CO2 instead of "topping off"?

Yes, you can do it that way, but it's harder to be sure you've got the airspace purged of oxygen than by just topping it off.

Since CO2 is heavier than air, you want to use a fill tube which goes down almost to the level of the wine. Purge with the CO2 with at least

3 times the volume of the airspace. Don't purge too fast; slower is better so you displace the air rather than just mix it up in the carboy.

Another way of purging the headspace is to drop a few chunks of dry ice into the wine, cover the opening lightly and let the sublimating CO2 do the air purging for you. This only has the disadvantage of the dry ice giving off cold CO2, so you get condensation in the airspace. Doesn't affect the displacement of the air, though.

Gene

CO2 blanketing a large "empty" volume isn't very effective as I have learned with last years white wines. You'll still get gas exchange (O2 in) when th3e carboy warms and cools throughout the day. With a solid cork, it might work fine. I'd top up the wine if possible. Warren Place

Would the dry ice carbonate the wine or beer as well?

I have an question that is not exactly on topic here but close. When bulk aging is it better to use just a solid bung or a bung and airlock or does it matter? I use bungs with airlocks now when I age.

Also talking about the CO2, I generally don't worry about the head space as long as the lock part of the airlock if floating a little. I have never had any problems, am I just lucky? You all are going to scream at me but I sometimes have a gallon of head space in my carboys (with the lock floating) but have never had an off tasting batch. The only time I thought I had an oxidized batch was the time I made wine from Welch's frozen concentrate _cocktail_. I have recently tried this again with both cocktail and concord and realized that it was just the cocktail not having enough flavor to support the wine.

David

It is better to use an airlock. If by chance a little more fermentation were to take place or the pressure in the carboy increased for some other reason such as CO2 coming out of solution, it can blow a solid bung off and then your wine can be ruined due to oxidation.

But I have a question. One of the things that need to be done after fermentation is to get the CO2 that is dissolved in the wine out. How can this be done if the wine is blanketed with CO2? Wouldn't the dissolved CO2 just stay in solution? Partial pressure of a gas in solution is a function of the partial pressure of the gas in contact with the solution and the partial pressure of CO2 in the blanket would be very high.

Ray

I would relate it to a balloon under water. Think about how much pressure it takes to hold it down. Much more than the weight of the filled balloon. With that in mind I don't think that the blanket of C02 would be heavy enough to hold the dissolved C02 under water/wine. The dissolved C02 would simply push the expanded C02 out of the carboy as it rises.

I'm sure some one can give a more scientific explanation.

Thanks,

David

I agree with Warren. A large amount of CO2 (or any gas) will expand and contract a lot more with temperature than an equal volume of liquid.

Also, CO2 is soluble in the water you've got in your airlock, so it will diffuse out, making the dread "suck-back" more likely.

---The Mad Alchemist---

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Hi: I would use a gas that ;is not very soluble in wine. An example would be nitrogen.

I'm guessing that the CO2 from fermentation is going to be largely dissipated while you rack the wine (definitely while pressing the reds after fermentation). Re-blanketing with CO2 will raise the dissolved CO2 some (due to the partitioning coefficient between CO2 in the headspace versus in the wine), but will again be largely dissipated the next time you rack.

Gene

Why is nitrogen not soluble in wine?

Maybe for reds, but if it's a cold-fermented white, racking by itself won't do it... said after spending 2-3 days last month degassing a year old Pinot Blanc with Vacuvin.

Pp

Most gases aren't very soluble in aqueous liquids- nitrogen would rather be free in the atmosphere than caged up in a solution.

Carbon dioxide is much more water-soluble than most gases, partially because it's a bigger molecule (so it's more polarizable], and partially because it forms a Lewis acid-base adduct with water (so you get equilibrium with "carbonic acid" and carbonates pulling the CO2 into solution].

Cheers,

---The Mad Alchemist---

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I prefer an airlock full of glycerin. Glycerin doesn't evaporate and when the whole carboy has completely finished fermentation, MLF, de-gassing etc, the level in the airlock is the same on both sides. It gives me what I have found to be a good visual indicator. Bob<

I asked this question here but didn't see any answer. Maybe it's a stupid question?

Would the dry ice carbonate the wine or beer?

It would work but you only need to add a gram or two per bottle and have to becareful adding it otherwise you run thermal contraction issues on your glass.

Dry Ice can be used to carbonate beverages, but it is very tricky....

Gassing the headspace is OK as a temporary measure, but for more than a couple of days storage it's an invitation to spoilage - particularly if the free SO2 isn't maintained.

Also, remember CO2 is soluble in wine. As it dissolves in the wine it will suck air in from outside if the carboy isn't stoppered tight.

Tom S