# Biab And Decoction Mashing



## felten (6/5/10)

I run a BIAB system, and I was planning on making a Baltic porter for my next brew (ala the Jamil show) it uses roughly 58% Munich I, 34% pilsner and 8% of specialty malts (I'm planning to use mostly Weyermann). 

So I'm looking at the different grains available and the Weyermann floor-malted bohemian pilsner malt sounds drool worthy. :icon_drool2: Has anyone used it before? There isn't much info on it via google but from what I've gathered it is under modified and could do with some kind of a stepped mash. 



Decoction sounds like fun, right, so I thought maybe dough in at 50c for a protein rest, raise the temp with my burner to 66c, then single decoct to 75c for a mashout. I'm not sure how I'd handle carrying 1/3rd of a full 44 litre BIAB mash inside to use the stove, then back at to the garage at boiling temps, but that's another problem altogether.



Am I cruising for a bruising? Should I just go for a direct heated step infusion? or should I save myself the trouble altogether and go with their standard well modified pilsner malt? 


I'm reading braukaiser's article on decoction as I type this. Anyway there it is, any comments on BIAB decoction or anything else welcome.


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## Wolfy (6/5/10)

I'm no expert on decoctions but one of the main reasons they were 'invented' was because there was no way to do step mashes because of the materials and technology available at the time.
Given that you are BIABing that - to me - seems like an ideal scenario for a step-mash without the need for a decoction at all, other than 'fun' is there any specific reason for the decoction?

The other thing to keep in mind is that often the decoction uses the 'thick' portion of the mash - mostly grains - so you'd need remove a mostly grain portion of your mash, boil it, return it to the bag and then mix well to distribute the added heat - the logistics of which may be difficult.
Having said that, I've just been reading 'Designing Great Beers' and it's mentioned that sometimes the last decoction is made from only the 'thin' portion of the mash, so if you wanted to do that, it should be fairly easy to drain just the liquid-wort portion.

Something else to consider, is that since you have the flexibility of a burner under your mash, have you considered doughing in at 35-40 for an acid rest before the protein rest?


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## katzke (6/5/10)

BIAB and decoction work as well as any other mash method.

A couple of different ways to do it. All require a second vessel. It can be as simple as a pot from the kitchen. Just needs to be sized to fit about a third of your grain.

You can lift the bag a bit to raise the grain to the surface. Then scoop out with a soup ladle or measuring cup. You can dip with one of the strainers that has a handle. Or come up with any suitable way with what you have in the house.

You take mostly grain and enough wort to keep from scorching the mixture. It will be kind of like half cooked rice or oatmeal. Needs to be wet but not thin like soup.

It is best to keep an eye on it so you do not burn any of the grain. Not constant stirring, more like occasional or frequent stirring.

Did it once so I am an expert, right?


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## Sammus (6/5/10)

Wolfy said:


> I'm no expert on decoctions but one of the main reasons they were 'invented' was because there was no way to do step mashes because of the materials and technology available at the time.
> Given that you are BIABing that - to me - seems like an ideal scenario for a step-mash without the need for a decoction at all, other than 'fun' is there any specific reason for the decoction?



Aren't decoctions all about melanoidins and yummy malty grain flavours that you cant get elsewhere?


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## RdeVjun (6/5/10)

Yes, BIAB and decoctions are indeed possible and quite simple. If you're worried about shifting the whole kettle, then don't, there's no need to, just remove the portion to decoct to another pot and put that on the heat source. In your case with Wey BP, I would actually do a protein rest, decoction (with a 4kg grain BIAB, about 4 or 5kg of the thick mash, leave as much liquid in the tun as you can and don't stop stirring the decoction) to get up to saccharification then decoct again to mashout if you really want.
Getting the quantities right takes some trial and error, if you have some room in your tun be prepared to adjust saccharification temperature with extra water.
The decoction flavours are really quite something else, sometimes difficult to replicate though. Braukaiser is an excellent resource for this sort of thing.

Weyermann Bohemian Pilsner malt is quite good, I use it in this decocted Munich Helles, drop the polenta and wheat though and use a bit more late hops would be my recommendations.


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## felten (6/5/10)

Wolfy said:


> other than 'fun' is there any specific reason for the decoction?


Well I had read (on braukaiser) that decoction helps make the starches in under modified grains more accessible to the enzymes, I'm not sure if the floor malted BoPils needs it though thb; Other than that and the much debated increase in malty/tastyness, not really.



Wolfy said:


> have you considered doughing in at 35-40 for an acid rest before the protein rest?


Since the mash comprises some darkly kilned malts I didn't think I would need an acid rest.



Katze said:


> You can lift the bag a bit to raise the grain to the surface. Then scoop out with a soup ladle or measuring cup


Nice idea, I hadn't thought of that. I do have a spare 20L (5gal) pot to use.



RdeVjun said:


> In your case with Wey BP, I would actually do a protein rest, decoction (with a 4kg grain BIAB, about 4 or 5kg of the thick mash, leave as much liquid in the tun as you can and don't stop stirring the decoction) to get up to saccharification then decoct again to mashout if you really want.


Yeah that is a possibility, if I can do it once, twice shouldn't be a problem  The grain bill is going to be roughly 9.355kg. Carrying it inside to use the stove is going to be a PITA, but I'm sure I'll figure out how to do it.. or burn myself in the process.


