What is Astringency?

Astringency is a mouthfeel associated with tannins and is commonly found in tea, young red wine, really hoppy beers, especially dry-hopped brews, and grainy and unbalanced beers.

Astringency there are some common causes:

1. Too high a percentage of particular speciality grains like dark caramel malts the dark fruit character of these malts can give an astringent note in the final beer if not balanced with the residual sweetness/body of the beer.
2. Sparge water temperature, when sparging water temperature is above 76°C (168.8°F) then this high temperature can promote the extraction of tannins during the sparge.
3. The most common and the highest contributing factor is the extraction of tannins due to pH. During the mash, the pH is typically between 5.2-5.8. if untreated then your sparge water pH is the same as your groundwater pH, which for most people is typically 6.2-8.5 pH. The extraction of tannins is very high above a pH of 6. Therefore, when we start sparging the pH remains low while the concentration of sugars remains high. But as the concentration of sugars drops as they are carried down to the boiler the pH increases towards the pH of the sparge water. So, over-sparging with non-treated sparge water will result in excess tannin extraction. Or if the flow through the grains is uneven, meaning areas of the grist will increase in pH early. So, ensure to use correct sparge volume to limit over-sparging. 

Treat your sparge water using the water calculator feature on the Grainfather app and ensure to evenly cover the top of the grains with the sparge water to limit localised grain over-sparging.