Raising mash temp with "decoction"?

Quick question: If I am low on my initial temp at dough-in can I draw off some liquid, heat it to a boil and stir it back into the mash tun? Would the high temp of the small decoction cause denaturing of enzymes or tannin extraction? I'd rather do it this way than adding extra boiling water since that would throw off my water/grist ratio. Thanks!

A decoction is boiling a portion of the entire mash (grains and liquid), not just the liquid.

It won't result in tannin extraction because the pH will stay low. It will denature the enzymes in that portion of the mash, but it shouldn't be a problem.

zachattack said:

A decoction is boiling a portion of the entire mash (grains and liquid), not just the liquid.

It won't result in tannin extraction because the pH will stay low. It will denature the enzymes in that portion of the mash, but it shouldn't be a problem.

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Right, so if I remove and boil about 2 quarts (of liquid only) to get the grain bed up to temp it shouldn't negatively affect my overall efficiency?

Would this method be preferable or should I just add extra boiling water?

You should be OK. There are enzymes left behind. The standard practice is to do a "thick" decoction, though, and save the "thin" decoction for mash-out, when stopping the enzyme activity is kind of the point. But you can always boost your temp with a decoction. That's what they are for, and when you don't have room for more water, it's a great approach.

"Step infusions" (adding boiling water) are your other option, though, if you have room in your mash tun. I've done both decoction and infusion. They both work.

I've usually done step infusions, so i have a pretty good idea of how much boiling water I need to add to raise temps to my target. My last batch, an Irish Red, just for fun and practice I did a decoction. Knowing I was going to do it, I started with more strike water than usual. It wasn't difficult and really didn't add much time to the brewing day(only did 1 decoction).
So, yes it can be done. My reading about decoction indicated that no you don't have to worry about tannin extraction(after all regular decocters don't produce tanniny beer). My efficiency was good(don't have my notebook here but it was at least as good as my usual infusion mashes). So, long winded answer= go for it. Good Luck and Good Brew!

So it sounds like this would work fine for my situation. To be clear, I'm doing a single infusion mash with one rest and just want to be able to raise the temp (assuming I'm low at dough-in) without adding extra water.

And out of curiosity, what do you mean by "thick" and "thin" decoctions? Thick being with grains and thin just liquid?

thanks

BassBeer said:

And out of curiosity, what do you mean by "thick" and "thin" decoctions? Thick being with grains and thin just liquid?

thanks

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Right. "Thick" means grain with enough liquid to keep it from scorching; "thin" means just the liquid with a few stray grains in there.

And no problem doing it with a single infusion. It's a remedy that some of the literature recommends.

I do decoction mashes all the time and frequently use a decoction to either add heat to the mash because I missed my intended target temp or to raise the mash to the next rest temp. Here is the formula for determining the qty to extract and boil.

(TT-CT)*(AG*(0.3125+R))/(212 - CT)

TT = Target Temp (F)
CT = Current Temp (F)
AG = Amount of Grain in Mash (LB)
R = Ratio of Grain to Water (quarts)

212 = boiling point of water
0.3125 thermodynamic constant

The answer will be in quarts round it up to whole quarts and should consist of mostly grain and only enough liquid to keep from scorching. Stir the decoction constantly and let it boil for 5 minutes or more. Pour it back in slowly and then mix it thoroughly before testing the temp.

Good Luck!

You don't want to pull just liquid for the decoction! You can do that for mash out, but not for saccrification rests.

You can either infuse boiling water to hit your mash temp, or decoct the thickest portion of the mash.

What I usually do is plan for a thick mash, and have an electric kettle ready with boiling water. That way if I miscalculated, I already have the boiling water ready to go, and I do not end up with an overly thin mash.

Trying to draw off a portion of the mash when you weren't planning on a decoction is just a pain.

Yooper said:

You don't want to pull just liquid for the decoction! You can do that for mash out, but not for saccrification rests.

You can either infuse boiling water to hit your mash temp, or decoct the thickest portion of the mash.

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I don't see why not, the diastatic power in most base malts is so high that adjusting the temp like this isn't going to affect your ability to convert. Now I don't know why you wouldn't pull the thick decoction (expose even more starch granules, take your time to get an alpha rest in at ~160, get a little melanoidin/maillard production on longer boils) if you're going to go to the hassle of pulling one in the first place.

It's more important to not pull a thick decoction for mash out because you'll have liberated lots of long starch molecules that can't be broken down anymore and make your beer hazy. I don't know of any reason that a thin decoction early would be bad unless you're doing like a 100% munich batch.

if you miss your target temp its going to take you extra time to get your decoction to a boil - much easier to have boiling water on hand in case your strike temp is low IMO

terrapinj said:

if you miss your target temp its going to take you extra time to get your decoction to a boil - much easier to have boiling water on hand in case your strike temp is low IMO

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Don't think this would be a viable alternative if the mash tun is near capacity.

I had a temp issue with my White House Honey Porter and chose to do an "emergency decoction" just like the op stated. Pulled a thick decoction and only boiled for about 5 minutes and returned to the mash and the temp held afterwards. It worked really well and I wouldn't hesitate to do it again.

TrubHead said:

Don't think this would be a viable alternative if the mash tun is near capacity.

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Obviously if there isn't any more capacity in the mash tun you would have to pull off some wort/mash and heat it separately.

I don't think anyone meant to fill it beyond capacity lol. That would be funny to see though.

BrewinHooligan said:

I had a temp issue with my White House Honey Porter and chose to do an "emergency decoction" just like the op stated. Pulled a thick decoction and only boiled for about 5 minutes and returned to the mash and the temp held afterwards. It worked really well and I wouldn't hesitate to do it again.

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Also had an "emergency decoction" last brewing. Fortunately had read up on decoction mashing recently and didn't hesitate to give it a go. Will see/taste the results in a few weeks.