I've been working part-time at my LHBS and one of the perks we receive as employees is first dibs at messed up recipes (ie someone out flaked grains through the mill, mis-measured, cancelled orders, etc) and yesterday I took home a grain bill and all they could tell me was that it was "for a stout" so I weighed it and its about 20lbs of grains. There is obviously some flaked stuff, most likely barley, and I can see the crushed dark grains. As it stands, is it possible to calculate the potential OG/IBUs without knowing exact grain proportion/type?
Help me figure this thing out
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GrogNerd
mean old man
depends on batch size
20 lbs of grain would make a normal-sized stout in a 10-gallon batch, imperial stout in a 5-gallon batch
mashing 1 lb in enough water to get you to 1 gallon pre-boil and measure that gravity would provide some answers
20 lbs of grain would make a normal-sized stout in a 10-gallon batch, imperial stout in a 5-gallon batch
mashing 1 lb in enough water to get you to 1 gallon pre-boil and measure that gravity would provide some answers
Because the maximum potential varies by grain, you can't get an exact number. But you can get a pretty good estimate.
Base malt will give you 37 PPG, Flaked Barley will give you 32 PPG, Black Patent or Roasted Barley will give you 25 PPG, and other specialty malts will give you between 31 and 35 PPG. You could try to back out a typical stout recipe and then do complicated math, but I would just guestimate that your blended average PPG will be somewhere in the neighborhood of 35 (I'm assuming the vast majority of the grain is base malt). So that means you have somewhere in the area of 700 total gravity points in potential from the grain. Then just divide the 700 by the number of gallons you intend to brew and multiply by your typical efficiency. For a 10 gallon batch with 80% efficiency, this would be: 700/10*.8 for 56 gravity points per gallon, so an OG of 1.056. For a 5 gallon batch with 65% efficiency, this would be: 700/5*.65 for 1.091. So like GrogNerd said a pretty standard stout for a 10 gallon batch and a strong RIS in a 5 gallon batch.
The bigger issue you have is that it would be good to know what the intended batch size was. In an RIS, you generally don't double the dark grain components. So if this was intended as a 10 gallon batch and you brew it as a 5 gallon batch it is going to have a much more pronounced roast, dark grain flavor than a typical RIS. If it was intended as a 5 gallon batch, on the other hand, and you brew it as a 1- gallon batch, you will likely have a beer that is not as roasty as a typical stout.
As for IBUs, you need to know the alpha acid percent for the hops to make the calculations.
Base malt will give you 37 PPG, Flaked Barley will give you 32 PPG, Black Patent or Roasted Barley will give you 25 PPG, and other specialty malts will give you between 31 and 35 PPG. You could try to back out a typical stout recipe and then do complicated math, but I would just guestimate that your blended average PPG will be somewhere in the neighborhood of 35 (I'm assuming the vast majority of the grain is base malt). So that means you have somewhere in the area of 700 total gravity points in potential from the grain. Then just divide the 700 by the number of gallons you intend to brew and multiply by your typical efficiency. For a 10 gallon batch with 80% efficiency, this would be: 700/10*.8 for 56 gravity points per gallon, so an OG of 1.056. For a 5 gallon batch with 65% efficiency, this would be: 700/5*.65 for 1.091. So like GrogNerd said a pretty standard stout for a 10 gallon batch and a strong RIS in a 5 gallon batch.
The bigger issue you have is that it would be good to know what the intended batch size was. In an RIS, you generally don't double the dark grain components. So if this was intended as a 10 gallon batch and you brew it as a 5 gallon batch it is going to have a much more pronounced roast, dark grain flavor than a typical RIS. If it was intended as a 5 gallon batch, on the other hand, and you brew it as a 1- gallon batch, you will likely have a beer that is not as roasty as a typical stout.
As for IBUs, you need to know the alpha acid percent for the hops to make the calculations.
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