Astringency
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Astringency is a complex sensory property, characterized by drying, roughing, and puckering of the skin or mucosal surface in the mouth. Immediate perception is not always possible; however, it is usually recognized in the mouth after swallowing the content.[1] Astringency is attributed to polyphenol interaction with proline-rich salivary proteins.[2][1]
astringency is characterized by drying, roughing, and puckering of the mucosal surface in the mouth. Astringency is not a taste but a tactile feeling. It is not always perceived immediately, but evolves after swallowing and increases upon repeated ingestion. Saliva contains proline-rich proteins that lubricate the mouth. A wide range of compounds can bind to these proteins: salts of multivalent metallic cations, dehydrating agents, acids, and polyphenols. This leads to formation of insoluble complexes, a decrease in salivary lubrication properties, and the perception of astringency. In beer, phenolic acids, flavonols, flavanoids, and stilbenes could be responsible for astringency. Polyphenol thresholds lie between 1 and 50 ppm.[3]
Sugars reduce polyphenol astringency whilst oxidation may enhance it by increasing the polymerization degree (DP) of polyphenols. If the DP is too high, however, precipitation may occur, making the beverage less astringent. Astringency is intensified at low pH, especially near 4.0–4.2, but a higher astringency has been measured in beers with a pH close to 5. In this case, it was suspected that the pH of the samples fell in the mouth to a value of 4.4 before polyphenol/protein interactions occurred. As regards the effect of beer temperature, astringency may be higher at 21°C than at 7°C, but a more recent paper mentions no significant difference.[3]
Polyphenols of the flavonoid family provide beer with astringency, perceived organoleptically as a drying or puckering sensation on the tongue. PPs of both low and high molecular mass may elicit an astringent response.[4]
Oxidation and lower pH enhances the astringency sensation.[1] Higher levels of CO2 decrease astringency sensation.
- Francois N, Guyot-Declerck C, Hug B, Callemien D, Govaerts B, Collin S (2006) Beer astringency assessed by time-intensity and quantitative descriptive analysis: influence of pH and accelerated aging. Food Qual Prefer 17:445–452
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References[edit]
- ↑ a b c Habschied K, Košir IJ, Krstanović V, Kumrić G, Mastanjević K. Beer polyphenols—bitterness, astringency, and off-flavors. Beverages. 2021;7(2):38.
- ↑ Wannenmacher J, Gastl M, Becker T. Phenolic substances in beer: Structural diversity, reactive potential and relevance for brewing process and beer quality. Compr Rev Food Sci Food Saf. 2018;17(4):953–988.
- ↑ a b Callemien D, Collin S. Structure, organoleptic properties, quantification methods, and stability of phenolic compounds in beer—a review. Food Rev Int. 2009;26(1), 1–84.
- ↑ Aron PM, Shellhammer TH. A discussion of polyphenols in beer physical and flavor stability. J Inst Brew. 2010;116(4):369–380.