In this blog entry, we will delve into what is perhaps the most famous fried dough in the world, donuts. Additionally, we will take the opportunity to discuss some other fried preparations typical of our culture. As we mentioned when discussing churros, another fried dough, frying involves an exchange of water, which leaves the dough, for oil, which enters it. Furthermore, high-temperature heat treatment occurs rapidly during frying, achieving changes similar to those that would occur during baking, such as starch gelatinization, gluten denaturation, Maillard reactions, and caramelization on the outer surfaces, among others. In general, fried products are very juicy due to their high fat content, but they are also high in calories for the same reason.

Due to its length, we will address this topic in two entries.

Before we talk about donuts, we need to delve into their history, particularly their curious history in Spain.

History

The origin of donuts is attributed to Dutch immigrants in the United States in the 19th century. However, the first known products did not have the central hole and were more similar to Berliner pastries. The first donuts with a hole, as we know them today, date back to the mid-19th century, and it appears that they originated in the state of Maine, USA. There are several versions explaining this variation. Some attribute it to a baker’s apprentice who decided to remove the central part because it seemed too soft (perhaps the most credible theory in my view). Others speak of a teenager who asked his mother to remove the central part because they were undercooked in the centre. There’s also a more extravagant version referring to a sailor who had to hang the donut on the ship’s wheel bars to navigate, and a hole came in handy for this purpose. Regardless of the explanation, having a central hole increases the surface area in contact with the oil, and thus, the amount of oil absorbed during frying. Consequently, it enhances the juiciness of the product but also its caloric content.

By the end of the 19th century, there were already patents for donut-making machines. However, it was after the end of World War I that they began to be sold in large cities like New York, and the first chains of this product were established in the United States. Donuts arrived in Spain in the second half of the 20th century, introduced by the company Panrico.

The Anglo-Saxon term used to describe these products is “doughnut,” a generic term that today refers to a sweet, ring-shaped pastry with a hole in the centre, made from yeast-fermented sweet dough, fried in vegetable oil or ample animal fat, and often sprinkled with sugar. However, this name is also used to refer to similar products, including those without a central hole or some filled varieties. In most of South America, this name has been adapted to “donas.” The term “donut” emerged in the late 19th or early 20th century as a reasonably phonetic transcription. Its usage became common after 1920. However, in Spain, in a clever commercial move, Panrico registered the name “Donuts” when introducing this product to the Spanish market. Therefore, the only company that could call what was known worldwide as a “Donut” was Panrico. But competitors also couldn’t use the terms “Dona” or “Doughnut” due to their similarity to Donut. Consequently, although we all call them donuts, regardless of the manufacturer, if they were not made by Panrico, other companies had to use different names. Some opted for the term “berlina,” although this pastry usually lacks the central hole. Others preferred to use the term “rosquilla” or “rosco,” although in Spain, these names are usually reserved for drier products. Some got creative with names like “ceros.” Nowadays, the company Panrico no longer exists as such, and the owner of the name in Spain is Bimbo, the world’s largest multinational bakery.

There are essentially two basic types of donuts: those based on fermented dough, which are more typical in Spain, and those based on batter and the use of leavening agents (cake donuts). It’s essential to consider this because both the processing and the ingredients can differ between these two types. Therefore, we will address these types separately. Both types of donuts can be filled or coated or left plain, but the foundation lies in these two types of preparations.

There is a third type, somewhat less common, based on choux pastry. We will discuss it briefly, but as I mentioned, it is much less common.

Fermented Donuts

Ingredients

These donuts are prepared similarly to sweet, fermented dough, like brioche, with some particularities and a final frying step that replaces baking. You can start with a basic formula consisting of flour, water (around 58-60%, but this may vary depending on the type of flour and formula used), sugars (8-10%), fat (10-12%), salt (1-2%), milk powder (less than 5%), egg yolk (less than 5%), and yeast (around 5%).

For the flour, strong or very strong flour is preferred. This is because the high fat and sugar content weakens the gluten network, preventing proper dough expansion, depending on the type and quality of the flour. Some producers use medium-strength flours, which can offer better dough handling and a slightly softer texture initially but may result in less volume and shorter shelf life. To strengthen the gluten network, additives such as oxidants (ascorbic acid) or reinforcing emulsifiers like DATEM, SSL, or Lecithin are commonly incorporated. Some manufacturers include vegetable protein, typically from soy, in small amounts to increase water absorption and enhance colour. However, this is not usually necessary and can harm the final volume by diluting the gluten network, especially if used in excessive amounts.

Regarding sugars, sucrose is commonly used, but glucose, inverted sugar, or even fructose syrups can also be used. Glucose, fructose, or inverted sugar have a higher potential for Maillard reactions than sucrose, resulting in a darker colour during baking. In the case of glucose, its sweetness is slightly reduced, contrary to what happens with fructose. In principle, sugars are nutrients for yeast, but in large quantities like those in these products, they inhibit yeast activity due to high osmotic pressures. To overcome this drawback, higher yeast amounts are often used compared to products like bread or osmotolerant yeast strains, which better withstand these conditions.

