Not to be confused with the bizarre robotic tongue prototype, "electronic tongues" have been in use for the past several years, for assessing the content of various foods and beverages - and no, unfortunately they don't look like actual tongues. While past examples have been used for purposes such as identifying the vintage and grape variety of wines, researchers from Spain's Universitat Politècnica de València (UPV) have recently developed one that analyzes the content of antioxidant powder, along with fruit and fruit products.
The system consists of electronic measuring equipment, linked to a PC running custom software. Fruit, juice or antioxidant samples are subjected to an electrical current. Their response is measured via voltammetry, in which the current is measured as the potential is varied, and dielectric spectroscopy, in which a material's impedance is measured over a variety of frequencies.
The tongue has so far been successful in measuring the antioxidant content in solutions including citric acid, ascorbic acid (vitamin C) and malic acid, along with binary mixtures of those substances. The UPV team are now looking into using it to measure vitamin C degradation in juices, particularly orange juice.
It's possible that the technology could also be used to detect residual glyphosate, which is a weed killer that is often used on fruit and vegetable crops. Another application could involve the monitoring of water quality in sewage plants.