Imhoppy
Well-Known Member
- Joined
- Aug 7, 2019
- Messages
- 320
- Reaction score
- 675
I'm trying to understand the water retention issue for grains as I venture from extract brewing to BIAB. As with brewing, there are seemingly endless schemes and methods other brewers use to make an excellent batch of home brew. I enjoy the math behind the process, and am doing all the calculations myself, instead of using a black-box calculator that hides the details and just spits out the answers. Not for me.
Per the American Homebrewer's Association (AHA), it is commonly accepted that 1lb of grain absorbs 0.1 - 0.125 gallons of water. This range will vary depending on grains used and the total grain weight.
Per John Palmer's article, "BIAB - Tips from the Pros" the BIAB water retention factor, 0.25 quart per pound of grain (or 0.0625 gallons/lb) is typically half that of a standard mash 0.5 quart per pound (or 0.125 gallons/lb). So the "standard mash" value agrees with the AHA value.
So my first question, is why is the water retention factor for BIAB lower than a standard mash?
Per biabcalculator.com, the grain absorption value in BIAB Calculator defaults to 0.045 gallons/lb and assumes you do not squeeze the grain bag after it is left to drain by gravity. If you DO squeeze the grain bag, change the grain absorption value to around 0.031 gallons/lb.
Also, Palmer doesn't recommend squeezing the bag to wring every last drop, and in particular, he certainly does not recommend it when you are brewing dark beers.
My second question, is which value should be used (0.0625 or 0.045 gal/lb) for calculating the water retention, assuming a gravity drain only (assuming brewing on planet Earth and not someplace else, lol)?
My initial BIAB technique will be to use a pulley hoist and gravity drain into the brew kettle (size is 8 gallon, not big enough for a no-sparge 5 gallon batch) until the flow slows down sufficiently enough to transfer the grain bag into a brew bucket for a dunk sparge (with volume about the same as for the mash (@ 1.5 qts/lb) with enough to achieve the desired pre-boil volume). Then stir the grains and let soak for 10 minutes or so, then use the hoist and do another gravity drain. Then transfer the sparge water into the brew kettle and then continue on to boiling. I will use warm water, heated to about 100-120F (to cool the hot grains making them easier to handle after the sparge, and to capture some of the heat that would otherwise be wasted). Note this may increase the time a bit to reach boiling temperature. I'm sure this plan will be modified as I get more experience with BIAB. Like buying more brewing stuff. It always ends up that way.
Per the American Homebrewer's Association (AHA), it is commonly accepted that 1lb of grain absorbs 0.1 - 0.125 gallons of water. This range will vary depending on grains used and the total grain weight.
Per John Palmer's article, "BIAB - Tips from the Pros" the BIAB water retention factor, 0.25 quart per pound of grain (or 0.0625 gallons/lb) is typically half that of a standard mash 0.5 quart per pound (or 0.125 gallons/lb). So the "standard mash" value agrees with the AHA value.
So my first question, is why is the water retention factor for BIAB lower than a standard mash?
Per biabcalculator.com, the grain absorption value in BIAB Calculator defaults to 0.045 gallons/lb and assumes you do not squeeze the grain bag after it is left to drain by gravity. If you DO squeeze the grain bag, change the grain absorption value to around 0.031 gallons/lb.
Also, Palmer doesn't recommend squeezing the bag to wring every last drop, and in particular, he certainly does not recommend it when you are brewing dark beers.
My second question, is which value should be used (0.0625 or 0.045 gal/lb) for calculating the water retention, assuming a gravity drain only (assuming brewing on planet Earth and not someplace else, lol)?
My initial BIAB technique will be to use a pulley hoist and gravity drain into the brew kettle (size is 8 gallon, not big enough for a no-sparge 5 gallon batch) until the flow slows down sufficiently enough to transfer the grain bag into a brew bucket for a dunk sparge (with volume about the same as for the mash (@ 1.5 qts/lb) with enough to achieve the desired pre-boil volume). Then stir the grains and let soak for 10 minutes or so, then use the hoist and do another gravity drain. Then transfer the sparge water into the brew kettle and then continue on to boiling. I will use warm water, heated to about 100-120F (to cool the hot grains making them easier to handle after the sparge, and to capture some of the heat that would otherwise be wasted). Note this may increase the time a bit to reach boiling temperature. I'm sure this plan will be modified as I get more experience with BIAB. Like buying more brewing stuff. It always ends up that way.