BIAB and decoction mashing

[Kaz]

I'm looking to brew a Czech Pilsner based on the "Polka Dot Pilsner" recipe in 'Radical Brewing'. I usually do BIAB full volume mashes. This recipe calls for a decoction mash using 1/3 of the of mash volume. My question centers on the volumes. Since I will be mashing with around 8.5 gallons, should I try to pull about 3 gallons of mash off and do the decoction steps or is there a better way? Is the decoction really necessary? I've never tried it before and in the book, Mosher gives an alternative to the decoction using Munich and/or Vienna malts, does that give similar results or would I be missing something? Just not sure how to approach this one. TIA!

 

[GMesick]

I do decoctions when the style calls for them. I have done the full triple decoction, but these days, I am more apt to do a step infusion (adding boiling water to my M/LT) and then a single decoction for mash out (boiling about a third of the mash for 15-30 minutes, then adding it back in before sparging). That way, I don't have to worry so much about hitting my temperature exactly at the end--and it's a bit simpler.

 

[cervid]

I hate bringing back old threads, but has anyone been doing this for certain styles?

 

[Oginme]

I've done it once. Actually, doing BIAB makes it easier to remove just the grains to boil. I lift up the bag just enough to bring some of the grains out of the water then scoop out what I want. I found it a little more difficult to control temperature (mostly because of my small volume brewing), but it was my first time doing a decoction mash and I was working my way through learning a new process...

 

[signpost]

I've done decoction mash BIAB several times. Instead of the general rule of pulling 1/3 of the mash, I've used the estimates from the BrewPal app to figure out how much volume to boil and have come pretty close (within a degree or 2) each time. And I generally do it for my Belgian styles.

 

[Don_Coyote]

I've been having a go at single decoctions w a bag, but can't figure out how decocting for the mash out should work with the sparge/teabag process. Since the mash out is taking care of the temp change, do i just heat the sparge water less and do the drain/teabag process as before? Would it make more sense to do the decoction at an earlier step if the style/malt calls for a rest (bock/Weyerman's Munich)?

 

[azazel1024]

Up to you. A number of blind trials have shown that Decoction mashing provides no noticable difference.

I do it occasionally when it is to style, but I personally do a "full volume" decoction, IE all of the grains at once.

Mash for the length of time that you want, then drain off most of the wort volume and bring the resultant grains and a bit of water (that is a couple of fingers below the top of the grains) to a boil for 15 minutes and done.

Its rather easy for me with my BiaB method as I normally do a 60% volume mash in my main 6 gallon pot and a 40% volume soak in my 5 gallon pot after 60 minutes, for 10-15 minutes.

So when I do a decoction, I do the regular mash in the main pot, I then dump the grains from the grain bag in to the 5 gallon pot with only 20% volume in that pot (and 80% in the main pot instead of my usual 60/40). That is generally enough to keep the water below the level of the grains enough that I should be getting good malliard reactions going on.

In theory. I certainly get some nice sludgy goodness at the bottom of the pot that I have to scrape off even with vigorous stiring.

I frankly don't trust doing this with the grains still in the bag. Once I am done I just dump it all back in to the main pot and strain with the bag still in the main pot.

 

[Siberian]

My wife and I (she did the decoction, I watched... ) did one triple decoction for a historic gruit that we brewed. Gruit turned out great, decoction... I might never do a triple again.

We used my RIMS to manage the step temperatures post adding the decoction so it was more about getting the flavors by removing a thick part of the mash and boiling it then temp raises.

I think there is a value in a single decoction for flavor, but after that... if you can just step mash with re circulation or something.

 

[dcuccia]

I do it occasionally when it is to style, but I personally do a "full volume" decoction, IE all of the grains at once.

Mash for the length of time that you want, then drain off most of the wort volume and bring the resultant grains and a bit of water (that is a couple of fingers below the top of the grains) to a boil for 15 minutes and done.

Its rather easy for me with my BiaB method as I normally do a 60% volume mash in my main 6 gallon pot and a 40% volume soak in my 5 gallon pot after 60 minutes, for 10-15 minutes.

So when I do a decoction, I do the regular mash in the main pot, I then dump the grains from the grain bag in to the 5 gallon pot with only 20% volume in that pot (and 80% in the main pot instead of my usual 60/40). That is generally enough to keep the water below the level of the grains enough that I should be getting good malliard reactions going on.

Necro-post, but I found this comment very interesting. If I understand correctly, this is exactly what I had in mind. With BIAB, some kind of false bottom, and well-modified grains, there's no reason (beyond tradition) that one couldn't step mash all the way to boiling for the mash out. Presumably, the mash is already stable at a good pH where you wouldn't worry about too much tannin extraction at higher temps. And with well-modified grains, the argument that decoction makes available more fermentables is fairly moo (like a cow said it...doesn't matter). The only clarification here I'd wonder is how much liquid removal (if any at all) is necessary to guarantee those malliard reactions?

 

[JohnSand]

I don't know. But I'm drinking a batch of IIPA that is darker than usual. Checking my notes reminded me that I brewed outside on a cold day. My mash temp fell, I pulled some out and boiled it in the kettle, adding enough back to reach my target. But as I was adding and stirring, the wort in the kettle was boiling faster and darkening. It's an unintentional decoction, and it definitely made a difference.

 

[dcuccia]

It's an unintentional decoction, and it definitely made a difference.

Unintentional Decoction sounds like a great name for either a song or an episode of Hannibal.

 

[jerrylotto]

I was toying with the idea of dividing the grain up into three bags. First step: mash at 142F all three bags in strike volume. Heat a sparge volume of water to 155F in a different pot and then move one of the three bags over to it. After 15 min, boil bag 1 in sparge volume for 30 minutes, then move the bag back to the strike container raising the mash temperature to 147F for the next step. Cool the sparge water back to 155F and repeat the process with bag number two ending up with all three bags in the strike at 153F for 30 min+. Heat the sparge water up to 170F and move all three bags over to mash out, then drain the bags and combine the sparge liquor with the original mash.

 

[jerrylotto]

Strike that last post. I hadn't considered the purpose of decoction in promoting Malliard reactions by concentrating the sugars in the presence of amino acids. Of course this is the main impact this technique has for producing flavor, and diluting the decoction in sparge water would contradict this.