In the industrial production of waffles, the masses are pumped through pipeline systems. This introduces mechanical energy into the mass, which can lead to a change in viscosity if gluten proteins are present. This in turn can have a negative impact on the dosage and the quality of the baked goods. There is also a risk of clogging of the dosing nozzles due to the formation of lumps.

A rapid flour check, e.g. B. with the GlutoPeak from Brabender. Small amounts of flour and water are mixed under controlled conditions, analyzed and monitored by means of monitoring. The “Low Protein Check” (LPC) method is available as a further development, which is specially tailored to the properties of low-protein flours. In the project described here, these GlutoPeak methods were tested on 20 different flours. The aim of the study was to check whether the methods in terms of their reliability and the possibility of obtaining information about the mixing and baking of wafer products in a short time,

20 different wheat flours were available for the project, which were referred to as waffle flour, waffle flour or biscuit flour. As a baking test, standard ice cream cones were produced and then tested. All flours were analyzed using GlutoPeak and standard laboratory analyzes (according to ICC) before mixing the waffle batter and baking the ice cream cones. With one exception, all samples met the basic requirements for waffle flour.

The analysis with the GlutoPeak was initially carried out using the standard “Rapid Flour Check” method and the evaluation algorithms supplied.

After measuring the moisture content of the flour sample, approximately 9 g of water (depending on the water content of the flour in question) was poured into the measuring pot and this was then placed in the GlutoPeak. The temperature of the receptacle for the sample pot (36°C) was previously controlled by means of a connected thermostat in order to ensure constant test conditions and to obtain a homogeneous temperature distribution in the container. After 2 minutes, in which a temperature equilibrium was established in the measuring pot filled with water, the appropriate amount of flour (depending on the water content of the respective flour) was added.

Depending on the properties of a flour, the measurement took 2-5 minutes at 2750 rpm. Due to the high energy input, depending on the quality and quantity of the adhesive, an adhesive network was formed over time, which showed a peak (gluten peak) as the maximum value (torque). The network is then destroyed by the force acting on it mechanically, the curve drops and the experiment is ended.

After the end of the test, the highest torque, shown as a peak (BEM/Maximum Torque), and the time required for this (PMT/Peak Maximum Time) are evaluated. Additional measurement points are the torque 15 seconds before and after the maximum (AM/PM). With the “Rapid Flour Check” evaluation, it is also possible to obtain correlations with other measurement methods. These are protein content, wet gluten content, water absorption and W value (alveograph method), the latter not being considered for this study. In a second step, the “Low Protein Check” (LPC) method, which was developed in the course of the project, was applied. With this method, approx. 12 g of water are weighed into 11 g of flour (depending on the water content of the flour in question). This method was carried out at a reduced speed of 2500 rpm and at 35°C. The evaluation already described did not change when using this method. All measurements were carried out in triplicate and then summarized and evaluated using the software supplied (MetaBridge).

In order to obtain precise information about the existing qualities, standard analyzes in accordance with ICC methods were carried out for all flour samples in an accredited laboratory in Austria.

The recipe with the ingredients for preparing the waffle mass: water 300 g, sodium bicarbonate 2 g, flour 200 g, sunflower oil 2 g, soy lecithin 2 g. After the water and sodium bicarbonate had been mixed, the flour was gradually added while increasing the stirring speed. The wafer mass was further mixed until homogeneous again and the premix of sunflower oil and soy lecithin was added. Immediately after mixing, the viscosity of the mass was measured using a gravity cup with a volume of 100 ml and a nozzle diameter of 8 mm (according to ASTM D 333). If the measured viscosity deviated from the defined viscosity by 20 seconds (+/- 1 second), the amount of water in the recipe was adjusted and a new waffle mass was produced.

(+/- 1 sec) the mechanical behavior during baking can be assumed to be similar for all flours, so the properties of the products depend only on the flour properties themselves. The water/flour ratio required for developing a specific viscosity is therefore an important flour parameter and was recorded for all test masses.

The waffle cones were baked on an electrically heated laboratory device LB-SWAK_STAK with an industrial baking mold and a corresponding core plate. The mold was heated to 180°C and the cores to 190°C. 7 ml of waffle mass were dosed with a syringe and the baking time was 80 seconds. Before the carrier tongs were closed for the actual baking process, they were closed and then briefly opened twice (so-called breathing: 2 seconds open, 2 seconds closed) to let steam out of the system. After baking, the bags were removed from the open mold and cooled at room temperature for about 10 minutes. After cooling, the waffle cones were placed in PE packaging, heat sealed and stored at 8°C until texture analysis.

Texture analysis was performed on a TA.XT.plus Texture Analyzer (Stable Micro Systems) using an ice cream cone mold (A/ICC). This tool can be used to measure the force required to cause a fracture. For the texture analysis, ten visually inspected bags were tested for each flour. The results obtained were then summarized and evaluated.

with the standard analysis

Comparing the results of the “Rapid Flour Check” with the results of the standard analysis shows that the basic correlation for the parameters protein and wet gluten content can still be described as good, for the However, water absorption is low (see Fig. 4-6). Brabender states that the correlated protein content varies by +/- 0.8 within a range of 10.5 to 15%. Similar results were obtained with the flour samples tested, even with very homogeneous samples (apart from W700 with its high protein content). The wet gluten should be in a range of +/- 2.3 compared to the standard analysis, which was also approximately achieved for the tested flour samples.

