When discussing the necessary quality of flour for making cookies or biscuits (we are going to use the term cookies for all of them), one must consider the various types of cookies, as the appropriate characteristics for one type may differ from those of another. Thus, we can distinguish between cookies where the gluten network develops, such as Maria cookies or some savoury varieties, and others where the gluten network does not develop. In the former, analysis equipment assessing the quality of proteins, or the gluten network, may be of interest, while in the latter, such equipment is less relevant.
General standards for all cookies
We have previously addressed negative aspects that should be carefully managed in all flours. This includes avoiding any abnormal presence of enzymes that can degrade flour components during processing, thereby compromising dough quality. Specifically, we refer to the presence of germinated wheat or wheat infested with some cereal bugs. In the former, amylases tend to predominate, while in the latter, proteases are more prevalent. In both cases, a complex mixture of enzymes is present in the flour, which can be challenging to control. Recently, there has been a trend towards using germinated flours in various products, including cookies. However, the key difference between these flours and those made from field-germinated wheat lies in the control of the germination processes. When producing germinated flour, the germination processes are carefully controlled, ensuring the flour’s characteristics remain consistent. These characteristics depend greatly on the degree of germination and the drying or toasting treatments, which can either maintain enzyme activity or deactivate them. We have previously discussed the characteristics of germinated flours and the processes involved in obtaining them in our blog.
It’s worth noting that some flour manufacturers incorporate enzymes, primarily amylases, proteases, and hemicellulases, for this type of production. However, similar to germinated flours, these enzymes are carefully controlled in terms of quantity and quality, tailored specifically for these processes.
Another critical factor common to all cookies flours that must be monitored is their moisture content and ash content. Excessive moisture can lead to microbial deterioration during flour storage and result in softer doughs. Conversely, excessively low moisture can yield dry, hard, and tough doughs that are difficult to handle. Generally, if you have a formula tailored to a specific flour moisture content, you should use flours with that moisture level or adjust the formula’s water content based on the flour’s moisture. Fortunately, in most countries, flours typically have fairly consistent moisture content, ranging between 14% and 15%, although storage conditions can cause variations.
The ash content provides information about how clean the milling process was and the amount of bran or aleurone layer that made it into the flour. These external grain layers have a different composition from the endosperm and tend to have higher water absorption capacity, an aspect we will discuss further. The presence of these layers also tends to affect the gluten network, resulting in looser and less extensible dough, which can be problematic in some applications. In extreme cases, the presence of external grain parts can even impact the organoleptic quality of biscuits by introducing strange flavours and discoloration.
Less well-known are the influences of damaged starch and particle size. While these aspects can be essential for all types of cookies, they are more critical in cookies where the gluten network does not develop. Therefore, we will address these topics later.
Cookies with gluten network development
In cookies where the gluten network plays a significant role, the characteristics of the dough are heavily influenced by gluten. These cookies often have formulas where the proportion of flour is higher (and sugar and fats or oils lower), with a higher water content necessary for gluten network development. Typically, they are made using a rolling process, which requires a dough with a certain consistency and extensibility, achieved through kneading and the introduction of mechanical work into the dough. Examples of such cookies include Maria cookies or some savoury varieties like crackers. In the case of Maria cookies, there is no fermentation (using yeast), but some savoury cookies undergo fermentation or, at the very least, longer resting periods.
In all these cases, it is essential to consider not only the quantity of gluten or proteins but especially their quality. For Maria cookies, flours that yield extensible and less elastic doughs are sought after. These qualities mean that once rolled out, the dough does not tend to shrink back. Otherwise, it would be challenging to maintain the rounded shape that results from cutting the dough sheets and packaging them cylindrically. To achieve more extensible and less elastic dough, cookies manufacturers often rely on the use of reducing agents, as previously discussed, such as sodium metabisulfite, or enzymes like amylases, proteases, or hemicellulases. When using these enzymes, they are usually of the exo-type (acting at the chain ends) and work rapidly, preventing further modification of the dough throughout the process. This also means that these actions may not be evident in analyses like the alveograph or extensograph, which typically occur after some dough resting time. However, it is possible to modify these tests to observe rapid enzymatic action.
In general, flours best suited for these processes are soft flours with low alveographic strength, high extensibility (high L), and not very tenacious, resulting in a low P/L value. In the alveograph, another parameter (Ie) more related to dough elasticity should be as low as possible. In the extensograph analysis, the characteristics should be similar, with high extensibility and low deformation strength. The farinograph analysis, which provides insight into gluten quality, does not provide comprehensive information for this type of application. In cookies with fermentation, you may require more strength, but always with adequate extensibility and reduced dough elasticity.
Since soft flours tend to be less expensive, cookies manufacturers often seek cost savings in the world of cookies production. Some flour mills may be tempted (in some cases, almost compelled) to produce these flours using lower-quality wheat varieties. These harder wheats yield flours that are slightly tougher and less extensible, and they lack suitable baking quality, which diminishes their value. Wheat hardness is essential because harder wheat, with a similar milling process, tends to produce flours with larger particle sizes and, in general, more damaged starch. If we push the milling process further to obtain finer particles, we will increase the amount of damaged starch. While particle size, within reason for wheat flours, is generally not problematic, a higher quantity of damaged starch can generate flours with greater water absorption capacity. Consequently, doughs can become more consistent (if moisture is not adjusted) and stickier if hydration is increased to compensate for these effects, which can pose a problem. Beyond this, inadequate dough extensibility or greater elasticity can indeed be problematic. To address these limitations, some flour mills turn to enzyme use, but this must be closely monitored.
