A research team has developed a gel-based artificial tongue capable of identifying the spiciness levels of a wide variety of foods — from mild bell peppers to the famously intense “facing heaven” chili often used in Sichuan cuisine. The new device, described recently in ACS Sensors, may provide an innovative way to quantify heat levels without putting human tasters through discomfort or risk.
Artificial taste sensors are not entirely new, and earlier models have successfully detected sweetness, sourness, umami, and other taste qualities. What sets this work apart is its exclusive focus on spiciness. The researchers aimed to create a tool that could measure heat levels with high precision, a feature that could be especially valuable for food manufacturers who need consistent quality control, says co-author Jing Hu, a chemical engineer at East China University of Science and Technology in Shanghai.
Inspired by Milk’s Soothing Effect
To build the device, the team took inspiration from a common culinary remedy: milk. Milk can reduce the burning sensation of spicy food because certain proteins interact with capsaicin, the chemical responsible for chili heat. Carolyn Ross, a food scientist at Washington State University, explains that these proteins help temper the burning sensation by binding with capsaicin molecules.
The artificial tongue reflects this natural interaction. It is constructed from a soft gel infused with milk powder, acrylic acid, and choline chloride. When an electrical current is applied, ions in the gel — mainly chloride and hydrogen — move freely and allow electricity to pass through. To detect changes in conductivity, the researchers sandwiched the gel between copper plates and connected it to a measuring device.
When the gel encounters capsaicin, the molecule binds with milk proteins inside the tongue. These interactions create larger complexes that disrupt ion flow. As a result, the gel’s conductivity decreases. The stronger the interaction, the greater the drop in conductivity, providing a measurable signal of how spicy the substance is.
Creating a New Spiciness Scale
To translate these electrical changes into a meaningful scale, the team allowed the artificial tongue to “taste” eight different varieties of peppers. Based on the electrical response of each pepper, they created a rating system ranging from 0 (not spicy at all) to 70 (extremely hot).
To evaluate the accuracy of this scale, the researchers tested eight spicy foods — including chili powder and tabasco sauce — and compared the device’s results with assessments from trained human tasters. According to Hu, the rankings generated by the artificial tongue aligned closely with the human panel’s evaluations. This suggests the device could serve as a reliable alternative to human taste testing, eliminating the health risks associated with repeatedly sampling very spicy foods.
Toward a Portable Spiciness Tester
Hu notes that the next step is to develop a more compact, portable version of the device. The current setup relies on a large workstation to measure conductivity, which limits its practicality for everyday use in kitchens, food factories, or restaurants. A handheld version would make it easier for chefs, manufacturers, or even consumers to check spice levels on the spot.
Ross adds that involving a broader range of taste testers — including people without formal training — could further refine the artificial tongue’s accuracy. Comparing its readings with a more diverse set of human responses might help improve how the device interprets different heat sensations.
As the food industry continues to embrace automation and precision tools, this gel-based artificial tongue may signal a new era in flavor analysis. For anyone who loves spicy food but prefers to avoid the burn, it could be a welcome technological breakthrough.
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