Baker's yeast is the common name for the strains of yeast commonly used as a leavening agent in baking bread and bakery products, where it converts the fermentable sugars present in the dough into carbon dioxide and ethanol...
, Saccharomyces cerevisiae
Saccharomyces cerevisiae
Saccharomyces cerevisiae is a species of yeast. It is perhaps the most useful yeast, having been instrumental to baking and brewing since ancient times. It is believed that it was originally isolated from the skin of grapes...
), though some recipes also rely on certain bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
. Yeast leaves behind waste byproducts (particularly ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
and some autolysis products) that contribute to the distinctive flavor of yeast breads. In the naturally leavened sourdough
Sourdough
Sourdough is a dough containing a Lactobacillus culture, usually in symbiotic combination with yeasts. It is one of two principal means of biological leavening in bread baking, along with the use of cultivated forms of yeast . It is of particular importance in baking rye-based breads, where yeast...
breads, the flavor is further enhanced by various lactic acid bacteria
Lactic acid bacteria
The lactic acid bacteria comprise a clade of Gram-positive, low-GC, acid-tolerant, generally non-sporulating, non-respiring rod or cocci that are associated by their common metabolic and physiological characteristics. These bacteria, usually found in decomposing plants and lactic products, produce...
(Lactobacilli
Lactobacillus
Lactobacillus is a genus of Gram-positive facultative anaerobic or microaerophilic rod-shaped bacteria. They are a major part of the lactic acid bacteria group, named as such because most of its members convert lactose and other sugars to lactic acid. They are common and usually benign...
) or acetic acid bacteria
Acetic acid bacteria
Acetic acid bacteria are bacteria that derive their energy from the oxidation of ethanol to acetic acid during fermentation. They are Gram-negative, aerobic, rod-shaped bacteria. Not to be confused with the genus Acetobacterium which are anaerobic homoacetogenic facultative autotrophs and can...
(Acetobacter
Acetobacter
Acetobacter is a genus of acetic acid bacteria characterized by the ability to convert ethanol to acetic acid in the presence of oxygen. There are several species within this genus, and there are other bacteria capable of forming acetic acid under various conditions; but all of the Acetobacter are...
).
Leavening with yeast is a process based on fermentation
Fermentation (food)
Fermentation in food processing typically is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof, under anaerobic conditions. Fermentation in simple terms is the chemical conversion of sugars into ethanol...
, biologically changing the chemistry of the dough or batter as the yeast works. Unlike chemical leavening, which usually activates as soon as the water combines the acid and base chemicals, yeast leavening requires proofing
Proofing (baking technique)
Proofing , as the term is used by professional bakers, is the final dough-rise step before baking, and refers to a specific rest period within the more generalized process known as fermentation...
, which allows the yeast time to reproduce and consume carbohydrates in the flour. Yeast can unhydrate itself and then rehydrate itself later.
Yeast can also be used to make alcoholic beverage
Alcoholic beverage
An alcoholic beverage is a drink containing ethanol, commonly known as alcohol. Alcoholic beverages are divided into three general classes: beers, wines, and spirits. They are legally consumed in most countries, and over 100 countries have laws regulating their production, sale, and consumption...
s like beer
Beer
Beer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...
or wine
Wine
Wine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...
. The resulting cast-off yeast, known as barm
Barm
Barm cake is type of bun with flour on top. It has a characteristically strong flavour that comes from the traditional barm leaven made from a natural leaven with the addition of hops. However, the Barm Cake is more likely made from commercial yeast today....
, can be used as a leavener and was probably ancestral to the use of modern pure-cultured yeast. Non-European cultures have used other by-products of making alcoholic beverages as leaveners, as in Ecuador: "In olden times when the sediment of chicha
Chicha
For the musical genre, see Peruvian cumbiaChicha is a term used in some regions of Latin America for several varieties of fermented and non-fermented beverages, rather often to those derived from maize and similar non-alcoholic beverages...
called concho was used as a ferment, we had good bread; and now with better mills good quality bread has disappeared entirely."
While not as widely known, bacterial fermentation is sometimes used, occasionally providing a drastically changed flavor profile from a yeast fermentation; a well-known example is salt rising bread
Salt rising bread
Salt rising bread is bread in which the main rising agent is a bacterium Clostridium perfringens, which leavens the bread along with lactobacillus and other wild microbes, as opposed to mainly yeast or baking soda. It is thought that the salt used in the starter is used to suppress yeast growth...