In general, ancient wheat varieties were more extensible than modern ones for the same protein content. However, they had lower field yields. Today, a similar situation exists, with soft and extensible wheat varieties typically having a higher cost than soft but less extensible varieties, as they often yield lower field returns. Therefore, quality flour for these processes must be valued, although it is generally more economical than good bread-making flour, which requires harder and stronger wheat varieties.
Cookies where the gluten network does not develop
This category includes cookies with formulas rich in sugars, fats or oils, and low water content, often subjected to minimal mixing to avoid gluten network development. These cookies are obtained through rolling and cutting or rotary moulding, wire cutting, extrusion, or even liquid batters that, due to their low resistance to mixing, fail to develop a gluten network.
In these cookies, flour acts as a thickening and binding agent, and its thickening power is crucial, closely tied to its water retention capacity. If a flour can absorb a significant amount of water, it usually has a high thickening power. Multiple factors influence this water absorption capacity, which we will attempt to summarize.
It is evident that lower flour moisture content results in the ability to absorb more water, highlighting the importance of moisture control, as previously mentioned. Additionally, fibres, particularly arabinoxylans present in wheat, have a significantly higher water absorption capacity than starch or proteins. In this context, we should aim to avoid the presence of external grain parts with higher fibre content, making ash content information valuable and controllable. However, some wheat varieties naturally contain more arabinoxylans than others, and measuring arabinoxylan content is complex. We will explore methods for obtaining information on this topic later.
It is also known that proteins have a greater water absorption capacity than starch. Therefore, when selecting flour for cookie production, the focus should be on protein quantity, not quality. Consequently, demanding a specific alveographic strength or farinographic values (aside from a certain absorption level) in cookie flour specifications is not particularly meaningful. Since protein production is costly, and varieties with higher protein content tend to be harder and more expensive to mill, cookie flours typically prefer flours with low protein content, but it is essential that this content is consistent.
Another factor influencing water absorption capacity is the presence of damaged starch, as damaged starch absorbs more water than undamaged starch and thus has a greater thickening power. Measuring damaged starch is complex, and although equipment like the SDMatic or kits can perform this analysis, it may not be worthwhile for smaller cookies manufacturers. Damaged starch primarily results from the milling process, with harder wheats generally producing more damaged starch. Therefore, soft wheats are preferable for cookie flours, as they are easier to mill (requiring less energy) and yield finer flours with lower damaged starch content.
Finally, particle size significantly affects flour’s water absorption capacity. Finer flour particles tend to absorb more water, provided their composition remains consistent. However, aiming for finer flour from the same wheat can lead to higher damaged starch content, further increasing water absorption capacity and thickening power.
All these variables can be controlled through a simple analysis, such as water absorption capacity. For this test, a specific quantity of flour is mixed with water and subjected to centrifugation, after which the supernatant is separated, and the residue is weighed. The percentage of water retained in the flour represents its water absorption capacity. This analysis can also be performed in a resting state, where flour and water are mixed in a beaker, left for 24 hours, and then the supernatant is removed. An evolution of these methods is represented by analyses known as “solvent retention capacity” or SRC. To obtain these data, a similar analysis to the one mentioned earlier (centrifugation) is performed, but with different solvents (water, sugar solution, lactic acid solution, and sodium carbonate solution). In general, the absorption capacity of each solvent is more related to one of the flour components. Glutenin (a component of wheat proteins) is more related to lactic acid, damaged starch to sodium carbonate, pentosans (mainly arabinoxylans) to sugar solution, while water absorption capacity provides a more general overview. Some years ago, the company Chopin introduced equipment for automating this type of analysis to some extent. However, in many cases, knowing the water absorption capacity of the flour or starting with this analysis can be sufficient, as it is a simpler test.
My advice for quality control of cookie flours, besides addressing potential issues related to moisture, ash content, or enzymatic activity variability, is to analyse flour water absorption capacity and particle size. Flour specifications can also include a specified protein content.
Cookies where the gluten network does not develop can also be produced with blends of gluten-free flours and starches without significant issues. In these cases, quality control can be similar to what we have discussed, focusing on the water absorption capacity and particle size of these gluten-free flours or blends. Although starches tend to be more consistent than gluten-free flours, the latter often yield better results. Personally, I prefer the results obtained with white corn flours, but rice flours are also suitable.
In these cases, we must consider that different types of rice or corn, or even different parts of the grain, have varying hardness levels. This can lead to much greater variability in these flours regarding damaged starch content, water absorption capacity, thickening power, and particle size, all of which must be standardized. Flour with coarser particles may be preferable because it absorbs less water and can yield doughs that are less consistent, expand more in the oven, and typically have a less firm and more brittle texture, which is often desirable. However, a portion of the flour must consist of fine particles, as they play a cohesive role, and without them, doughs become very brittle and cannot be rolled or formed using other methods.
A common practice in the cookies industry is adjusting the amount of water added to the dough based on the consistency observed by the mixers. While this can address specific issues temporarily, it is not ideal. Ideally, cookies should be made with regular flours exhibiting homogeneous properties that do not necessitate hydration adjustments. Let me provide a simple example. If a flour contains a lot of damaged starch, it requires more water. Increasing the water content can match the consistency to what is familiar, but the doughs will be much stickier and can cause problems on the production lines. Therefore, the practice of modifying hydration can correct minor differences but should not be a common occurrence. Nor should the responsibility for fixing problems arising from significant flour variability be left to the skill of the mixers. Unfortunately, this variability is often more pronounced in gluten-free flours.
For more information on flour quality control, you can refer to these blog entries:
Aspects such as moisture, ash content, particle size, and enzymatic degradation are discussed in this entry.
Topics related to protein quality are covered in these entries.
Information regarding starch quality can be found here.
To expand your knowledge on flour quality and other ingredients in sugar snap-type biscuit production, I recommend this article.