Determination of Methylcafestol in Roasted Coffee Products According to DIN 10779

Significance of Topic

Cafestol, a diterpene in coffee beans, is degraded during roasting yet remains an important marker for coffee authenticity and quality control. Accurate determination according to DIN 10779 ensures consumer safety, regulatory compliance and insights into health-related impacts of coffee consumption.

Objectives and Overview

This study presents a validated HPLC method to quantify 16-O-methyl cafestol in roasted coffee. It evaluates system performance—linearity, precision, accuracy—and explores solvent-saving columns and throughput optimization to support routine quality testing.

Methodology and Instrumentation

• Instrumentation: Agilent 1260 Infinity LC system with binary pump (G1312B) and degasser (G1322A), standard autosampler (G1329B) with thermostat (G1330B), thermostatted column compartment (G1316A), diode array detector (G4212B).
• Columns: ZORBAX Eclipse Plus C18 (4.6×150 mm, 5 µm); Poroshell 120 EC-C18 (3.0×150 mm & 3.0×50 mm, 2.7 µm solvent saver).
• Solvents and Conditions: Water (A)/acetonitrile (B) isocratic 50% B; flow rates 1.0 mL/min (4.6 ×150 mm), 0.43 mL/min (3×150 mm), injection volumes 20 µL and 8.6 µL; detection at 220 nm (4 nm bandwidth), reference 360 nm.
• Sample Preparation: Soxhlet extraction of 5 g coffee with tert-butyl methyl ether; saponification in KOH/ethanol; liquid–liquid extraction; evaporation; reconstitution in water/acetonitrile (50/50).

Main Results and Discussion

The calibration curve spanning 0.781–100 mg/L showed R²>0.9999. On the 4.6×150 mm column, LOD/LOQ were 0.17/0.58 mg/L; on the Poroshell solvent-saver column they improved to 0.12/0.38 mg/L. Retention time RSD ≤0.2% and area RSD ≤0.34%; concentration precision ~0.3% RSD; accuracy ~90–92%. No carryover was detected. Analysis of a commercial roasted coffee yielded ~50 mg cafestol per kg. Using a 3×50 mm column and elevated flow rates reduced run times from 30 to as little as 2.7 min while maintaining performance.

Benefits and Practical Applications

This method delivers robust, high-throughput quantification of 16-O-methyl cafestol with low solvent consumption. It supports routine quality control, authenticity testing and regulatory compliance in the coffee industry.

Future Trends and Potential Applications

Advances in core-shell ultrafast LC and higher-efficiency columns will further increase throughput. Integration with mass spectrometry could expand analyte scope. Automated sample preparation and micro-scale extraction techniques may enhance laboratory workflow and sustainability.

Conclusion

The validated HPLC procedure conforms to DIN 10779, achieving precise, accurate and rapid determination of 16-O-methyl cafestol in roasted coffee while significantly reducing solvent use and enabling flexible throughput.

References

• DIN 10779:2011 – Coffee products: Determination of 16-O-methyl cafestol by HPLC.
• ISO 20481:2008 – Coffee: Determination of caffeine content by HPLC.
• DIN 10767:1992 – Coffee: Chlorogenic acids determination by HPLC.
• DIN EN 14132:2009 – Coffee: Ochratoxin A determination by HPLC with immunoaffinity cleanup.
• EFSA Journal 2011;9(4):2057 – Scientific opinion on health claims related to coffee.