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A croissant (, ) is a French
pastry Pastry refers to a variety of Dough, doughs (often enriched with fat or eggs), as well as the sweet and savoury Baking, baked goods made from them. The dough may be accordingly called pastry dough for clarity. Sweetened pastries are often descr ...
in a crescent shape made from a laminated yeast dough similar to puff pastry. It is a buttery, flaky, '' viennoiserie'' pastry inspired by the shape of the Austrian '' kipferl'', but using the French yeast-leavened laminated dough. Croissants are named for their historical
crescent A crescent shape (, ) is a symbol or emblem used to represent the lunar phase (as it appears in the northern hemisphere) in the first quarter (the "sickle moon"), or by extension a symbol representing the Moon itself. In Hindu iconography, Hind ...
shape. The dough is layered with
butter Butter is a dairy product made from the fat and protein components of Churning (butter), churned cream. It is a semi-solid emulsion at room temperature, consisting of approximately 81% butterfat. It is used at room temperature as a spread (food ...
, rolled and folded several times in succession, then rolled into a thin sheet, in a technique called laminating. The process results in a layered, flaky texture, similar to a puff pastry. Crescent-shaped breads have been made since the
Renaissance The Renaissance ( , ) is a Periodization, period of history and a European cultural movement covering the 15th and 16th centuries. It marked the transition from the Middle Ages to modernity and was characterized by an effort to revive and sur ...
, and crescent-shaped cakes possibly since antiquity. The modern croissant was developed in the early 20th century, when French bakers replaced the brioche dough of the ''kipferl'' with a yeast-leavened laminated dough. In the late 1970s, the development of factory-made, frozen, preformed but unbaked dough made them into a
fast food Fast food is a type of Mass production, mass-produced food designed for commercial resale, with a strong priority placed on speed of service. ''Fast food'' is a commercial term, limited to food sold in a restaurant or store with frozen, preheat ...
that could be freshly baked by unskilled labor. The croissant bakery, notably the ''La Croissanterie'' chain, was a French response to American-style fast food, and as of 2008, 30–40% of the croissants sold in French bakeries and patisseries were baked from frozen dough. Croissants are a common part of a continental breakfast in many European countries.


Origin and history

The '' kipferl'', an Austrian crescent-shaped pastry, can be dated back to at least the 13th century in Austria, and came in various shapes. The ''kipferl'' can be made plain or with nuts or other fillings (some consider the rugelach a form of ''kipferl''). In either 1838 or 1839, an Austrian artillery officer, August Zang, founded a Viennese bakery ("Boulangerie Viennoise") at 92, rue de Richelieu in Paris. This bakery, which served Viennese specialties including the ''kipferl'' and the Vienna loaf, quickly became popular and inspired French imitators (and the concept, if not the term, of '' viennoiserie'', a 20th-century term for supposedly Vienna-style pastries). The French version of the ''kipferl'' was named for its crescent (''croissant'') shape and has become a universally identifiable shape across the world. The earliest known recipe for the present-day croissant appears in 1905, although the name croissant appears among the "fantasy or luxury breads" in 1853. Earlier recipes for non-laminated croissants can be found in the 19th century and at least one reference to croissants as an established French bread appeared as early as 1850. Zang himself returned to Austria in 1848 to become a press magnate, but the bakery remained popular for some time afterwards, and was mentioned in several works of the time: "This same M. Zank ...founded around 1830 ic in Paris, the famous Boulangerie viennoise". Several sources praise this bakery's products: "Paris is of exquisite delicacy; and, in particular, the succulent products of the Boulangerie Viennoise"; "which seemed to us as fine as if it came from the Viennese bakery on the rue de Richelieu". By 1869, the croissant was well established enough to be mentioned as a breakfast staple, and in 1872,
Charles Dickens Charles John Huffam Dickens (; 7 February 1812 – 9 June 1870) was an English novelist, journalist, short story writer and Social criticism, social critic. He created some of literature's best-known fictional characters, and is regarded by ...
wrote (in his periodical '' All the Year Round'') of "the workman's ''pain de ménage'' and the soldier's ''pain de munition'', to the dainty croissant on the boudoir table" The puff pastry technique that now characterizes the croissant was already mentioned in the late 17th century, when La Varenne's ''Le Cuisinier françois'' gave a recipe for it in the 1680 – and possibly earlier – edition. It was typically used not on its own but for shells holding other ingredients (as in a
vol-au-vent A ''vol-au-vent'' (pronounced , French for "windblown", to describe its lightness) is a small hollow case of puff pastry. It was formerly also called a patty case. . A ''vol-au-vent'' is typically made by cutting two circles in rolled out p ...
). It does not appear to be mentioned in relation to the croissant until the 20th century. The first recipe corresponding to the modern croissant, not only for the shape but also the texture of the dough and the taste, was published in 1906, in
Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...
, in Colombié's ''Nouvelle Encyclopédie culinaire.'' Sylvain Claudius Goy was a French chef who is sometimes said to have recorded the earliest recipe of the modern croissant. His 1915 book ''La Cuisine Anglo-Americaine'' contains a croissant recipe which Frey Fine Books consider to be the first such recipe published, and they describe the recipe as having " ivenbirth to the croissant of present day". Goy's recipe uses a laminated yeast dough known in French as ''pâte feuilletée levée''.


