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Astrigency

Northern Brewer General
#1

A while ago we had a discussion about tannins where I stated too hot steeping could cause astringency and was quickly correct that pH is the cause, not temps.

I was reading an article in the September 2016 BYO Be your own beer judge/Decode your homebrew like a pro by Brad Smith of BeerSmith fame. It states “For extract brewers, tannins come from steeping grains in water that is too hot or steeping with too much water”. It goes on to say “For all-grain brewers the most common problem is getting the grain bed too hot during the sparge”. For both it states the temp should be no hotter than 168°.

It does go on to say “You can also extract tannins from an elevated pH (above 6.0), which can happen at the end of the runnings, though this is not very common for homebrew scale systems…”.

I think our original discussion started from the instructions in a kit saying to steep in a very hot temp.

Thoughts?

#2

You can boil the mash as long as you have the correct pH without extracting tannins. I don’t regularly do decoctions, but have done enough to say with confidence that you won’t extract tannins from the grains as long as your pH is in line.

Before I started adjusting my water chemistry, I brewed several astringent beers while mashing at 152F with my straight-up well water. My well water is very high in bicarbonate which pushes the mash pH very high without the addition of acid.

Tannin extraction is both a function of temperature and pH, but in my experience pH has a much bigger impact in that if you control it well enough, temperature is not a factor.

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#3

I can’t argue with real results from experience. I guess my thing was that it was burned into my head over the years not to get the grain too hot or it will come out astringent. I have never had any astringency problems. I have never even tried a decoction mash, too much work for me :wink: Lagers have been done with them for a long time and came out very good though.

So the info in BYO is incorrect or just a good rule of thumb in case the pH level is too high? I wasn’t really defending my position as much as just wanting to know.

#4

No worries, I think it’s a good topic of discussion.

I wouldn’t go so far as to say he’s providing incorrect information. Too hot at too high of a pH will certainly lead to tannin extraction. For an extract brewer, they’re almost certainly not adjusting pH. So knowing their pH is probably too high, it’s good advice to keep the temperatures down. Larger amounts of water will dilute the ability of the grains to lower pH, so it makes it even worse.

But I’m not so sure about his advice on sparging too hot being the cause of astringency. Unless he’s assuming that an all-grain brewer is going to control pH better… I guess my issue with this information is that it’s not giving a complete picture as to what’s happening, with too many possible assumptions buried in there. The real cause is pH getting too high, which can happen at the end of fly sparging or if you sparge hot with water that is not adjusted below pH 6.0. Control your pH in both the mash and sparge, and temperature really isn’t an issue for tannin extraction.

#5

The “old school” thought was keep it at 168° and my PID controlled HLT is set to 170° to this day figuring it will lose a couple degrees on the way. I still use old fashion pH strips. They are hard to read but get me in the ball park and the beer tastes good. That’s what it’s all about!

I haven’t been checking the pH because with the municipal water supply we have it was coming in around 5 anyway but who knows if something has or will change so next batch I will give it a test again.

I do extract brews during the winter when I can’t have all my equipment with me and you are correct PC, I never even thought about testing the pH. Did always steep at lower than 168° though.

That article was very good BTW. It had most off flavors, the cause and solution. Unfortunately it only seems to be in print, not online.

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#6

From the water knowledge tab of Bru’n Water (any spelling errors are my own since I can’t copy/paste from the cell):
“During mashing, a pH greater than 6.0 can leach harsh-tasting silicates, tannins, and polyphenols from the grain into the wort (Briggs et. al., 1981). Adjusting sparge water pH to between 5.5 and 6.0 helps avoid raising the mash pH above 6.0 during sparging.”

#7

Since I built my two burner system with pump and plate chiller I’ve always heated my sparge water to boiling then pumped it through the system for sanitizing. By the time I’m ready to sparge the water has cooled but is generally 180-190F. I alway treat my sparge wtih acid to make sure pH is below 6 and lately more toward 5.2 to adjust my kettle pH, especially with lagers. I’ve never had an astringency issue.

I’ve only done a handful of decoctions and again focused on keeping the pH in range to avoid tannin extraction. YMMV.

Since I started brew just a few years ago I’ve always heard tannin extraction is a function of high pH and not high temp.

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#8

If the ‘steeping’ process involves only crystal malts, then the following may be of interest:

Also, the book Brewing Better Beer has a couple of pages on cold steeping variations for darker crystal malts.

If the ‘steeping’ process also involves grains that need to be mashed, then it may be that applying the guidelines for mashing to the partial mash (water volume, pH, …) will produce better results.

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