Reusing dry hopping hops AA calculation

[matth]

Just a quick question,
I have brewed a few beers using hops that I had previously used for dry hopping in as the 60 min bittering addition. These have worked great but my calculations are just nock of a percent or 2 from the alpha acid for ibu calculation - this has got me roughly near. I'm sure I have read somewhere before a calculation to use for this but cannot find one, does anyone use a calculation? Ie percent reduction of aa or anything. Or is there another approach others use?

Cheers

 

[Brewberoza]

This all sounds new to me.

Are you assuming that dry hopping strips all aromatic compounds but leaves AA untouched so you can go off what it says on the pack? What hops are you using?

I admire your recycling of hops but remain skeptical. How did you measure IBU?

 

[Stone Cold]

I have been wanting to try this as I'm using more hops in dry hopping than i am for bitter hops. have you found any info on net?

 

[matth]

This all sounds new to me.

Are you assuming that dry hopping strips all aromatic compounds but leaves AA untouched so you can go off what it says on the pack? What hops are you using?

I admire your recycling of hops but remain skeptical. How did you measure IBU?

I am nota assuming that all aroma is stripped, but certainly most - my question is "how to calculate IBU?"

I have dine this a few times and it works for bittering but I do not know of a way of calculating how much alpha acid is lost during dry hopping.

Because I dry hop in a grain bag I can strain off any left over liquid and freeze the hops, remembering what their dry weight was for future reference. I have used both American and British hops for this including Calypso, Amarillo, Boadicea, EKG, Fuggles, Challenger, citra etc. my calculations so far are pretty basic - I just knock off a percent or 2 depending on how strong AA is - for instance if I used 10g fuggles at 5.4% AA, then to reuse for bittering in a future brew I would calculate 10g at 4.5%AA and dump them I at 60 mins.

The bitterness is not too far off, but I am no expert on IBU levels

I have been wanting to try this as I'm using more hops in dry hopping than i am for bitter hops. have you found any info on net?

I am sure I found something a while ago, but can't remember it or refind it. The search terms make it almost impossible to find it amongst lost of stuff about dry hopping.

It just seems to make sense to reuse hops when there is still something of use left in them.

 

[Dr Mike]

AIUI, a lot of the alpha acids are extracted from dry hops, it's just that they are not isomerised so don't contribute bitterness to the beer.

 

[matth]

AIUI, a lot of the alpha acids are extracted from dry hops, it's just that they are not isomerised so don't contribute bitterness to the beer.

Thanks, i just wonder how much AA is left to use for bittering?

I have found this, but again seems more of an art rather than a science;
http://www.homebrewtalk.com/f13/reusing ... ng-430225/

Stonecold - if you brew certain types of beer regularly commercially then i suppose as long as you use the same weight and addition time each time then you'll be fine - should certainly save you a few pennies! Nice brewery by the way, i'll have to track down your beers to sample some!