Culinary legends

Stories of how the ''kipferl'' — sometimes confused with the croissant — was created are widespread and persistent culinary legends, going back to the 19th century.Karl August Schimmer, The Sieges of Vienna by the Turks: Translated from the German of Karl August Schimmer and Others, trans. Earl of Francis Egerton Ellesmere (London: John Murray, 1879), p. 30–31 However, there are no contemporary sources for any of these stories, and an aristocratic writer, writing in 1799, does not mention the ''kipferl'' in a long and extensive list of breakfast foods. The legends include tales that it was invented in Europe to celebrate the defeat of the
Umayyad The Umayyad Caliphate or Umayyad Empire (, ; ) was the second caliphate established after the death of the Islamic prophet Muhammad and was ruled by the Umayyad dynasty. Uthman ibn Affan, the third of the Rashidun caliphs, was also a membe ...
forces by the
Franks file:Frankish arms.JPG, Aristocratic Frankish burial items from the Merovingian dynasty The Franks ( or ; ; ) were originally a group of Germanic peoples who lived near the Rhine river, Rhine-river military border of Germania Inferior, which wa ...
at the Battle of Tours in 732, with the shape representing the Islamic
crescent A crescent shape (, ) is a symbol or emblem used to represent the lunar phase (as it appears in the northern hemisphere) in the first quarter (the "sickle moon"), or by extension a symbol representing the Moon itself. In Hindu iconography, Hind ...
; that it was invented in
Buda Buda (, ) is the part of Budapest, the capital city of Hungary, that lies on the western bank of the Danube. Historically, “Buda” referred only to the royal walled city on Castle Hill (), which was constructed by Béla IV between 1247 and ...
; or, according to other sources, in
Vienna Vienna ( ; ; ) is the capital city, capital, List of largest cities in Austria, most populous city, and one of Federal states of Austria, nine federal states of Austria. It is Austria's primate city, with just over two million inhabitants. ...
in 1683 to celebrate the defeat of the
Ottomans Ottoman may refer to: * Osman I, historically known in English as "Ottoman I", founder of the Ottoman Empire * Osman II, historically known in English as "Ottoman II" * Ottoman Empire The Ottoman Empire (), also called the Turkish Empir ...
by Christian forces in the siege of the city, as a reference to the crescents on the Ottoman flags, when bakers staying up all night heard the tunneling operation and gave the alarm. The Islamic origin story seems to have originated with the 20th-century writer Alfred Gottschalk, who gave two versions: For this reason, the
Islamic State The Islamic State (IS), also known as the Islamic State of Iraq and the Levant (ISIL), the Islamic State of Iraq and Syria (ISIS) and Daesh, is a transnational Salafi jihadism, Salafi jihadist organization and unrecognized quasi-state. IS ...
attempted to ban croissants during the Syrian civil war.


