IBU Changes

[rodwha]

I had used the Hopville brew calculator, and from what I had read, using a small amount of extract in the beginning of the boil increased the hop utilization. I've since read otherwise, and notice that the Brewtoad calculator, which took over Hopville, doesn't make changes for this.

If this is so then I could do a partial mash with my grains in one pot (~5 qts) and deal with the rest in my 5 gal pot and combine these instead of using top off water (which I kinda liked how it helped drop the temp faster) without needing to make any changes, correct?

Why has it been proven to not be the case (better utilization)? What made them think it did?

 

[ncbrewer]

From what I have read, there is a difference in opinion as to whether boil gravity affects hop utilization. For example, a podcast experiment http://www.basicbrewing.com/index.php?page=basic-brewing-radio-2010
with Better Brewing Radio and Brew Your Own teaming up, concluded that for extract beers, boil gravity does not affect hop utilization. But a 2013 BYO article http://byo.com/departments/item/2401-dry-hopping-continual-hopping-mr-wizard
states that “In general terms utilization increases as wort gravity goes down”. Same magazine, opposite opinion. I’ve seen several other examples of expert opinions on both sides. I’m just hoping it gets resolved soon.

 

[rodwha]

I figured up a change in recipe for a kit a friend got, and we worked up what the IBU's ought to be when using the bulk of the extract at the end, and he felt it was way under what it was supposed to be, which has made me wonder. I've also had some that I thought may have been a little shy myself, but I have no way to know exactly what say 30 IBU's with a hop schedule such as mine would actually be.

Thanks for those links!