Randy Mosher's Radical Brewing and IBUs

[ITbrewer229]

I have been using BeerSmith to add recipes from Randy Mosher's book, "Radical Brewing". My question is related to hop amounts and IBUs.

He mentions that all recipes assume whole hops and if using pellet hops, there will be 25% higher utilization. Therefore, I am taking his hop amounts and dividing by 1.25 to account for the higher utilization. The issue I am having is BeerSmith's IBU calculations are off from Mosher's stated IBU amounts for the recipe. I am even making sure to make sure the alpha percent matches the stated alpha percent in Mosher's book.

My question is this. Do I just blindly go with Mosher's recommendations and adjust the hop amounts by dividing by 1.25 or keep tweaking the hop levels in BeerSmith until the IBU calculation matches Mosher's stated IBU level for the recipe (making sure to keep the ratios the same)?

Thanks in advance for any feedback.

 

[BigEd]

I think a 25% differential is a bit overstated. Ten percent would be more like it.

 

[Beernik]

Target the IBUs, not the hop amounts.

10% is a better rule of thumb.

 

[ITbrewer229]

Thanks!

I've found BeerSmith to be pretty reliable so I decided to just enter the recipes as is but I have the target IBUs in the recipe notes. When I order my hops and confirm the Alpha Acids, I will adjust to meet the target IBUs. There didn't seem to be a set factor I could multiply everything by to get the numbers to jive. Each recipe seemed to be different from BeerSmith calculations by a different amount.

I'm working on Mosher's 12 beers of Christmas and since many of these take 6-9 months to mature, I want to get cracking on them soon for next Christmas.

Thanks everyone for their input. It sounds like the better practice is to target IBUs. It was probably a rookie question, but since I only have about 10 beers under my belt so far, I still think of myself as a rookie

 

[sqhead]

Just an FYI: Here is a link to a list of corrections for Radical Brewing. I did not check for the recipe you mentioned, but the list may help you in the future.
http://www.radicalbrewing.com/rberrat.html

 

[ITbrewer229]

Thanks for the link! My particular issue isn't mentioned but there are some helpful corrections here. I also stumbled across another last night that isn't listed so I'll email the author. The recipe for Black Ship Pirate Stout has 2 different hop additions for the same exact hop (Willamette) at 90 minutes. After some Googling, it looks like the 2nd one may be intended for the 60-minute mark.

Thanks again though! I'll definitely bookmark this one.