The mysterious villian known as tannin

joelabe05 · 05-26-2011, 01:57 AM

So I've been lurking about this board for a couple years, working on making my beer, and knowledge, more refined. I've learned a lot more than I thought I would, but there has been a topic I see referred to quite a bit in several areas of this forum. It's the dreaded tannin extraction when brewing with steeping grains or mashing all grain. Everyone seems to know that tannins make your beer have the "pucker face taste," and many people have theories about pH, temperature, and bag squeezing being the cause.

I've read a little on what tannins actually are, but I've failed to find a definitive answer on how to detect them- in the home brewery environment, anyway. Has anybody looked at the science behind tannin extraction, or is everyone content with mashing at ~150F and mash out at 170F? Does measuring pH during mash out give you an indication of tannin presence? Is there another indicator?

- Background info -
I'm working on my process for BIAB and have been squeezing the @#$! out of the bag at mash out. People say that it's a bad idea, but no one can tell me why. I'm a naturally inquisitive type of person, so the "we do it this way because everyone else does it that way" doesn't really work for me. And no, I haven't encountered any bad astringent flavors in my beers with my current process...yet.

Any thoughts?

**Stevo2569** · 05-26-2011, 02:14 AM

I'm been wondering the same thing. I forget the thread and youtube link but there are several veterans who squezze their grain bags in BIAB and dont mention any tannin extraction. I myself have done Partial and Allgrain with squezzing or pressing with no ill efffects. The Kaiser could definitely answer the question.

rycov · 05-26-2011, 02:23 AM

i think the thought is since you're getting more liquid out of the grains than you would have normally that you could be getting liquid that you don't want. i don't think its really an issue. i don't know, i'm not a scientist, but wtf? why would that extract tannins? i have never done a BIAB, but when i was doing extract with steeping, i squeezed my bag... er, i mean grain bag, and never got any tannins.

BigEd · 05-26-2011, 02:36 AM

The extraction of unwanted tannins from grain requires two conditions: high pH (6+) and high temperature (+180F). They will not be in solution otherwise. Squeezing a grain bag isn't going to release excessive tannins unless those two conditions have been met. However, that doesn't mean it's a good idea as you are going to squeeze out additional compounds (gums, proteins, particulate matter, etc) that would ordinarily be left in the grain that you really don't want in the beer.

rycov · 05-26-2011, 02:40 AM

Quote:

Originally Posted by BigEd

However, that doesn't mean it's a good idea as you are going to squeeze out additional compounds (gums, proteins, particulate matter, etc) that would ordinarily be left in the grain and you really don't want in the beer.

this seems like a better argument for why not to squeeze. again, i don't know anything about it, but its much more logically pleasing.

**Yooper** · 05-26-2011, 02:41 AM

Quote:

Originally Posted by BigEd

The extraction of unwanted tannins from grain requires two conditions: high pH (6+) and high temperature (+180F). They will not be in solution otherwise. Squeezing a grain bag isn't going to release excessive tannins unless those two conditions have been met. However, that doesn't mean it's a good idea as you are going to squeeze out additional compounds (gums, proteins, particulate matter, etc) that would ordinarily be left in the grain and you really don't want in the beer.

I agree. Also, consider that there is some tannin already in the beer, but it's not an "unwanted tannin" level. If you make beer, you should have some tannins in the beer from both the malt and the hops. It's the "excess" tannins that you don't want to extract!

**Malticulous** · 05-26-2011, 03:16 AM

I've found that it has much more to do with pH than anything else.

BigEd · 05-26-2011, 03:24 AM

Quote:

Originally Posted by Malticulous

I've found that it has much more to do with pH than anything else.

Probably true. When I have tasted beer that was tannic it was typically in a brewpub where I suspected the ownership trying to make 7 BBL of beer with 6 BBL worth of ingredients and making up the volume by oversparging.

**ajdelange** · 05-28-2011, 12:43 PM

http://www.beerandloafing.org/hbd/fetch.php?id=40273 should get you started. Steve also wrote an excellent article on the subject for Brewing Techniques. It's not on their website but if you can find a copy of the particular issue it will be worth your while.

There is a simple test for phenols in which they are complexed with ferric ions to give a red color. This is usually read in a photometer for a quantitative determination but I suppose you could use it without to get a qualitative answer the questions like "does squeezing the bag make extraction worse?"

mabrungard · 05-28-2011, 01:33 PM

I know of some commercial breweries that have a mashing system that actually compresses the grist at the end of sparging. So, I don't think that squeezing the grist is a strong cause of tannin extraction. I lean toward temperature, pH, and oversparging as the primary causes.