Help with IBUs: Partial Mash Recipe

“IBUs (Rager): 68.22

IBUs (Tinseth): 49.72”

One thing that I think should be kept in mind that the various hop utilization ‘calculators’ would be best termed as being “estimators”. You have determined results for the Rager and Tinseth versions of these estimators but there are others like Garetz, Daniels, etc.

There was a presentation at the 2014 NHC where they brewed beers and estimated the IBUs via a variety of estimators (Tinseth, Rager, one other) and then actually measured the IBUs of the beer and all three of the estimators were ‘off’ for this particular beer. All three of the estimators under-predicted the measured IBU value.

Given that it is not realistic to expect that an Hop Utilization estimator is going to provide an accurate answer to the beer’s IBU value, perhaps your thought of “Perhaps stick to the plan as is and go from there (i.e. stop over thinking it)?” is the proper course of action here.

Cheers!

 

if you bought a recipe kit and you haven't made it before, I would make it as-is the first time and see if it needs adjustments. Remember, if it ain't broke, don't fix it.

Any software made to calculate beer parameters is going to need to be tweaked to your system before it's going to be really accurate... i.e. "dialing in" your system to your software. Have you done this yet? For instance, it took about 4 batches before I had beersmith giving me numbers that were reproducible within 1 or 2 points. The first batch I was off by 10 on the OG.

And I would just use tinseth all the time. I think most of us use tinseth and most of the talk here is probably tinseth, so it's just easier. But keep an eye if you get something like a kit and they're using different units (and obviously, you were paying attention on this one!).

 

According to the StrangeBrew software that I use, your gravity value is way off for 5 gallons, will be closer to 1.072, and the IBUs (Tinseth) will be about 64 assuming mid-range alpha acid for each hop (you did not specify the exact alpha). Then, using my own Taylor formula, I get 70 IBUs. So you're going to be in that ballpark, unless the alpha acid is much lower than average, especially for the Columbus boil hop -- my calculations assume about 13.5% alpha for the Columbus. For insurance, you could simply add another quarter ounce hops to the 60-minute boil and you might be just fine, or maybe just change your 15-minute addition to 30 minutes, something like that.

Cheers.