, which uses a culture of the Clostridium perfringens
Clostridium perfringens
Clostridium perfringens is a Gram-positive, rod-shaped, anaerobic, spore-forming bacterium of the genus Clostridium. C. perfringens is ever present in nature and can be found as a normal component of decaying vegetation, marine sediment, the intestinal tract of humans and other vertebrates,...
bacterium.
Some typical biological leaveners are:
- beerBeerBeer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...
(unpasteurised—live yeast) - buttermilkButtermilkButtermilk refers to a number of dairy drinks. Originally, buttermilk was the liquid left behind after churning butter out of cream. It also refers to a range of fermented milk drinks, common in warm climates where unrefrigerated fresh milk otherwise sours quickly...
- ginger beerGinger beerGinger beer is a carbonated drink that is flavored primarily with ginger and sweetened with sugar or artificial sweeteners.-History:Brewed ginger beer originated in England in the mid-18th century and became popular in Britain, the United States, and Canada, reaching a peak of popularity in the...
- kefirKefirKefir is a fermented milk drink that originated with shepherds of the North Caucasus region, who discovered that fresh milk carried in leather pouches would occasionally ferment into an effervescent beverage...
- sourdough starterSourdoughSourdough is a dough containing a Lactobacillus culture, usually in symbiotic combination with yeasts. It is one of two principal means of biological leavening in bread baking, along with the use of cultivated forms of yeast . It is of particular importance in baking rye-based breads, where yeast...
- yeast
- yogurt
Chemical leaveners
Chemical leaveners are chemical mixtures or compounds that release gases (usually carbon dioxide) when they react with moisture and heat; they are almost always based on a combination of acid (usually a low molecular weight organic acid) and an alkali; these leave behind a chemical salt. Chemical leaveners are used in quick breadQuick bread
Quick bread is an American term used to denote a type of bread which is leavened with leavening agents other than yeast. Quick breads includes many cakes, brownies and cookies, as well as banana bread, beer bread, cornbread, biscuits, muffins, pancakes, scones, and soda bread.-History::"Quick...
s and cake
Cake
Cake is a form of bread or bread-like food. In its modern forms, it is typically a sweet and enriched baked dessert. In its oldest forms, cakes were normally fried breads or cheesecakes, and normally had a disk shape...
s, as well as cookie
Cookie
In the United States and Canada, a cookie is a small, flat, baked treat, usually containing fat, flour, eggs and sugar. In most English-speaking countries outside North America, the most common word for this is biscuit; in many regions both terms are used, while in others the two words have...
s and numerous other applications where a long biological fermentation is impractical or undesirable.
Chemical leavening was first publicized by Amelia Simmons in her American Cookery, published in 1796, wherein she mentions the use of pearl ash as a leavening agent.
Since chemical expertise is required to create a functional chemical leaven without leaving behind 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
Baking powder is a dry chemical leavening agent used to increase the volume and lighten the texture of baked goods such as muffins, cakes, scones and American-style biscuits. Baking powder works by releasing carbon dioxide gas into a batter or dough through an acid-base reaction, causing bubbles in...
s.
Chemical leavening agents include:
- baking powderBaking powderBaking powder is a dry chemical leavening agent used to increase the volume and lighten the texture of baked goods such as muffins, cakes, scones and American-style biscuits. Baking powder works by releasing carbon dioxide gas into a batter or dough through an acid-base reaction, causing bubbles in...
- baking soda (sodium bicarbonateSodium bicarbonateSodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula Na HCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda . The natural mineral form is...
) - monocalcium phosphateMonocalcium phosphateMonocalcium phosphate is a chemical compound with the formula Ca2. It is commonly found as the monohydrate, Ca2·H2O.-Fertilizer:Phosphorus is an essential nutrient and therefore is a common component of agricultural fertilizers...
- sodium aluminum phosphate (SALP)
- sodium acid pyrophosphate (SAPP)
- other phosphates
- ammonium bicarbonateAmmonium bicarbonateAmmonium bicarbonate, a compound with formulaNH4, also called bicarbonate of ammonia, ammonium hydrogen carbonate, hartshorn, AmBic or powdered baking ammonia, is the bicarbonate salt of ammonia....
(hartshornHartshornHarts' horns, are the horns of the male red deer. Various substances were made from the shavings of the animals' horns.The oil of hartshorn is a crude animal oil obtained from the destructive distillation of the deers' bones or horns....
