Pumping air into partially full beer bottles to preserve carbonation

[Flatliner]

I was thinking of buying a cheap device to pump air into large bottles of beer that I didn't finish drinking to keep up the carbonation for another day or so, but the following Amazon reviews of a similar more expensive device got me wondering if it's a waste of time and money.

https://www.amazon.com/dp/B00006331V/?tag=pfamazon01-20

The second reviewer, Erik L. Russell, M.D., (click on "See all 14 customer reviews..." and proceed to Page 2) brings up the law of partial pressure to debunk the usefulness of this device. Since the air being pumped into the bottle consists of only approximately 0.04% carbon dioxide (Dr. Erik claims 2%), is he correct that this device won't be effective? Or will the pressure of any gasses pushing down on the liquid prevent carbon dioxide from escaping?

 

[mgb_phys]

Or will the pressure of any gasses pushing down on the liquid prevent carbon dioxide from escaping?

Yes it will, however it will also force oxygen into the beer turning it stale.

 

[Flatliner]

Yes it will, however it will also force oxygen into the beer turning it stale.

I realize oxygen is generally not great for beer (oxidation actually gives desired tastes in beers that age well), but I'd rather have a beer that hasn't gone flat than one that doesn't have a day's worth of oxidation (different story with red wine containing lots of tannins, and you'd use a vacuum pump for red wine anyway).

So why doesn't the principle of partial pressure render these types of products ineffective as Dr. Erik claimed?

 

[mgb_phys]

I'm guessing the pressure inside a CO2 bubble is so high that you would have to pressurise the air above the bottle to a ridiculous amount to keep it in solution.

 

[Flatliner]

I'm guessing the pressure inside a CO2 bubble is so high that you would have to pressurise the air above the bottle to a ridiculous amount to keep it in solution.

Now it seems you're saying these devices don't work.

 

[mgb_phys]

I don't know the particular product claims - but i would be surprised if the couple of extra PSI you could put in a bottle with a wine-pump type gadget makes a significant difference to the amount of CO2 in solution as opposed to just putting the cork back in and keeping it cool.

 

[Flatliner]

I don't know the particular product claims

"The champagne function pumps air into the bottle, preventing the dissipation of the bubbles and preserves your champagne for days."

but i would be surprised if the couple of extra PSI you could put in a bottle with a wine-pump type gadget makes a significant difference to the amount of CO2 in solution as opposed to just putting the cork back in and keeping it cool.

Okay, I'm going to send for similar device, perform an experiment and I'll post the results here. :)

 

[mgb_phys]

The pressure in a champagne bottle is about 3-4 atm so this gadget is going to need a hefty mechanism to hold it to the bottle and a fairly chunky pump to produce that.

 

[Flatliner]

The pressure in a champagne bottle is about 3-4 atm so this gadget is going to need a hefty mechanism to hold it to the bottle and a fairly chunky pump to produce that.

You're assuming that the pressure that's present in an unopened bottle of champagne is necessary to prevent an appreciable loss of carbonation; a less amount of pressure may suffice. For instance, the amount of pressure present in the head space of a soda bottle is much less, but it's enough to keep the soda from going flat.

 

[Danger]

You could try my approach—don't quit drinking until the bottle is empty.
On the other hand, beer stays acceptable until the next day when open. If it's going to be longer than that, just cork the bloody thing. In absence of a cork, a chunk of plastic such as Saran Wrap, held on with a rubber band, works fine for a couple of days.

 

[The Dagda]

There are little devices, screw on with a small pump, called fizz keepers you can buy that enable you to pump air into the bottle to increase the pressure, they also act as bottle tops as well. These stop most of the CO2 from leaking into the bottle, and they double the life of fizz in my experience, I think they are about £2 each. Simple and much cheaper than paying out on gas, nozzle and so on. They definitely work, but they do take some effort once the bottle is fairly empty.

 

[cristo]

You could try my approach—don't quit drinking until the bottle is empty.

Alternatively, just buy smaller bottles!

 

[dE_logics]

Apart from keeping the fluid under pressure, you also need to ensure that the gas on the beer should be the right one and no bacteria inside (I'm not sure of this point though).

One idea that came to my mind is...why not pressurize the fluid itself?

 

[Math Jeans]

The beer has to be carbonated from an originally non-carbonated state anyway. Couldn't you just find a way to just re-carbonate it period?

 

[Flatliner]

There are little devices, screw on with a small pump, called fizz keepers you can buy that enable you to pump air into the bottle to increase the pressure, they also act as bottle tops as well.

That's similar to the cheaper device I mentioned getting in the OP, but that's basically what the more expensive device in the Amazon link does.

