In-vitro tongue-inspired hydrogel sensor for wine astringency evaluation

Astringency, as a complex oral sensation, poses challenges for in-vitro detection and quantification due to the intricacy of its perception mechanism and the complexity of the astringent substances involved. To address this challenge, we developed a chitosan hydrogel-based sensor inspired by the human tongue. Mucins were embedded within the sensor to detect astringent polyphenols. When in contact with astringent phenolic compounds, the resulting precipitate aggregates entangle or block the pores, restricting ion conductivity within the sensor. Astringency detection is achieved using cyclic voltammetry. The tongue-inspired sensor can detect a wide range of tannic acid (1E −4 wt% - 5wt%), including the human sensory threshold for astringency, and construct a standard astringency quantification curve from the sensing data. It was demonstrated to revert the actual astringency sensing process by overall astringency detection and synergistic effect, simulating the in-vitro function of the tongue. In addition, the sensor provides insights for evaluating the optimal drinking time of open red wines based on astringency, offering a novel approach for wine astringency evaluation, demonstrating its potential for a variety of applications in the food and beverage industry.