Variants

Uncooked croissant dough can also be wrapped around any praline, almond paste, or
chocolate Chocolate is a food made from roasted and ground cocoa beans that can be a liquid, solid, or paste, either by itself or to flavoring, flavor other foods. Cocoa beans are the processed seeds of the cacao tree (''Theobroma cacao''); unprocesse ...
before it is baked (in the last case, it becomes like ''
pain au chocolat ''Pain au chocolat'' (, ), also known as ''chocolatine'' () in the south-west part of France and in French language, French speaking parts of Canada, ''couque au chocolat'' in Belgium, or ''chocolate croissant'' in the United States, is a type ...
'', which has a different, non-crescent, shape), or sliced to include sweet or savoury fillings. It may be flavored with dried fruit such as sultanas or raisins, or other fruits such as
apple An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...
s. In France and Spain, croissants are generally sold without filling and eaten without added butter, but sometimes with
almond The almond (''Prunus amygdalus'', Synonym (taxonomy)#Botany, syn. ''Prunus dulcis'') is a species of tree from the genus ''Prunus''. Along with the peach, it is classified in the subgenus ''Amygdalus'', distinguished from the other subgenera ...
filling. In the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
, sweet fillings or toppings are sometimes used, and warm croissants may be filled with ham and
cheese Cheese is a type of dairy product produced in a range of flavors, textures, and forms by coagulation of the milk protein casein. It comprises proteins and fat from milk (usually the milk of cows, buffalo, goats or sheep). During prod ...
, or
feta cheese Feta ( ; ) is a Greek brined white cheese made from sheep milk or from a mixture of sheep and goat milk. It is soft, with small or no holes, and no skin. Crumbly with a slightly grainy texture, it is formed into large blocks and aged in b ...
and
spinach Spinach (''Spinacia oleracea'') is a leafy green flowering plant native to Central Asia, Central and Western Asia. It is of the order Caryophyllales, family Amaranthaceae, subfamily Chenopodioideae. Its leaves are a common vegetable consumed eit ...
. In the
Levant The Levant ( ) is the subregion that borders the Eastern Mediterranean, Eastern Mediterranean sea to the west, and forms the core of West Asia and the political term, Middle East, ''Middle East''. In its narrowest sense, which is in use toda ...
, croissants are sold plain or filled with chocolate, cheese, almonds, or zaatar. In
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
, croissants are sometimes filled with
Nutella Nutella ( , , ; stylized in all lowercase) is a brand of brown, sweetened hazelnut cocoa spread. Nutella is manufactured by the Italian company Ferrero and was introduced in 1964, although its first iteration dates to 1963. History Pietro ...
or persipan; in southern Germany, there is also a popular variety of a croissant glazed with
lye Lye is the common name of various alkaline solutions, including soda lye (a solution of sodium hydroxide) and potash lye (a solution of potassium hydroxide). Lyes are used as cleaning products, as ingredients in soapmaking, and in various other c ...
(''Laugencroissant''). In the German-speaking part of
Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...
, the croissant is typically called a ''Gipfeli''; this usually has a crisper crust and is less buttery than the French-style croissant.


Argentina and Uruguay

Croissants are commonly served alongside coffee for breakfast, ''aperitivo'' (a light mid-morning meal), or '' merienda'' (a mid-afternoon meal). They are referred to as ''medialunas'' ("half moons") because of their shape and are typically coated with a sweet glaze (''medialunas de manteca'', "half moons of butter"). Another variant is a ''medialuna de grasa'' ("half moon of lard"), which is not always sweet.


Italy

A cousin of the croissant is the Italian '' cornetto'' (in the center and
south South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both west and east. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...
) or
brioche Brioche (, also , , ) is a bread of French origin whose high egg and butter content gives it a rich and tender crumb. Chef Joël Robuchon described it as "light and slightly puffy, more or less fine, according to the proportion of butter and e ...
(in the
north North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...
). These variants are often considered to be the same, but that is not completely true: the French version tends to be crispy, whereas an Italian ''cornetto'' or brioche is usually softer. Furthermore, the ''cornetto vuoto'' () is commonly accompanied by variants with filling, which include ''crema pasticciera'' (
custard Custard is a variety of culinary preparations based on sweetened milk, cheese, or cream cooked with Eggs as food, egg or egg yolk to thicken it, and sometimes also flour, corn starch, or gelatin. Depending on the recipe, custard may vary in con ...
), apricot jam or
chocolate Chocolate is a food made from roasted and ground cocoa beans that can be a liquid, solid, or paste, either by itself or to flavoring, flavor other foods. Cocoa beans are the processed seeds of the cacao tree (''Theobroma cacao''); unprocesse ...
cream. They often come covered with powdered sugar or other toppings. ''Cornetto'' with cappuccino at the bar is one of the most common
breakfast Breakfast is the first meal of the day usually eaten in the morning. The word in English refers to breaking the fasting period of the previous night. Various "typical" or "traditional" breakfast menus exist, with food choices varying by regi ...
s in Italy.


