Question regarding hop IBU's using BeerSmith Software

Hello guys (and maybe gals),
I've got a fundamental question regarding the BeerSmith software and it's probably something simple. My issue is in calculating the IBU's for different recipes I'm putting together. Okay, here's some quick background regarding my setup. For now, I'm simply extract brewing. I use a 5 gal pot with a total boil volume of about 5 gallons. I just brewed a pale ale utilizing 2 oz. of Chinook hops at about 11.0% AAU for a 60 minute boil. I finished with 2 oz. of Cascade hops at 5.4% AAU for the last 3 minutes of the boil. When inputing this info into my BeerSmith calculator, it tells me that my total IBU's is 169.5! Is this possible? I tasted the beer prior to bottling and while it was bitter, it wasn't off the chart bitter for an IPA style. As a point of reference, Sierra Nevada Pale Ale is supposed to be around 37.5 IBU based on info from their website. The beer I made isn't 4 times as bitter as that.

I'm creating a lot of independent recipes and for reference, I just want to know if I'm getting my IBU's right. I realize there are a few different methods of calculating IBU's but I just feel like I must have a setting wrong in the software.

Can anyone shed any light on this? Your feedback is greatly appreciated.

Roguedog said:

I use a 5 gal pot with a total boil volume of about 5 gallons.

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Five gals in a five gallon pot would likely boil over.  Check that one?  Boil volume affects boil gravity which drives utilization formula. 

Roguedog said:

I just brewed a pale ale utilizing 2 oz. of Chinook hops at about 11.0% AAU for a 60 minute boil.

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Two oz. of 11% for 60 mins is pretty high IBUs.  I got 72 Tinseth and 100 Rager using both hop drops you listed. 

Roguedog said:

...my total IBU's is 169.5! Is this possible?

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Sure, the IBU is just a calculation based on what we enter.  I entered a full pound of Chinook and got 751 IBU's calculated.  No telling what would actually happen in that pot though. 

Post your recipe file for more specific help;  people could download it and look for the settings issue that way.

Thanks for the reply Maltlicker. I meant to say that I use a 5 gallon pot and boil about 4 gallons max. It sounds like based on your calc's, the hop utilization percentage that I'm getting may still be a tad higher than actual. I will try to tweak the program to get more inline with the numbers that you got.

My recipe is as follows:
6 lbs. of pale malt extract
1 lb of light dry malt extract
8 oz. carapils malt
8 oz. crystal 15L malt
2 oz. Chinook Hops (11%) for 60 minutes
2 oz. Cascade Hops (5.4%) for 3 minutes
Wyeast American Ale #1056 yeast

I actually sampled the beer tonight and while it was bitter, it was pretty well balanced and very good. However, for future recipes, I would like to have a more realistic idea of what my IBU's are. Thanks again.

Roguedog

I know this doesn't answer your question, you might consider adding the Chinook in two stages, about .75 oz for 60 min, and the remaining 1.25oz for 15 min. You wouldn't believe the fantastic  flavors they will impart with a late kettle addition instead of a full 60 min! And the bitterness will still be strong and balanced. Keep you Cascades at 3 min, although adding them at 10 would add a LOT more nose.

I am assuming that even tho you boil only 4 gal, you add water to make a 5g batch, and if so my calcs are that you should end up with appx 80 lovely IBUs.

( I am also assuming that your extract is UNhopped)


BTW: I didn't get the same results when I plugged you recipe (above) in ....... so SOMETHING must be awry in your settings somewhere.

I made a pot profile fitting what you said, and got ~63 IBU; certainly drinkable. 

Increasing from 6# DME to 7# DME reduced IBU by 7, the gravity effect reducing utilization.  I'd also recommend you try first-wort hopping, which with extract would be soaking some hops with the specialty grains I guess.  Soaking hops at ~155F mellows out the flavor and creates compounds that are less volatile and do not boil away as easily.  IBUs are similar but not as harsh.