Adjusting Recipe / Boil Volume

[jalgayer]

Hey All

I am making a beer that calls for a 2.5 gallon boil size. It is the Pliny from Austin home brew which calls for a 90 min boild with 2.5 gallons. But I have since upgraded to a 7 gallon pot so I am able to larger boil sizes (5-6 gallons)

I have beersmith and I think what I need to do is as follows:

[a] Enter the Recipe as it is given and check the IBU and note it
Change the boil size from 2.5 gallons to 5.5 gallons
[c] Adjust the bittering hops to get the IBU back to where it was in step 'a'

So that brings me to my questions...

[1] Is my though process above accurate?
[2] Do I need to make any changes to the amount of hops for the 45/30/0 minute additions?
[3] Are there any other issues to think of when altering the boil sze?

 

[Hex23]

[1] - That's what I do and it works fine. Perhaps there is a faster way in BS, but I don't know of one
[2] - Generally you won't want to adjust your aroma hops additions (0 min). You'll find that in the IBU calcs BS uses, altering them won't affect IBU anyway. That makes sense since IBU is a measure of bitterness. You could try to get really technical and scale your flavoring (middle) hops differently than your bittering (earliest) hops, but I think most would just scale them proportionately.
[3] - Hopefully you also have chilling equipment since it will take longer to chill a full boil

 

[jalgayer]

But what about the 30 and 45 minute addition? They affect the ibus. Do I change just the bittering 90 hops enough and leave all others alone? Our should I change the 90 45 15 all a little until I get to the correct ibu

 

[Hex23]

I think you should reduce all of the 90, 45, 15 additions. The question is in what proportion. In thinking about hops utilization dynamics, if your aim is to keep both IBUs and flavor/aroma exactly the same, it seems that you really would not want to make proportional reductions to the 90/45/15 additions. My thinking is that it's like a continuum where the 90 minutes are entirely for bittering, the 0 minutes are entirely for aroma and the middle ones (45/15) are partly for both (a.k.a flavoring). Continuing the trend and logic about the 0 minute addition, you would want to reduce the ealier hops by more percent i.e. not proportional.

Now, with that said, I think most people are not intrested in being that sophisticated and would just scale back all three (90/45/15) additions proportionately. E.g. If your additions are 2 oz, 1 oz, 0.5 oz, then try scaling them back by 25% (1.5, 0.75, 0.375 oz) and see where BS tells you your IBUs are.

The other thing to keep in context is that IBU calculations are not really an exact science. Cosider how many utilization formulas are out there, Tinseth, Raeger, others, etc. The idea is to go in the right direction and get as close as practical. You may find that you want to make further adjustments based on personal taste the next time you brew the batch.

 

[jalgayer]

I guess that makes sense and is along the lines of what I was thinking.
The 45 and 30 min additions are just 1 ounce each and not sure I want to alter them a whole lot. Just not sure here.

 

[Hex23]

Good luck. I'm not a big hop lover, but I do enjoy an occasional IPA. As much as folks rave about Pliny I should probably try one. I don't think I've even seen one locally.

 

[jalgayer]

Thanks,
Its is really excellent. I am suprised that more people dont know how to adjust the middle addition hops in a recipe. There are several threads but they focus on the bittering hops mostly. Or the 0 min addition. Thanks anyway, guys
J

 

[Hex23]

I am suprised that more people dont know how to adjust the middle addition hops in a recipe.

Well maybe now there is one! At least something to get someone using the right logic.

I assume part of the reason for what you noted above is that to my knowledge, there is no formula for calculation of how hops contribute to aroma and flavor. If there were then you could try to apply a more precise method. There are lots of things like this in home brewing where science could be applied, but isn't because people have been just fine with trial and error and getting "close enough".

 

[arnoldk2]

Well, i'm interested in my final ibu's. Let's say my final ibu is 40. I hand calculate what each addition of hops will give me. If I want my beer to be bitter I will add most of my ibu's in the 60 minute boil and make up the rest in flavor and aroma. A great book to read is designing great beers. This book freed me from following someone elses recipe to making my own recipe. This book goes through all the calcs needed to make your own recipe