Astringency: Molecular Mechanisms, Sensory Profiles, and Mitigation Strategies

Abstract

Astringency is a tactile-oral sensation—perceived as drying, roughening, and puckering—that emerges when dietary polyphenols (tannins, flavonoids) complex with salivary proline-rich proteins, depleting lubrication and increasing mucosal friction. Unlike canonical tastes, astringency is mediated mainly by trigeminal mechanoreceptors rather than taste GPCRs and is not suppressed by sweetness. The same molecular features that drive this aversive mouth-feel underlie a broad spectrum of bioactivities, including antioxidant, anti-inflammatory, antimicrobial, antiviral, cardioprotective, and chemopreventive effects. This review integrates current knowledge on: (i) the chemistry of hydrolysable and condensed tannins and their interactions with saliva; (ii) physiological transduction pathways involving epithelial sodium and acid-sensing ion channels; (iii) the diversity of astringent food matrices and the sensory descriptors they evoke; (iv) pharmacological outcomes ranging from NF-κB inhibition to modulation of digestive enzymes; (v) analytical and tribological methods for quantifying astringency; and (vi) emerging mitigation strategies such as polysaccharide viscosity engineering, inclusion complexes, enzymatic polymerisation, encapsulation technologies, and pharmaceutical taste-masking. Traditional Chinese Medicine perspectives and inter-individual variability linked to salivary protein genetics are also discussed. Finally, research frontiers—high-resolution tannin–protein structures, machine-learning prediction of astringency, green extraction processes, microbiome-derived metabolites, and biomimetic oral lubricants—are highlighted. Understanding and manipulating astringency at the molecular level will enable the development of foods, beverages, and therapeutics that retain the health benefits of polyphenols while delivering superior sensory acceptance.