Protein Precipitation in Bottled Absinthe

[Josh]

Hi all,

Our absinthe is building a small amount of protein solids after sitting in the bottle for a few weeks. The solids dissolve back into solution with a little agitation, but was curious if anyone else has had issues along these lines and what they did to remedy the issue. Our basic process is distill, botanical soak, course filter, rest in stainless, and then 1um filter in pre bottling. I thought the 1um PP filter would pull out these prior to bottling, but I was clearly mistaken.

We tested chilling the absinthe down in the lab to see if chill filtering would work, but it did not seem to cause proteins to fall out, at least in our bench trial.

If anyone would be willing to share their secrets on the matter, I would much appreciate it.

Thanks,

Josh

[SlickFloss]

How are you sure they are proteins?

 

How long is your initial rest?

 

At what point in time of your process are you proofing your spirit, with what type of water, and how long are you taking to do that proofing?

 

[nabtastic]

probably colloidal instability.  Pall filters may help (can't speak to your exact specifications).  It's also possible that your filters are getting overloaded - it may help to rack the spirit too.  Are they absolute or nominally rated?

[Josh]

Hi Slick and Nab,

Thanks for the responses. Yes, after some discussion with a local lab, it is likely colloidal instability, not protein precipitation. We are getting it tested now to identify the exact issue. The final filter is 1um nominal, which could also be part of the issue. We monitor filter pressure pre bottling and it doesn't look like it's clogging/slowing down in any way, but it might be worth investing in some absolutes for this process. I will check out the Pall filters once we hear back from the lab. We also have Scott Labs in town, who work with the lab company (ETS), so maybe they might also have a solution. This product has definitely given us the most headache of all that we make. All part of the fun I guess!

Another distillery in town owns a Rosedale Products basket filter, with a 6um basket, so we might add that to the process to see if we can't do a little better job lautering the solids away after our botanical soak.

I'll try to respond to the thread once we resolve the issue to share our results.

Cheers,

Josh

 

[bluestar]

Missing info: you are also distilling with botanicals, correct? How neutral is the base spirit? And then extracting with more botanicals, after distillation (typical 2 step for absinthe verte)? What temperature are you running the extraction? Are you using dried or fresh herbs? I wouldn't expect much from the traditional herbs for the second phase extraction: pontica, lemon balm, and hyssop. Are you using something unusual? A root or seed extractive might be more likely to have issues, but this would normally be in the first phase, not the final extraction. Oh, and what proof, for all stages.