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Validation of the Micro-Extensograph and the Extensograph rapid method

Relevant for: Extensograph, Micro-Extensograph, Flour, Rapid Method, Reproducibility, Validation

 

The Micro-Extensograph opens up new possibilities to analyze the elasticity of doughs with the small sample sizes of breeders. This ensures a better understanding of the flour properties during the breeding process and a more reliable development of new breeds. The Extensograph Rapid Method enables laboratories to produce similar results to the standard method in a significantly shorter time. It ensures production quality control in a shorter time frame.

Introduction

In the milling and baking industry, various bakery products place different demands on the qualitative properties of the flour used. The Brabender Extensograph-E measures the dough’s extensibility properties, primarily the resistance to extension and extensibility, providing reliable information about its subsequent baking behavior.

 

Unlike many other devices, the Extensograph-E demonstrates the impact of flour additives such as ascorbic acid, enzymes (e.g., proteinases), and emulsifiers. This allows for dependable assessments of the rheological properties of each flour and the determination of the “rheological optimum” for its specific intended use.

 

The measurement of flour quality involves assessing the dough’s extensibility properties, crucial for understanding its behavior during processing. Baking behavior is a key aspect, providing insights into how the flour performs in the final baked products. The influence of additives, including substances like ascorbic acid and enzymes, is examined to understand their impact on flour properties. Determining the rheological optimum ensures identifying the ideal conditions for viscosity and elasticity, optimizing flour performance for specific applications.

1.1 Measurement principle

Before the Extensograph-E measurement, a dough made from flour, distilled water, and salt is kneaded in the Farinograph. This ensures objectivity and reproducibility in sample preparation, as well as a consistent initial consistency. After a defined resting period, the dough is stretched to the point of rupture in the Extensograph-E. The applied force is measured and recorded, and this process is repeated three consecutive times get a full understanding of the dough performance during a typical proofing process.

1.1.1 Standard and Short Methods

The Extensograph-E measurement method is described in various standards, including:

– ICC Standard No. 114/1
– AACC Method No. 54-10.01
– ISO 5530-2
– RACI, GB/T, GOST R, IRAM, FTWG, and others.

In addition to these standards, there are recognized short methods with either reduced waiting times or shorter resting periods compared to the standard methods. These short methods deliver comparable results while offering time savings and good alignment with production fermentation times.

1.1.2 Automated Experimentation

The entire experimental process is menu-driven, providing a user-friendly interface. Clear online diagrams allow for real-time tracking of the measurement procedure.

The evaluation goes beyond standard methods, allowing for measurements without duplication and with customizable resting periods. The software efficiently manages daily measurements, indicating completed resting periods for each sample. This flexibility enhances the adaptability and productivity of the Extensograph-E system.

2 Experimental

The tensile strain measurement of wheat flour dough is a comprehensive process that includes the evaluation of four measured values and a ratio. It is conducted over three resting periods, each involving dublicate measurements per analysis.

This thorough analysis is designed for the determination of key factors such as flour quality, baking properties, and the identification of the optimal treatment for the flour.

 

By measuring four parameters and a ratio at various resting periods, the experiment provides a detailed understanding of the flour’s characteristics and behavior during baking (Fig 2). The ultimate goal is to guide the optimization of flour treatment methods for specific applications in the food industry.

 

 

Alternative methods include the Extensograph Rapid Method, which reduces resting periods from 45 to 30 minutes, providing time savings and practical relevance.

The Micro-Extensograph Method requires extensograph modification, decreasing sample size from 150g to 20g—especially pertinent for wheat breeders and research institutes. Validation of alternative methods is essential, ensuring their reliability and accuracy compared to the standard procedure.

Eight different flours were utilized in this study:

• Flours 1 to 4: Soft wheat flour doughs with a Extensograph Ratio ranging between 1.5 and 2.
• Flours 5 to 7: Tough wheat flour doughs with a Extensograph Ratio ranging between 4.5 and 9.
• Flour 8: Weak flour with a Extensograph Ratio of 4 and an energy of 90 cm².

 

The comparison involved eight individual measurements per method, including four duplicate determinations. The experimental procedures were conducted promptly to ensure the timeliness of the results. This comprehensive approach aimed to assess and compare the rheological properties of different flours using various methods.

