Hey Guys,

I'm sure this has been addressed before but I couldn't find an answer by searching. The recipe I want to brew calls for a hop stand with 57g of 10.3% AA Centennial, starting 10 mins after flame out and steeping for 20 mins. I'm not sure how this should be entered in the BIABacus especially regarding target IBU calculation.

Thanks,
Steve

Steve, you can enter them in the hops list and put dh in the time column. The BIABacus won’t increase the IBUs for dry hops.

There’s data points not specified that can make a difference, At 10 minutes after flame out, what is the wort temperature AND what does the temperature ramp look like? In other words, how fast is the temp going down after flame out?

Isomerization to bitterness contribution is time and temp dependent. Above 75 degrees C, it happens, below 75 the rate is negligible. If after 10 min post FO the wort is 95 degrees C and you add hops then get down to 75 degrees in the next 20 minutes, it could be (depending on other stuff) like a hop addition at 10 min left in the boil*. If, instead of adding the hops at 10 min post FO you add them at 75 degrees, there will be lower probability of any increasing bitterness in IBUs. It’s part of the art and what you want to get in your beer.

* Assuming an immediate and rapid cooling to 75 degrees C follows...

This is a Gordon Strong recipe from Modern Homebrew Recipes so I went back to have a look. I now see that he is talking about adding the hops 10 mins after knockout. I've not done this before so I did some googling. If I understand correctly, a knock out hop addition means adding the hops and chilling at the same time, therefore, adding more hop flavor without more bitterness. The underlying assumption is that it takes like 20 to 30 mins to chill with a standard immersion chiller. Ironically, I just upgraded to a Jaded tri-coil chiller, which cools from 212F to 90F in like 6 mins. So I need to use my old chiller to do a knockout hop addition? Think I'll just do a straight dry hop.

In any case, I learned some new things about isomerization so thanks for the great feedback, ShorePoints!

Happy to help.

It’s a reminder about “recipe integrity” discussed elsewhere on this site. https://www.biabrewer.info/search.php?k ... Integrity+ The variables in play during a brew day seem innumerable and any data that could make a difference in the outcome (beer) should be included.

I am working toward using my Inkbird temperature recorder to eventually give a time / temp graph that has tick marks for when things changed. eg. stirring mash, end of mash mashout period, pulled bag,, hop additions, FO, post knockout additions, transfer from kettle, pitch time & temp and lastly, the whole fermenting track record.. don’t hold your breath, I am almost halfway there. If ingredient weights and AA% are honest, I think it would make a recipe record pretty useful.