Poland

On 11 November, St. Martin's Day is celebrated in the Polish region of
Greater Poland Greater Poland, often known by its Polish name Wielkopolska (; ), is a Polish Polish historical regions, historical region of west-central Poland. Its chief and largest city is Poznań followed by Kalisz, the oldest city in Poland. The bound ...
, mainly in its capital city
Poznań Poznań ( ) is a city on the Warta, River Warta in west Poland, within the Greater Poland region. The city is an important cultural and business center and one of Poland's most populous regions with many regional customs such as Saint John's ...
. On this day, the people of Poznań purchase and eat considerable amounts of sweet, crescent-shaped pastries called ''rogale świętomarcińskie'' (" St. Martin's croissants"). They are made specially for this occasion from puff pastry filled with ground white poppy seeds, almonds, raisins, and nuts.


Portugal

The first type of Portuguese croissant is similar to the French, and can be plain or filled with custard, chocolate, fruit jam, or a typical Portuguese cream made of egg yolk and sugar, "doce de ovo". It is customary for these to also have powdered sugar on top. The second version has a similar consistency to
brioche Brioche (, also , , ) is a bread of French origin whose high egg and butter content gives it a rich and tender crumb. Chef Joël Robuchon described it as "light and slightly puffy, more or less fine, according to the proportion of butter and e ...
and is commonly eaten with ham and cheese. Sometimes this type is also served like toast, with a spread of butter. While the first type of croissant is considered sweet and is eaten during breakfast or tea, the second type is a more filling meal and is usually considered a sandwich and often prepared for picnics or as travel food. Both types share the same name (French/Portuguese: "croissant") but are typically found in different bakeries: the sweet croissant is more commonly found in Portuguese pâtisseries and the brioche croissant is usually found in coffeehouses.


Turkey

A pastry with croissant shape is the Turkish ''ay çöreği''. It is filled with
cinnamon Cinnamon is a spice obtained from the inner bark of several tree species from the genus ''Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, biscuits, b ...
,
walnut A walnut is the edible seed of any tree of the genus '' Juglans'' (family Juglandaceae), particularly the Persian or English walnut, '' Juglans regia''. They are accessory fruit because the outer covering of the fruit is technically an i ...
,
hazelnut The hazelnut is the fruit of the hazel tree and therefore includes any of the nuts deriving from species of the genus '' Corylus'', especially the nuts of the species ''Corylus avellana''. They are also known as cobnuts or filberts according to ...
, cacao and
raisin A raisin is a Dried fruit, dried grape. Raisins are produced in many regions of the world and may be eaten raw or used in cooking, baking, and brewing. In the United Kingdom, Republic of Ireland, Ireland, New Zealand, Australia and South Afri ...
. Its rectangular shape variant is known as ''pastiç'' or ''İzmir çöreği''. It is generally eaten during breakfast or with tea.


Overview of manufacturing

The first step of manufacturing croissants is the "predough" formation. To prepare predough, flour, water, in-dough fat, yeast, salt, and sugar are mixed together in a single step. Typically, croissant predough is mixed in a relatively cool environment, for a longer time than other pastries. The ideal temperature of the dough should be around , to best hydrate the ingredients. In comparison to the mixing of bread dough ingredients, pastry predough is considered underdeveloped in that mixing is stopped as soon as the dough appears homogeneous, to allow for further dough development in the next step. The second step is the lamination process. Lamination is necessary to produce multilayered dough with alternating layers of predough and fat. Generally, there are two methods for folding fat into the dough: the English method and the French method. In the English method, one fold results in two fat layers and three dough layers. After spreading out predough, roll-in fat is flattened to a similar thickness as the predough and spread over two-thirds of the surface of the laminated predough. The exposed third of predough is then folded over half of the roll-in fat, while the other end (one predough and one fat layer) is folded on top. In the French method, one fold results in one fat layer and two dough layers. After spreading out the predough and putting a layer of roll-in fat over the center surface of the dough, the corners of the predough are folded toward the middle of the fat. Croissant dough is typically laminated until 16–50 fat layers are obtained. The optimal number of layers can be determined by balancing certain crumb properties with specific volume. On one hand, a low number of layers yields large specific heights as well as irregular crumb structure with large voids. On the other hand, a large number of relatively thin layers leads to interconnections between different dough layers as well as less dough lift. After lamination, the dough is formed into its famous
crescent A crescent shape (, ) is a symbol or emblem used to represent the lunar phase (as it appears in the northern hemisphere) in the first quarter (the "sickle moon"), or by extension a symbol representing the Moon itself. In Hindu iconography, Hind ...
shape. First, the laminated dough is cut into triangles of the desired size. The triangles are then rolled with three-and-a-half to four full turns, and finally, the ends of the roll are curved inwards to form a crescent. The third step is the
fermentation Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic molecules, such as glucose or other sugars, are catabolized and reduce ...
process. Croissants are different from other puff pastries in that they include yeast, which, during proofing, increases the dough volume. Ideally, the optimum croissant quality is achieved at a yeast level of 7.5%, with a proof time of 60 minutes at . The croissants are finished proofing when the dough has expanded two-and-a-half times its original volume. The fourth step is the baking process. Also known as "pastry lift" or "dough lift", the dough expands as water is converted to
steam Steam is water vapor, often mixed with air or an aerosol of liquid water droplets. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Saturated or superheated steam is inv ...
, thus increasing the pressure between each dough layer. As a result, the croissant dough rises up to yield its characteristic flaky texture. Depending on the type of oven used and specific size of the croissant, the baking time can range from 10 to 20 minutes and the oven temperature can be set anywhere from . The final steps are the cooling and storage of the croissant. Croissants are generally not stored for very long and are typically consumed soon after baking.