In both cases, the GlutoPeak method underestimated the results of the standard measurements, i.e. was slightly below: by approx. 3.5% for protein and 11% for wet gluten content.

The water absorption, on the other hand, is overestimated by about 2% using the GlutoPeak method (see Fig. 6).

Brabender indicates a variation of +/- 2.8 for the water absorption. However, it can be clearly seen that the deviation increases with low WA values ​​(wafer flours with a WA < 55%). This is a disadvantage of the Rapid Flour Check method, which was developed for flours with higher levels of protein and water absorption.

In order to increase the potential of the GlutoPeak results for wafer flours and to optimize the informative value, Brabender later included the newly developed “Low Protein Check” method. For this purpose, the data already recorded was re-evaluated and then compared with the data from the ICC method. The result was good agreement between the two methods, which will be discussed later in this study.

In order to demonstrate a correlation between required amounts of water or product weights on the one hand and flour parameters on the other hand, the data from the standard analysis and the GlutoPeak analysis are separated treated. The correlations and results for the Low Protein Check method are listed in a separate section.

The basic correlation between the amount of water required (for a certain dough viscosity) and the water absorption of the flour is well known in waffle production and can also be shown for very similar flours (see Fig. 6).

Flours with a higher water absorption require more water to obtain a defined dough viscosity. This can be unfavorable for waffle baking since baked waffles typically have a water content of only 1-2%. Thus, all of the water in the waffle mass, except for this residual amount, has to be evaporated during baking. During the baking process, the evaporating water acts as a leavening agent, so that too high a water content can lead to very brittle or even incomplete products (incorrect distribution of the mass in the baking pan). However, it is not always possible to reduce the amount of water in such doughs, since the resulting increase in viscosity in turn has a negative impact on the properties of the dough and the product. The water requirement of the flour is therefore a crucial parameter.

An easily ascertainable effect of the water requirement is the product density, the specific weight. The higher the amount of water - or the need for water - the lower the density of the waffle product (ie the product weight). High water absorption thus leads to products with low density, as shown qualitatively in Fig. 8. In addition to the flour properties, parameters such as the baking temperature (especially the core temperature can vary greatly during batch baking), the dosing volume, etc. affect the density of wafer products.

From these additional influencing factors during baking it follows that a correlation of the product weight with the water absorption is less significant than the correlation with the water requirement in the dough preparation.

This is all the more true for batch baking of wafer sheets on a laboratory scale, where significant differences in wafer density can occur within a wafer sheet.

GlutoPeak data

The correlation of the water intake measured with the GlutoPeak method “Rapid Flour Check” with the water requirement gives a less significant result compared to the standard analysis (see Fig. 9).

Sample W700 (very high protein and wet gluten content) can be clearly identified within the sample points. However, if you only look at the waffle flours, no clear trend can be seen. The same applies to the product density (see Fig. 10). Therefore, the GlutoPeak parameter WA is less meaningful compared to water uptake, which is measured using standard analysis.

Slightly better correlations are achieved if the parameter G (content of wet gluten) is selected instead of the parameter WA (water absorption) (see Fig. 11 and 12).

Predicting wafer properties from flour data is difficult because not only the batter has a significant influence on the product, but also the temperature/temperature fluctuations of the oven or the dosage (amount, speed), among other things. The data collected from the texture analysis of the wafer products already show a significant statistical scatter and are also difficult to correlate with the flour properties.

After the results of the “Rapid Flour Check” (RFC) method did not lead to optimal statements, the evaluation was carried out using the newly developed “Low Protein Check” method. With the modified method, flour data for weak flours can be estimated with satisfactory accuracy - in comparison with ICC methods - in a quick method (see Fig. 13-15).

In contrast to the RFC method, the LPC method is tailored to flours with a low protein (< 11%) and wet gluten content (< 25%). The correlation of dough or baking-related parameters to the flour parameters in the ICC methods and the modified gluto-peak method is almost as reliable (see Fig. 16 and 17).

The basic predictions for the product properties (e.g. the stability) thus allow similarly good conclusions (see Fig. 18) as is already possible with the data based on ICC methods. This leads to the statement that the “Low Protein” method with the GlutoPeak is a valuable alternative to the ICC methods. During the gluto-peak experiments, two flours showed the phenomenon that no peak was formed. The necessary aggregation of glue-forming proteins obviously did not take place, so that no relevant change in the rotational moments could be measured (see Fig. 19/20). These tests were also carried out as a triple determination in order to rule out possible application errors. Due to the course of the curve and the resulting missing values, it was not possible to include these flours in the evaluation. The reason for the missing peak can be assumed that the proportion of gluten-forming protein in the flour was too low to aggregate and thus have an influence on the torque. However, protein damage in the form of denaturation due to excessively high temperatures in the grinding process could also be the cause.

Of the 20 flours tested, 19 turned out to be suitable raw materials for the production of waffles. Only one flour was clearly outside the specification. The selected random sample can therefore be described as homogeneous.

The prediction of qualitative trends in the baked waffles is very difficult - regardless of the flour analysis method used - since a large number of other influencing factors affect the product properties.

Based on the characterization of the flours using the LPC method, a quick test of very small amounts of flour for the basic suitability of a flour for wafer production is just as possible as a quick comparison of different flour batches. In addition, the measurement data can be used to provide quick estimates of the required water requirement and thus any necessary recipe changes or energy consumption. Regardless of the measurement method, it is not possible to predict product properties purely from flour analysis.