# Spent Grain Water Absorption



## Thefatdoghead (18/1/12)

G'day,

Im just reading through "designing great beers" and im on pg 64 where the table is telling me that 22 pounds of spent grain absorb 4.75 gallons of water so 10kg of grain absorb's 18L of water. I certainly don't get that much absorption loss in my 50L braumeister. How iv'e always done the calculation is just take grain weight in kg and account for the loss in Litters. So 10kg of grain will absorb 10L of water. Iv'e always been spot on within 1 litter with my volumes so im a little confused how he's got that much loss? Am I missing something here? :blink:


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## dr K (18/1/12)

Always use your own brewhouse results, as they say "efficiency may vary" as will grain absorption, temperature gradients and so on.
DGB is an excellent reference, but its a pointer not a slave master

K


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## MHB (18/1/12)

Without digging out the book and reading the reference.
If you put 1 Kg of crushed malt (sort of medium) and add water to just cover it; you will need very close to 2 L, so its quite possible that the reference is to the mash in.
At the end of the mash the amount of water retained will vary according to the fineness of the grind, roughly, for a Lauter Tun grist just under 1L/Kg (mashed in weight), a bit less for finer grist, for really fine like some BIAB just over 0.8L/Kg.
Mark

Yes to what DrK said, I was off typing (slowly) in word when he posted.
M


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## Thefatdoghead (18/1/12)

dr K said:


> Always use your own brewhouse results, as they say "efficiency may vary" as will grain absorption, temperature gradients and so on.
> DGB is an excellent reference, but its a pointer not a slave master
> 
> K


Yes I agree I just didn't think there would be that much difference from system to system.


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## Thefatdoghead (18/1/12)

MHB said:


> Without digging out the book and reading the reference.
> If you put 1 Kg of crushed malt (sort of medium) and add water to just cover it; you will need very close to 2 L, so its quite possible that the reference is to the mash in.
> At the end of the mash the amount of water retained will vary according to the fineness of the grind, roughly, for a Lauter Tun grist just under 1L/Kg (mashed in weight), a bit less for finer grist, for really fine like some BIAB just over 0.8L/Kg.
> Mark
> ...


Ok Mark, So I start with 53L in the BM and after I pull the malt pipe out im pretty close to 42-43L of wort after the malt pipe drains and that is with 10kg of grain crushed with a crankenstein 3 roller mill, gap factory set whatever that is.
What are you left with after the malt pipe drains and how much water are you starting with?


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## BjornJ (18/1/12)

on my BIAB setup hanging the bag over a bucket and giving it a gentle squeeze only, the grain bag weights 0.55 kg more per kg of grain in the bag when finished.

My water loss to grain is therefore 0.55 litre x kg of grains = litres of water


thanks
Bjorn


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## MHB (18/1/12)

Generally I add 1L/Kg of 80oC water to the malt pipe while its sitting on top of the Braumeister, so at the start of the boil Im back almost exactly where I started (a finger width above the top mark on the spindle 52-53 L).
I then move the malt pipe off, rest it on the lid of the Braumeister that is sitting on a bucket, over the course of the boil (60-90 minutes) about 3-5 more litres drains down, I will use this to top up near the end if I need it or not if I dont or want higher gravity.
Generally from there I knock out into 2 x 20 L cubes so about 45 L without having to fight with the trub (moving back to chilling so will have to make some adjustments) but there is a litre or three there if the evaporation was up a bit, just by tilting the Braumeister a bit.
Hope thats close enough for you
Mark




BjornJ said:


> on my BIAB setup hanging the bag over a bucket and giving it a gentle squeeze only, the grain bag weights 0.55 kg more per kg of grain in the bag when finished.
> 
> My water loss to grain is therefore 0.55 litre x kg of grains = litres of water
> 
> ...


Dont squeeze - nothing good can come of it, there are a lot of proteins (particularly the very high molecular weight ones that are the worst for the beer) a lot of these will condense at mashing temperatures and will stay in the grain if you let them.
If there is one big down side to BIAB its wort turbidity and the amount of trub that forms (well more precisely the unwillingness of some brewers to leave it in the kettle where it belongs), and having done a couple of BIAB brew I know the temptation to squeeze (just a little bit) is nearly irresistible, you shouldnt.
If you leave the bag hanging during the boil, you should get pretty much the same amount of drain down as you would if you squeezed, without the possible down sides, this can be added back to the boil 10-15 minutes from the end to get rid of any break material if you want.
I would be interested to know what sort of crush you are doing to get the type of drainage you mentioned.
Mark


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## Thefatdoghead (18/1/12)

MHB said:


> Generally I add 1L/Kg of 80oC water to the malt pipe while its sitting on top of the Braumeister, so at the start of the boil Im back almost exactly where I started (a finger width above the top mark on the spindle 52-53 L).
> I then move the malt pipe off, rest it on the lid of the Braumeister that is sitting on a bucket, over the course of the boil (60-90 minutes) about 3-5 more litres drains down, I will use this to top up near the end if I need it or not if I dont or want higher gravity.
> Generally from there I knock out into 2 x 20 L cubes so about 45 L without having to fight with the trub (moving back to chilling so will have to make some adjustments) but there is a litre or three there if the evaporation was up a bit, just by tilting the Braumeister a bit.
> Hope thats close enough for you
> Mark



