Calculating loss of AA in stored whole hops?

Is there any formula, other than flat-out guessing, for estimating what the drop in AA% is after whole hops have been in the freezer for a certain time?

I bag hops in 1 oz portions when they arrive, then put the 1-oz bags in larger freezer bags and put the whole thing in the freezer. I try to adjust what the AA% might be a month or two months later. Anyone have anything better to go on than just guessing?

Boy, I am not sure that there is a formula. I would guess, however, like most things it is a decaying exponential, or at least that would give you a ballpark. So I think most of your loss will occur in the short term, followed by a more gradual loss. It would be different for all hops. It would be temperature dependent. It would also be dependent on the air infiltration. I would also imagine the rate of oxidation would be affected by the compactness of the cones, moisture content, etc. I am just guessing though.

There is something wrong with "AA" in a posting on a brewers forum. "Hi, my name is BP, I make beer..."

Promash will calculate this for you (given months and temperature), but I'm not sure which formula they're referencing.

If the hops are frozen, there will be very little loss. You can get some idea by looking up the hop here http://www.freshops.com/usda_hop_desc2.htm, but most of the time they just say poor, fair, etc. and the ratings are for room temperature.

STORAGE STABILITY: very good, 30% transformation after 6 months room temperature storage.

Another joker in the pile, high beta acid hops will balance out the decline of the alphas by the betas becoming more available.

I have some Columbus pellets (I bought 2 pounds) in the freezer that are 18 months old & I haven't noticed any change.

Age decay will be most of the problem, but you can eliminate the air infiltration side of the equiation by using a FoodSaver to vacuum pack them. I have one of these that I use for long term meat storage and I also use it for hops to keep them relatively fresh when I buy a large quantity. They can be had for well under $100 and you can get the accessories for drawing oxygen out of wine bottles and the cannisters for marinating meats work great.