Two worts from one grain bill - Re-mash or not?

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hogg44

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Next weekend I'm brewing a Russian imperial stout using my normal procedures. I stir/dunk-sparge and squeeze the bag. I have been getting 79% efficiency.

I then am going to try making a second wort by stirring and dunk-sparging the same grain with a second batch of sparge water.

Should I re-mash the grains or just go for it? I read about some people re-mashing for about 30 minutes, but If conversion has already happened, wouldn't re-mashing be wasted time?

Disclaimer: I know there won't be a ton of sugar left after squeezing the first time.
 

Aristotelian

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You could do the re-dunk, then take a gravity sample to see if additional mashing will be necessary.
 

doug293cz

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Remashing won't do anything, unless you add more base malt to the mash.

If you post your proposed grain bill, strike water volume, sparge 1 water volume, sparge 2 water volume, and typical grain absorption rate. I can give you a prediction of the SG's for each of your runnings. The second sparge running will be pretty low SG.

Brew on :mug:
 
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hogg44

hogg44

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If you post your proposed grain bill, strike water volume, sparge 1 water volume, sparge 2 water volume, and typical grain absorption rate. I can give you a prediction of the SG's for each of your runnings. The second sparge running will be pretty low SG.
Awesome! Thank you.

It's a 1-gallon batch (0.94 gallons to be more precise):

2.27 lbs Maris Otter
0.24 lbs Wheat Malt
0.24 lbs Chocolate Malt (350 SRM)
0.18 lbs Crystal 120
0.15 lbs Roasted Barley

Strike Water: 1.15 gallons
Sparge Water #1: 0.53 gallons
Grain Absorption: 0.019 gallons/lb
Sparge Water #2: 0.94 gallons

I guess if the SG of the second batch is too low, I could just make a half-gallon batch out of it instead of a whole gallon.
 

wilserbrewer

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Just spitballing ideas, but I think you should consider making batch 1 with the initial runnings, and batch 2 with the second runnings.

I would collect runnings and measure gravity, then distribute and dilute, or boil down to achieve desired results. Guessing your second dunk sparge might be rather lean, unless you want toakr a small batch of light beer idk.
to
 

doug293cz

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Awesome! Thank you.

It's a 1-gallon batch (0.94 gallons to be more precise):

2.27 lbs Maris Otter
0.24 lbs Wheat Malt
0.24 lbs Chocolate Malt (350 SRM)
0.18 lbs Crystal 120
0.15 lbs Roasted Barley

Strike Water: 1.15 gallons
Sparge Water #1: 0.53 gallons
Grain Absorption: 0.019 gallons/lb
Sparge Water #2: 0.94 gallons

I guess if the SG of the second batch is too low, I could just make a half-gallon batch out of it instead of a whole gallon.
A grain absorption of 0.019 gal/lb is unbelievably low. The lowest I have ever gotten with squeezing is 0.065, and the lowest credible claimed value I have seen is 0.055 gal/lb. Unless you are using some kind of mechanical press, I can't see how you could get that low.

I went ahead and ran the numbers anyway. Two critical assumptions of the simulation are:
  • Mash is stirred aggressively at the end of the mash, and the end of each sparge step.
  • Bag is squeezed after each drain step to achieve the same grain absorption after each step.
The results:
  • First runnings: 1.09 gal @ 1.0813
  • Second runnings: 0.53 gal @ 1.0261
  • Third runnings: 0.94 gal @ 1.0055
The above is for 100% conversion efficiency. At 90% conversion efficiency, the results are:
  • First runnings: 1.09 gal @ 1.0742
  • Second runnings: 0.53 gal @ 1.0227
  • Third runnings: 0.94 gal @ 1.0045
That third runnings beer is gonna be pretty damn thin.

Brew on :mug:
 
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hogg44

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A grain absorption of 0.019 gal/lb is unbelievably low. The lowest I have ever gotten with squeezing is 0.065, and the lowest credible claimed value I have seen is 0.055 gal/lb. Unless you are using some kind of mechanical press, I can't see how you could get that low.
Since I'm doing small batches, my grain bag is pretty small. I can fit most of the grains in my hands all at once. Do you think that might allow me to get more wort out?

I calculated that number by:
1. doing a boil of just water for an hour and measuring the boil off.
2. Then using that boil-off number in BrewCipher, I used a 0.08 gal/lb default as my grain absorption value.
3. I made the beer.
4. I had way more wort than I should have, so I adjusted the absorption value until the strike plus sparge water minus previously calculated boil-off and absorption equaled my final volume.

I'm not sure if that's the right way to go about finding that number.

The results:
  • First runnings: 1.09 gal @ 1.0813
  • Second runnings: 0.53 gal @ 1.0261
  • Third runnings: 0.94 gal @ 1.0055
The above is for 100% conversion efficiency. At 90% conversion efficiency, the results are:
  • First runnings: 1.09 gal @ 1.0742
  • Second runnings: 0.53 gal @ 1.0227
  • Third runnings: 0.94 gal @ 1.0045
That third runnings beer is gonna be pretty damn thin.
That's really helpful. Thanks for doing that. Looks like that would be a waste of time.
 

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Since I'm doing small batches, my grain bag is pretty small. I can fit most of the grains in my hands all at once. Do you think that might allow me to get more wort out?



I calculated that number by:

1. doing a boil of just water for an hour and measuring the boil off.

2. Then using that boil-off number in BrewCipher, I used a 0.08 gal/lb default as my grain absorption value.

3. I made the beer.

4. I had way more wort than I should have, so I adjusted the absorption value until the strike plus sparge water minus previously calculated boil-off and absorption equaled my final volume.



I'm not sure if that's the right way to go about finding that number.







That's really helpful. Thanks for doing that. Looks like that would be a waste of time.

I think the 3rd runnings would be a waste of time, but you could certainly get two nice beers from some combination of your first and second runnings. From dougs numbers above, you might want to blend a bit of the first back into the second to up the gravity a tad on the second.

It will take a little thinking outside the box but very doable.
 

doug293cz

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Since I'm doing small batches, my grain bag is pretty small. I can fit most of the grains in my hands all at once. Do you think that might allow me to get more wort out?

I calculated that number by:
1. doing a boil of just water for an hour and measuring the boil off.
2. Then using that boil-off number in BrewCipher, I used a 0.08 gal/lb default as my grain absorption value.
3. I made the beer.
4. I had way more wort than I should have, so I adjusted the absorption value until the strike plus sparge water minus previously calculated boil-off and absorption equaled my final volume.

I'm not sure if that's the right way to go about finding that number.

...
That method should give you a reasonably accurate absorption. The best way to measure absorption is to subtract the first runnings volume from the strike volume and divide by the grain bill weight. Both volumes should be measured at the same temperature, or expansion compensated to the same temperature.

Brew on :mug:
 
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