[svejk]

I made a low gravity (~1.060) mead that finished below 1.000 and my intention is to carbonate it to about 3 volumes of CO2 to make it spritzy.  I have had it in a keg at 40F and 18PSI for about a month now and even though it is well carbonated coming out of the tap, it goes flat almost immediately. 

At first I thought it had something to do with the short serving line so I put some in a soda bottle with a carbonator cap and poured it carefully into a glass with the same results.

Is it possible that dissolved sugars in regular FG beers help "hold onto" CO2 and in the case of a super dry solution it outgasses more quickly?  Any other ideas why this would be the case?

[Jimmy K]

Dissolved sugars and more importantly, proteins, help it hold a head. But it should continue to bubble just like a cider or sparkling wine. A short serving line would have been my guess. Otherwise I'm short on ideas (assuming everything is properly clean). What size/length lines do you have?

[svejk]

Thanks for the reply.  I was just using a cobra tap with a 2.5 ft hose which was why I tried the soda bottle/carbonator cap method.  The lack of a head didn't bother me as much as the perception that it didn't hold onto the carbonation.  I'm sure there was some carbonation still in solution, but there were no bubbles being released once it was in the glass and I was hoping that the bubbling would increase the nose.

In my google searches I did find a few references to the same phenomenon, but no explanations as to why it happens.  I may play around with hose length and pressures to see if I can figure it out.

[klickitat jim]

Maybe drop temp to just bout freeze. I think I heard somewhere that most gasses stay in solution longer in cold.

[svejk]

That's worth a try.  I did find a couple more references to this phenomenon, and it appears that no matter what I try, I may be SOL:

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http://www.homebrewtalk.com/f30/carbing-mead-223537/

"My understanding (and as I am not very familiar with meads, it wouldn't surprise me to learn I was wrong) is that grape wine and mead both have a hard time keeping co2 in solution (ie you can carb it, but as soon as you open, a gush will spring forth and little co2 stays in solution). This is one reason that true champaign takes so long to make: the wine stays on the lees for an extended period of time. Something about the breakdown of the dead yeast fortifies the solution with a substance that helps keep co2 in solution."

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http://www.homebrewtalk.com/f30/force-carbing-dry-mead-175226/

"Forcing a wine to hold carbonation can be challenging to say the least. It's the only thing in wine/mead making that has made me upset enough to stand there cussing.

That's one reason that Champagnes get all that lees aging - the mannoproteins and other whatnot that are released as the yeast undergo autolysis help hold CO2 in solution. You can either do lees aging, or you can use a big dose of a product like biolees and that may help. I've read that gum arabic also can help - I just got some but haven't tried it yet."
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My hunch is that there is some other factor that I'm bumping up against.  I guess I should have paid more attention in Physics and Chemistry classes...

[klickitat jim]

Interesting! My only experience/ knowledge on the subject come from NAUI. But I'm sure the human body and nitrogen are different that CO2 and beverages.

[svejk]

I guess I should be glad that my issue isn't regarding diving since those stakes are much, much higher!

[Jimmy K]

Thanks for the reply.  I was just using a cobra tap with a 2.5 ft hose which was why I tried the soda bottle/carbonator cap method.  The lack of a head didn't bother me as much as the perception that it didn't hold onto the carbonation.  I'm sure there was some carbonation still in solution, but there were no bubbles being released once it was in the glass and I was hoping that the bubbling would increase the nose.

In my google searches I did find a few references to the same phenomenon, but no explanations as to why it happens.  I may play around with hose length and pressures to see if I can figure it out.

At 18psi and a 2.5foot hose, I'd expect it to decarbonate very quickly. The rapid pressure drop at the tap causes it to degas quickly. If it were beer and could hold the bubbles, you'd have a glass full of foam.
 
This is a great resource. Look at Chapter 5: A Matter of Balance.
http://www.kegworks.com/faqs/Draft-Beer-Quality-Manual.pdf

[svejk]

Thanks for the link!  I did finally end up getting it to hold onto a bit of carbonation by using a soda bottle and carbonator cap in the 30's, but if I decide that I want to serve it directly off the keg then I'll have to set up a new cobra with an extra long hose. I still suspect there is another factor in play that doesn't apply to beers because they rarely drop below 1.000, but I'm stumped.

[Jimmy K]

You may be right. I think sparkling wines are carbonated to levels far higher than 3atms and that may be why.

- Sent by my R2 unit