After discussing general aspects of cake making and the role of each major ingredient, in this entry, we will delve into the preparation method and how the chosen variables influence each step of the process. This process is straightforward, involving mixing and beating the ingredients, followed by baking. However, there are different ways to perform these steps, especially the beating of the ingredients.

Mixing and Beating

During the beating process, the goal is to evenly disperse the ingredients and create a stable emulsion. Another important objective in this phase is to incorporate air into the batter in the form of small bubbles. The ways to achieve these goals are diverse and depend on the type of cake desired and the ingredients used. However, they can be divided into three types of beating, although alternative methods exist. The final characteristics of the beating, and consequently, the obtained cake, will depend on the type of mixer, its speed, the order of ingredient addition, and its temperature, among other factors.

Methods for fat-based cakes

Creaming Method

In this method, start by mixing fat with sugar at medium or low speed. Sometimes, some dry ingredients are incorporated in this initial phase, obtaining a homogeneous mixture and initiating air incorporation. After this initial stage, add the egg, and finally, the milk and flour in small doses. This process lasts 15-20 minutes in total, with the initial creaming taking 8-10 minutes, followed by 5 minutes after adding the egg, and 5-6 minutes for the addition of milk and flour. Note that these times are indicative and depend on the type of mixer and its speed.

This method enhances air incorporation and reduces gluten formation, as flour is added at the end of the process, resulting in cakes with greater volume. The water in eggs and milk, along with fat, forms an oil-in-water emulsion. If the liquid components are incorporated too early, a water-in-oil emulsion may form, resulting in overly thick batter. This issue can be corrected by adding flour, making the batter smoother. The creaming method does not adapt well to formulas with a high sugar content.

Beating in stages

This method involves mixing fat and flour in one mixer until a liquid mass is obtained. At the same time, mix eggs and sugar in a second mixer at medium speed until a semi-firm foam is obtained. In this second beating, large amounts of air are incorporated into a very fine dispersion. Later, both products must be mixed gently to avoid breaking the structure created. Milk should be added in the last phase in small doses.

This method has the advantage of producing a finer and more uniform structure in the cake, allowing the incorporation of larger amounts of sugar and liquids than the creaming method. However, as a drawback, this method incorporates less air into the beating, resulting in a smaller volume of the cake. It also leads to greater gluten network development and, consequently, a cake with a firmer texture. Nevertheless, a gluten network as in bakery products does not develop in any case. This method is common in small pastry shops; however, at an industrial level, other methods are preferred due to ease of automation.

One-Stage Beating

This is the most convenient method, as all ingredients are incorporated from the beginning. It is advisable to start at low speed for 1-3 minutes and gradually increase it (3-5 minutes at medium speed) and lower it again towards the end (2 minutes). In the first phase, the mixing of ingredients is enhanced, while higher speeds improve air incorporation. The leavening agent is usually added in the final stages to prevent premature reactions, especially if it is a fast-acting one.

This method is the most convenient, but the resulting cakes have a larger and less uniform grain. Due to its convenience, it is widely used, both in the industry and for homemade cakes.

Methods for foam cakes

The methods described so far are designed for formulas based on fats or oils, not so much for lighter cakes. These may not contain fats or do so in small proportions, and in some cases, they do not require the help of leavening agents. Simply with the expansion of gas trapped in the beating, much less dense than the previous ones, an adequate volume is achieved.

Spongy Cakes with Whole Eggs

These cakes rely on the egg’s ability to form stable foams. The ability of egg whites to incorporate air when beaten, forming a stable white foam, is well known. However, the presence of fats, such as those in egg yolk, reduces this capacity. Nevertheless, egg yolk, in addition to fat, contains proteins and lecithin that make it possible to incorporate tiny air bubbles when the whole egg is beaten, surrounded by yolk particles. The ability to retain air and form a stable foam will depend on the formula used (sugar cannot exceed 25% more than the egg quantity, i.e., a ratio of 1.25/1), egg temperature (between 24 and 27ºC), yolk concentration, egg quality, and beating method (type of whisk, speed, and order of ingredient addition). Although egg yolks alone cannot form an acceptable foam, whole eggs usually contain a lower amount of yolks than desired. It is common to add egg yolk powder to improve the amount of air trapped in the beating and its stability.

