What causes astringent taste?

jackmaxcy said:

My first brew was a Scottish ale and aside from the contamination, it had a very astringent taste. My second brew (which doesn't have a contamination) has been in the bottle for 2 weeks and I plan to start drinking it next week. I tasted a bottle last evening and find it also has an astringent taste, but not as bad as the first.

What causes an astringent taste? Might it be that both batches went through the primary and secondary fermentations at about 78-80 F? That was my fermomenter reading on the outside of the fermentors.

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jackmaxcy said:

I don't have the exact recipe but will find it. If memory serves me right, it was an extract recipe using Munton wheat extract (6.6 lbs). There were no specialty grains and my initial boil was 4.5 gallons.

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Astringent
Astringency differs from bitterness by having a puckering quality, like sucking on a tea bag. It is dry, kind of powdery and is often the result of steeping grains too long or when the pH of the mash exceeds the range of 5.2 - 5.6. Oversparging the mash or using water that is too hot are common causes for exceeding the mash pH range. It can also be caused by over-hopping during either the bittering or finishing stages. Bacterial infections can also cause astringency, i.e. vinegar tones from aceto bacteria.

The brown scum that forms during fermentation and clings to the side of the fermentor is intensely bitter and if it is stirred back into the beer it will cause very astringent tastes. The scum should be removed from the beer, either by letting it cling undisturbed to the sides of an oversize fermentor, or by skimming it off the krausen, or blowing off the krausen itself from a 5 gallon carboy. I have never had any problems by simply letting it cling to the sides of the fermentor.

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Alcoholic
A sharp flavor that can be mild and pleasant or hot and bothersome. When an alcohol taste detracts from a beer's flavor it can usually be traced to one of two causes. The first problem is often too high a fermentation temperature. At temperatures above 80°F, yeast can produce too much of the higher weight fusel alcohols which have lower taste thresholds than ethanol. These alcohols taste harsh to the tongue, not as bad as cheap tequila, but bad nonetheless.

Fusel alcohols can be produced by excessive amounts of yeast, or when the yeast sits too long on the trub. This is one reason to move the beer off of the hot and cold break when the beer is going to be spending a lot of time in the fermentor.

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