Double decoction that should be equal to a tripple

[Kaiser]

I came across this in a german brewing text book and found it very interesting for the home brewer as well. It's one of the ways you can conduct a double decoction. I used it for my Doppelbock last Sunday.

Dough in a little below 40C and rest for about 15-20 min. A rest at that temp will get your enzymes into solution and help the beta glucan degradation. The latter is of little importance for modern malts. Then you pull enough mash to raise the mash temp all the way to the connversion rest (and a little more). This should be about 50% - 60% of your mash. Pull this as a thick mash, but not to thick (see my other posts on decoction ).

Start heating this mash. Since this is a substantial portion of the mash you may want to rest it at 50C for 20-30 min (lower modified malts) or 55C 10-15min (higher modifiesd mats) and then continue heating to the conversion rest at 70C - 72C. Best done by taking the pot off the burner, putting the lid on and wrapping in blankets. I prefer this rest more than the low 60s like Dr. Scot mentioned because the majority of the conversion is done in 15 min and the maltose can easily formed from the dextrines throgh the betas once the decoction has been mixed in with the rest of the mash. Once the conversion is done heat again and bring it to a boil. Now boil for 10 - 15 min before you combine part of this mash with the main mash to reach the protein rest at 50-55C. Hold this rest for 10-30 min while you keep boiling the rest of the decoction.

Then use the remaining decoction to get the mash to the saccrification rest. A rest around 65C should give you best results. After 45min the mash should have converted and you can pull the 2nd decoction to raise its temp to mash-out at 75C.

The advantage of this decoction scheme is, that you can keep the protein rest short, which might be benefitial for modern malts, while still boiling as much mash as you would for a tripple decoction.

Kai

[Ozbrewer]

Thats very interesting especialy being able to drop the 55 deg rest time down,


but hows this, i had a fit of A.D.D the other night and some crazy ass thoughts come to mind, hows this, now when were decocting the enzymes are coming out of solution, and not being boiled, well for most of them anyway, so why are we bothering holding the decoction at sacc temps prior to boiling, its a great Idea, or are we as the Doc would say, spinning our tires, during the decoction, as i understand, the starch is being exploded ready to be converted into the sweet stuff, so if we take out a thick perportion, then bring straight to boil, bringing the temp up to what ever then let the enzymes work on it all, are we not doing the same thing anyway???????


Am i a genius, or jsut a fat ass Ozzie with no idea, and nothing better to do?

[Kaiser]

Oz,

I don't think that there is much harm in not converting the decoction as long as you have malt with hight enzymatic strength (lighter malts like pale and pilsner). And many home brewers may already do it like this.
But the saccrification may actually produce sugars that then undergo changes during the boil. Converting the decoction will also help your attenuation as the beta amylase will have so many more ends to work on once you put the decoction back to the main mash.

Kai

[Speyedr]

Converting the decoction will also help your attenuation as the beta amylase will have so many more ends to work on once you put the decoction back to the main mash.

But are we achieving conversion in the decoction with so few enzymes present? I think what OZ is saying is that we may not be doing much of anything with such a thick mash and a 15 -20min. rest? So, can the same thing be achieved by just bringing the whole thing directly to a boil (it will pass through these temps anyway along the way) and skipping the rests? Is there such a thing as a Pragmatic DOUBLE Decoction, and did you two just invent it??

[Kaiser]

The sources I read so far suggest a conversion of the deoction because some of the enzymes are denatured and you wanted to harness their power before they are gone. Given the high enzymatic content of pilsner malt, that might not be necessary and you could be pragmatic by simply bringing it to a boil.

When I take an iodine test after resting the decoction at 70-72C for 10-15min I still get a slight reaction, but the majority of the conversion is done. I also don't keep my decoctions as thick as Doc and Oz suggested.

Kai