Astringency

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peebee

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Watch out! PeeBee's got an itchy writing hand (this is going to go on a bit!).

Astringency is one of those topics designed to terrify home-brewers. Must say there have been times when it has terrified me in the past! The big scare is "sparging" - sparge water too hot, or sparge water too alkaline, and he dangers of over-sparging.

But recently I've been faced with real situations that "astringency" has played a part in. The outcome is "interesting".

Firstly I'll start with what astringency ISN'T. Because many get very mixed up with what they think astringency is.

Astringency cannot be "tasted! And therefore it does not taste bitter. It has a fascinating mechanism, you feel astringency, not taste or smell it (or hear or see to throw in the remaining two of five basic human senses). It's not "bitter" (or sweet, sour, salty or "umami" if you insist to include it with the four basic tastes). Astringency is the result of interactions with proteins which is the subject of plenty of ongoing research. You feel astringency as a combination of drying, roughness, tightening, and puckering (drawing) of the skin (in the mouth usually!). Apparently astringent substances interact with salivary proteins (right in the salivary ducts) to create the sensations. The interaction of milk proteins with astringent substances (tannins, polyphenols) is the reason why we put milk in tea.

Astringency will modify how we taste, as a benefit as well as a distraction, so it is wrong to see astringency in beer as solely a bad thing.


So, onto my recent experiences of it: I'd brewed a Porter for Christmas (Whitbread 1850 recipe from Durden Park Beer Club's publication). I've experienced large losses during runoff from the boiler of these recipes in the past, so this time I brewed slightly too much then diluted the remainder in the boiler after running off the Porter (sort of parti-gyled). This second boil and runoff went to make a low gravity (1.045) "stout" (bit of irony for those well up on the history). The porter is maturing well into a very mellow strong ale. The "stout" has been drunk, but I didn't get the bitterness down enough and the beer had a strongly astringent quality. Bitter and astringent, both qualities that can come from the roast grains. I could appreciate the reasons for using "dehusked" grains to avoid this. And also appreciate how bitter and astringent can be seen as the same thing - they did seem to go hand-in-hand. Meanwhile the porter, which should be bitter and astringent too, is nothing of the sort.

Lesson 1 in my appreciation of astringency and bitterness.

Next, I'm brewing another ale from the Durden Park Beer Club's publication: No. #1 "Amber Small Beer". @An Ankoù had mentioned this one as having a pronounced flavour due to the very high proportion of Amber Malt. I'm not using Amber Malt, but the lighter "Imperial Malt" from Simpsons. Because it's lighter I bump up the proportion from 30% to 40%. I should have taken more notice of what @An Ankoù wrote, that it had a dry and thirst inducing quality: The result was strongly astringent!
But this time no hand-in-hand bitterness; the beer only had a calculated IBU of 42.

Lessson 2. Astringency in beer does not have to be associated with bitterness. Also, we worry about "over-sparging" creating astringency, but it is several magnitudes behind what you can do with a seemingly innocuous ingredient.

And lesson 3? Well here I have an "old recipe" beer that is borderline drinkable. I'm trying to use up another "old recipe" beer (Usher's 60/-) which at 9 months is getting a bit tired. So using another "old" technique of bringing on a harsh young beer with an old matured ("stale" was the term once used) beer I mixed 1/3 "Usher's 60/-" (easy, it pours out as foam!). Let a glass full of foam settle and top up with "Amber Small Beer". A "Step-mother" (old and bitter!). Surely the astringency peeks around the addition of other beer? Not a bit of it! And the tired flavours of the 60/- vanish too. The lesson being, astringency is not an irreversible "defect", there may even be situations where lack of astringency is a defect!

Or: So what if the sparge water is 80C (or even 85C). Basically, don't get sloppy, but don't fret over "it might of been too hot ... it might of been over-sparged ... perhaps the temperature wasn't right ... arghhhhhhhh.
 

Drunkula

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It's not "bitter" (or sweet, sour, salty or "umami" if you insist to include it with the four basic tastes).
I insist that we include oleogustus, too. (aaaand I'm leaving that open for follow ups)
 

Clint

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I insist that we include oleogustus, too. (aaaand I'm leaving that open for follow ups)
Is that when you burp and get some nasty sour taste in the back of the throat that takes ages to shift?
 

peebee

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I insist that we include oleogustus, too. (aaaand I'm leaving that open for follow ups)
Oleogustus? What's that then? Nearest I could get was ("oleo" relating to oil, "gustus" sounding a bit Roman) … a greasy Roman. Na, don't want any of them (I guess that would cause a sour taste in the back of the throat?).
 

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