Decoction Woes

[Kevnlis]

OK, I have long been planning to do my first decoction mash. I have done a fair bit of reading on the subject (wish I had Papazian's book...) and I have a few questions. First off the mash profile in Beersmith is very confusing.

Decoction Mash, Triple, Lager Step Time Name Description Step Temp
15 min Dough-In Add 9.39 L of water at 21.1 C 21.1 C
20 min Acid Rest Add 6.52 L of water at 74.2 C 40.6 C
10 min Protein Rest Decoct 3.05 L of mash and boil it 50.0 C
20 min Dextrinization Rest Decoct 7.03 L of mash and boil it 68.3 C
5 min Mash Out Decoct 5.04 L of mash and boil it 76.7 C



Mash Notes: Derived from Noonan, "New Brewing Lager Beer". A pure infusion/decoction mash with no temperature steps. The book recommends adding boiling water for the second step, though it appears it would come in too high in temperature.
The first two decoctions are from the "heaviest" part of mash while the third is from the "thinnest".
He also recommends you hold Dextrinization until it passes an iodine test (probably more than 20 minutes)

The 15 minute dough in I understand, that is to hydrate the grist before it is taken for decoction. Then after 15 minutes of hydrating the grain I add 6.52L of 74.2C water to hit the Acid Rest temp, and this is where I get fuzzy. It says to rest at this temp for 20 minutes, have I already taken the grist and begun the boil? Do I wait until the end of this rest and then decoct and boil for 10 minutes as it seems to suggest? Also these rests and boil times seem to be a bit far fetched in being possible, not to mention going against everything I have read which suggests boiling the grist for a minimum of 30-45 minutes. Beersmith even contradicts itself by telling me to do a 20 minute Dextrinization Rest, then going on to tell me that Noonan recommends holding it until and iodine test passes and that it is "probably more than 20 minutes"?

Further I wonder how you skim "protein scum" from the top of a boil that has no standing water? I have not done it, so the answer to that may be obvious, but in my head if the boiling mash is so thick that there is no free water how will it get a layer of scum at the top of it? I plan to do the boiling in a 13L stockpot on a three ring burner. Would the three ring be too hot and scorch the grain? Maybe if I just use the two inner rings?

I realise this is a very long post but I appreciate anyone taking the time to clear this up for me!

[warra48]

I haven't done a decoction mash myself, but it is my understanding that the decoction is taken from your main mash, raised to the rest temperature for the specified period, then brought to the boil for 5 minutes or so, before adding back into your main mash.
As odd as it sounds, AFAIK it doesn't add tannins (polyphenols?) to your mash.
Adding the boiled volume back to your main mash will obviously also help to raise your main mash to the next rest temperature.
The decoctions are not the boil you do at the end of your total mash, and obviously are only an interim short boil of a portion of your mash schedule.
It will mean you end up with a long period of mashing, compared to a single or even double temperature infusion mash.
Some will say that with todays fully modified malts there is no need to do decoction mashing, and that adding some melanoidin will achieve much the same thing in terms of final flavour etc. I don't know about that, and if you want to experiment, then go ahead. I'd be interested in the results. As I understand it, it was a process used by German/Bavarian brewers in the early days, because their malts were not fully modified, and this was one way of dealing with the shortcomings of their malts to ensure full conversion. Malts we use today are pretty much fully modified.
I'm open to correction by others more knowledgeable and skilful than I am, but hope it helps in some way.

[Kevnlis]

Thanks for the input warra!

The reason tannins are not extracted is that the grist is so thick that the polyphenols are not soluble in the highly concentrated solution, also the proteins are broken down and congealed at the surface of the boil (so they say). Even with the highly modified malts and spec grains it is said that a triple decoction is still the only way to achieve the rich malty flavours in a Bo Pils (which happens to be the beer I am trying to do). It is true that early brewers did it to make up for the quality of malt they were using, also because thermometers were not available and it was easier to experiment with decoctions than to work out what volume of boiling water should be added to reach the next rest. I believe it still has its place in modern brewing and I can see how many styles could benefit from it.

You do raise one more question though, should the grist be brought to and rested at the next temp step before being brought to the boil? If so how do you calculate times etc.

I am willing to put in the time if I can figure out what to do, I think it will be worth it in the end

[Ed]

Kev, mash thick, pull around 40% of the thickest part of the mash for the decoctions, and stir like crazy while heating. Use the stove top if you can or just use 1 ring on low. Also, forget Beersmith for setting out a decoction, I saw a printout for a decoction and it made absolutely no sense to me.

