astringent

I just got back my score sheets from the Michigan beer cup. A couple of comments about my chocolate milk stout were the fact that it was astringent. I did enter for the feedback but what would cause that? I don't taste it myself and others love this beer. Is it the mash or sparge that would contribute this off flavor? Thanks and cheers!

The most common cause of astringency is alkaline sparge water. Try using RO or distilled sparge water. When I did this, the difference was huge.

If your water is too alkaline, the sparge pH gets too high and extracts tannins from the grain. 6.0 is the generally accepted cutoff. Do you have a water report? How about measuring pH?

I didn’t notice astringency in my pales, but when I did the RO sparge, the old ones became hard to drink. When you compare beers the difference really jumps out. This is, of course, what the judges do.

I'll get some ph stabilizer and try that. I just use Detroit city water. No idea as to the composition of it.

No No, that stuff doesn’t work. There’s been a lot of discussion about that.

I’m sticking with my RO recommendation. If you don’t have a water report it will be tough to guess on an acid addition.

The solution to pollution is dilution.

What about filtering my water? I don't want to buy gallons of water.

Ooh Ooh! I just found this:

https://www.homebrewtalk.com/f128/detroit-water-analysis-thoughts-226200

Great information from a real expert.

Filtering will not reduce alkalinity. The mineral content of the water is not affected. Carbon or charcoal filters are described as CTO for Chlorine Taste Odor. Definitely a good idea, but it won’t do anything to your astingency.

Detroit water is good stuff.
You'd probably be fine just adding a little acid (phosphoric or lactic) to the sparge water to lower the ph to 5.5 or so.
That and keep your sparge temp below 170.
+1 on avoiding ph stabilizer. Junk IMHO.

I'm going to try a lower sparge temp in the future. The crazy thing is that I don't taste the astringent qualities in my beer.

LouBrew13 said:

I'm going to try a lower sparge temp in the future. The crazy thing is that I don't taste the astringent qualities in my beer.

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How low do you intend to go? I do modified BIAB and my sparge water is cold. I measured the results and decided to keep doing it this way because my efficiency was 85%. No chance of getting astringency with cold water but it still dissolves the sugars pretty well.

That would save on propane having to heat the sparge water. And you still get good efficiency?

Sparging is rinsing the remaining sugars out of your grains after mashing and draining the mash tun. Sugars dissolve faster in hot water so using cold water isn't quite as good but I doubt your efficiency will suffer a lot. However, the real cause of astringency is leaching tannin which is related to high pH and higher temperatures leach it faster. Beg, borrow, or buy a pH meter so you can find out what your pH really is and correct any fault there first, then sparge with cooler water.

I would also take into consideration the age of the beer and the grain bill. You said it was a stout and depending on how much chocolate/black malt was used and how long it was aged, those grains will come across as astringent.

What was the OG? If it was on the lower end, then you will typically be using more sparge water and then the PH becomes a bigger issue. You can also pick this up if your efficiency is on the high end.

Lots of little things but the feedback is good and will help you develop better brewing practices.

Bull

It is a sweet stout and not that old. The weird thing is that I never tasted any astringent qualities. But I'm going to lower my sparge temp in the future.

LouBrew13 said:

It is a sweet stout and not that old. The weird thing is that I never tasted any astringent qualities. But I'm going to lower my sparge temp in the future.

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I'd suggest buying some RO water just once for the sparging, and see if it fixes the issue. (It will). If you can't taste the difference, though, you may not want to spend the money or the effort to do it.

I'd definitely either use RO water for sparging, or acidify the sparge water with some phosphoric or lactic acid and not worry about the temperature so much. If you're not sparging above 170, sparging with cooler water won't make much, if any, difference anyway. It's more than likely the alkalinity of the sparge water and not the temperature that is causing the astringency.

Another thing to consider is mash pH. If you're not checking mash pH, some of the astringency could be coming from there. It's not likely in a stout that your mash pH was too high, or at least by much, if your water is a bit alkaline but mash pH is important.

RM-MN said:

No chance of getting astringency with cold water but it still dissolves the sugars pretty well.

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The extraction of tannins, causing astringency, is more about pH during the sparge than the temperature, so I rather doubt cold sparging necessarily removes the chance of tannins being extracted.

EDIT: Nevermind, I guess you rephrased your opinion above.

I agree that sparging is a likely culprit in this case. The Detroit water is just a little too alkaline and could be a contributor to tannin extraction. As Yooper mentions, using RO water for sparging is a good way to reduce tannin extraction potential. But looking at the Detroit water report, it appears that minor acidification of the tap water could reduce the alkalinity of that water to more modest level to make it more suitable for sparging. I recommend bringing sparge water alkalinity down to around 20 ppm to reduce tannin extraction potential.

RO water alkalinity is less than that and is quite suitable for use. The problem with RO is that you need to add ions back to make the water more suitable for brewing use, but that is fairly easy.

Bru'n Water has a tool for calculating what the acid dosage is for reducing sparge water alkalinity to proper limit.

I won't discount the possibility that the modest alkalinity of the tap water could also have had an influence in the flavor problems. The OP mentioned that this was a stout. The tap water alkalinity might be a little low for that grist, so its possible that some of the flavor impacts rose from that. I tend to doubt that this problem would be great enough to cause significant impact, but its possible. Again, Bru'n Water allows a brewer to assess this possibility with a little greater accuracy than guessing. A better bet would be to check the mash pH to assure that it did not fall too low.

If all else fails try doing a test with two small batches. Put a healthy dose of Polyclar in one and see if that reduces the astringent taste (tannins ?).

Only my 2 cents.

bosco

A few questions to add to this. When you talk about testing your PH do you mean testing the water in the kettle before you add it to the grains or after it is added to the grains and its running off? Do lighter beers tend to show more of this astringent taste? Does batch sparging make a difference in this? I had a batch that I think has this problem.

You want to know the pH of the mash, generally twenty minutes or more into the mash. Most people shoot for 5.4 - 5.6. Lighter beers are less acidic and will show astringency more than beers with darker more acidic malts.

Batch sparging is said to be less of a problem with astringency, I’ve never done it. The idea is that the pH could go high (6 or more) at the end on a continuous (fly) sparge but the batch will balance out.

Great questions.

I prefer to check mash pH within 10 minutes since most of the enzymatic reactions and conversion are complete in about 15 minutes. Checking pH after 20 minutes is like closing the barn door after the horse is gone. The problem I keep hearing is with brewers that use acid malt. It takes a little longer for it to react, whereas a dose of liquid acid is at work instantly.

The Mash, is normally not the problem with astringency. The mash pH is most important because it presents the scenario of "is the pH sufficient for your enzymes to break the starches." This is not astringency, and usually the mash pH with today's modified malts is sufficient.. However, as we sparge, the pH tends to rise above those acceptable levels. Of course, as we sparge we do pick up the sugars AND the enzymes that cause the lower mash pH, and the darker roasted malts do provide for a lower pH. Do remember, that pH should be tested at room temperature, not 150*.