Chemists use phenolic compounds to verify Spanish wine origins and varieties

Analytical chemists at the University of Barcelona used chemical profiling to identify the geographical origin and grape variety of Spanish red wines.

The team analyzed 150 commercial red wines from four major Protected Designations of Origin, including Rioja and Ribera del Duero, as well as various monovarietal styles like Tempranillo and Syrah. By measuring 22 different phenolic compounds, the researchers developed a method to verify if a bottle of wine matches its label.

The researchers used high-performance liquid chromatography coupled with tandem mass spectrometry to quantify the compounds. They found that while no single compound served as a definitive marker, the specific patterns of relative abundances across the 22 compounds provided enough information to categorize the wines. The study showed that wines from Somontano were the easiest to distinguish geographically, while Rioja and Ribera del Duero were harder to separate because both regions primarily use the Tempranillo grape.

The models achieved varying success depending on the wine type. The team identified Syrah with a prediction error of only 4.3 percent. However, Tempranillo proved more difficult to classify accurately, with errors between 16.0 and 22.3 percent. The researchers attributed this difficulty to the lack of unique phenolic markers for Tempranillo and the challenge of distinguishing pure monovarietal wines from blends where Tempranillo is the dominant grape.

The scientists suggest this method can be scaled to other regions and grape varieties to help regulators and distributors verify wine authenticity. Because the method relies on concentration-based profiling rather than a single unique chemical signature, it allows for the continuous addition of new samples to the calibration set to improve accuracy over time.