Doughnut

Clockwise from upper left: doughnuts in two shapes; Tim Hortons "Timbits" doughnut holes; glazed doughnuts from Five Daughters Bakery; and a pink Christmas doughnut

Rings

Hanson Gregory, an American, claimed to have invented the ring-shaped doughnut in 1847 aboard a lime-trading ship when he was 16 years old. Gregory was dissatisfied with the greasiness of doughnuts twisted into various shapes and with the raw center of regular doughnuts. He claimed to have punched a hole in the center of dough with the ship's tin pepper box, and to have later taught the technique to his mother.^[31] Smithsonian Magazine states that his mother, Elizabeth Gregory, "made a wicked deep-fried dough that cleverly used her son's spice cargo of nutmeg and cinnamon, along with lemon rind," and "put hazelnuts or walnuts in the center, where the dough might not cook through", and called the food 'doughnuts'.^[7]

Ring doughnuts are formed by one of two methods: by joining the ends of a long, skinny piece of dough into a ring, or by using a doughnut cutter, which simultaneously cuts the outside and inside shape, leaving a doughnut-shaped piece of dough and a doughnut hole (the dough removed from the center). This smaller piece of dough can be cooked and served as a "doughnut hole" or added back to the batch to make more doughnuts. A disk-shaped doughnut can also be stretched and pinched into a torus until the center breaks to form a hole. Alternatively, a doughnut depositor can be used to place a circle of liquid dough (batter) directly into the fryer.

There are two types of ring doughnuts, those made from a yeast-based dough for raised doughnuts, or those made from a special type of cake batter.^[11][32][33] Yeast-raised doughnuts contain about 25% oil by weight, whereas cake doughnuts' oil content is around 20%, but have extra fat included in the batter before frying. Cake doughnuts are fried for about 90 seconds at approximately 190 to 198 °C (374 to 388 °F), turning once. Yeast-raised doughnuts absorb more oil because they take longer to fry, about 150 seconds, at 182 to 190 °C (360 to 374 °F). Cake doughnuts typically weigh between 24 and 28 g (0.85 and 0.99 oz), whereas yeast-raised doughnuts average 38 g (1.3 oz) and are generally larger, and taller (due to rising) when finished.^{[citation needed]}

Daniela Galarza, for Eater, wrote that "the now-standard doughnut’s hole is still up for debate. Food writer Michael Krondl surmises that the shape came from recipes that called for the dough to be shaped like a jumble – a once common ring-shaped cookie. In Cuisine and Culture: A History of Food and People, culinary historian Linda Civitello writes that the hole was invented because it allowed the doughnuts to cook faster. By 1870 doughnut cutters shaped in two concentric circles, one smaller than the other, began to appear in home-shopping catalogues".^[11]

Topping

After frying, ring doughnuts are often topped. Raised doughnuts are generally covered with a

Traditionally, doughnut holes are made by frying the dough removed from the center portion of the doughnut.[37] Consequently, they are considerably smaller than a standard doughnut and tend to be spherical. Similar to standard doughnuts, doughnut holes may be topped with confections, such as glaze or powdered sugar.

Originally, most varieties of doughnut holes were derivatives of their ring doughnut (yeast-based dough or cake batter) counterparts. However, doughnut holes can also be made by dropping a small ball of dough into hot oil from a specially shaped nozzle or cutter.^[38] This production method has allowed doughnut sellers to produce bite-sized versions of non-ring doughnuts, such as filled doughnuts, fritters and Dutchies.

Filled

Filled doughnuts are flattened spheres injected with fruit preserves, cream, custard, or other sweet fillings, and often dipped into powdered sugar or topped off with frosting. Common varieties include the Boston cream, coconut, key lime, and jelly.

Other shapes

Others include the fritter and the Dutchie, which are usually glazed. These have been available on Tim Hortons' doughnut menu since the chain's inception in 1964,^[39] and a 1991 Toronto Star report found these two were the chain's most popular type of fried dough in Canada.^[40]

There are many other specialized doughnut shapes such as

Yeast doughnuts and cake doughnuts contain most of the same ingredients, however, their structural differences arise from the type of flour and leavening agent used. In cake doughnuts, cake flour is used, and the resulting doughnut has a different texture because cake flour has a relatively low protein content of about 7 to 8 percent.[43] In yeast doughnuts, a flour with a higher protein content of about 9 to 12 percent is used, resulting in a doughnut that is lighter and more airy.^[43] In addition, yeast doughnuts utilize yeast as a leavening agent. Specifically, "Yeast cells are thoroughly distributed throughout the dough and begin to feed on the sugar that is present ... carbon dioxide gas is generated, which raises the dough, making it light and porous."^[44] Whereas this process is biological, the leavening process in cake doughnuts is chemical. In cake doughnuts, the most common leavening agent is baking powder. Baking powder is essentially "baking soda with acid added. This neutralizes the base and produces more CO₂ according to the following equation: NaHCO₃ + H⁺ → Na⁺ + H₂O + CO_2."^[45]

