"Variety's the very spice of life, That gives it all its flavor!" (from a poem by William Cowper's 1785)
"... Scientists have previously developed artificial tongues that measure sweet and umami flavors, so researchers wanted to alter the technology for spicy foods by using the milk protein casein, which binds to capsaicin, the active compound in spicy peppers. They added skim milk powder to a flexible, opaque, tongue-shaped gel that conducted an electrical current; when the technology touched capsaicin, as well as pungent compounds in garlic, onion, horseradish, and ginger, the current changed and signaled their presence.
To validate their fake tongue against real ones, the researchers exposed their gel and a panel of taste testers to eight peppers and eight spicy foods. The tongue’s electrical responses matched the taste testers’ spiciness rankings and measured capsaicin concentrations from undetectable-by-humans to painful. ..."
"... So, researchers made an artificial tongue to quickly detect spiciness. Inspired by milk’s casein proteins, which bind to capsaicin and relieve the burn of spicy foods, the researchers incorporated milk powder into a gel sensor. The prototype, reported in ACS Sensors, detected capsaicin and pungent-flavored compounds (like those behind garlic’s zing) in various foods. ...
As a proof-of-concept, the researchers tested eight pepper types and eight spicy foods (including several hot sauces) on the artificial tongue and measured how spicy they were by changes in electrical current. A panel of taste testers rated the spiciness of the same items. Results from the artificial tongue and the tasting panel matched well. ..."
From the abstract:
"Artificial tongues have been extensively studied to detect the five basic tastes like humans. Spiciness, or pungency, is essential for food selection for both humans and animals. However, it is challenging to fully mimic human tongue-like performance for spicy taste.
Inspired by the fact that milk can relieve the pungent taste on the tongue, we introduced a soft gel-based artificial tongue as a flexible chemiresistive sensor for pungency detection.
When exposed to pungent compounds, it leads to the formation of hydrophobic complexes and conformational changes that decrease the ionic conductivity. The artificial tongue enables pungent compounds to be detected over a wide range (0.0001–1 wt %) with high sensitivity (0.259 wt %–1) and fast response times (<10 s).
Moreover, our artificial tongue can detect the pungency degree in a variety of spicy foods and condiments with intertranslatable ionic currents. Our work could enable both pungent compound detection and spicy sensation estimation, making a powerful platform for future applications involving movable humanoid robots and portable spicy taste monitoring devices."
