Hop Question

[ECH]

Planning my first brew of the year (getting a late start, but been too damn cold in my garage).

Just doing a simple IPA with Chinook for bittering, and Centennial late in the boil. Designing it in Beersmith.

All the hops are leaf, the Chinook I grew myself, the Centennial I got from someone that was ripping out the plant (unfortunately I didn't get there in time to get the rhizome)

When I enter 2oz of Centennial at 10 mins, I get about 22IBUs, however if I put another 2oz in as a steep/whirpool it is nearly 40IBUs.

First I have seen this as I never get much for IBUs on late addition hops, and usually just get the aroma and flavor.

I feel like I am missing something as to why it is throwing the IBU calculations out of wack.

Keep in mind I have no idea what the alpha acids are in either of these, and just going by what is default on Beersmith.

[robcoombs]

I learned recently that the hop utilization calculations are off quite a bit for steep/whirlpool additions. Having said that the hops will continue to isomerize (?spelling) as long as the temp is kept above 170-180F. So yes it will contribute to IBUs but not as much as BeerSmith is telling you.

I wouldn't worry too much about the IBUs since you don't know the AA%.

[ECH]

Yeah, can't imagine how you would get almost twice as much IBU out of a whirlpool addition than you would from the same size addition with 10mins left in the boil. Would have thought it would be half or maybe even 1/4 what it would be at 10mins.