Analysis of volatiles in Beer, Malt and Wort using the Bruker three channel “Off-Flavor” Beer analyzer

Importance of the Topic

The precise monitoring of volatile compounds in beer, malt and wort is essential for ensuring consistent product quality and avoiding undesirable off‐flavors. Analytical methods capable of quantifying trace levels of flavor and off‐flavor compounds support brewers in process control, product development and troubleshooting.

Study Objectives and Overview

This application note describes the use of a Bruker three‐channel gas chromatograph (GC) “Off‐Flavor” Beer analyzer configured for headspace analysis. The system aims to identify and quantify key flavor compounds (alcohols, esters, aldehydes) and off‐flavors (vicinal diketones, sulfur compounds) in beer, malt and wort. Conformance testing against a reference beer is performed using ChromSync software.

Methodology and Instrumentation

Sample Introduction and Headspace Conditions:

• Headspace sampler with tray cooling for volatile enrichment
• Split/Splitless injection at 155 °C

Three Independent GC Channels:

1. Channel 1 – Flame Ionization Detector (FID) with BR-SWax 60 m column for alcohols and esters
2. Channel 2 – Electron Capture Detector (ECD) with BR-5 50 m column for vicinal diketones and ketones
3. Channel 3 – Pulsed Flame Photometric Detector (PFPD) with BR-SWax 30 m column for sulfur compounds such as dimethyl sulfide (DMS)

Operating Parameters:

• Carrier gas: hydrogen at 3.5–5.0 mL/min
• Split ratios: between 1:7 and 1:10
• PFPD gate delay: 6 ms, gate width: 10 ms

Data Processing:

• CompassCDS software for acquisition
• ChromSync plug-in for batch‐to‐batch conformance analysis

Main Results and Discussion

Detection Performance:

• FID channel achieved clear resolution of oxygenated hydrocarbons (e.g., ethanol, esters).
• ECD channel selectively quantified vicinal diketones with minimal interference.
• PFPD channel provided enhanced sensitivity for sulfur compounds down to sub‐ppm levels, enabling robust dimethyl sulfide (DMS) analysis in beer and wort.

Conformance Testing with ChromSync:
The software compared sample chromatograms to a reference, generating a similarity score of 0.9620. Key metrics included:

• 81.7% identical peaks
• 4.9% out‐of‐tolerance peaks
• 7.3% reference‐only peaks
• 6.1% sample‐only peaks

Benefits and Practical Applications

The three‐channel analyzer facilitates:

• Comprehensive profiling of flavor and off‐flavor compounds in a single system
• High sensitivity for trace-level analytes such as DMS
• Automated conformance testing to maintain batch consistency
• Rapid troubleshooting of process deviations and microbial infections

Future Trends and Potential Uses

Emerging opportunities include:

• Integration with laboratory information management systems (LIMS) and real‐time data analytics
• Further miniaturization of headspace modules and on‐line coupling
• Application to a broader range of fermentation products (e.g., craft beverages, spirits)
• Advanced chemometric tools for pattern recognition and predictive quality control

Conclusion

The Bruker three‐channel “Off‐Flavor” Beer analyzer offers a robust and selective platform for monitoring volatile flavor compounds, vicinal diketones and sulfur off‐flavors in beer, malt and wort. Combined with ChromSync software for conformance testing, it delivers a comprehensive solution for quality control and process optimization in brewing.

Reference

1. Odor measurement review: Measurement of Odor Threshold by Triangle Odor Bag Method, Office of Odor, Noise and Vibration, Bureau of Environmental Management, Ministry of the Environment, Government of Japan
2. Bruker Application Note CA-1818791: Analysis of “Off‐Flavors” in Beer using the Bruker Two‐Channel Off‐Flavor Beer Analyzer