Donuts II

Donuts II

This entry is a continuation of the first one dedicated to doughnuts and is dedicated to alternative processes to those seen in the first entry.

Cake-Style Doughnuts

In addition to doughnuts made from fermented dough, there are also doughnuts made from batter, more similar to cake batters. To make the batter, you can start with a formula similar to that of a cake, based on wheat flour, water (around 70% of the flour weight), sugar (40-45% based on flour), fat (6-15%), powdered milk (8-12%), egg yolk (6-8%), soy flour (6-8%), salt (1-2%), and baking powder (4-5%), along with flavours.

Some references recommend using medium-strength flours, but there are also companies that use weaker flours. Since there is no gluten network formation in cake batters or it is less than in other doughs, the strength of the flours should not be a determining factor, or at least not as much. However, their protein content is essential since it influences the flour’s water absorption capacity and, therefore, the batter’s rheology and hydration requirements. The addition of soy flour (which can be replaced with wheat flour) is partly justified for this reason, increasing the dough’s water absorption capacity, and reducing its oil absorption capacity.

The role of sugars is similar to what was discussed for fermented doughnuts, except for being a possible food for yeast, which is not incorporated in this case. But we must consider their sweetening power and their influence on the final product’s colour primarily. Hence, combinations of sucrose (the most commonly used) and dextrose or fructose (granulated or in syrup form), inverted sugar, or other forms are used. Skim milk powder and egg yolks also play a similar role to what was mentioned for fermented doughnuts. These ingredients influence the final structure, primarily powdered milk, affecting moisture (egg yolk), flavour, crumb colour (egg yolk), and crust colour through Maillard reactions (milk). Sometimes, food colourings are used to achieve a colour similar to that provided by egg yolk. Skim milk powder also reduces fat absorption during frying.

As you can see, unlike cake batters, this type of dough does not include whole eggs, and the fat content is low. It is possible to use whole eggs or egg whites, but these give a somewhat harder texture to the final product due to protein coagulation with heat treatment and can also reduce oil absorption during frying. Therefore, their inclusion should be limited to small quantities. The fat used is usually a vegetable fat that helps stabilize the bubbles in the dough, thus contributing to the expansion of the dough. However, it also adds juiciness to the final product.

Considerations regarding salt, flavours, additives (excluding those that act on the gluten network), and frying oils or fats are similar to those already mentioned for fermented doughnuts. Pre-gelatinized starches can also be used, as we mentioned earlier, to retain water and extend shelf life. Regarding emulsifiers, lecithin is the most used to aid in the mixing of all the ingredients.

Regarding the leavening agent or baking powder, its proper selection is important. It consists of a base (sodium bicarbonate) and one or more acids. Normally, a fast-acting acid (sodium acid pyrophosphate) is used along with slower-acting ones, such as glucono delta lactone (GDL), sodium aluminium phosphate, or monocalcium phosphate. It is also possible to experiment with different sodium acid pyrophosphates with different reaction speeds.

The process begins with the mixing of the ingredients. At this stage, it is advisable to control the temperature and mixing time. An excessively low temperature (below 10°C) can prevent the ingredients from mixing properly, but a very high temperature (over 30°C) can accelerate the leavening agent’s action, causing gas to form before the dough is ready to retain it, resulting in gas escaping and altering the final texture, making it coarser. Therefore, although temperature is less critical than in fermented doughs, as it does not affect yeast activity, it is important to control it. As for mixing time, proper mixing ensures optimal incorporation of bubbles, both in number and size. A short mix can result in poor aeration, but an excessively long mix can break down the structure and, in some cases, start forming the gluten network, which is undesirable in these cases. The mixing time is typically 2-3 minutes but depends greatly on the equipment and speed used. We will discuss this further in the section dedicated to cake batters. Mixing time also seems to influence oil absorption, with longer mixing times leading to less oil absorption.

The resting time of the batter is also a factor to consider. A short rest time can lead to inadequate hydration of some ingredients, while a long rest time can cause coalescence of bubbles, resulting in system instability and gas escape in subsequent operations. This phenomenon is exacerbated by the fact that the batters are usually placed in hoppers over the fryers, which increases their temperature and can also cause the leavening agents to start reacting. Therefore, the resting time is typically 10-20 minutes, without exceeding the latter time.