, horn salt, bakers ammoniaAmmoniaAmmonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
) - potassium bicarbonatePotassium bicarbonatePotassium bicarbonate , is a colorless, odorless, slightly basic, salty substance...
(potashPotashPotash is the common name for various mined and manufactured salts that contain potassium in water-soluble form. In some rare cases, potash can be formed with traces of organic materials such as plant remains, and this was the major historical source for it before the industrial era...
) - potassium bitartratePotassium bitartratePotassium hydrogen tartrate, also known as Potassium bitartrate, has formula KC4H5O6, is a byproduct of winemaking. In cooking it is known as cream of tartar. It is the potassium acid salt of tartaric acid, a carboxylic acid.-Occurrence:...
(cream of tartar) - potassium carbonatePotassium carbonatePotassium carbonate is a white salt, soluble in water , which forms a strongly alkaline solution. It can be made as the product of potassium hydroxide's absorbent reaction with carbon dioxide. It is deliquescent, often appearing a damp or wet solid...
(pearlash) - hydrogen peroxideHydrogen peroxideHydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
Mechanical leavening
CreamingCreaming (food)
Creaming is used to refer to several different culinary processes.- In baking :Creaming, in baking, is the technique of blending ingredients — usually granulated sugar — together with a solid fat like shortening or butter. The technique is most often used in making buttercream, cake...
is the process of beating sugar crystals and solid fat (typically butter
Butter
Butter is a dairy product made by churning fresh or fermented cream or milk. It is generally used as a spread and a condiment, as well as in cooking applications, such as baking, sauce making, and pan frying...
) together in a mixer
Mixer (cooking)
A mixer is a kitchen appliance intended for mixing, folding, beating, and whipping food ingredients. Mixers come in two major variations, hand mixers and stand mixers....
. 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 leavener. This is often used in cookies.
Using a whisk
Whisk
A whisk is a cooking utensil used in food preparation 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 joined at the end. The wires are usually metal, but some are...
on certain liquids, notably cream
Cream
Cream is a dairy product that is composed of the higher-butterfat layer skimmed from the top of milk before homogenization. In un-homogenized milk, over time, the lighter fat rises to the top. In the industrial production of cream this process is accelerated by using centrifuges called "separators"...
or egg white
Egg white
Egg white is the common name for the clear liquid 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 around either fertilized or unfertilized egg yolks...
s, can also create foams through mechanical action. This is the method employed in the making of sponge cake
Sponge cake
Sponge cake is a cake based on flour , sugar, and eggs, sometimes leavened with baking powder which has a firm, yet well aerated structure, similar to a sea sponge. A sponge cake may be produced by either the batter method, or the foam method. Typicially the batter method in the U.S. is known as a...
s, where an egg protein matrix produced by vigorous whipping provides almost all the structure of the finished product.
The Chorleywood Bread Process
Chorleywood Bread Process
The Chorleywood bread process is an industrial process used to lower the cost of bread production. The CBP, or no time method, was developed in 1961 by the British Baking Industries Research Association based at Chorleywood, and is now used to make 80% of the UK's bread...
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.
Other leaveners
SteamSteam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...
and air 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
Popover
A popover is a light, hollow roll made from an egg batter similar to that of Yorkshire pudding, typically baked in muffin tins.Popovers may be served either as a sweet, topped with fruit and whipped cream for breakfast or with afternoon tea, or with meats at lunch and dinner.-Name:The name...
s, Yorkshire pudding
Yorkshire pudding
Yorkshire Pudding is a dish that originated in Yorkshire, England. It is made from batter and usually served with roast meat and gravy.-History:...
s, and to a lesser extent in tempura
Tempura
], is a Japanese dish of seafood or vegetables that have been battered and deep fried.-Batter:A light batter is made of cold water and soft wheat flour . Eggs, baking soda or baking powder, starch, oil, and/or spices may also be added...
.
Nitrous oxide
Nitrous oxide
Nitrous oxide, commonly known as laughing gas or sweet air, is a chemical compound with the formula . It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...
is used as a propellant in aerosol whip cream cans. Large densities of N2O are dissolved in cream at high pressure. When expelled from the can, the nitrous oxide escapes emulsion instantly, creating a temporary foam in the butterfat matrix of the cream.
External links
- WikibooksWikibooksWikibooks is a Wiki hosted by the Wikimedia Foundation for the creation of free content textbooks and annotated texts that anyone can edit....
Cookbook has a recipe/module on Leavening agent