Isomerization as temps drop...is.it on/off or a gradient?

[Hwk-I-St8]

I did my first winter brew on Friday and had a bit of a snafu. If I'd known how long it would take to chill I'd have made a mid brew change to the recipe. I had ordered a pond pump from amazon prime that was supposed to arrive Thursday but got delayed. Mail usually comes by noon so I timed my brew to finish the boil around 1pm. We had a big snowstorm so the mail didn't arrive until 2:30.

TL;DR:

Chilling my beer to 170 took way longer than expected. I had a large 5 minute hop addition and another large addition at FO. With the slowed chill, those hops were at high enough temps to isomerize longer than planned. I changed my recipe making those additions boil additions for the entire duration they were above 180. That shows an IBU of 160. Will it really be that bitter or does the rate of isomerization drop with the temp?

This beer will be much more bitter than planned, but will it be that bad?

The good news is that once the pump arrived, it worked very well.

 

[MrHadack]

Hello!

It's a curve. This link goes to a fairly in-depth study on it (though I cannot comment on its veracity, and I haven't read it all). Here's a quick chart from that page:

It seems to me that it would be very difficult to determine the actual IBU since you'd somehow have to work out how the temperature dropped over time. All IBU calculators I can find assume the temp is "boiling."

 

[Dcpcooks]

The last half bbl batch I brewed had 10 ibu’s at fwh and 90 ibu’s at whirlpool for 1 hour. Beersmith has overhauled the whirlpool hop calculations in the latest version because whirlpool hops are getting more popular and it wasn’t calculating ibu’s correctly.

As temps drop your extraction drops. The intensity of the extraction drops as well.

There are lots of opinions on what you extract as the temps drop. I use 170 as the cut off point where I get more aroma and less bitterness from a whirlpool addition.

You may want to read through this guys blog. It’ll answers some questions for you. It may cause a few more questions but that’s a good thing.

http://scottjanish.com/blog/


Short answer is you didn’t extract 160 ibus as that most likely exceeded the solubility capabilities of the wort. Lack of a boil also limited your extraction.

 

[Hwk-I-St8]

I figured it wasn't going to be 160, but I won't be surprised if it's double or more the intended 50. I get all my bittering from late hop additions so it was 3 oz at five minutes and 3 more at FO. Those were all above 170 for 20-25 minutes

 

[Dcpcooks]

What were the hops and what is the beer?

 

[mongoose33]

Hello!

It's a curve. This link goes to a fairly in-depth study on it (though I cannot comment on its veracity, and I haven't read it all). Here's a quick chart from that page:

It seems to me that it would be very difficult to determine the actual IBU since you'd somehow have to work out how the temperature dropped over time. All IBU calculators I can find assume the temp is "boiling."

Help me with this--it suggests that you can get about 90 percent of potential isomerization in about....zero minutes at 212 degrees? I'm struggling to figure out what this means. I'm trying to reconcile it with this chart, which suggests a much different time frame; what am I missing here?

 

[ncbrewer]

It's a curve. This link goes to a fairly in-depth study on it (though I cannot comment on its veracity, and I haven't read it all). Here's a quick chart from that page:

I just read that blog. It's great - thanks for posting.

 

[Hwk-I-St8]

What were the hops and what is the beer?

2 oz mosaic @ 5 mins
1 oz simcoe @ 5 mins
Same as above @FO

This was a NEIPA