Tracing the Geographical Origin of Roasted and Green Coffee Using Isotope Fingerprints

Background: Coffee is one of the most popular beverages worldwide, sourced from different geographical regions. To ensure that coffee beans come from labelled locations, laboratories need an analytical solution that can discriminate geographical origin. Coffee beans have a fingerprint, a unique chemical signature that allows them to be identified: Isotope fingerprints of carbon, nitrogen, sulfur, hydrogen, and oxygen have been reliably used for origin claim verification. Objective: Show that hydrogen and oxygen isotope fingerprints from green and roasted coffee beans can determine the origin of coffee beans. Methods: The coffee beans were initially ground to as fine as possible a powder using a cryo-mill. Following, samples were weighed into tin capsules and introduced to the Thermo Scientific EA IsoLink^™ IRMS System via the Thermo Scientific MAS Plus autosampler, where they were pyrolyzed at 1450°C, and converted to H₂ and CO for analysis. Results: The hydrogen and oxygen isotope fingerprints of the coffee beans show that they can be clearly differentiated at the continent scale. Conclusions: It is evident that measuring the isotope fingerprint of coffee beans helps support legislation on food integrity and labelling (EC Reg. No. 1169/2011) and product geographical indication/origin (EC Reg. No. 510/2006), therefore protecting consumers and brands. The origin of a coffee bean can be determined using their hydrogen and oxygen isotope fingerprints. Highlights: Hydrogen and oxygen isotope fingerprints can help determine the origin of coffee beans, allowing the label claim to be verified.