Tracing the geographical origin of green and roasted coffee with isotope fingerprints

Importance of the topic

Coffee is one of the most consumed beverages worldwide and commands high commercial value. Its complex supply chain exposes it to mislabeling of origin and adulteration. Analytical tools that can authenticate geographic provenance protect consumers, uphold brand reputation and enforce food integrity regulations.

Study objectives and overview

This work evaluates hydrogen (2H) and oxygen (18O) isotope signatures in green and roasted coffee beans from twelve countries across Asia, Africa and the Americas. The goal is to demonstrate the capability of stable isotope fingerprinting, using an EA IsoLink IRMS system, to discriminate country or continental origin and detect mislabeling.

Methodology

Preparation and analysis steps included:

• Cryo-milling dried green coffee beans and aliquoting ~800 µg into silver capsules.
• Pyrolysis at 1450 °C in the EA IsoLink reactor under helium carrier gas.
• Separation of H₂ and CO gases via a 1 m molecular sieve GC column at 70 °C.
• Isotope ratio measurement on a Delta V IRMS calibrated against SLAP and VSMOW standards.
• Analysis time under 5 minutes per sample.

Instrumentation used

The analytical setup comprised the Thermo Scientific™ EA IsoLink™ IRMS with MAS Plus Autosampler, pyrolysis reactor (glassy carbon), a 5Å GC column and ConFlo IV interface connected to a Delta V isotope ratio mass spectrometer.

Main results and discussion

Isotope data revealed distinct 2H and 18O clusters corresponding to continental regions, driven by local precipitation patterns, altitude and proximity to ocean. Both green and roasted beans maintained geographical signatures. An outlier in the Bio Sumatra sample grouped with Central American profiles, indicating possible mislabeling. Table structure summary: stable isotopes C, N, S, O and H each provide specific biogeochemical indicators valuable for tracing food origin.

Benefits and practical applications

Key advantages of this approach include high-throughput, low-cost automated workflows; robust differentiation of origin at continental and national levels; and support for regulatory compliance in food authentication and labeling.

Future trends and potential applications

Prospective developments include expanding isotopic databases, integrating additional elements (e.g., carbon, nitrogen, sulfur), applying multivariate and machine learning classification, and extending fingerprinting to other high-value commodities.

Conclusion

Hydrogen and oxygen isotopic fingerprinting via EA IsoLink IRMS provides a reliable, automated method for determining coffee provenance and detecting mislabeling, thereby strengthening food authenticity controls.

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