Following a first entry on basic aspects, more focused on batters, this second entry will delve into breading. We will analyse its types and the quality criteria for good breading.

Industrial breading is similar to homemade ones, but while at home, we typically use traditional breadcrumbs, the industry has access to a greater variety. In recent years, some of these breads for home use can be found in different specialized stores. Let’s take a look at the most common ones.

Traditional

This product is essentially breadcrumbs or ground bread, closely resembling what we can achieve at home by grinding stale bread. In some manuals, especially those of American origin, it is called “American style,” in contrast to the “Japanese style,” which we will discuss later. It is also referred to as “homemade style.”

Basically, it involves making bread (mixing ingredients, dividing, rounding, forming, placing pieces in molds, fermenting, and baking). Once the bread is baked, it is removed from the molds, allowed to cool and harden (as starch dries and retrogrades). At this point, the bread is crumbled into smaller pieces and dried to about 10% moisture, subsequently grinding these dry pieces to the desired particle size.

These breads have a light interior and a brown crust, so grinding them produces intermediate colours. It is also possible to colour them using some type of colouring (and flavouring) substance, such as paprika, beets, spinach, caramel, etc. Modifying fermentation conditions can result in breadcrumbs with a more or less open structure, generating crunchier breadcrumbs. The baking process can also be modified to enhance the crust, although this is not common. Finally, sourdough and long fermentation processes can be used, but economically, it is usually not cost-effective compared to potential benefits (flavour and acidity).

Panko

This type of breading, also known as “oriental style” or “Japanese style,” is based on making bread with a system very similar to the traditional one but with a different final heat treatment. In this case, instead of conventional baking, the dough undergoes dielectric heating inside large molds. Here, heat is generated by resistance to the passage of electric current through the molds. Unlike traditional breadcrumbs, this product does not form a crust, and therefore, its colour is much whiter, although there are versions coloured with different ingredients. Since no crust is formed, the dough expands more inside the mold, resulting in a more open structure. This produces much crunchier breadcrumbs with a more elongated particle shape.

The heating of the dough will depend largely on its moisture and salt content. As the water content decreases, so does the heating, as in microwaves. Thus, as the dough heats up and reaches 100°C, the water will evaporate, progressively reducing the heat to which the dough is subjected. Salt also promotes dielectric heating, so the salt content in these doughs should be limited (less than 2%) to avoid excessive or very rapid heating.

Once the heat treatment is done, the resulting product is demolded, allowed to harden naturally, and broken into small pieces before drying and final grinding. Special mills are used to avoid excessive breakage of particles, preserving the shapes and crispness of the product.

Cracker

This product is more of a cracker (as its name suggests) than bread, as the dough does not ferment. Thus, a dough composed mostly of flour and water, with a moisture content around 35-40%, is rolled and baked. The process is much faster than bread making, significantly reducing production costs. Complete gelatinization of the starch is achieved, and the colour will depend on the heat treatment received. Like other breads, this “cracker” is broken for final drying, and it is ground once dry. Like other breading, colouring substances can be incorporated. However, this product is not as expanded; it is denser, and the resulting breadcrumbs are less crunchy and harder. To minimize this effect leavening agents can be employed, but even with this solution, the final bread does not have the crunchiness of other breadcrumbs.

Extruded

Today, the use of products that mimic breadcrumbs obtained through extrusion has increased significantly. These are not really bread, since they have not undergone a fermentative process, but extrusion offers wide possibilities to obtain products with very different characteristics. In this process, a mixture of flour and water passes through an extruder where it undergoes thermal treatment, partially drying upon exiting. This drying occurs because the water inside the extruder is at a temperature above 100°C (at higher pressure than atmospheric). Upon exiting the extruder, at atmospheric pressure, it quickly turns into vapor. The resulting product is broken, dried, and ground to the desired particle size.

Extrusion is a very fast process compared to other systems for breading. Moisture and temperature inside the extruder (and shear) can be manipulated to achieve a greater or lesser degree of starch gelatinization. Expansion can also be regulated by controlling raw materials and formulation, especially with the use of leavening agents. Through this control, more or less porous and crunchy “breads” can be obtained. Lastly, both colouring and flavouring substances can be included.

This technique is also ideal for obtaining gluten-free “breadcrumbs” since it is not necessary to produce dough capable of retaining gases during a fermentation and baking process, for which, in the case of gluten-free products, gums with a high water retention capacity are usually used, not suitable for a product that intends to dry. This allows gluten-free breading to be obtained with simpler formulations, minimizing the use of additives, and regulating colours and flavours with natural ingredients.

Italian

The use of the term “Italian style” breading is not common in technical books on the food industry but is found in cooking manuals. It refers to breadcrumbs that incorporate spices, mainly traditional ones in Mediterranean culture. But as mentioned earlier, the use of flavouring and colouring ingredients is an option in any type of breading mentioned.

Others

Both at the domestic and industrial levels, other easily obtainable products have been tried for breading or achieving a crispy texture in these types of products. It is possible to use corn flakes, although these often impart a sweet taste since they contain sugar in their formulation. Ground roasted (or fried) corn has also been used, providing a very distinctive flavour. In recent years, the use of vegetable products, especially tubers, for this purpose has increased. Carrot puree or mashed potatoes in various forms have been tested for this. In these cases, a better nutritional image is sought. However, these are emerging trends that need to be studied carefully.

