Re-using a dry hop in a second beer?

[Wynne]

I took them out of one brew and put them straight in the new brew with a additional new dry hop for that brew. I can taste the old hops as they were a different hop combination in the second beer and I would say no noticeable extra bitterness from the re-used hops.
Ps the re-used hops were a 100g dry hop

Please would you describe the point in the brewing process and the timing of your used hop addition?

 

[The Baron]

I Dry hop after 4/5 days as the most vigorous fermentation has stopped and it is slowing down/cleaning up. I then added the dry hop from the first brew which I had timed to coincide with roughly 4/5 days of fermentation on the second brew then added the new dry hop into the same bag as the old dry hop and added it to the second brew. As I have said the beer seems no more bitter than I expected but i can detect the flavours from the first dry hop so yes I seem to have get something extra out of them

 

[Wynne]

I Dry hop after 4/5 days as the most vigorous fermentation has stopped and it is slowing down/cleaning up. I then added the dry hop from the first brew which I had timed to coincide with roughly 4/5 days of fermentation on the second brew then added the new dry hop into the same bag as the old dry hop and added it to the second brew. As I have said the beer seems no more bitter than I expected but i can detect the flavours from the first dry hop so yes I seem to have get something extra out of them

Thank you, that’s clear. I would expect that you would extract bitterness only if you added the re-used hops early on in the boil. Hop alpha acids have to be boiled to make them isomerise (change molecular shape) and become soluble in wort. I would expect hops used for dry hopping to have their full content of alpha acids. It is interesting that you extracted more hop flavour when re-using dry hops in your beer.

 

[The Baron]

Thank you, that’s clear. I would expect that you would extract bitterness only if you added the re-used hops early on in the boil. Hop alpha acids have to be boiled to make them isomerise (change molecular shape) and become soluble in wort. I would expect hops used for dry hopping to have their full content of alpha acids. It is interesting that you extracted more hop flavour when re-using dry hops in your beer.

You would expect that but as usual in this hobby some boffins bring up theories that they try/or substantiate with some science but all I can tell you that if there was not any further bitterness extraction in this case at 19c, it was not noticeable to me and yes I think that at lower temps there is no noticeable AA extraction so I just benefitted in my mind from extra taste so maybe I could throttle back the second dry hop and save on the expensive American style hops in any further additions

 

[The Baron]

After the success with the first experiment of re-using a dry hop which turned out well drinkable with extra flavour and hardly any extra bitterness I have now saved a dry hop of Punk'd hops again and put it in the freezer. I have now taken this out of the freezer and dry hopped a Amarillo/Ahtanum IPA with this and the original dry hop of Amarillo and Ahtanum.
If this works I will be freezing more dry hops and cutting down on the expensive IPA hops from now on. Fingers crossed