Apart from keeping the fluid under pressure, you also need to ensure that the gas on the beer should be the right one

That's the question posed in the OP- Will ordinary air pressure pressing down on the beer in the bottle help keep the beer carbonated?

and no bacteria inside (I'm not sure of this point though

Bacteria is fine. The fermentation process is done and beer that's recapped and stored in the fridge for a few days doesn't suffer off-tastes from contamination, just from loss of carbonation and to some degree oxidation.

One idea that came to my mind is...why not pressurize the fluid itself?

Huh?

The beer has to be carbonated from an originally non-carbonated state anyway. Couldn't you just find a way to just re-carbonate it period?

Possibly. But getting it just right would be difficult and I'm not interested in a complicated system. Also, I'm interested in the answer to the OP from a physics standpoint.

 

[mgb_phys]

The beer has to be carbonated from an originally non-carbonated state anyway. Couldn't you just find a way to just re-carbonate it period?

The carbonation is produced by the yeast - only in 'fizzy beer-like drink' is CO2 added.

 

[russ_watters]

I agree with mgb, but don't see any mention of partial pressure here. All gases in a mixture act independently of each other and since air contains very little carbon dioxide, using pressurized air will have virtually no effect on how fast CO2 escapes from a beer. You'd need thousands of psi of air pressure to get the partial pressure of CO2 high enough to matter.

 

[The Dagda]

Of course they do actually work in practice though: and no I don't mean I assume they work, if you have an almost empty bottle it goes flat very quickly, but with those it lasts a few days, which is a problem for theory.

 

[Subductionzon]

Over the long run the partial pressure problem will mean that your beer will go flat. But if you notice when you open a beer or a soda you get bubbles of CO2 all throughout the bottle. The pressure drop is enough so that CO2 comes out of solution in the middle of the bottle, basically anywhere it can find a nucleation site. By raising the pressure of the air in the bottle you limit the CO2 loss to the surface of the beer. If you have it in a cold refrigerator that is not disturbed you will definitely extend the life of the carbonation.

 

[mgb_phys]

but don't see any mention of partial pressure here.

Would the partial pressure affect bubbles forming out of solution?
Isn't that just total pressure, otherwise the gas in solution at the bottom of the bottle has to 'know' what mixture of gasses are present in the air above the liquid.

 

[Flatliner]

The carbonation is produced by the yeast - only in 'fizzy beer-like drink' is CO2 added.

That's true for bottle conditioned beer, but your average cheep macro beers (bud/miller/coors) are force carbonated. The CO2 produced during fermentation escapes through the airlock.

The other night I sent for a few cheaper devices that get good reviews and are supposed to perform well. When I get them I'll perform an experiment. First I'll store an unopened beer in the fridge. I'll empty another half way and cork it. A third bottle will also be emptied half way and this one will get the device. I'll wait 48 hrs and pour equal amounts into three glasses and test for visual differences and mouthfeel and taste. I'll post the results in this thread.

 

[russ_watters]

Isn't that just total pressure, otherwise the gas in solution at the bottom of the bottle has to 'know' what mixture of gasses are present in the air above the liquid.

Good point.

 

[russ_watters]

Isn't that just total pressure, otherwise the gas in solution at the bottom of the bottle has to 'know' what mixture of gasses are present in the air above the liquid.

Good point. I wonder how much time that could really buy you.

 

[Subductionzon]

Good point. I wonder how much time that could really buy you.

That is why one of the reasons I said that the refrigerator should undisturbed. The fewer vibrations etc. would keep the exchange of gases at the surface only. And in answer to a previous question, no the CO2 does not know what gas is causing the pressure. CO2's solubility is very pressure dependent. That is why these devices work, not perfectly but better than nothing at all. This also applies in the real world in why CO2 levels have historically followed temperature change and not led it (the opposite of what Al Gore would have you believe) the oceans are huge CO2 reservoirs that can only exchange CO2 on the surface. With various currents the ocean has it takes hundreds of years for it to come back into equilibrium after a change in temperature.

 

[suncake]

And in answer to a previous question, no the CO2 does not know what gas is causing the pressure. CO2's solubility is very pressure dependent.

I don't think that's right.

The http://en.wikipedia.org/wiki/Solubility#Solubility_of_gases" of CO2 should only be a function of the temperature and PARTIAL O2 pressure.

By Henry's Law: p_CO2 = constant * [CO2 (aq)]

I'm curious though (and I don't mean this as a rhetorical/jerkish question) --- have any of the customers done a blind test between two half-full beer/champagne bottles: one with the Epivac and one with just an air-tight stopper?