That is just about exactly what i'll do but I usually like to finish with 55L at end of boil so im rinsing more water through the pipe @ 78-80deg than you are and starting boil volume of around 65 litters. A couple of litters for trub and a couple for my next starter and then straight into the 60L fermentor through the plate chiller. I'll get 84% efficiency every time when I make this amount without overloading the pipe.
Gav


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## katzke (19/1/12)

MHB said:


> Don't squeeze - nothing good can come of it, there are a lot of proteins (particularly the very high molecular weight ones that are the worst for the beer) a lot of these will condense at mashing temperatures and will stay in the grain if you let them.
> If there is one big down side to BIAB its wort turbidity and the amount of trub that forms (well more precisely the unwillingness of some brewers to leave it in the kettle where it belongs), and having done a couple of BIAB brew I know the temptation to squeeze (just a little bit) is nearly irresistible, you shouldn't.
> If you leave the bag hanging during the boil, you should get pretty much the same amount of drain down as you would if you squeezed, without the possible down sides, this can be added back to the boil 10-15 minutes from the end to get rid of any break material if you want.
> I would be interested to know what sort of crush you are doing to get the type of drainage you mentioned.
> Mark



The squeeze question has been dealt with. No problems with the finished beer. I can, however agree that not squeezing will keep more gunk in the bag.

The error in his post is you can not go by weight of the spent grains. The simple reason is we are extracting stuff from the grains. So X amount of grain after the mash will be X-Y, with the Y added to the water to make wort. Part of that will be left as hot and cold break and part will get consumed by the yeast and ultimately us.

To answer the OP. How much water the grain absorbs all depends on the grain and how dry it is. In a home brew scale it will be always about the same. Use what works for your system. If you are new use proven recommended numbers for your method. Dont believe everything you see in print. Sometimes it is wrong information, and other times it is a simple error in the text.


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## stux (19/1/12)

At 84% efficiency... Is that into fermenter or into boil? Sounds like into boil

You're extracting 84% of the extract in the grain. If your grain had 80% HWE potential that's 8Kg from 10Kg OG grain of which you get 84% into your boil

6.72Kg

But what matters is the 8Kg. That 8Kg of extract displaces water, and it displaces about 0.614 L/Kg

So 4.912 L

So you are missing 10L of water and you extracted 4.9L of extract so your real absorption was actually closer to 15L

So 1.5ish L/kg was really absorbed


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## Thefatdoghead (19/1/12)

Stux said:


> At 84% efficiency... Is that into fermenter or into boil? Sounds like into boil
> 
> You're extracting 84% of the extract in the grain. If your grain had 80% HWE potential that's 8Kg from 10Kg OG grain of which you get 84% into your boil
> 
> ...


Yeah that would sound about right. Once cooled I would probably measure about that much loss plus boil of coarse. If using around 10kg of grain I always set my efficiency to 84% and my OG pre boil comes up spot on and i'll be within the 42-43L mark when @ 100deg C after removing the grain. 
Starting with 53L in the kettle @ 38deg (which would read a few litters more @ 100deg C) so yeah I reckon it must be fairly close to 13-15liters which isn't to far off the 18L in DGB book.


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## Nick JD (19/1/12)

katzke said:


> The squeeze question has been dealt with. No problems with the finished beer.



+1

But there are still dickheads guessing that it's bad to make themselves seem smart. 

High molecular weight proteins? They are the main contributors to head retention. 

I think what he meant to say was high molectular weight carbohydrates. 

And anyway - what I (a dreaded squeezer) am pouring into my fermenter is crystal clear - all these "bad things" are in the break material.


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## MHB (19/1/12)

No nick I actually meant High Molecular Weight Proteins, I am mainly referring to n = 40,000 + protein, mot the medium weight ones that are a part of what builds head. To the best of my knowledge any carbohydrate small enough to be soluble but too big/complex for yeast to tackle is called a dextrin and they tend not to condense in the boil.
The Art of brew in a bag is still very young and there is a lot left to learn, the jury is still out on lots of questions among them the benefits or otherwise of squeezing, based on my observations and the research I have done well I have expressed my opinion and the reasoning that leads to it.

Its funny that every time I disagree with you, Im trying to prove Im smart, thats just crap.
My aim is to make better beer; I havent shut my mind to any new ideas and am fully aware that there is a lot left to learn. Learning comes from testing ideas, discussing the results with others and developing an understanding of the processes involved (the science of brewing if you like).
Frankly if you think your beer is perfect and cant be improved well youre lucky, you will never have to learn anything new or change anything you are doing, I lack the arrogance to take that view of my brewing.
Mark


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## felten (19/1/12)

I generally don't like to squeeze the bag, but when brewing a 40%+ rye beer especially, or even a 50%+ wheat beer, I've found it's almost a necessity.


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## Fodder (19/1/12)

I love squeezing my bag. Perfect for getting out all those juciy proteins. :blink: 

Not sure what BIAB is though.... h34r:


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## Jazzafish (19/1/12)

Fodder said:


> I love squeezing my bag. Perfect for getting out all those juciy proteins. :blink:
> 
> Not sure what BIAB is though.... h34r:



Ha Ha Ha HA HA :lol:


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## stux (19/1/12)

Fodder said:


> I love squeezing my bag. Perfect for getting out all those juciy proteins. :blink:
> 
> Not sure what BIAB is though.... h34r:



Best not to over-squeeze though, you may damage the seams


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