Ever wondered if that old carton of fruit juice in the back of your fridge is still safe to drink? A new "electronic tongue" could tell you. The system, powered by artificial intelligence (AI), can identify issues with food safety and freshness. It also offers a glimpse at how AI makes decisions, researchers reported [October 9th] in the journal Nature.

To make the tongue, researchers used an ion-sensitive field-effect transistor -- a device that detects chemical ions. The sensor collects information about the ions in a liquid and turns that information into an electrical signal that can be interpreted by a computer.

In the new system, the sensor acts as the tongue, while AI plays the role of the gustatory cortex, the brain region responsible for perceiving taste. The team linked the sensor to an artificial neural network, a machine learning program that mimics the way the human brain processes information, to process and interpret the data that the sensor collected.