Using older hops

[BadWolfOregon]

I was just given a SIGNIFICANT amount of older hops by a friend. They are all around 4 years old, but are all securely vacuum sealed and been stored in a freezer the whole time.

Should I be making any adjustments to recipes if I'm using them? Are there any rules for how much hops degrade over time?

 

[jimdkc]

Here's a hop aging calculator:

http://brewerslog.appspot.com/HopAlphaCalc

There's also one built into Beersmith.

General rule of thumb is to replace hops that have lost 50% of their original AA value...

Note that different varieties of hops age at different rates, so be sure to do separate calculations for each variety.