Blandy, I hope the IPA came out well.
Thanks to all for this educational and informative thread.
I haven't made a single batch of HB yet, so I am certainly no expert, but I'd like to offer my opinion for anyone who cares. When I was reading John Palmer's book, I got the impression that IBUs were a standard of sorts. (Sure, the IBU calculation is only an estimate; after all, few or none of us are chemists, and we want this to be a relaxing hobby. If we wanted it to be complicated, I'm sure we could come up with some nice, chewy differential equations, but simplifying the math is what charts, and especially computers, are good for.)
As I read this thread, though, I get the profound impression that there really is no <i>standard</i> at all in the true sense of the word. The various IBU computation methods mentioned in the following quote yield some pretty significant differences:
chris. wrote:(from
http://brewingtechniques.com/library/ba ... iller.html)
...
One of the first IBU formulas for amateur brewers that I know of was published by Byron Burch (4). This formula predicted an IBU level of 45.6 for the HBD Palexperiment beer. Jackie Rager's seminal work, which has formed the basis for many subsequent efforts, estimated an IBU level of 53.5 (5). Greg Noonan's well-regarded methodology predicts 56.9(6). Mark Garetz's popular formulation, which he based on Rager's work, gave 41 IBUs (7).* Glenn Tinseth's approach, which makes very different assumptions than the other commonly-used formulas, generated an IBU level of 48 (8 ). Ray Daniels' approach, which uses the basic Rager formula but with separate and more comprehensive utilization charts for whole and pellet hops, predicted that the IBU level would be 67.9 (3). But the top place in the HBD Palexperiment IBU sweepstakes goes to a fiendishly simple little device created by Randy Mosher known as "Dr. Bob Technical's Incredible Hop Go Round" (Alephenalia Publications, Seattle, Washington). This slide-rule device estimated the IBUs for the beer in question at 61.# (The Palexperiment hopping schedule is shown on page 21.)[/i]
http://brewingtechniques.com/library/ba ... onham.html
Wow...on the low end, you have 41 IBU, with 67.9 IBU on the high end. That wide a variance in beers would be quite perceptible to the taste buds, I'd think. How is someone going to know what kind of IBU to expect from a recipe, given such a broad spectrum of possibilities, unless the IBU estimation method (e.g., Tinseth) is known?
Most of you blokes are really experienced, but I'm not. For just a minute, forget everything you know about IBUs, software, books, etc. Pretend that you're a first-time brewer without brewing software and aren't aware of, or don't know how to use, an IBU calculation chart. You want to brew an ale with an IBU of approximately 35-40. Sierra Nevada's website says its Pale Ale has "37 bitterness units". They've probably used some sophisticated equipment to arrive at that value, whereas a homebrewer must perform an estimate. Anyway, you find a recipe, here or elsewhere, that says it should yield about 40 IBU, or has a computer printout attached that says 40 IBU. So, you reckon that this recipe, particularly the hops portion of this recipe, might work for you, if your utilization is representative of what is to be expected given your boil volume, boil gravity, how long you allowed the hops to boil, etc.
But wait...whose IBUs are those? If I'm understanding the problem correctly, if those are Rager IBUs as opposed to Tinseth, you might end up with an ale that's less bitter than you hoped.
Now I realize in the grand scheme of things, topics like war, world hunger, global warming, etc. are infinitely more important. And I'm sure that the beer I brew is probably going to be drinkable no matter what. But I would like to know whether the recipe I'm wanting to use should, within reason, be expected to deliver the approximately 37 IBU that I am hoping for. It seems to me that without standardization in the methodology and without knowing whose method was used in estimating IBU, there's no real way to know.
I wish that the HB community could and would decide upon an IBU calculation method as a standard and adhere to it. But from what I've read here, that doesn't even sound possible given the methods we have. E.g., the Rager method appears to be better suited to a concentrated boil whereas the Tinseth method is better suited to a full wort boil. Deciding upon one or the other as an <i>international standard</i> (which I thought was what the IBU was supposed to accomplish) would yield more accurate or less accurate estimates depending on the type of boil.
I'm sure I am pontificating over nothing here. And I certainly do not wish to impugn the good work of some well-intentioned and obviously very intelligent gentlemen, in arriving at their various IBU formulae.
But anyway, does anyone know whether in the HB community, there is a movement toward coming up with a unified standard?
