Is Boiling Grains Really So Bad?

Everyone is always saying don't boil the grains, Alton Brown's beer will taste like sh*t since he boiled the grains, don't sparge too hot or you extract tannins, etc. Seems like a pretty hard and fast rule. But then why doesn't it have a negative effect when you do a decoction mash? It seems that in a decoction mash, boiling the grains is actually said to add wonderful complex malt flavors unobtainable otherwise. I did my first decoction mash today and I've gotta tell you, it felt very unnatural boiling the grains after all of the talk against it here. So what's the difference?

Found this from BYO:

The (in)famous decoction mash is frequently recommended when a brewer is in search of more malt flavor. Decoction mashes boil malt and — among analytical brewers who are not afraid of rocking the boat with unpopular ideas — are known to increase the astringent character associated with tannins.

Click to expand...

I guess it's a matter of taste, but if your trying to stay within style guidelines I'm not sure what if any style you'd be brewing.

I had the same reservations when I decocted the first time. RDWHAHB

Before I learned more about recommended technique, I did make three or four grain with extract batches where I left the grains in for the whole boil. I was always happy with the results.

Speaking of the Alton Brown episode, I also did use the "buy a few bags of ice" cooling method in the same batches.

Kaiser has written much more intelligent explanations that I can give (and it's definitely worth a read!) but the gist of it is that there is a difference between boiling specialty grains and decoction mashing. First, when decocting, the grains have already been converted and it's recommend to hold them at a saccrification rest before boiling and adding back to the mash. The other issue is ph. Since you're decocting from a mash, the ph is 5.2-5.4-ish. If you were just boiling specialty grains, the ph would be much higher, allowing tannin extraction. When you do a decoction, you pull from the thickest part of the mash.

Some info: BYO - Aren't tannins a problem when you boil part of your mash during a decoction?
SBC: Decoction Mashing, Part 1

yooper, thanks for the links. i have a better idea now of what's actually going on in the decoction. it does get me interested to try two beers brewed with identical ingredients side-by-side, but with one decoction mashed and the other step-mashed. should make for a very interesting comparison.

The difference is understanding and being able to make an educated decision.

KingBrianI said:

Everyone is always saying don't boil the grains, Alton Brown's beer will taste like sh*t since he boiled the grains, don't sparge too hot or you extract tannins, etc. Seems like a pretty hard and fast rule. But then why doesn't it have a negative effect when you do a decoction mash? It seems that in a decoction mash, boiling the grains is actually said to add wonderful complex malt flavors unobtainable otherwise. I did my first decoction mash today and I've gotta tell you, it felt very unnatural boiling the grains after all of the talk against it here. So what's the difference?

Click to expand...

IMO the answer to this question should be in every brewing forum FAQ. I've lost count how many times I have answered it over the years. So here it is: A decoction boil is done with a thick portion of the mash at low mash pH (~5.2). The dreaded tannin extraction has two requirements, high temperature and higher than mash pH (6 and above). The boiling temperature alone does not extract unwanted tannins hence decoction mashing does not create tannin problems. Boiling steeping grains in a large volume of water, however, can create the conditions of higher temperature and pH6+ that will extract excess tannins.

BigEd said:

IMO the answer to this question should be in every brewing forum FAQ. I've lost count how many times I have answered it over the years. So here it is: A decoction boil is done with a thick portion of the mash at low mash pH (~5.2). The dreaded tannin extraction has two requirements, high temperature and higher than mash pH (6 and above). The boiling temperature alone does not extract unwanted tannins hence decoction mashing does not create tannin problems. Boiling steeping grains in a large volume of water, however, can create the conditions of higher temperature and pH6+ that will extract excess tannins.

Click to expand...

so then i can batch sparge with water at whatever temperature i want, including boiling water, so long as the water is treated with fivestar 5.2 stabilizer? that might increase efficiency!

BigEd said:

IMO the answer to this question should be in every brewing forum FAQ. I've lost count how many times I have answered it over the years. So here it is: A decoction boil is done with a thick portion of the mash at low mash pH (~5.2). The dreaded tannin extraction has two requirements, high temperature and higher than mash pH (6 and above). The boiling temperature alone does not extract unwanted tannins hence decoction mashing does not create tannin problems. Boiling steeping grains in a large volume of water, however, can create the conditions of higher temperature and pH6+ that will extract excess tannins.

Click to expand...

Hmmm... Is this true? Does it take high PH and high temperature to extract tannins?

I was curious because I was doing an AG this past weekend and I added a quart boiling water to bring up the mash temperature. Unfortunately, I got distracted and it was about a minute before I stirred the mash.

Pretty sure the mash was below 6 thanks to the PH stabilizer.