whirlpool hops

[Riot]

I,m trying to make something similar to Wychwood's King Goblin, and after listening to the Wychwood can you brew it episode I am wondering how to apply whirlpool hops on my system. It takes about 90 minutes to cool to pitching temps, as all I have to work with is submersion in my basement utility sink. How should I handle that with a 10-15 minute delay between bringing the kettle in, and it dropping to below 140. I'm also somewhat confused on how to calculate IBUs, having read conflicting things on the subject. Thanks to anyone who can help.

 

[bmcwood]

I believe hop isomerization drastically drops off after 175F, could be wrong though. Check this out: https://www.homebrewtalk.com/f39/what-temperature-do-hops-add-bitterness-256406/
I personally wouldn't worry about the 15 minute delay, just throw them in at flame out and chill as fast as you can. Good luck!

 

[Riot]

Should I just figure no bitterness at flameout, cool immediately and add a large10-15 minute addition?

 

[bmcwood]

I think you will probably get some additional hop bitterness, it's just going to be really hard to accurately measure. You might want to try putting the recipe into BrewToad, http://brewtoad.com, and see the IBU's. This might help too: http://www.howtobrew.com/section1/chapter5-5.html

 

[Riot]

I feel like every software measures it differently. I've seen anything from 0 to 20 ibus from a 35 g whirlpool addition. I don't want it to be overwhelming, but I definitely don't want it too sweet. This is going to be a malty brew.

 

[Riot]

Just finished the boil, ended up adding about another ounce at 10 min. If it comes out too hoppy it can mellow in bottles for awhile.