Fat provides tenderness to the final product and reduces its hardness, increasing shelf life. Some fat is incorporated into the dough, but the final product will also absorb fat from the frying process. The percentage of fat absorbed by the dough during frying ranges from 20 to 30%, depending on the ingredients, size (smaller sizes absorb more due to the increased surface area for exchange), and processing. In both cases, vegetable fats such as palm or palm kernel fats or margarines are commonly used. These fats tend to melt in the mouth, giving a refreshing sensation, and are appreciated by consumers organoleptically, but they contribute a high amount of saturated fats, which are less favourable nutritionally. Frying fats also withstand multiple frying cycles without deteriorating, although this deterioration should be checked regularly.

The use of eggs is also common. Egg white provide structure as they coagulate during frying, but an excess can result in excessively tough textures. Yolks also contribute colour, flavour and fats that enhance the organoleptic qualities of the product. In both cases, if provided in liquid pasteurized form, the water they contain should be taken into account. Powdered milk, on the other hand, contributes lactose and proteins that can contribute to the final product’s colour through Maillard reactions and also provide some structure while slightly reducing fat absorption during frying.

Salt enhances flavour, reinforces the gluten network, and slightly slows down fermentation. In addition to salt, the incorporation of flavours or spices is common. The most common ones include nutmeg and mace (both from the same plant), vanilla, and lemon.

The use of pre-gelatinized starches or flours or some form of thickener, such as guar gum, is also common. These products increase water absorption and, therefore, reduce oil absorption during frying. They can also contribute to extending the shelf life by reducing dough drying. If you want the donut to remain fresh, preservatives are commonly used. Without preservatives, microbial deterioration would occur more rapidly. However, because it is a fermented dough, sorbates cannot be used as they would inhibit yeast activity. Therefore, propionates or encapsulated sorbic acid are commonly used.

Processing

There are many variations in the processing of donuts. They can be made using a direct method or a sponge (incorporating dough that has been resting for several hours beforehand). It is also possible to use sourdough, both liquid and solid, although this is less common in industrial processes. Kneading, which can be done using different types of kneaders, should ensure the correct formation of the gluten network without over-kneading, which could weaken the dough, depending on the type and quality of the flour.

As in all fermentative processes, it is important to control the final dough temperature, as it influences the start of fermentation and changes in the dough’s rheology. The final dough temperature is usually slightly above 25°C. The dough obtained typically rests at temperatures between 25-30°C for 60-90 minutes before shaping, although this will depend on the formulation and the type of shaping. This rest period should be conducted under high humidity conditions to prevent the formation of crust or skin on the exterior.

Shaping can be done through rolling and cutting or extrusion (more common). The first system generates scraps, which are usually reintegrated during the kneading phase. These scraps can account for a little over 15% of the dough. If these scraps are reintegrated into the dough, it must be considered since the percentage of scraps must always be the same to ensure some uniformity. Their effect on the dough’s temperature should also be taken into account. The extrusion shaping system, using pressure or vacuum, does not generate scraps and usually adapts better to high-yield processes. However, it is very sensitive to dough rheology and, therefore, requires very consistent processes, especially regarding pre-fermentations.

After shaping, the dough undergoes a short fermentation of about 30 minutes at high temperatures (around 40°C) and low humidity. This low humidity causes the outer part of the pieces to dry, reducing their expansion but helping to reduce oil absorption during frying. As water exchange occurs, if the water content in the outer area is lower, so will the oil absorption be. If you want to reduce oil absorption without reducing expansion, some equipment allows working with higher humidity in the initial part of the final fermentation and lower humidity in the final part.

Once fermentation is complete, the dough is fried in special fryers that flip the pieces halfway through frying. These pieces usually float, so only the bottom would fry if they were not flipped. The frying process is rapid and takes only a few minutes, depending on the size of the donuts.

The final product, once cooled, is often coated with glaze or icing. For this reason, it is not uncommon to find ingredients like agar or carrageenans among the donut’s ingredients. These are gelling hydrocolloids commonly used for such finishes.

Alternatives

Firstly, let’s address two important points about donuts. They freeze very well, which is why some manufacturers freeze them after frying to extend their shelf life and facilitate distribution. These products are thawed by the final retailer, whether it’s a supermarket or a hospitality establishment, so consumers are often unaware that the product has been frozen. In these cases, the final expiration date, if required to be marked, as is the case in supermarkets, should be determined by the establishment that thaws them.

These products, while highly appreciated for their organoleptic quality, are not valued for their nutritional properties. In Spain and other countries, attempts have been made to improve their nutritional attributes by using whole grain flours or reducing calorie content. Technologically, it’s not a complex process, but these practices always involve a loss of organoleptic quality that consumers typically do not accept. To achieve these improvements, ingredients with high water-absorbing capacity are often added to reduce oil absorption during frying. These ingredients include fibres and other techniques. The result is that none of these attempts has been successful, despite some significant advertising campaigns, at least in Spain. I often say that consumers already know they are indulging when consuming these products, but at the very least, they want the indulgence to bring them maximum pleasure. In a future entry, we will discuss other types of donuts.