Milk-inspired artificial tongue promises faster food spiciness tests

Scientists in China have developed a “soft and flexible” artificial tongue that can detect the heat level in spicy foods, and support or reduce reliance on human taste panels. The device can detect capsaicin and pungent-flavored compounds found in garlic, ginger, and black pepper, which could streamline spiciness testing in F&B development.

The transparent “tongue-shaped” gel-based film is inspired by milk’s casein proteins, which bind to capsaicin and relieve the burn of spicy foods. The researchers created the prototype device by combining acrylic acid, choline chloride, and skim milk powder.

The Shanghai Institute of Technology, Fujian Provincial Key Laboratory of Leather Green Design and Manufacture, and East China University of Science and Technology conducted the study to support current methods of measuring food flavor compounds that require taste testers and “complex laboratory methods,” note the researchers.

As an alternative, scientists are developing artificial tongues to address food industry concerns, such as milk and wine spoilage, as well as detecting counterfeit alcohol. However, the authors say capsaicin in chili peppers, piperine in black pepper, and allicin in garlic produce “stinging, tingling, or burning” sensations that are difficult to mimic and measure with synthetic materials.

Author Jing Hu highlights that it is possible to “neutralize” the heat of peppers by binding their capsaicin with casein proteins in milk. This discovery inspired the research team to develop the artificial tongue by adding casein to an electrochemical gel material and measuring spiciness with the help of an electrical current change that occurs when casein binds to capsaicin.

The flexible artificial tongue holds tremendous potential in “spicy sensation estimation for portable taste-monitoring devices, movable humanoid robots, or patients with sensory impairments like ageusia,” says Weijun Deng, the study’s lead author.

Detecting food pungency

To develop the artificial tongue, the team combined the ingredients and exposed the solution to UV light. 

The resulting opaque gel conducted an electrical current, which decreased after ten seconds when capsaicin was added to the film. This process showcased the device’s potential as an “artificial, spice-detecting tongue,” explain the researchers.

In initial tests, the device responded to capsaicin concentrations ranging from below the human detection threshold to levels perceived as painful, known as the “oral pain threshold.” 

The device also detected other pungent-flavored compounds found in common hot sauce ingredients, such as ginger, black pepper, horseradish, garlic, and onion.

The transparent square acts like an artificial tongue, reacting to capsaicin and similar pungent compounds in proportion to a food’s spiciness (Image credit: Weijun Deng, adapted from ACS Sensors 2025).

Protecting human taste buds

The study, published in the American Chemical Society Sensors, tested eight pepper types and eight spicy foods, including several hot sauces, on the device and measured the degree of their spiciness as a proof-of-concept.

Results from the artificial tongue and a panel of taste testers “matched well,” signaling the device’s potential role in reducing or supporting human testers.

The casein-containing artificial tongue could be used to quickly test a food’s spiciness level — “without putting one’s taste buds at risk,” notes the study.

The National Natural Science Foundation of China and the Fund of Fujian Provincial Key Laboratory of Leather Green Design and Manufacture funded the research.