Posted by Jeffrey Donovan on July 22, 2003 at 15:28:15:
In Reply to: scaling homebrew recipes to 10 bbls posted by Linus on July 21, 2003 at 20:12:02:
Linus,
You're correct in that scaling to this size will have some major impact on IBU's as your utilization is going to be much higher. We have a field in the ProMash System Settings, Hop Section called "Kettle Size Hop Utilization Factor" that you will want to adjust (read what this is in the help section) to your system.
However, as far as what the actual adjustment should be I cannot say. I've seen this range from 1.5 to 3.0 for a 17 bbls system, and your going to need a trial run or two in order to determine the approximate number. Most professional brewers I know will send a bottle or two to a lab (if they do not have the required lab equip in house) to determine the IBU levels with some degree of accuracy, then adjust the Kettle Size Utilization factor so that the IBU prediction for a recipe matches the lab numbers. You only need to do this once, as subsequent batches should remain consistent with the initial findings. If you are comfortable with your own judgement as to what IBU levels are present in the beer, then lab analysis would not be needed, but a trial run or two will be.
Let me know if I can be of any further assistance,
Cheers!
- Jeff