A sensor that can discriminate between different tannins and be used to fingerprint a wide variety of red wines to confirm their authenticity has been developed by US scientists. Eric Anslyn and colleagues at the University of Texas at Austin and University of California Davis have developed a sensor made with colour-changing indicators. They used the sensor to test wine samples from different vintners and managed to distinguish between specific flavonoids - chemicals found in fruit and vegetables, tea and red wine - in particular looking at tannins, which are responsible for colour, aging ability and texture.