Bitterness from steep hops (with Wheeler's Beer Engine)

[kebabman]

In recent discussions regarding dry hop steeping I note that some bitterness does come from steep hops. I use Graham's Beer Engine for recipe formulation and so was wondering if anyone could help me out regarding what I could put in to simulate the bitterness than you get from post boil additions. For my latest brew I added a lot more steep hops than normal and the beer has turned out a little too bitter but it was a previously untried recipe so just may be too bitter overall .
I was thinking whether the IBU's that you get from say the last minute or two of boil time would give the same IBU addition as from an 80 degree steep for half an hour? So I could enter some hops into Beer Engine say 2mins from end of the boil to give a total IBU figure but making a note to self that they represent the steep addition.
Any thoughts anyone please?

[soupdragon]

Unless Graham knows different, the hop boil times are in 5 min increments. It would be helpful to have 1 min adjustments but that's up to Graham, if/when he updates Beer Engine......

Cheers Tom

[Dr. Dextrin]

You'd have to form an opinion on what the utilisation rate might be for post-boil hops. Then you could add a fictitious quantity of hops to Beer Engine during the boil (at 90 mins even) to simulate their bittering effect.

I think the first bit is the tricky bit.

[kebabman]

the hop boil times are in 5 min increments.

whoops, yes you are quite right, I had overlooked that problem!

Does anyone have any info as to the likely utilisation from steeped hops please?

[Tinkerer]

I remember (from the dim and distant past) a rule of thumb that reaction rates generally double for an increase of 10 degrees C. So an 80 degree C steep should see the isomerisation rate drop to about a quarter of that at boiling. So a 30 minute steep at 80 C would be similar to 30/4 = 7.5 minutes at boiling. Also, the temperature will be dropping all the time, so maybe putting your steeping hops into Beer Engine as a 5 minute addition would be not too far off the mark. My feeling is that it wont be a big effect unless you use silly amount of hops for steeping.

[kebabman]

Cheers Tinkerer, looks like a trial like you suggested is the way to go, especially as we have to stick to 5 minute increments in Beer Engine.
Does any of the other brewing software have a facilty for steeped hops?

[Bobba]

Cheers Tinkerer, looks like a trial like you suggested is the way to go, especially as we have to stick to 5 minute increments in Beer Engine.
Does any of the other brewing software have a facilty for steeped hops?

Beersmith allows aroma steep hops but does not add any ibu for those additions

[kebabman]

Bobba, thanks for letting me know.