Astringency in Coffee
Astringency is a tactile characteristic of coffee, which also involves the sense of taste. It is a sensation rather than a flavor or taste. The acidity in coffee comes from the roasted beans’ fermentation process. If the extraction process goes into overkill, the coffee will become more acidic and overwhelm the taste palate.
What does astringent taste like?
Astringency creates a dry, rough feeling in the mouth. It is caused by tannins binding proteins in saliva. Astringency mutes other flavors when strong. There are multiple reasons for the astringent sensation, making the mechanism hard to determine. Coffee is naturally bitter, not harsh. If brewed correctly, some sweetness comes through.
The Astringent Effect of Coffee
The polyphenols and tannins in coffee contribute to astringency, along with organic acids. Astringency is generally stronger when pH is lower. When drinking astringent coffee, tannins and polyphenols bind with salivary proteins, reduce oral lubrication, and increase oral friction – hence the dry sensation.
Astringent polyphenols found in brewed coffee likely extract via channeling in percolation brewing. Astringency is less likely to occur in immersion brewing due to no channeling. Increased astringency comes from: underripe cherry beans, underdeveloped roasts, and channeling during percolation.