During deposition, the correct viscosity of the batter is crucial. This will depend on all the parameters mentioned earlier, but some manufacturers add a small amount of gum, such as guar, xanthan, or locust bean gum, in percentages well below 0.5%, to increase viscosity. These products also help retain water, like pre-gelatinized starch, and reduce oil absorption during frying.

Frying is perhaps the most delicate step in making this type of doughnut. When the batter is deposited into the fryer, it initially sinks to the bottom but then rises to the surface after 3-7 seconds and tends to float, so only the bottom half of the batter is fried. This leads to an initial expansion of the bottom part, followed by an increase in consistency, which limits further expansion due to the gelatinization of the starch (and coagulation of gluten and egg white proteins if present). This operation defines the diameter of the doughnut. On the other hand, the other half of the doughnut remains in the air, not receiving the same strong thermal treatment or receiving it much more gently through conduction inside the batter. For this reason, the treatment must be rapid. Once the doughnut is flipped, with the bottom part already set, the other part is fully fried. These differences result in the characteristic circular mark on the central part of the doughnuts.

In the final product, three parts can be distinguished: a central core surrounded by the top and bottom parts with a coarser structure. The central part does not come into contact with the oil, so it heats primarily through conduction and is the slowest to cook. The part that was fried first has a denser structure as its structure has set earlier due to the gelatinization of starch, unlike the top part where expansion was prolonged, modifying the internal structure of the bubbles by reducing batter viscosity in the early stages. Because of these changes, the top part (last to be fried) usually has a more open cellular structure and a higher oil content due to greater oil absorption during frying. The fact that different parts receive thermal treatment at different speeds necessitates the use of acids with varying reaction rates.

Choux Pastry Doughnuts

There is a much less known variety of doughnuts made from choux pastry. Choux pastry is a well-known pastry dough used to make cream puffs, éclairs, or choux buns. These doughs start with a mixture of water, milk, and fat (usually butter, but it can be replaced with margarine). The quantities of water and milk are the same, and the fat is slightly less than the amount of water (around 90%). The water and milk mixture can also be replaced with an equal amount of water (for lactose intolerant individuals or those allergic to dairy protein) or the same amount of milk. Using more milk will result in a slightly less crispy final product with more colour due to Maillard and caramelization reactions. This mixture is brought to a boil, and the flour is added once it reaches this point. The water and milk mixture accounts for 170-180% of the flour weight, so each of these ingredients is about 85-90%. Due to the presence of hot water, the flour’s starch will partially gelatinize, significantly increasing the mixture’s viscosity. Gelatinization is not complete because the temperature drops rapidly. Partial denaturation of gluten will also occur. The mixture continues to be mixed at a controlled temperature until the dough pulls away from the sides of the container, and then the egg is added (in weight, as much as the water and milk mixture, or slightly less, around 90%). The egg should be added slowly while continuously mixing to ensure proper integration. Temperature control throughout the process is crucial because it determines the extent of starch gelatinization, gluten denaturation, or egg white coagulation, which should not occur until the final heat treatment.

These doughs can also incorporate salt (less than 5% of flour weight) and sugar (less than 10%) to enhance flavour, and in the case of sugar, contribute to the final colour. These ingredients would be incorporated into the initial mixture.

These doughs expand significantly during baking or frying due to the gas generated from the dough’s water, which is retained thanks to the foaming ability of egg white. In this process, the egg white coagulates and contributes to the structure of the final product, which tends to be dry. Therefore, these products are often filled with some type of cream to add juiciness.

In these doughs, gluten strength is not usually critical (heat denatures these proteins), but starch and protein content are essential since they greatly affect the final result. Therefore, these factors need to be standardized. In the literature, you will find some who recommend using strong flour and others who talk about weak flours. It is true that for supermarket flour purchases, strong flours tend to be better cared for and more consistent, but at the industrial level, I would try with weaker flours that are more economical, as long as they are consistent and yield good results, which will depend on the formulation.

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