I have a question concerning Alpha Acid levels in hops. I’ll be making Jamil’s Cali Common recipe from Brewing Classic Styles in a couple of weeks and as I was putting the recipe together in BeerSmith to make adjustments for my system, I noticed that the AA levels in the Northern Brewer hops in recipe were 6.5%, and then noticed that the hops I purchased were labeled as 10.6%. This cut the amount of hops I need by roughly a third (Glad I checked! My beer would have come in at 62 IBUs instead of 42), but I was wondering if it is common for these percentages to vary so widely. I always thought that the percentages were generally within one or two points across the board for a given hop variety - apparently this is not so?
The acid content will vary from year to year, crop to crop. Beersmith has a default percentage assigned to all its hops but you may have to adjust it to match your hops. The northern brewer hops I got last year were around 8.5.
I learned to watch out for this when mine were actually significantly lower than listed in beersmith. Beer wasn’t bad, but could definitely used more of a bittering addition.
Hops usually vary by a few percent, Northern Brewer hops are listed in the NB catalog as being in the 8-10% range. You definitely want to check that, although honestly you’re looking at a test that was done on some bales of hops and so theres variation as well as storage conditions that could make what you are brewing with somewhat different. I don’t count on it being all that exact.
