Beersmith Flame-out IBU's

[RunDadRun]

I just noticed while creating a new IPA recipe that Beersmith adds a positive IBU value for Steep/Whirlpool hops but not for flame out hops (entered as Boil hops for zero minutes). My understanding is that IBU's are a function of the Alpha acid (mainly), the volume of the hops, and the time spent being boiled or held above a certain temperature threshold. By my logic, hops added at flameout would be exposed to hot wort longer than steep/whirlpool hops and should reflect a higher resultant IBU.

Am I doing something wrong here? Or do i have a fundamental misunderstanding of what is going on here.

Maybe i am not supposed to enter the flame out as zero minute boil?

Thanks for the help.

 

[Gnomebrewer]

It's all an inexact science. If you add whirlpool hops and keep the temperature near boiling, you'll extract some bitterness. If you add flameout hops then immediately begin chilling, you'll extract very little bitterness. You can change those numbers in beersmith (I have steep/whirlpool additions set as 0 IBU contribution because I do it at 80C, which should extract very little bitterness).

 

[rupert130]

I believe that the BS software is set to assume a 0 min addition involves immediate chilling and steep/whirlpool are added just after flameout and allowed to cool naturally. This accounts for the added IBUs with steep/whirlpool additions. The software is extremely customizable, so get in there and have at it!

 

[Oginme]

It's all an inexact science. If you add whirlpool hops and keep the temperature near boiling, you'll extract some bitterness. If you add flameout hops then immediately begin chilling, you'll extract very little bitterness. You can change those numbers in beersmith (I have steep/whirlpool additions set as 0 IBU contribution because I do it at 80C, which should extract very little bitterness).

I believe that the BS software is set to assume a 0 min addition involves immediate chilling and steep/whirlpool are added just after flameout and allowed to cool naturally. This accounts for the added IBUs with steep/whirlpool additions. The software is extremely customizable, so get in there and have at it!

These two posts describe it in spades.

I use 0 minute boil hop additions when I am moving directly from the stove to chill (basically, less than 1 to 2 minutes). For any end of boil additions where the hops will end up steeping for more than that, I change the hop addition to represent a whirlpool/steep.

After changing a couple of recipes from 0 minute additions to steeping for 20 minutes, I lowered the hop utilization for the whirlpool/steep to match what my perceived bitterness from that addition gave me.

In the end, the IBU calculations represent a model based upon one person's system and set of experiments. While I think a model such as Tinseth's is pretty close, I am under no illusion that the number calculated is exact, or even under certain circumstances close.