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Infusion mash volumes

Azfrom Oz

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Howdy,

Am doing an India Session Lager with just under 3kg of grain, two infusion mash steps (67 degrees for 60 minutes, 74 for 10) and a batch sparge.  Am using Beersmith for volume and heat calculations, and have had to tinker with the mash profiles to get one that matches what I want to do.  I've come up with some volumes based on what Beersmith initially spat out but it's just guess work on my part so I wanted to check....

The closest mash profile is the single infusion, xx body, batch sparge, but that only gives me one mash step, telling me to use just under 8L of water and then two batch sparge steps with a total of 25L.  When I add the second mash step Beersmith makes me estimate the water volume, so I subtracted 13L from the sparge and used that for the second step.  My mash profile now reads (I rounded the volumes):

    8L @ 77.8 degrees (mash in) for 60 minutes.
    13L @ 79.9 degrees (mash in) for 10 minutes
    drain mash tun
    batch sparge with 12.5L.

So, my question is how do I know what volume to use for my second mash step?  When I add the volume for the second mash step, Beersmith just subtracts that from the batch sparge, which is fair enough as it's trying to hit a kettle volume of 30L.  I could put in three liters of near-boiling water or 20 liters of 78 degree water and both steps would hit my mash step temperature with either a huge or small sparge volume to follow.  I've just guessed and taken Beersmith's recommended volume for the first batch sparge (it wanted me to batch sparge in two steps).  Is there a rule of thumb for subsequent mash step volumes?

Cheers


Az
 
First, the mash profiles in BeerSmith are meant to be customized to how you brew and what you want your process to be.

Now, in your mash profile your first step is a mash in and your second step appears to be a mash out.  So, you can open up your mash profile which you want to use and edit the mash in step for the first step to be at a target of 67C and select an appropriate mash consistency.  Most people use a water to grain ratio of 2.6 l/kg up to generally 3.2 l/kg and let beersmith calculate your infusion water volume and temperature for you based upon this information.  Your present step is 8 liters for your 3 kg of grain, so you are right at the lower end.

For your next step (the mash out), you can 'add step' and set the volume to what you want it to be.  This would be the volume of water you want to add to the mash and will set the temperature of the water to reach that target step temperature.  You are correct that there are a number of ways of doing this to reach your end target.  What I usually do is aim for approximately equal runnings from the mash and the sparge steps.

You can do this by taking the 'total water needed' for the recipe and subtracting what BeerSmith is calculating for grain absorption and your set mash tun dead space.  Now divide that number by two to get what should be your runnings from each step.  Add back to that number the grain absorption and mash tun dead space.  Now, take the initial infusion volume (your 8 liters) and subtract this from your volume (runnings + grain absorption + dead space) and use the result as your mash out volume. 

So, for instance, if your total water is around 33 liters, your grain absorption from Beersmith in the recipe is 1.5 liters and your mash tun dead space is 0.5 liters, then take your water needed (33 Liters) minus the 1.5 liters from grain absorption plus the 0.5 liters for dead space and you will end up with 31 liters.  Divide this by two and you get 15.5 liters of expected runnings.  Add back in the 1.5 + 0.5 liters and your volume before draining your mash tun should be 15.5 + 1.5 + 0.5 = 17.5 liters.  Now you mashed in with 8 liters, so your mash out step (infusion) should be set to add 17.5 - 8 = 9.5 liters.  To check your mash, the sparge step should be 15.5 liters as well.

Mind you, this is just one way of doing this.  You can also increase your mash in volume a bit to 10 liters and still make this work well for you (you will just be swaping 2 liters from the mash out step to add 2 liters for the mash in step). 

The equal runnings is not a requirement either, but it has been demonstrated that it will lead to achieving higher efficiency when batch sparging. [see www.dennybrew.com]
 
I have a related question, specifically about grain absorption.  In my last two or three batches, I seem to be experiencing a higher amount of grain absorption than fits the default setting in BS (.96 fl oz per oz of grain).  In all three, I have added right about 5 gallons of strike water in my single infusion mash process and yielded right about 3 gallons of wort before doing my two-step batch sparge.  So my grain absorption rate, at least for these batches, seems to be more like 1.2 fl oz per oz of grain.  Is it too soon to go into my preferences and change BS's default absorption rate?  Are there other factors that could be responsible to my apparently higher grain absorption rate?  I am relatively new to all-grain brewing (just brewed my fourth batch yesterday) and to crushing my own grain.  I have my grain crusher set (as best I could) for .038" as recommended.  Could grain that is crushed a bit too much account for higher absorption rates?
 
The only other contributor to loss between volume added to mash and post mash volume would be any losses due to dead space in your mash tun.  If you feel that you already have this covered, then three points that far away from the current set point for grain absorption would be a good indication that it needs to be changed.  I would suggest that you lay out all your data so far and make sure of the number before you change it and continue to watch it for the next few brews.
 
Thank you, Oginme, for your reply to my post.  Based on what you've told me, I've had a crack at changing my volumes on Beersmith and have come up with an initial volume of 9 litres, an infusion of 9.5 litres and a sparge of 15 litres.  With no deadspace and grain absorption of 3 liters of water (according to BS), that gives me 15 litres of equal runnings in both steps.  Total water volume, 33.5 litres.  Took me a while with the pen and paper to work it out, but now it all makes sense.  :)

I wonder why Beersmith doesn't automatically update and suggest a volume as you add a mash step? 

Cheers
 
Azfrom Oz said:
I wonder why Beersmith doesn't automatically update and suggest a volume as you add a mash step? 

Cheers

Basically it is that BeerSmith is modeling software and not an optimization software package.  To have the software recommend an optimized water infusion for mashing would also serve to limit the types of processes it would effectively model. 
 
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