Anyone who has bitten into a fiery chili pepper knows that appearances can be deceiving — a sauce that looks mild might actually set your mouth on fire.
Now, scientists have developed an artificial tongue that can accurately measure how spicy a food is, all without risking any human taste buds.
The new device, described in the journal ACS Sensors, is inspired by a simple fact: milk helps cool the burn of spicy foods.
That’s because milk contains proteins called caseins, which can bind to capsaicin — the chemical compound that makes chili peppers hot — and neutralize its sting.
Building on this idea, researchers created a sensor that mimics how casein interacts with capsaicin, allowing it to “taste” the heat level of food electronically.
“Our flexible artificial tongue holds tremendous potential for portable taste-monitoring devices, humanoid robots, or people who’ve lost their sense of taste,” said Weijun Deng, the study’s lead author.
Currently, measuring flavor and spiciness is difficult and often relies on human taste testers or complicated lab procedures.
Artificial tongues have been developed before to detect sweetness, saltiness, and other basic tastes, but accurately measuring spiciness has been a major challenge.
Substances like capsaicin in chili peppers, piperine in black pepper, and allicin in garlic trigger burning or tingling sensations that are tough to reproduce with synthetic materials.
To solve this problem, Jing Hu and colleagues created a new kind of electrochemical gel that acts like a tongue.
They mixed acrylic acid, choline chloride, and skim milk powder, then hardened the solution with ultraviolet light.
The resulting gel, shaped like a tongue, was both flexible and able to conduct electricity.
When a spicy compound such as capsaicin touched the surface, the milk proteins bound to it — just as they would inside your mouth. This reaction caused a measurable drop in the electrical current running through the gel.
Within ten seconds, the “tongue” could detect how much capsaicin was present, ranging from mild to painfully hot levels.
The team tested the artificial tongue with eight kinds of peppers and eight spicy foods, including several hot sauces. They also compared the results to ratings from a human taste panel. Remarkably, the artificial tongue’s readings matched the human testers’ perceptions of spiciness almost perfectly.
Beyond chili heat, the milk-based sensor also detected other sharp or pungent flavors from ingredients such as ginger, black pepper, horseradish, garlic, and onion.
The researchers believe this technology could lead to new tools for food quality control, allowing manufacturers to measure spiciness quickly and safely. In the future, it could even help design better-tasting products, train robotic chefs, or assist people who have lost their sense of taste.
In short, the team’s milk-powered “tongue” may one day help us scientifically measure just how hot that hot sauce really is — no brave volunteers required.