Ingredient functionality during processing


Predough

Gluten Gluten is a structural protein naturally found in certain Cereal, cereal grains. The term ''gluten'' usually refers to the elastic network of a wheat grain's proteins, gliadin and glutenin primarily, that forms readily with the addition of water ...
proteins affect the water absorption and
viscoelastic In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both Viscosity, viscous and Elasticity (physics), elastic characteristics when undergoing deformation (engineering), deformation. Viscous mate ...
properties of the predough. The role of proteins can be divided into two stages of dough formation: hydration and deformation. In the hydration stage, gluten proteins absorb water up to two times their own weight. In the deformation or kneading stage, the action of mixing causes the gluten to undergo a series of polymerization and depolymerization reactions, forming a viscoelastic network. Hydrated glutenin proteins in particular help form a polymeric protein network that makes the dough more cohesive. On the other hand, hydrated gliadin proteins do not directly form the network, but do act as plasticizers of the glutenin network, thus imparting fluidity to the dough’s viscosity.
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 diet ...
also affects the viscosity of predough. At room temperature and in a sufficient amount of water, intact starch granules can absorb water up to 50% of their own dry weight, causing them to swell to a limited extent. The slightly swollen granules are found in the spaces between the
gluten Gluten is a structural protein naturally found in certain Cereal, cereal grains. The term ''gluten'' usually refers to the elastic network of a wheat grain's proteins, gliadin and glutenin primarily, that forms readily with the addition of water ...
network, thus contributing to the consistency of the dough. The granules may not be intact, as the process of
milling Milling may refer to: * Milling (minting), forming narrow ridges around the edge of a coin * Milling (grinding), breaking solid materials into smaller pieces by grinding, crushing, or cutting in a mill * Milling (machining), a process of using ro ...
wheat into flour damages some of the starch granules. Given that damaged starch granules have the capacity to absorb around three times as much water as undamaged starch, the use of flour with higher levels of damaged starch requires the addition of more water to achieve optimal dough development and consistency. Water content affects the mechanical behavior of predough. As previously discussed, water is absorbed by gluten and starch granules to increase the
viscosity Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for e ...
of the dough. The temperature of the water is also important as it determines the temperature of the predough. In order to facilitate processing, cold water should be used for two main reasons. First, chilled water provides a desirable environment for gluten development, as the temperature at which mixing occurs impacts the dough’s hydration time, consistency, and required amount of mixing energy. Secondly, cold water is comparable to the temperature of the roll-in fat to be added later, which better facilitates the latter’s incorporation. In-dough fat affects the texture and lift of predough. Although higher levels of dough fat may lower dough lift during baking, it also correlates with a softer end product. As such, the main function of in-dough fat is to produce a desirable softness in the final croissant.