Physical structure

The physical structure of the doughnut is created by the combination of flour, leavening agent, sugar, eggs, salt, water, shortening, milk solids, and additional components.^{[2]: 232 [46][47][41][42]} The most important ingredients for creating the dough network are the flour and eggs. The main protein in flour is gluten, which is overall responsible for creating elastic dough because this protein acts as "coiled springs."^[48] The gluten network is composed of two separate molecules named glutenin and gliadin. Specifically, "the backbone of the gluten network likely consists of the largest glutenin molecules, or subunits, aligned and tightly linked to one another. These tightly linked glutenin subunits associate more loosely, along with gliadin, into larger gluten aggregates."^[49] The gluten strands than tangle and interact with other strands and other molecules, resulting in networks that provide the elasticity of the dough. In mixing, the gluten is developed when the force of the mixer draws the gluten from the wheat endosperm, allowing the gluten matrix to trap the gas cells.^[48]

Molecular composition

Eggs function as emulsifiers, foaming agents, and tenderizers in the dough. The egg white proteins, mainly ovalbumin, "function as structure formers. Egg solids, chiefly the egg white solids combined with the moisture in the egg, are considered structure-forming materials that help significantly to produce proper volume, grain, and texture."^[44] The egg yolk contributes proteins, fats, and emulsifiers to the dough. Emulsifying agents are essential to doughnut formation because they prevent the fat molecules from separating from the water molecules in the dough. The main emulsifier in egg yolk is called lecithin, which is a phospholipid. "The fatty acids are attracted to fats and oils (lipids) in food, while the phosphate group is attracted to water. It is this ability to attract both lipids and water that allow phospholipids such as lecithin to act as emulsifiers."^[49] The proteins from both the egg yolk and the egg whites contribute to the structure of the dough through a process called coagulation. When heat is applied to the dough, the egg proteins will begin to unfold, or denature, and then form new bonds with one another, thus creating a gel-like network that can hold water and gas.^[49]

Shortening is responsible for providing tenderness and aerating the dough. In terms of its molecular structure, "a typical shortening that appears solid [at room temperature] contains 15–20% solids and, hence, 80–85% liquid oil ... this small amount of solids can be made to hold all of the liquid in a matrix of very small, stable, needlelike crystals (beta-prime crystals)."^[44] This crystalline structure is considered highly stable due to how tightly its molecules are packed. The sugar used in baking is essentially sucrose, and besides imparting sweetness in the doughnut, sugar also functions in the color and tenderness of the final product. Sucrose is a simple carbohydrate whose structure is made up of a glucose molecule bound to a fructose molecule.^[49] Milk is utilized in the making of doughnuts, but in large scale bakeries, one form of milk used is nonfat dry milk solids. These solids are obtained by removing most of the water from skim milk with heat, and this heat additionally denatures the whey proteins and increases the absorption properties of the remaining proteins.^[49] The ability of the casein and whey proteins to absorb excess water is essential to prolonging the doughnut's freshness. The major whey protein in the nonfat milk solids is known as beta-lactoglobulin, and a crucial feature of its structure is that there exists a single sulfhydryl group that is protected by the alpha helix, and when heating of the milk solids occurs, these groups participate in disulfide exchanges with other molecules. This interchange prevents the renaturation of the whey proteins.^[50] If the crosslinking of the sulfide groups does not occur, the whey proteins can rebond and weaken the gluten network.

Water is a necessary ingredient in the production of doughnuts because it activates the other ingredients, allowing them to perform their functions in building the doughnut's structure. For example, sugar and salt crystals must be dissolved in order for them to act in the dough, whereas larger molecules, such as the starches or proteins, must be hydrated in order for them to absorb moisture.^[49] Another important consideration of water is its degree of hardness, which measures the amount of impurities in the water source. Pure water consists of two parts hydrogen and one part oxygen, but water used in baking often is not pure. Baker's salt (NaCl) is usually used as an ingredient due to its high purity, whereas the salts in water are derived from varying minerals. As an ingredient, "salt is added to enhance the flavour of cakes and breads and to ‘toughen up’ the soft mixture of fat and sugar."^[45] If relatively soft water is being used, more salt should be added in order to strengthen the gluten network of the dough, but if not enough salt is added during the baking process, the flavor of the bread will not be appealing to consumers.

Health effects

Doughnuts are unhealthful,

An important property of the dough that affects the final product is the dough's rheology. This property measures the ability of the dough to flow. It can be represented by the power law equation: ${\displaystyle \tau =kD^{n}}$ where ${\displaystyle \tau }$ is the tangentic stress, ${\displaystyle k}$ is the viscosity coefficient, ${\displaystyle D}$ is the shear rate, and ${\displaystyle n}$ is the flow index.^[54] Many factors affect dough rheology including the type of ingredients, the amount of the ingredients, or the force applied during mixing. Dough is usually described as a viscoelastic material, meaning that its rheology depends on both the viscosity and the elasticity. The viscosity coefficient and the flow index are unique to the type of dough being analyzed, while the tangentic stress and the shear rate are measurements obtained depending on the type force being applied to the dough.