The beating process can vary, but the most common is to beat the eggs, previously tempered, at medium speed, adding sugar either at the beginning of the process or progressively as the beating progresses. Once the foam is obtained, liquid components and flour should be added very gently to avoid breaking the formed foam. If the final mixture is too violent, part of the incorporated air will be lost, resulting in a loss of final volume. In cases where the formula contains fats, they should be added in the final stages of mixing to minimize volume loss. It is also common to beat egg whites and yolks separately, with the corresponding proportion of sugar. Once beaten, they are mixed gently, and the remaining ingredients are incorporated. This process achieves higher volumes but is a more cumbersome method and, at an industrial level, the first method is usually preferred. The addition of certain emulsifying agents can improve the result obtained through the first method, enhancing foam stability and the final volume of the cakes.

Spongy Cakes with Egg White

When egg whites are beaten, air is incorporated in the form of small bubbles. As the beating continues, the bubbles become smaller, the initial greenish-yellow color transforms into a matte white, and the surface loses its gloss until an optimal volume is reached. In this process, both air incorporation and the stability of the obtained beating are essential. Stability can be measured by the amount of liquid released by the foam obtained in a given time, increasing with the beating time up to a certain point. The characteristics of the obtained foam will depend on the type of whisk used, its speed, the characteristics of the egg white used, its temperature, the beating time, and the way other ingredients, such as sugar, are added. Note that the presence of fat drastically reduces the ability of egg whites to retain air. Therefore, it is necessary to ensure the absence of egg yolk and clean the mixer surfaces to eliminate fat residues.

There are numerous formulas for sponge cakes with egg white foam. However, the most common is based on a combination of egg white, sugar, and flour, or starch, in proportions of 3:3:1. To prepare the beating, start with egg whites, salt, and an acidifying agent, beaten at medium speed until the foam begins to take shape. At this point, slowly start adding sugar (approximately 50%) while continuing the beating operation until the meringue consolidates its structure. Once the meringue is obtained, add the flour and mix at the lowest possible speed, ensuring a uniform distribution of ingredients while maintaining the foam structure as much as possible.

In this type of beating, certain aspects must be considered. Firstly, the beating must reach a specific density because insufficient air incorporation is as harmful as excessive air in the beating. In the former case, a deficit of air will result in sponge cakes with less volume. However, an excess of air leads to instability of the beating, and consequently, excessive contraction of the product during baking. Secondly, it is known that the pH of egg whites influences their foaming ability, and a pH between 5 and 6.6 improves the ability to trap gas and foam stability. The natural pH of egg whites is slightly higher, so it is common to use an acidifying agent, usually tartaric acid, although other acids such as acetic or citric acid are also useful. When choosing an acid, consider not only its influence on the foaming capacity of egg whites but also its effect on the organoleptic properties of the cake, especially its taste and aroma.

The characteristics of the egg whites used will also be crucial. Fresh egg whites are known to produce cakes with greater volume and a finer, more uniform texture. This phenomenon is based on the hydrolysis of albumin that occurs over time, especially if stored at high temperatures. On the other hand, poorly stored egg whites increase their pH, which can reach 9.5. Therefore, it is necessary to increase the dose of the acidifying agent used to achieve the optimal pH for beating. It is also known that the temperature of the egg whites greatly influences the characteristics of the obtained cake. The egg whites used should have a temperature between 17 and 22ºC, ensuring that the beating reaches 21-24ºC. In this type of cake, leavening agents are not usually used, and the increase in volume during baking is mainly due to the vapor pressure inside the bubbles. Batters introduced into the oven at low temperatures take longer to raise vapor pressure, and the structure may collapse before reaching the expected volume, resulting in cakes with lower volume than expected. On the contrary, if the batter is introduced very hot, excessive expansion may occur before the structure collapses, resulting in a coarser texture.

Baking

After obtaining the batter, it should be transferred to the oven as quickly as possible and with minimal mechanical damage. Aggressive treatments can break the batter structure in some cases, causing a loss of air that translates into a cake with less volume. If the time elapsed between obtaining the batter and baking is high, two negative phenomena can occur. Firstly, in formulas containing leavening agents, CO₂ generation may begin, and some gas loss may be inevitable before baking. Secondly, in less viscous batters, coalescence phenomena between the created bubbles may occur, and in some cases, these bubbles may rise to the surface and escape. Therefore, batters that are not baked quickly usually result in cakes with less volume and a coarser, irregular texture.

