The Electronic Tongue

Geschmacksknospe

When a king in the Middle Ages feared falling prey to a competing heir to the throne he would have a taster taste his food before eating to be sure it wasn’t poisoned. Nowadays an electrical tongue can take care of such dirty work.

As the name implies, how the device works is modeled on the human organ of taste. While our taste buds are responsible for registering different flavors, the e-tongue employs ion-sensitive sensors. The data measured are sent to a computer for analysis – it assumes the role of the brain. Like us the e-tongue is able to distinguish among basic flavors: sweet, sour, salty, bitter and the fifth Japanese taste, umami. In terms of external appearance, however, it has very little in common with its prototype.

This technology is primarily intended for use in the quality control of industrially prepared foods. Until now flesh-and-blood tongues were required. As usual when technology copies humans the electronic sensory organ has far surpassed its human counterpart. Where we may only be able to determine sourness, the e-tongue registers the exact percentage of hydrogen ions, which are responsible for the formation of various acids. Every test generates a chemical profile, the ionic composition of which corresponds to a flavor combination. So far it has only worked with liquids, meaning solid food must first be dissolved.

With liquids as their forte, the artificial connoisseurs have become professionals in the field of alcohol. Spanish scientists have created an e-tongue that reliably distinguishes among various kinds of beer. Other models have tried themselves successfully at whiskey, cognac and brandy.

In Thailand the new technology has peaked interest at the governmental level. At the state-run National Innovation Agency the “e-delicious tasting machine” was developed to test the quality of Thai cuisine abroad. Apparently too many liberties have been taken in its name, causing the nation to fear for its national cuisine’s reputation. When a Thai restaurant passes the e-delicious taste test, it receives and is allowed to display the official “Thai Delicious” certificate.

In the future this technology could identify bad foodstuffs before they go into circulation. Water quality in conflict zones could also be tested. (Shame on anyone who was tempted by the thought of a personal taster.) Oh, and our biological senses seem to have inspired science in other realms: the e-nose is already a work-in-progress.

Image: Lingual papilla with taste buds. ©Pädagogische Hochschule Heidelberg

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