Lamination

In laminated croissant dough, the gluten network is not continuous. Instead, the gluten proteins are separated as thin gluten films between dough layers. The formation of thin, well-defined layers affects the height of dough lift. Generally, laminated croissant dough contains fewer layers than other puff pastry doughs that do not contain yeast, due to the presence of small bubbles in the gluten sheets. Upon proofing, these bubbles expand and destroy the integrity of the dough layers. The resulting interconnections between different dough layers would over-increase dough strength and allow water vapor to escape through micropores during baking, consequently decreasing dough lift. The role of fat also influences the separation of layers, as will be discussed next. Roll-in fat affects the flakiness and flavor of the croissant. In laminated dough, fat layers alternate with dough layers. As such, the most important function of roll-in fat is to form and maintain a barrier between the different dough layers during sheeting and folding. As previously stated, the ability for fat to maintain separation between folded dough layers ensures proper dough lift. The type of roll-in fat used is typically
butter Butter is a dairy product made from the fat and protein components of Churning (butter), churned cream. It is a semi-solid emulsion at room temperature, consisting of approximately 81% butterfat. It is used at room temperature as a spread (food ...
or margarine. Butter and margarine are both water-in-oil
emulsion An emulsion is a mixture of two or more liquids that are normally Miscibility, immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloi ...
s, composed of stabilized water droplets dispersed in oil. While butter is appealing due to its high consumer acceptance, its low melting point, , actually makes it undesirable for production purposes. The use of butter as roll-in fat during the lamination step will cause problems of oiling out during sheeting and fermentation if the temperature is not tightly controlled, thus disrupting the integrity of the layers. On the other hand, kinds of margarine are commonly used as roll-in fat because they facilitate dough handling. Generally, roll-in margarine should have a melting point between , at least higher than the fermentation temperature to prevent oiling out prior to baking. It is also important to consider the plasticity and firmness of the roll-in fat, which is largely determined by its solid fat content. Generally, a greater proportion of solid fat coincides with larger croissant lift. At the same time, the roll-in fat should have plasticity comparable to that of the dough, such that the fat layers do not break during sheeting and folding. If the fat is firmer than the dough, then the dough can rupture. If the fat is softer than the dough, then it will succumb to the mechanical stress of sheeting and potentially migrate into the dough.


Fermentation

Croissants contain yeast, ''
Saccharomyces cerevisiae ''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungal microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have be ...
'', which is incorporated during predough formation. When oxygen is abundant, the yeast breaks down sugar into carbon dioxide and water through the process of respiration. This process releases energy that is used by the yeast for growth. After consuming all of the oxygen, the yeast switches to anaerobic
fermentation Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic molecules, such as glucose or other sugars, are catabolized and reduce ...
. At this point, the yeast partially breaks down sugar into
ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...
and carbon dioxide. Once saturates the dough’s aqueous phase, the gas begins to leaven the dough by diffusing to preexisting gas cells that were incorporated into the predough during mixing. Yeast action does not produce new gas cells, as the immense pressure required for a single molecule to create a new gas bubble is not physically attainable In order to ensure the flaky texture of the croissant, it is important to balance the yeast activity with
steam Steam is water vapor, often mixed with air or an aerosol of liquid water droplets. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Saturated or superheated steam is inv ...
production. If the yeast overproduces , then the well-defined layers may collapse. During the baking process, this would cause steam to escape too early from the bread, reducing dough lift and flakiness of the final product. Thus, to offset the negative effects of yeast on layer integrity and dough lift, croissants usually contain fewer layers than other puff pastries.