Once the batter is introduced into the oven, its viscosity decreases to about half of its initial value as its temperature increases, although this decrease will depend on the formula used. As the temperature rises, starch granules begin to gelatinize, at which point viscosity increases. This effect is slight at first, accelerating until the structure collapses, loses flexibility, and the cake stops rising. The gelatinization temperature of starch will depend on the ingredients of the batter, especially the amount of sugar present in the formula, as sugar increases the gelatinization temperature. Thus, in cakes that include the same amount of sugar as flour in their formulation, starch will begin to gelatinize at around 65ºC, an effect that will increase dramatically when reaching 80ºC. However, for cakes with a sugar/flour ratio of 140/100, these temperatures increase by 5ºC. The presence of emulsifiers and other ingredients will also affect the starch gelatinization temperature, as well as the type of starch (some cakes incorporate cornstarch in their composition). It is also known that sucrose increases the gelatinization temperature more than glucose or fructose. Alongside starch gelatinization, there is denaturation of proteins involved in the final structure of the cake, a denaturation that usually occurs in the final part of baking, 5-10ºC above the gelatinization temperature. This denaturation helps give cohesion to the final crumb of the cake.

Several phenomena occur until the structure collapses, resulting in beating expansion and an increase in the cake’s volume. On one hand, the vapor pressure inside the bubbles created during the beating phase increases, and on the other hand, there is a reaction between the basic component and the leavening agent’s acid, generating CO₂, which is retained in the bubbles and increases their size. This expansion must occur at the right time, as premature expansion, with very low batter viscosity, causes the formed gas to escape. Conversely, if it occurs too late, and the cake’s structure has already collapsed, expansion does not happen, and crust ruptures can occur.

During baking, a temperature gradient occurs inside the cake, as the outer parts heat up more quickly and reach gelatinization temperatures before the inner parts. This fact, in addition to influencing the gelation process, will also affect the leavening agents’ action, as the solubilization of acids and their reaction with bicarbonate are temperature-dependent. In cakes with a low sugar-to-flour ratio, most of the CO₂ production should occur between 70 and 80°C. CO₂ produced below 65°C, when the batter viscosity is low, can rise to the surface and escape. Conversely, CO₂ formed above 80°C will not result in a volume increase, as viscosity is excessive, and the structure has already collapsed; it may even cause cracks in the crust.

In the case of batters with a higher sugar percentage, gas production should occur at slightly higher temperatures. If leavening agents perform their function at the end of the baking cycle, it’s possible that in the outer parts of the cake, gelatinization temperature of starch has been reached, and therefore, no expansion occurs, while in the central parts, where the temperature rises more slowly, expansion is still possible. In this case, the typical crown of muffins, where the central part rises more than the outer part, would form.

It’s challenging to establish an optimal baking temperature, but some basic recommendations can be given. Baking time will be inversely proportional to the baking temperature. The baking temperature should be lower for larger cakes. Finally, the higher the sugar percentage in the formula, the lower the baking temperature should be. However, the combination of baking temperature and time must be determined through practice, as it depends on the type of cake, oven type, batter viscosity, formula used, mold size, among other factors. It’s also essential to note that insufficient baking, which fails to achieve the right texture and colour, is as detrimental as excess baking, which often results in cakes with a very dark colour, bitter flavours, lower moisture, leading to a drier cake with a shorter shelf life. In any case, the internal temperature of the cake will not exceed 98-99°C, as when the water’s evaporation temperature is reached, the applied heat is consumed in the phase change, and the temperature does not increase.

In industrial ovens it is possible to set different temperatures in the different zones of the oven. This gives greater flexibility to adapt the baking conditions, being able to reduce the temperatures in the last phase of baking, to avoid excessive drying or excessively dark colours. It is also possible to increase the temperature at the beginning of baking, accelerating the phenomena that occur in this phase, which can be interesting depending on the formulations used. These aspects, as well as the position of the oven draught, must be studied in each case.