Factors Determining the Quality of Breading

Particle Size and Porosity

These are the most important factors in the quality or characteristics of breading. The particle size is determined by how the product obtained is ground in the final processing, whether it’s traditional bread, panko, cracker-type, or extruded product. Grinding can be done by various means to obtain finer or coarser products. But once ground, they can also undergo sieving to remove particles of larger or smaller sizes. The possibilities are endless, but in principle, we will talk about coarse particles (between 1000 and 5000 microns), intermediate (between 250 and 1000 microns), and fine particles (less than 250 microns).

Coarse particles have less water absorption capacity due to their smaller surface area. For the same reason, their oil absorption capacity will be lower. The time required for their final drying in breading production will also be longer, resulting in slightly higher costs. Another drawback of coarse particles is their lower adhesion to the batter, requiring longer soaking times and being more prone to separating from the final product. Care must be taken to improve the adhesiveness of batters when using these coarser particles. Poor application of these coarser particles can lead to differences in the coating layer on different parts of the final product. However, coarse particles also have advantages. The first is a more attractive external appearance for some consumers, and the other is their greater crispiness, making them suitable for products to be finished in an oven or microwave, where the final crispiness of the product is reduced compared to frying. Particle size will also influence the colour of the final product, but in this case, there is a combination of the actual colour and the consumer’s perception due to the rougher appearance of the final product, which must be analysed case by case.

Fine particles, on the other hand, exhibit the opposite behaviour. They may not be as visually appealing to consumers, especially in some products, and may produce less crispy products. However, their cost is somewhat lower due to shorter drying times. They absorb water more easily, exchange water for oil (oil absorption) more in frying, and adhere better to batters, resulting in more uniform breading layers.

Intermediate particles present behaviour between fine and coarse particles. The crucial point is not to limit oneself to using one type or another. It is more convenient to mix some of these types to obtain the advantages of each. Thus, a percentage of fine particles can be used to improve adhesion and the uniformity of breading, as well as oil absorption, mixed with a percentage of coarse or intermediate particles to enhance visual appearance and crispiness.

Porosity (inversely related to density) will depend on the manufacturing process. It will be higher in panko type and lower in cracker type, being intermediate in traditional bread. For those obtained by extrusion, it will depend on production parameters. This effect is more noticeable in coarse particles than in fine ones. Generally, more porous particles increase surface area, improving their drying, water absorption speed, percentage of absorbed water, and the exchange of this water for oil. Moreover, they provide a greater sensation of crispiness. In contrast, denser and more compact particles have the opposite effect. More porous or less dense particles also change their colour more rapidly during thermal treatment. For all these reasons, they are more suitable for products that need to be reconstituted using a conventional oven, air fryer, or microwave.

Colour

A final crucial factor in the quality of breaded products is their colour, both the initial colour and the one obtained after thermal treatment. The initial colour depends on one hand on the processing and type of breading. Traditional breads, for instance, exhibit a crust, more or less dark depending on the treatment received, resulting in somewhat brown tones. In contrast, panko lacks a crust since the thermal treatment does not exceed 100°C, making it whiter. The cracker type’s colour depends on the applied thermal treatment, generally avoiding very dark hues, and although not as light as panko, they tend not to be darker than traditional bread. Those subjected to extrusion typically don’t develop very dark colours, as the temperature inside the extruder usually exceeds 100°C, but water does not evaporate as in the crust, and the treatment time is very brief.

However, the colour of breaded products can also be altered by incorporating ingredients with colouring capabilities, aiding in colouring the entire breading. The possibilities here are endless, both in terms of products to incorporate and the sought-after shades. So, if panko or extrusion-obtained bread wants to have more brown tones, caramel can be used. But one can also seek reddish, greenish, yellowish, or even bluish tones. Substances that require very small amounts to “dye” the breading are typically sought. Still, in some cases, slightly larger quantities are necessary, or the products used have a strong flavour. In such cases, their influence on the final taste, whether negative or positive, must be analysed.

It’s also important to consider that a breaded product, with a proportion of reducing sugars and proteins, will darken when subjected to thermal treatment due to caramelization and Maillard reactions. Some breaded products darken more quickly than others. The former are those containing more reducing sugars and proteins or have a higher pH. These characteristics can be present in the prepared “bread” or can be sought through the addition of powdered ingredients such as sugars, proteins (milk, egg, etc.), or basic products like bicarbonate to the obtained breading. Products that darken rapidly may be suitable for items intended to finish in an oven or microwave, where the final treatment temperatures won’t be as high as in frying, and where colour development occurs during pre-frying. However, in conventional applications, they may cause issues with excessively dark colours. On the other hand, breaded products that take longer to darken may be more suitable for items undergoing conventional frying, minimizing problems with excessively dark colours, which often come with more bitter flavours. Another potential issue is that the frying time can be determined based on the product’s colour, a common practice. In such cases, if the breading darkens too quickly, the time may be excessively short, and the interior may not receive the required treatment to improve its culinary quality. It is often said that the latter tolerate frying better.

Batters and Breading: Basic Aspects I – Innograin (uva.es)