Baking

During baking, the transient
gluten Gluten is a structural protein naturally found in certain Cereal, cereal grains. The term ''gluten'' usually refers to the elastic network of a wheat grain's proteins, gliadin and glutenin primarily, that forms readily with the addition of water ...
network turns into a permanent network. At higher temperatures, intermolecular disulfide bonds form between glutenin molecules, as well as between gliadin and glutenin. With more bonds being made, the gluten network becomes more rigid, strengthening the croissant’s crumb texture. Additionally, the baking process significantly stretches the dough layers due to the large macroscopic deformation that occurred during fermentation’s dough lift. Starch undergoes gelatinization as a result of baking. Prior to baking, starch granules absorb a small amount of water at room temperature as it is mixed with water to form predough. As long as the dough’s temperature stays under the gelatinization temperature, this granule swelling is limited and reversible. However, once the baking process begins and the dough is exposed to temperatures above the gelatinization temperature,
amylopectin Amylopectin is a water-insoluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. Plants store starch within specialized organelles called amyloplas ...
crystallites become more disordered inside the starch granules and cause an irreversible destruction of molecular order. At the same time, starch gelatinization actively draws water from the gluten network, further decreasing the flexibility of the gluten. Currently, the extent of
amylose Amylose is a polysaccharide made of α-D-glucose units, bonded to each other through α(1→4) glycosidic bonds. It is one of the two components of starch, making up approximately 20–25% of it. Because of its tightly packed Helix, helical struct ...
leaching and granular structure distortion during the baking of croissants is still unknown. Roll-in fat gradually melts as the temperature in the oven increases. Some of the melting fat can migrate into the dough, which could then interfere with gluten protein crosslinking. The fat phase also contributes to dough lift through gas inflation, which will be described next. Water is converted to
steam Steam is water vapor, often mixed with air or an aerosol of liquid water droplets. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Saturated or superheated steam is inv ...
during the baking process, which is the main factor behind the leavening of the dough. The water for steam production comes from both the dough layers and the roll-in fat. As the fat melts, the continuous oil phase is no longer able to stabilize the water droplets, which are then released and converted to steam. Although the exact mechanism of steam entrapment is still unclear, it is likely a result of both steam expanding inside each dough layer and steam migrating to oil layers, where it inflates gas bubbles. The steam migration to oil phase is likely due to the smaller pressure differential required to inflate a bubble of steam in liquid fat than in solid dough. As the concentration of steam increases between dough layers, the increased pressure causes the dough to lift. During the entire baking process, only half of the water vapor contributes to dough lift, as the other half is lost through micropores and capillaries of interconnected dough layers.


Storage

The effect of
gluten Gluten is a structural protein naturally found in certain Cereal, cereal grains. The term ''gluten'' usually refers to the elastic network of a wheat grain's proteins, gliadin and glutenin primarily, that forms readily with the addition of water ...
proteins during cooling and storage is still unclear. It is possible that gluten proteins influence croissant firming through the loss of plasticizing water, which increases the stiffness of the gluten network. Starch plays a major role in the degradation of croissants during storage.
Amylopectin Amylopectin is a water-insoluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. Plants store starch within specialized organelles called amyloplas ...
retrogradation occurs over several days to weeks, as amorphous amylopectin chains are realigned into a more
crystalline A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...
structure. The transformation of the starch causes undesirable firmness in the croissant. Additionally, the formation of the crystal structure of amylopectin requires the incorporation of water. Starch retrogradation actively draws water from the amorphous gluten network and some of the amorphous starch fraction, which reduces the plasticity of both. Water migration influences the quality of stored croissants through two mechanisms. First, as previously stated, water redistributes from
gluten Gluten is a structural protein naturally found in certain Cereal, cereal grains. The term ''gluten'' usually refers to the elastic network of a wheat grain's proteins, gliadin and glutenin primarily, that forms readily with the addition of water ...
to
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 diet ...
as a result of starch retrogradation. Secondly, during the baking process, a moisture gradient was introduced as a result of heat transfer from the oven to the croissant. In fresh croissants, there is high moisture content on the inside and low moisture content on the outside. During storage, this moisture gradient induces water migration from the inside to the outer crust. On a molecular level, water is lost from the amorphous
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 diet ...
fraction and
gluten Gluten is a structural protein naturally found in certain Cereal, cereal grains. The term ''gluten'' usually refers to the elastic network of a wheat grain's proteins, gliadin and glutenin primarily, that forms readily with the addition of water ...
network. At the same time, water diffuses from the outer crust to the environment, which has less moisture. The result of this redistribution of water is a firming up of the croissant, caused by a decrease in starch plasticity and an increase in gluten network rigidity. Due to the presence of large pores in croissants, moisture is lost to the environment at a faster rate than bread products. As such, croissants generally become harder in texture at a faster rate than breads. Fat also affects the quality of croissants in storage. On one hand, an increased amount of in-dough fat has been found to correspond to a reduction in crumb hardness immediately after baking. This is likely attributed to the high-fat content of croissants, as increased fat levels decrease moisture diffusion. On the other hand, although roll-in fat softens the croissant’s initial crumb, its effect on croissant hardness during storage is still unclear.


See also

* List of bread rolls * List of brunch foods * List of butter dishes * List of French dishes * List of pastries * Cornetto * Cruffin


References

{{Authority control Foods featuring butter Austrian cuisine French pastries