As some of you know, I've been working a bunch over the past couple months to put together spreadsheet to help determine what the present AA value of hops are at, given AA at testing, time, storage temperature & conditions, etc. Remember that all hops' AA drops over time, some more than others. Have made a bunch of progress, and have learned a lot...but have some uncertainties yet. Here is a link to that conversation for those interested. http://biabrewer.info/viewtopic.php?f=150&t=3637" onclick="window.open(this.href);return false; Have expanded greatly above & beyond the spreadsheet at the above link. The updated file is not posted yet, and not sure if/when I will... Want to make sure it is something easy to understand and that it for sure is more help than hindrance. Even if I hit the IBU numbers on exactly, it doesn't mean the adjusted hop AA estimate was exact. (Perhaps the Tinseth formula could be "off" slightly as well...).

Sample 1:
Dry Irish Stout
Brew Date: 22 April, 2016
US Goldlings Hop IBUs were NOT Adjusted.
IBU (Tinseth Estimate): 37.1
Actual IBUs Tested: 30 (+/- 1)
Sample 2:
German Inspiration American Pilsner - Santiam Hops
(Great Northwestern Pilsner Malt, Magnum & Santiam Hops)
Brew Date: 7 May, 2016
Hop IBUs on the Santiam's were "guesstimate" adjusted...knowing they seemed low, multiplied IBU by 2/3. Magnum bittering hops not adjusted.
IBU (Tinseth Estimate): 39.0
Actual IBUs Tested: 31 (+/- 1)
Sample 3:
Vienna Lager
Mt. Hood flower hops both for bittering and aroma...
Brew Date: 17 May, 2016
Hop IBUs WERE adjusted per the formula... Finished good but too bitter for the style... 18-30 IBUs are the goal per BCS book.
IBU (Tinseth Estimate): 23.7
Actual IBUs Tested: 31 (+/- 1)
Sample 4:
German Inspiration American Pilsner - Liberty Hops
(Great Northwestern Pilsner Malt, Magnum & Liberty Hops)
Brew Date: 4 July, 2016
Hop IBUs for Liberty & Magnum WERE adjusted per the formula.
IBU (Tinseth Estimate): 39.0
Actual IBUs Tested: 38 (+/- 1)
I brewed the two pilsners which are similar... Just racked the Liberty into keg on Saturday, and that's when I took the samples. Wanted to see if I could make good pilsner with our "local" pilsner malt, and wanted to be able to compare Santiam vs. Liberty hops. Also though...the Santiam I did with an infusion mash, and Liberty got to do a step mash along with mash out. Malt base seems to taste better with the Liberty... Liberty isn't carbonated fully yet but first post fermentation taste I liked the malt base taste better (maybe / probably because of step mash / temps).
The laboratory IBU testing was an interesting exercise. Will likely do it again, but certainly will not be an "all the time" thing...
Adjusting Hop AAs - Efforts & Thoughts:
At this point I think the file is of value and have spent a ton of time on it. BUT...you have to know when the hops were tested, along with storage conditions, etc. Or at least enough to make some "estimated guesses" - plural, and this is still better than just listed the AA on the package. Another thing related that would be interesting - purchase a large enough batch of hops to get them tested to help "prove" the formula (AA Loss Over Time). I'm sure it's not perfect and there will be a range. AA loss will likely vary year-to-year, and finished beer will likely drop IBUs too over time, depending on storage condition.
I was discouraged initially that the Vienna was noticeably a little too hoppy - my formula input data resulted in my overhopping my beer. Likely had some wrong input information... Lab results confirmed this, IBU level at the outer range of the style, but the beer still tastes good...
By the way, I'm not under any illusion that this Formula I've been working with and compiling will be a perfect science... We use IBU estimates in our BIABacus files along with other data, right? Why do we do this? Aren't we trying to be as scientific as possible to closer scale existing recipes and also to be as "Consistent" as possible with our brewing? (It's a good help to guide our brew day as well...). Yes, it's going to be hard to be perfect but we're trying to get it as good as possible. This hop AA loss spreadsheet is meant to get the same result - help provide a more accurate "AA loss over time" estimate, and help guide to a more accurate estimate.