Old Hops AA Calculation

http://brewerslog.appspot.com/HopAlphaCalc

Hello,
I am always annoyed when I have to calculate my hop additions based on AA differences and to top it off, I have some hops that are around a year old now that I am brewing with. There are some other calculators out there that can be used together to meet this need, but I wanted something easy all in one place.
I created this calculator to allow you to:

• Find out the Alpha Acid value of your hops based on their type, age, and storage factors.
• Have a list of the amount of hops for each addition for your brew based on the required amount of hops and AA in relation to your hops actual AA

Please leave feedback here or with the feedback tool on the site. I have only done a bit of testing and think it is pretty useful and working well. I believe the calculations to be accurate and only have possible concerns with the interface. It currently will save (locally to the browser) your current list of hops so a refresh or browser restart won't lose your data. Amounts are in any measurement.
Let me know what you think.
Thanks.

Sounds great!



Erm...where is it?

MalFet said:

Sounds great!



Erm...where is it?

Click to expand...

Boy you just want it all! hehe Updated my original post sorry..

garcara said:

Boy you just want it all! hehe Updated my original post sorry..

Click to expand...

Looks great! Thanks for making and posting!

Old thread revival... nice work! I am interested in the math behind these calculations. I pulled some of your .js to take a peek. Did the equations come from the forum here or from a book?

I am also curious of where the data comes from that were used for this calculator. As far as I can tell, this is the same calculator that is used in BeerSmith. I've been looking for studies on how hops age for the Milk The Funk Wiki. I've only been able to find two studies that have looked at this in much depth:

http://onlinelibrary.wiley.com/doi/10.1002/jib.40/abstract
http://www.actahort.org/books/1010/1010_26.htm

I've written a summary of them here: http://www.milkthefunk.com/wiki/Hops#cite_ref-Miky.C5.A1ka_2012_31-0

Can anyone please share the references for which this Hop Age tool is based on?

Thanks and cheers,
Dan the MTF Wiki guy

UPDATE: I believe that I've found the source of the calculator here: http://www.morebeer.com/brewingtechniques/library/backissues/issue2.1/garetz.html