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## Bribie G (6/5/10)

Yes a good thick bottomed stockpot should do the trick. I already have one that I use as a cereal cooker to provide 'cooker mash' such as rice and polenta, basically what the Americans (commercials) do with their mashes and which the German Immigrant brewers no doubt adapted from their decoction mashing equipment. If it works for cooker mash it would work fine for decoction mash. Personally I would be a really girly woos and transport my lidded stockpot on a hand trolley for safety to avoid skin transplants to the groin, front thighs etc 

Edit - a 20 litre stocky should handle the angle of the hand trolley fine, as you wouldn't be transporting a full third of the mash each time, maybe more like only 10 litres of more concentrated porridge, as Katzke mentioned. Trolleys are sub $20 at Bunnings - I've had one for 2 years and couldn't live without mine.


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## Wolfy (6/5/10)

felten said:


> Well I had read (on braukaiser) that decoction helps make the starches in under modified grains more accessible to the enzymes, I'm not sure if the floor malted BoPils needs it though thb; Other than that and the much debated increase in malty/tastyness, not really.
> 
> Since the mash comprises some darkly kilned malts I didn't think I would need an acid rest.


I suspect that a stepped mash would do as much to release the starches especially if you are only doing the decoction as the mash-out step. My feeling would be that the vast majority of enzyme activity will have been completed at that stage and that you're actually destroying them (which is the purpose of the mash-out). For the sake of starch-conversion I'd be more tempted to use the decoction to raise temperatures from protein to saccrification rests. Decoction is fun however and it may (or may not) improve the malt flavour and/or colour of the beer.

If you have a pH meter, I'd be interested to know what the mash pH ends up being. My _very-rough/still-under-development_ mash pH calculator spreadsheet predicts 5.56 - 5.58 (depending on how you split the specialty malts) for untreated Melbourne water, but it may not give enough weight to the darker malts yet, but then you have 'only' 8%.


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## Thirsty Boy (6/5/10)

When you decoct a BIAB mash it happens slightly differently to a normal decoction, because you have a greater mash volume.

Easiest way is to pull up one edge of the bag and raise the grain mass to the surface, then just scoop out the thick portion. You want to scoop out the same amount as a traditional masher would scoop - a 3rd of the mash is the norm... but a third of the _traditional_ mash volume not a 3rd of the BIAB mash volume. So say 15-20 litres is the volume of a normal mash and you would take 5-7L of thick mash for the decoction - you still take 5-7L of thick mash for a BAIB decoction - or the decoction wont be thick enough and it pH could end up too high.

This means that when you return the boiling fraction... it will not raise your mash temp by the same amount. You will need to add extra heat with your main burner. You dump in the decoction, whack on your burner and stir it up to your next rest temp.

Its all pretty easy - if you consider doing a decoction at all easy... well a BIAB one is no harder.

TB


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## felten (6/5/10)

> If you have a pH meter, I'd be interested to know what the mash pH ends up being. My very-rough/still-under-development mash pH calculator spreadsheet predicts 5.56 - 5.58 (depending on how you split the specialty malts) for untreated Melbourne water, but it may not give enough weight to the darker malts yet, but then you have 'only' 8%.


 I have some pH strips, and I'll be making a few measurements along the way.




Thirsty Boy said:


> So say 15-20 litres is the volume of a normal mash and you would take 5-7L of thick mash for the decoction - you still take 5-7L of thick mash for a BIAB decoction - or the decoction wont be thick enough and it pH could end up too high.


 Thanks TB, I wasn't sure if there was a difference between trad and BIAB. It might be a while until I actually do this, and even longer until it's finished lagering, but I'll post my results back here at some point.


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## Thirsty Boy (7/5/10)

> Thanks TB, I wasn't sure if there was a difference between trad and BIAB. It might be a while until I actually do this, and even longer until it's finished lagering, but I'll post my results back here at some point.



Differences - but quite sensible and predictable ones. And ones that would have become quickly apparent when you tried it - just oping to save you a brewday surprise 



> Well I had read (on braukaiser) that decoction helps make the starches in under modified grains more accessible to the enzymes, I'm not sure if the floor malted BoPils needs it though thb; Other than that and the much debated increase in malty/tastyness, not really.



Ah - even "under modified" malts these days are pretty well modified. I doubt if there is a malt in common usage that needs a decoction to brew successfully. Certainly not one that couldn't be coached over the line with a non-decoction step mash. But still - your decoction will probably give you a minor boost in efficiency over a single infusion mash. Even with modern malts, in most (especially single infusion) mashes there are some unaccessed and unconverted starches left at the end. The process of boiling and stirring the decoction; and of stirring and mashing out the main mash when you incorporate the decocted fraction will get to some of that left over starch.... it wont be much, but I suspect you might notice it.

Your decoction will certainly (there is no real debate) change the flavour and character of your beer. Usually by making it maltier, certainly by making it darker. There really is no debate around that. The debate is centered around 1. Whether the change it makes is actually "better"? 2. If it is, whether its worth all the bother? 3. Whether you can get the same effect by simply changing your recipe to use a malt that was kilned to a level that includes more mailard reaction products.

That decoction will make a difference of some description - good, bad, pointless or otherwise - is patently true.

TB


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