Take each decoction slowly up to around 68 to 70C and hold there for 10 minutes before then ramping quickly to boiling. Hold at boiling for around 5 to 15 minutes before returning to the main mash to get your next step. For the first time it might be best not to add all the decocted part back at once, add most and then check the temp, add the rest if under, or wait for it to cool a little so you don't overstep the mark. If under, you could always pull another quick decoction and take straight to boil, but I find around 40% hits the mark by the time transferring and carefully mixing back in is done.

You should get pretty quick conversion during the saccrification rest. 15 to 30 minites should do it, but test with iodine if unsure.

The protein break is occurring in the process and there won't be anything to skim.

Hope that helps?

Cheers, Ed

[Kevnlis]

Hey Ed, long time no see! Thanks for the reply. I found a nice little document that has a formula for calculating the decoction volume and I think I will make my own steps using that. If anyone is interested it can be found at:

http://www.strandbrewers.org/techinfo/decoct1.htm

and

http://www.strandbrewers.org/techinfo/decoct2.htm

for the formula.

I now have a more technical question. How do I calculate "K" or "temperature loss constant"?

[Kevnlis]

Here are my thoughts for my first go:

Strike for 53C using a ratio of 2.5L/kg rest 30 min
Decoct 1/3 of mash and slowly heat to 65C, rest 20 min then boil 20 min
Add back to mash with target of 63C rest 30 min
Decoct 1/3 of mash and boil 20 min
Add back to mash with target of 72C rest for 45 min
Decoct 1/3 of mash and boil for 5 min
Add back to mash with target of 78C for mash out

This will make about 3 hours of mash time

I will let you all know how I go.

[brew.exe]

Good luck with it Kevnlis
Be interesting to know if all the extra work makes a big difference.

[Trough Lolly]

Here are my thoughts for my first go:

Strike for 53C using a ratio of 2.5L/kg rest 30 min
Decoct 1/3 of mash and slowly heat to 65C, rest 20 min then boil 20 min
Add back to mash with target of 63C rest 30 min
Decoct 1/3 of mash and boil 20 min
Add back to mash with target of 72C rest for 45 min
Decoct 1/3 of mash and boil for 5 min
Add back to mash with target of 78C for mash out

This will make about 3 hours of mash time

I will let you all know how I go.

Sorry, been away - but your pulls from the mash and boil times are roughly in line with my calcs. I tend to prefer 2.3L per kg of mash but there you go...

Cheers
TL

[Kevnlis]

Thanks TL, glad to know I am not far off! I have a few brews lined up in the near future to use this process on. It will be interesting to see how it goes, and I may use the same recipes with a single infusion just to compare the results.

[Trough Lolly]

Triple decoctions take all grain brewing to a new level....but so does adding 700g of Weyermann melanoidin malt!

Cheers,
TL

[Kevnlis]

Triple decoctions take all grain brewing to a new level....but so does adding 700g of Weyermann melanoidin malt!

Cheers,
TL

I have done 500g and still did not find it got to where it should have. I am very eager to have a go now that I know how and will surely report back as soon as I have tasted the result. Though that is sure to be months from now since it is a pilsner I am doing first up.

[Ed]

Kev, just a couple of suggestions from what I've experienced: You may want to pull a bit more than the 1/3 out for the decoction. Unless you can maintain the main mash exactly at each step and your transfer is is done with minimal heat loss, you could easily find yourself falling short of the expected rest temp. I know 1/3 is about right from calculations, but in practice I find you end up needing more, plus it's difficult to exactly judge the correct amount until you've done a few.

Also, I would suggest a shorter time for the protein rest and subsequent decoction. You can start to pull that first lot out 5 to 10 minutes after hitting the temp. The rest for the decocted part at 65C really just needs to sit for about 10 minutes because after you've boiled it, it will be returned back to the main mash.

Triple decoctions take all grain brewing to a new level....but so does adding 700g of Weyermann melanoidin malt!

Cheers,
TL

TL, do you find you get the same rich development with the Melanoidin as with the decoction? I have some sitting there but so far haven't used it as a substitute.

Cheers, Ed

[Kevnlis]

Thanks again Ed. I usually lose 1C or less over a 1 hour mash. The longest the tun will be without an addition is about 1 hour so it should not be a big deal. I will be doing the boil just inches from the mash tun, so I will lose less heat when I transfer the decoction back to the mash tun. Should even itself out in the end.

Strike for 53C using a 12.50L rest 5 min
Decoct 5L of thick mash and slowly heat to 65C, rest 10 min then boil 20 min
Add back to mash with target of 63C rest 30 min
Decoct 5L of thick mash and boil 20 min
Add back to mash with target of 72C rest for 45 min
Decoct 3.5L of thin mash and boil for 5 min
Add back to mash with target of 78C for mash out