Bitterness in Beer – Prediction, Measurement, and Innovation

This study published in Brauwelt International (Issue 3/2025) aims to evaluate the analytical performance of the CDR BeerLab for the determination of bitterness in beer, comparing its results with the official EBC 9.8 reference method. The objective was to verify accuracy, repeatability, and practical advantages in terms of speed, sustainability, and ease of use for routine quality control in breweries.

Understanding Bitterness in Brewing

Beer bitterness primarily originates from α-acids in hops, which are transformed into iso-α-acids during wort boiling. The extent of this conversion depends on several parameters, including pH, gravity, and boiling time, and the resulting concentration defines the beer’s International Bitterness Units (IBU).

While IBU remains a standardized measure of bitterness widely used in industrial brewing for quality control and process consistency, its correlation with sensory perception is not always linear. Factors such as alcohol content, residual sugars, malt composition, and aroma compounds also influence the overall sensory impression. Nevertheless, IBU analysis remains a critical parameter for both large and small breweries, supporting recipe development and product standardization.

Prediction Versus Analytical Determination

In the brewing industry, bitterness can be predicted using empirical formulas based on hop addition parameters—such as alpha acid percentage, hop weight, utilization factor, and wort volume—but these models cannot account for all process variables.

Therefore, direct quantification through analytical methods is essential to ensure accuracy and consistency. The official reference procedures are defined by the ASBC, EBC, and MEBAK, and include two principal approaches:

• UV Spectrophotometric Method (ASBC Beer-23A / EBC 9.8 / MEBAK B-400.17.110):
  In this method, iso-α-acids are extracted from acidified beer with isooctane and measured by their absorbance at 275 nm. The simplicity of the formula (IBU = A275 × 50) makes it practical, but it requires large sample volumes and involves manual handling that can lead to interference from polyphenols and other compounds
• High-Performance Liquid Chromatography (ASBC Beer-23C):
  HPLC enables the precise quantification of specific iso-α-acids but demands specialized instrumentation and skilled operators, limiting its applicability for routine in-brewery testing

The CDR BeerLab Approach: Simplifying IBU Determinationr

The CDR BeerLab system introduces a modified spectrophotometric method for the rapid determination of bitterness in beer. Operating at 270 nm, it delivers results in just 5–6 minutes, compared to 15–55 minutes for official methods, while requiring only 1 mL of sample. Its main advantages include:

• Minimal sample and reagent use, reducing waste and improving environmental sustainability.
• Ready-to-use reagents, stable for up to 12 months.
• No glassware or complex preparation steps.
• User-friendly interface, suitable for operators without advanced technical training.
• Beyond IBU, the CDR BeerLab allows simultaneous measurement of Alcohol by Volume (ABV), Free Amino Nitrogen (FAN), fermentable sugars, and Vicinal Diketones (VDKs), providing a comprehensive analytical platform for brewery quality control

Analytical Validation: Correlation and Repeatability

To validate the analytical accuracy of the CDR BeerLab IBU method, a correlation study was conducted by the CDR Chemical Laboratory “Francesco Bonicolini”. Beer samples with varying bitterness levels were analyzed using both the CDR BeerLab and the official EBC 9.8 method.

The results demonstrated an excellent linear correlation with a coefficient of determination R² = 0.9994, confirming the strong equivalence between the two methods (Figure below). The comparative dataset revealed near-identical values across all samples tested, indicating analytical consistency.

A repeatability test was also performed by repeatedly measuring the same beer sample. The results showed a relative standard deviation (RSD) of just 0.55%, underscoring the high precision and robustness of the method. This low variability proves the reliability of the CDR BeerLab even under routine testing conditions.

Furthermore, a comparative study on IBU determination conducted by the University of Hamburg confirmed that the CDR BeerLab method is statistically equivalent to the MEBAK reference method.

The correlation between the mean IBU values obtained with the MEBAK reference method and those measured with the CDR BeerLab was R² = 0.9993

Advantages for Modern Brewing Operations

By significantly reducing sample handling, analysis time, and reagent volumes, the CDR BeerLab enables real-time control directly in the brewery, supporting quick decisions during production or recipe optimization.

Its combination of analytical reliability, ease of use, and cost efficiency makes it suitable for both craft and industrial breweries. Furthermore, the reduced environmental impact and absence of hazardous reagents align with modern sustainability goals in brewing quality management.

Conclusion

The study published in Brauwelt International (Issue 3/2025) highlights how the CDR BeerLab provides a validated, rapid, and reliable alternative to traditional IBU analysis methods. With proven correlation to the EBC 9.8 reference and excellent repeatability, it represents a next-generation analytical tool for bitterness monitoring and comprehensive quality control in the brewing industry.

17/11/2025