IBUs - BeerSmith (pure fiction)

[m1k3]

I have a "on tap" monitor that I display next to the kegerator. It use to have a field to display the IBUs of the beers but I removed it. The number of calculated IBUs is so far off that it's not a helpful descriptor of a beer. Sure I'll still use BeerSmith to calculate my IBUs for bittering additions when I'm building my recipes but without having a beer tested at a lab the number is helpful for a finished beer. I can even taste a huge difference when I put a beer on tap and as it ages.

Not bashing Brad... or BeerSmith. I think it's just the nature of bitterness calculations.

It doesn't help that I made hoppy beers with lots of late/whirlpool/dry hops.

 

[Oginme]

BeerSmith uses standard available models for calculating IBU values (Tinseth, Garetz, Rager). When it comes to calculating IBU values from whirlpool additions, there is presently a very small amount of modeling which has been published. The only way to know how accurate a model is to your process is to have some of your beers tested.

When people constantly requested that Brad add this calculation before the next big upgrade (which is currently being finished and in beta testing), he added the ability to adjust the utilization factor in the 'options' under the 'bitterness' tab.

As far as the bitterness changing over time, this is a known factor, especially with highly hopped styles. This is one of the reasons that a lot of commercial DIPAs recommend that they be consumed shortly after being shipped.

 

[pricelessbrewing]

As far as I know, there really aren't any accurate formulas for IBU.

Tinseth' testing was done in a closed container, so volatilization is not accounted for and neither is changing gravity throughout the boil. Wort was cooled immediately, so hop stands and chilling after flame out isn't really accounted for at all. However the biggest issue is that fermentation lowers the ibu and dry hopping contributes some ibu as well (see scott janish' blog post on the subject).

Brulosophy has submited ~3 exbeeriments to have their IBU tested, each time tinseth has been higher by 20-35%. IIRC garetz has been the most accurate so far, but was substantially off when the calculated IBU started to exceed 70 IBU.

Beersmith 2 uses a modification of tinseths formula, where it takes the average of the preboil and postboil sg, since tinseth used a closed container, there was no change in sg.

Until somebody comes up with a better formula, just stick with one and realize that it's going to be off if it's high ibu.

 

[55x11]

I have a "on tap" monitor that I display next to the kegerator. It use to have a field to display the IBUs of the beers but I removed it. The number of calculated IBUs is so far off that it's not a helpful descriptor of a beer. Sure I'll still use BeerSmith to calculate my IBUs for bittering additions when I'm building my recipes but without having a beer tested at a lab the number is helpful for a finished beer. I can even taste a huge difference when I put a beer on tap and as it ages.

Not bashing Brad... or BeerSmith. I think it's just the nature of bitterness calculations.

It doesn't help that I made hoppy beers with lots of late/whirlpool/dry hops.

Please clarify. The IBU count is "so far off" compared to what? Your own IBU perception?

You taste a difference as beer ages - again, using your taste buds? You are talking about IBU, not hop aroma, right?

 

[pricelessbrewing]

Tinseth is far off from every lab testing I've seen done.

For me, I note the calculated IBU but label if according to taste:
Not bitter
Slightly Bitter
Moderately bitter
Bitter
BitterAsF&$*