 

3 Results and Discussion

The Micro-Extensograph method demonstrates a higher coefficient of variation across all measured values, indicating increased variability. This heightened sensitivity to inaccuracies during weighing suggests a more pronounced impact on measurement consistency. ( Table 1 )

Additionally, the uneven shaping of the sample within the Micro-Extensograph apparatus contributes to variations in the results. These observations highlight the importance of meticulous handling in the application of the Micro-Extensograph method to ensure precise and reliable measurements. ( Figure 3 )

3.1.1 Measurement Variability in the Extensograph Rapid Method:

The Extensograph Rapid Method demonstrates minimal or no deviations in coefficient of variation values, indicating consistent measurement variability. Surprisingly, the reduced resting period does not influence measurement variability, suggesting stability in the obtained results.

3.1.2 Parameters in the Micro-Extensograph Method:

In the Micro-Extensograph Method, the results of the Welch T-Test reveal distinct patterns:

The analysis shows no significant differences in extensibility and maximum values across all samples. However, there are elevated values in energy, tensile strength, and Extensograph Ratio (VZ) for samples 1 to 4. Notably, samples 1 to 4 display low ratio values, below 2.

These observed differences are attributed to variations in the extensogram curve shapes, emphasizing the method’s ability to capture nuanced rheological distinctions.

 

 

 

3.1.3 Comparison of the Curve Shapes

The increased rise in the Extensograph curve (figure 4) is attributed to various factors. It is associated with heightened measured parameters and a more pronounced registration of dough sample deformation during the “immersion” of the hook. The increased sensitivity of the force sensor plays a role, while the extensograph hook’s diameter remains consistent with the standard method.

 

 

Notably, this effect is less pronounced in tougher wheat flour doughs, indicating a nuanced response influenced by the specific characteristics of the flour being tested (figure 5)

In the Extensograph Rapid Method, the measured parameters show notable distinctions compared to standard methods. The shortened resting period leads to the development of tougher wheat flour doughs characterized by elongated and higher Extensograph curves (figure 5).

 

Elevated values are observed in energy, tensile strength, maximum values, and Extensograph Ratios (VZ). However, this method results in reduced extensibility. These findings underscore the significant influence of the altered procedural timeframe on crucial rheological aspects of the dough.

 

 

 

4 Results and Discussion

The Micro-Extensograph Method and the Extensograph Rapid Method, while both serving as alternatives in assessing wheat flour dough rheology, exhibit distinct characteristics and implications.

4.1.1 Micro-Extensograph Method:

Increased Measurement Variability:

This method demonstrates a slightly higher measurement variability, with a coefficient of variation raised by 0.1% to 1.4%. This indicates that the precision of measurements may be influenced by certain factors, such as sample handling and sensitivity to variations in the dough’s behavior.

Suitability for Specific Dough Types:

It proves to be suitable for wheat flour doughs with Extensograph Ratio (VZ) values exceeding 4. This highlights its potential applicability for specific flour types.

For soft wheat flours the method still provides an indication about dough extensibility. However, these values are not directly comparable with the standard method.

4.1.2 Extensograph Rapid Method:

Consistency and Independence:

In contrast, the Extensograph Rapid Method displays no increased measurement variability. Deviations in results are largely independent of the rheological properties of the wheat flour dough. This indicates that the method can consistently yield reliable results, irrespective of specific dough characteristics.

Conversion Factors for Comparisons:

The calculated conversion factors play a crucial role in aligning the results, enabling meaningful comparisons with historical and literature data. This feature enhances the method’s utility for broader contexts and research purposes.

Time Efficiency:

An additional practical advantage of the Extensograph Rapid Method is its reduced analysis time by 45 minutes. This can be a significant consideration for laboratories and industries seeking more time-efficient testing methods.

5 Summary

In summary, the Micro-Extensograph method provide a trade-off between precision and the ablility to measure the dough extensibility for very small sample sizes, with consideration given to the specific characteristics of the flour and the goals of the analysis.

The Extensograph Rapid Method provides reliable results in a shorter time frame and can be correlated well to the standard method.

Contact: Gabrielle Chebou – Product Manager for Rheology
+27829028943
gabrielle.chebou@anton-paar.com

 

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