Astringency and bitterness are organoleptic properties widely linked to tannin compounds. Due to their significance to food chemistry, the food industry, and to human nutrition and health, these tannins’ taste properties have been a line of worldwide research. In recent years, significant advances have been made in understanding the molecular perception of astringency pointing to the contribution of different oral key players. Regarding bitterness, several polyphenols have been identified has new agonists of these receptors. This review summarizes the last data about the knowledge of these taste properties perceived by tannins. Ultimately, tannins’ astringency and bitterness are hand-in-hand taste properties, and future studies should be adapted to understand how the proper perception of one taste could affect the perception of the other one.

Polyphenols have been the subject of numerous research over the past years, being referred as the nutraceuticals of modern life. The healthy properties of these compounds have been associated to a natural chemoprevention of 21st century major diseases such as cancer and neurodegenerative diseases (e.g. Parkinson's and Alzheimer's). This association led to an increased consumption of foodstuffs rich in these compounds such as red wine. Related to the ingestion of polyphenols are the herein revised sensorial properties (astringency and bitterness) which are not still pleasant. This review intends to be an outline both at a sensory as a molecular level of the mechanisms underlying astringency and bitterness of polyphenols. Up-to-date knowledge of this matter is discussed in detail.

Polysaccharides are described to inhibit aggregation between food polyphenols and salivary proteins (SP) and may hence lead to astringency modulation. In this work, the effect of two wine polysaccharides (arabinogalactan proteins-AGPs and rhamnogalacturonan II- RGII) on SP-polyphenol interaction was evaluated. In general, both polysaccharides were effective to inhibit or reduce SP-polyphenol interaction and aggregation. They can act by two different mechanisms (ternary or competitive) depending on the SP-tannin pair. In the case of salivary P-B peptide, AGPs and RGII seem to act by a ternary mechanism, in which they surround this complex, enhancing its solubility. Concerning acidic proline-rich proteins (aPRPs), it was possible to observe both mechanisms, depending on the tannin and the polysaccharide involved. Overall, this work point out for a specific property of wine polysaccharides important to modulate this and other beverages and food astringency perception.