Regional variations

Asia

Cambodia

Nom kong (នំបុ័ងកង់), the traditional Cambodian doughnut, is named after its shape – the word ‘កង់’ (pronounced kong in Khmer) literally means “wheel”, whilst nom (‘នំបុ័ង’) is the general word for pastry or any kind of starchy food. A very inexpensive treat for everyday Cambodians, this sweet pastry consists of a jasmine rice flour dough moulded into a classic ring shape and then deep fried in fat, then drizzled with a palm sugar toffee and sprinkled with sesame seeds. The rice flour gives it a chewy texture that Cambodians are fond of. This childhood snack is what inspired Cambodian-American entrepreneur Ted Ngoy to build his doughnut empire, inspiring the film The Donut King.

China

A few sweet, doughnut-style pastries are regional in nature. Cantonese cuisine features an oval-shaped pastry called ngàuhleisōu (牛脷酥, lit. "ox-tongue pastry", due to its tongue-like shape).

A spherical food called saa1 jung (沙翁), which is also similar to a

Chinese restaurants in the United States sometimes serve small fried pastries similar to doughnut holes with condensed milk as a sauce.

In India, an old-fashioned sweet called gulgula is made of sweetened, deep-fried flour balls. A leavening agent may or may not be used.^{[citation needed]}

There are a couple of unrelated doughnut-shaped food items. A savory, fried, ring-shaped snack called a vada is often referred to as the Indian doughnut. The vada is made from dal, lentil or potato flours rather than wheat flour.^[55] In North India, it is in the form of a bulging disc called dahi-vada, and is soaked in curd, sprinkled with spices and sliced vegetables, and topped with a sweet and sour chutney. In South India, a vada is eaten with sambar and a coconut chutney.

Sweet pastries similar to old-fashioned doughnuts called badushahi and jalebi are also popular.

Along with these Indian variants, typical varieties of doughnuts are also available from U.S. chains such as Krispy Kreme and Dunkin' Donuts retail outlets, as well as local brands such as Mad Over Donuts and the Donut Baker.^[57]

Indonesia

The Indonesian, donat kentang is a potato doughnut, a ring-shaped fritter made from flour and mashed potatoes, coated in powder sugar or icing sugar.^[58]

Japan

In Japan,

Malaysia

Kuih keria is a hole doughnut made from boiled sweet potato that is mashed. The sweet potato mash is shaped into rings and fried. The hot doughnut is then rolled in granulated sugar. The result is a doughnut with a sugar-crusted skin.[69]

Nepal

Sel roti is a Nepali homemade, ring-shaped, rice doughnut prepared during Tihar, the widely celebrated Hindu festival in Nepal. A semiliquid dough is usually prepared by adding milk, water, sugar, butter, cardamom, and mashed banana to rice flour, which is often left to ferment for up to 24 hours. A sel roti is traditionally fried in ghee.^[70]

Pakistan

Doughnuts are available at most bakeries across Pakistan. The Navaz Sharif variety,^{[citation needed]} available mainly in the city of Karachi, is covered in chocolate and filled with cream, similar to a Boston cream. Doughnuts can readily be found at the many Dunkin' Donuts branches spread across Pakistan.^[71]

Philippines

Local varieties of doughnuts sold by peddlers and street vendors throughout the Philippines are usually made of plain well-kneaded dough, deep-fried in refined coconut oil and sprinkled with refined (not powdered or confectioner's) sugar. Round versions of this doughnut are known as

buñuelos (also spelled bunwelos, and sometimes confusingly known as "bicho-bicho"), similar to the doughnuts in Spain and former Spanish colonies. Indigenous versions of the doughnut also exist, like the cascaron, which is prepared similarly, but uses ground glutinous rice and coconut milk in place of wheat flour and milk.^[72][73]

Other native doughnut recipes include the shakoy,

maruya, among others.^[79][80]

Taiwan

In Taiwan, shuāngbāotāi (雙胞胎, lit. "twins") is two pieces of dough wrapped together before frying.^[81]

Thailand

In Thailand, a popular breakfast food is pa thong ko, also known as Thai donuts, a version of the Chinese yiu ja guoy/youtiao. Often sold from food stalls in markets or by the side of the road, these doughnuts are small, sometimes X-shaped, and sold by the bag full.^[82] They are often eaten in the morning with hot Thai tea.

Vietnam

Vietnamese varieties of doughnuts include bánh tiêu, bánh cam, and bánh rán. Bánh tiêu is a sesame-topped, deep-fried pastry that is hallow. It can be eaten alone or cut in half and served with bánh bò, a gelatinous cake, placed inside the pastry. Bánh cam is from Southern Vietnam and is a ball-shaped, deep-fried pastry coated entirely in sesame seeds and containing a mung bean paste filling. Bánh rán is from Northern Vietnam and is similar to bánh cam; however, the difference is that bánh rán is covered with a sugar glaze after being deep-fried and its mung bean paste filling includes a jasmine essence.^{[citation needed]}

Europe

Austria

In