Calculating Dough In Water Volume

[dhempy]

Seems to me like I should know this but I'm drawing a blank ...

At issue is how to include the "dead space volume" below the false bottom in the calculation.
Let's make the following assumptions:
1) Dead Space Volume = 1 gallon
2) Grain = 20 lbs
3) Mash ratio 1 qt per pound (for simplicity)

So based simply on the grain and mash ratio ... one would need 20 qts or 5 gallons. But if the dead space volume is added, then dough in would require 6 gallons.

Which is correct?

Dan

[lexuschris]

Hey Dan,

I was just wondering if you need to include dead space in the dough-in volume calculation at all...?? I know it is important with calculating the volume of your 1st runnings (as is grain absorption), but do you need to consider it in dough in? While the water below the false bottom is not in direct contact with the grain, it certainly circulates and will have grain enzemes in it...

Just a thought...
--LexusChris

[JonW]

Sure you have to take the dead space into consideration. Your water/grain ratio is all about how much water is in the grain and how fluid the grist is. Take an extreme example - let's say your dead space is 3 gallons (because of Dan's crazy plumbing ). Do you still only use 5 total? No, you use 8 because you need 5 gallons in contact with the grain.

[dhempy]

Yeah .. that is the dilemma ... seems to me that one of the things one wants to control in the mash is the "thickness" of the mash. So if you add the 6 gallons with a gallon below the false bottom, you have the correct thickness in terms of the water in the grains. If you only add 5, then you are demonstrably "thicker" because you only have 4 gallons in touch with 20 pounds .. an equivalent of .8 qts / lb. That is a significant difference.

When you look at the BrewCaptain's Mash guidelines, it seems to me that the ideal ranges are 1.25 to 1.75 qts/lb. Obviously, with larger batches the effect is smaller but if you have a larger system and want to brew 5 gallon experiment batches, I think you may need to take this into account.

Sure you have to take the dead space into consideration. Your water/grain ratio is all about how much water is in the grain and how fluid the grist is. Take an extreme example - let's say your dead space is 3 gallons (because of Dan's crazy plumbing ). Do you still only use 5 total? No, you use 8 because you need 5 gallons in contact with the grain.

Well Jon, it isn't the plumbing I had in mind here ... just the dead space in those 20 gallon pots. I actually have about the same "plumbing loss" as I had before ... but I do have a bigger deadspace now ... and it could significantly impact mash thickness. BTW my gut tells me that deadspace should be added, but it wasn't obviously clear in either BeerSmith or ProMash "water needed" calcs.


Dan

[lexuschris]

I am still new to all the details of mashing calculations and such ... however, it sure seems to me that the dead space factor is more about the inability to get that fluid out of the mash tun (lauter volume) into the next stage. When you are mashing, the water circulates between the false bottom and above it. The enzymes swim into the dead space and back. Enzyme conversion happens below & above. While it is not perfectly homogeneous, I'd bet it is not a large effect to the total mash thickness ratio...

When I took a quick look around a few mash volume calculators, they did not include dead space. That may just have been their oversight...

Also, if you shoot for a 1.5 qt/lb ratio, even with the dead space, you would be in the 1.25 - 1.5 ratio range ...which is pretty good.

Anyways, just throwing a few observations out there to help the discussion!
--LexusChris

[JonW]

Well Jon, it isn't the plumbing I had in mind here ... just the dead space in those 20 gallon pots. I actually have about the same "plumbing loss" as I had before ... but I do have a bigger deadspace now ... and it could significantly impact mash thickness. BTW my gut tells me that deadspace should be added, but it wasn't obviously clear in either BeerSmith or ProMash "water needed" calcs.

Dan, my comment on the plumbing was a joke to show an example with exagerrated losses. Whether the water is filling the plumbing or the dead space in the kettle, you still need to add that amount so that the grain has the proper amount of water absorbed.

[dhempy]

Yes ... the more I think about it the more I agree ... deadspace water is physically isolated from the grain and it is the "thickness" of the mash which is at issue ... not the "total ratio" of water to grain. If I recall correctly, it is the beta-amylase that is most sensitive to thickness and the thicker the mash, the more beta-amylase activity (beta-amylase is responsible for the creation of maltose molecules off of the starches created by the alpha amylase-enzymes). A thicker mash provides more substrate for the beta-amylase to interact with. Of course, beta-amylase is less effective at higher temps but thicker mashes reduce the high-temperature degradation somewhat.

So even though there is more liquor in the system, the thickness (I believe) is determined by what is in contact with the grain in the mashtun (above the false bottom).

Upon a re-look at ProMash, I believe there is accommodation for this calc in the water needed area .. it isn't blatantly obvious and it doesn't tie into the next steps in the water needed calcs. I don't see anything in the BeerSmith calcs.

Dan

P.S. No offense taken Jon ... just providing clarity!

[jward]

The other gotcha is strike temp. The dead space water contributes heat to the mash even if not to the thickness. You may find your strike temps off.

[BrewMasterBrad]

The other gotcha is strike temp. The dead space water contributes heat to the mash even if not to the thickness. You may find your strike temps off.

Good point. I was also thinking that the mash thickness is not just about the concentration of the enzymes, but also the buffering capacity and residual alkalinity of the water used for the mash. All of this makes my head hurt. I would say include the dead space so that the mash is the correct thickness and so you can hit your temps.

[dhempy]

Yes, strike temp is another concern but more easily adjusted for I think. I am changing my process such that the mashtun and strike water will be pre-heated and then grain added versus my old process of adding hot water to the tun pre-loaded with grain. I wouldn't expect the deadspace to make more than a couple of degrees difference but I will find that out when I get there. Also, since I will have direct heat applied to the mashtun, I won't have the external insulation so I suspect that the HERMS process will be more active.

Dan

[BrewMasterBrad]

I have always used the "add grains to hot water" method as opposed to the "add hot water to grains" method. That's just the way I have always set up my systems, plus it is easier to lift and pour a bucket of grains than it is to lift and pour a kettle of hot water. Now that I have a two pump system, I suppose it doesn't matter as much, but I have always stuck with the former process.

[bwarbiany]

I have always used the "add grains to hot water" method as opposed to the "add hot water to grains" method. That's just the way I have always set up my systems, plus it is easier to lift and pour a bucket of grains than it is to lift and pour a kettle of hot water. Now that I have a two pump system, I suppose it doesn't matter as much, but I have always stuck with the former process.

I've got a two pump system, but the "add grains to hot water" method is my preferred method as well...

It helps that I typically measure my strike water first, fire the burner, then weigh and mill my grains, though, so I've already got my strike water ready in the mash tun once the grains are crushed...

[BrewMasterBrad]

I have always used the "add grains to hot water" method as opposed to the "add hot water to grains" method. That's just the way I have always set up my systems, plus it is easier to lift and pour a bucket of grains than it is to lift and pour a kettle of hot water. Now that I have a two pump system, I suppose it doesn't matter as much, but I have always stuck with the former process.

I've got a two pump system, but the "add grains to hot water" method is my preferred method as well...

It helps that I typically measure my strike water first, fire the burner, then weigh and mill my grains, though, so I've already got my strike water ready in the mash tun once the grains are crushed...

Exactly what I do. Great minds and great names think alike.