Decoction mash questions

[Wild Duk]

Doing my first Double decoction mash in the am. I plan to mash in at 120. Pull 1st decoction, heat to bring the mash to 150, pull 2nd decoction, heat to bring mash to 170.

A few questions:

1. When I pull the 1st decoction, do I need to stop the heat and let it rest at 150 before I bring it to a boil.

2. When I add the 1st decoction back to the mash, how long does it need to rest before I pull the 2nd decoction


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[stpug]

1. Yes, generally speaking, you'll stop at saccharification temp for 20 minutes. Most times the stop is a bit higher though; 154-158, and then to a boil for 10 minutes or so.

2. Generally speaking, about 20 minutes because your next decoction will take you another 35-40 minutes before you're adding back since you'll be stopping in the mid- to upper-150s again for 20 minutes prior to the 10 minute boil.

Again, this is all very general because you can complete decoctions various different ways and at various different temperatures.

Edit:
Read through here. It's probably more than you want to know right now but you'll have a better understanding of the history and process of decoction mashing.
http://braukaiser.com/wiki/index.php?title=Decoction_Mashing

 

[Wild Duk]

Thx for the reply.

After my rest at 150, shouldn't my next temp be the mash out temp??168-170




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[BigEd]

Doing my first Double decoction mash in the am. I plan to mash in at 120. Pull 1st decoction, heat to bring the mash to 150, pull 2nd decoction, heat to bring mash to 170.

Bear in mind that a 20F rise between steps is the ROT with a decoction mash. Considering that and that a rest in the 118-122F range is of little consequence with most malts I'd suggest starting at a higher temp, 128-132F, and then make the jump to your main sugar rest in the vicinity of 150F. At 128-132F you will be at the border of the beta and alpha stages. A short rest there will lessen the likelihood of excessive peptide degradation and will give you a jump on saccharification. It will probably also lessen your frustration in trying to make a 30F+ jump on your first decoction.

 

[BigEd]

Thx for the reply.

After my rest at 150, shouldn't my next temp be the mash out temp??168-170




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Yes.

 

[stpug]

Assuming you're using mostly highly modified malt, I would recommend your dough in at acid rest temperatures (~95F) so that you don't kill the body and head of the beer by sitting at protein rest temperatures (120-130) for too long. Your first decoction will take the longest since you'll need to rest at saccrification temps long enough for conversion and you'll want to get there gently. I suspect the first decoction will take 40-60 minutes to complete fully and if you leave your main mash of highly modified malts at the protein rest temperatures to too long you'll break down the medium length protein that are the main contributors to the body and head retention of the beer. Therefore, dough in at acid rest and you'll be much safer in regards to body/head plus you'll help to acidify your mash and resulting beer.

In regards to your second decoction, I suppose you could go directly from 150 to mash out without a brief pause at dextrinization temps (158-162). The pause would give you a little extra buffer/insurance in case you have not had full conversion but you can easily check for that with the iodine test, or simply forego checking and assume you've had full conversion.

I would personally be much more concerned with the initial dough in temperature with highly modified malts than the second decoction dextrinization pause.

 

[VladOfTrub]

As the brewers mentioned, having an initial dough in mash temp of 120F may not be the best. Protein rest temps are based according to the SNR number or the Kolbach number. The numbers indicate level of malt modification.

Dough in for a mash temp of 95F, like the other brewers recommend.

The 1st decoction should be pulled when the mash is at 5.8 pH. Rest briefly at protein rest temp determined by SNR, before being heated to conversion temp. Conversion temp is based on pH of the mash. Higher the pH, higher the conversion temp. The 1st decoction is used to hit protein rest temp in the main mash.

The 2nd decoction is pulled soon as main mash temp is stable. Without knowing the SNR number, waiting 20 minutes before pulling the 2nd decoction may over extend the protein rest if high modified malt is used. The temp needed is 128F to 130ish for protein rest using high modified. The protein rest is skipped in the 2nd decoction, because the main mash is in the protein rest temp. Conversion temp of the 2nd decoction is in the beta temp range. Usually lower than 148F. The pH determines the conversion temp.

When using high modified, mash pH will stick at pH created in the malt during kilning. Most lager malt will be around 5.8 pH, unless brewing water is real crappy. While the 1st decoction is taking place, check pH of the main mash. If it is stuck at 5.8 add sauer malz half way through the decoction time period. The pH will drop to 5 or a little below after completion of the 1st decoction.

Boil both decoctions until the foam is reduced. This will lessen hot break in the boiler, reduces hard starch, makes fly sparging easier and increases hop utilization. Test for conversion in both decoctions at 10 minutes. If conversion isn't evident, add mash liquid. Conversion will occur quickly when the decoction is thinned. Complete conversion may not take place during a 140-148F beta temp in the 2nd decoction. Wait 20 or 30 minutes, then, boil it up. The 170F rest won't be needed if you boil longer than 10 minutes.

Low modified malt is more suitable for decoction method brewing. Better LHBS carry Weyermann floor malt or Crisp Malting's Euro Pils. Using low modified, a brewer relies less on brewing water pH. The malt is enzymatically richer than standard malt.

 

[Wild Duk]

Would this work

Dough in at 95 Degrees for the acid rest.
Add water to bring mash up to 133 degrees for protein rest

Pull first decoction and bring it up to the saccharification rest of about 150 degrees

Pull Second decoction to bring up to mash out of 168 degrees...

yes? No?

Thx

 

[stpug]

I think keeping your protein rest to a short amount of time is the key here. However you do this is probably fine. I am no decoction expert but I have a decent understanding of the basic necessities and things to keep in mind.

One option similar to your proposal above:
-Dough in at 95F with near-full water:grist ratio; have remaining water on stove at/near boil
-Pull first (thick grist) decoction (give it protein rest, sacc rest, bring to boil)
-When the first decoction is approaching 15 minutes left, add stove water to come up to 133F protein rest for 15 minutes
-Add first decoction to main mash to bring from 133F to amylase rest
-Proceed with second decoction as normal

An alternative would be the enhanced double decoction as outlined by Kai here:
http://braukaiser.com/wiki/index.php?title=Decoction_Mashing#Enhanced_Double_Decoction
This one will take more time but _should_ give the better decoction characteristics without a huge rest in the protein rest range.