Discriminating counterfeit beer with Raman spectroscopy and PCA

Importance of the Topic

Counterfeit beers pose significant risks to consumer safety, brand reputation, and regulatory compliance. As criminals replace labels and caps or fill bottles with unregulated mixtures, rapid and reliable authentication methods are critical.

Objectives and Study Overview

This application note demonstrates the use of a portable 1064 nm Raman spectrometer (i-Raman EX) combined with principal component analysis (PCA) to distinguish genuine lager beers from different breweries and to detect adulteration in beer mixtures.

Methodology and Instrumentation Used

Four commercially available lagers were decanted from 355 mL cans and measured under controlled conditions to minimize variability. One of the brands was an American-style light lager with lower calorie content.

• Instrument: i-Raman EX portable Raman spectrometer with patented 1064 nm CleanLaze® laser
• Probe: RIS100-SS immersion probe featuring a sapphire ball tip to reduce CO₂ nucleation
• Acquisition parameters: 330 mW laser power, 10 s integration time, single scan average
• Software: BWSpec for spectrum acquisition and BWIQ for PCA and multivariate analysis

Field test notes:

• 1064 nm excitation minimizes fluorescence interference from natural beer components.
• Consistent sampling conditions (temperature, probe immersion depth) yield the most reproducible spectra.

Key Results and Discussion

Beer Raman spectra are dominated by ethanol peaks around 880, 1050, 1090, 1280, and 1450 cm⁻¹, with the 880 cm⁻¹ C–C stretching band correlating linearly with alcohol content by volume (ABV). PCA separated each lager brand into distinct clusters. The light lager (4.2 % ABV) formed a unique cluster, while a 1:1 mixture of two brands appeared between their respective clusters, confirming the method's sensitivity to adulteration.

Benefits and Practical Applications

• Non-destructive, reagent-free analysis requiring minimal sample preparation
• Portable system suitable for on-site quality control and customs inspections
• High specificity through multivariate statistical discrimination of similar products

Future Trends and Potential Applications

Advancements may include integration with machine learning models for automated classification, development of handheld Raman devices for real-time field screening, and extension of this approach to other beverages and complex food matrices.

Conclusion

The combination of 1064 nm Raman spectroscopy and PCA provides a robust, portable solution for authenticating beer and detecting counterfeit or adulterated products, supporting consumer protection and industry quality control.

References

• 14.8 million litres alcoholic drinks seized across Europe. Anti-fraud EC, accessed 21 March 2023.