[zippy]

So my wife and I were having a disagreement about the best way to keep 2-liter bottles of soda fresh - without the aide of special re-pressurizing attachments. My wife thinks it is wise to squeeze all of the extra air out of the bottle before capping it. I disagree. It would seem to me, that this gives the air in the soda too much room to escape, since it can just keep expanding the plastic before it ever reaches any kind of stabilizing pressure.

So, we picked up two bottles of Diet Dr. Pepper (our favorite) and will proceed as follows:

We will empty an equal amount from each bottle, then squeeze the air out of one, but not the other, and re-cap them.

Simple, yes?

But other details are less certain. When, and how often should we check for freshness. Obviously, the more it is opened, the faster it will go flat. Also, we don't have any room in the fridge, so they will have to remain on the counter. Might this negatively impact the integrity of the experiment? At least they will both be in the same environment, so it should be "fair", just maybe not optimal for finding out just how long the winner would remain fresh.

Feel free to share any thoughts, or opinions on which you think will win, and I will post results as they come in.

Now I need to go drink some Dr. Pepper.

[digitalprimate]

Hmmmm... at first sight, I would agree with your wife, but yes, the bottle will expand more easily, thus creating more gas to fill the vacuum until the walls of the bottle start to resist. One might even try and experiment by filling a standard balloon with the same amount of soda, as a third container and a GLASS bottle as a fourth...

EDIT: Oh, and I would advise against drinking fizzy drinks, as they erode your teeth. No longer holes in your teeth are the problem, dissappearing teeth are, apparently.

[drewprops]

You need to wrap the bottles with tin foil to keep in the Carbon Dioxide.
Wrap something in it anyway.

[Majost]

There's absolutely no question, zippy... you leave as much air in there as possible.

Carbon Dioxide only stays dissolved in liquid if it is pressurized. That's why new sodas release air when opening them. By keeping as much air in the bottle as possible, you allow pressure to build back up in the bottle. Although some carbon dioxide will initially be released, you'll be taking advantage of it.

If you squeeze out the extra air, you'll never pressurize the bottle to be more than the ambient pressure -- the bottle itself will just expand back out to its original shape.

Now, if it makes any noticeable difference, that's a different question. But there's no way the latter will keep it fresh longer.

[zippy]

digitalprimate - good suggestions, we might have to do some extra experiments based on what we find in the initial study. As for the teeth, I ground enough of mine off in my sleep over my life that they're disappearing already.

drewprops - I may wrap my wife in tinfoil if she'll let me, could make for a nice sci-fi fantasy

Majost - that's the principle I'm going on. We'll see if there is a detectable difference, but I think the science of it seems clear.


Further info:
we've decided to open them once a day and poor equal sized glasses from each. They have been set off to the side in order to minimize the risk of being knocked over, an event that would severely compromise the entire study.

[alcimedes]

Yeah, your wife is totally wrong. Bet her something worth your time. It will be worth it.

The main factor though is to make sure the tops are on tight enough. Both bottles will have enough CO2 dissolved in them to repressurize the bottle, so whichever one has the cap on tighter will win.

[Majost]

Originally Posted by zippy Further info: we've decided to open them once a day and poor equal sized glasses from each. They have been set off to the side in order to minimize the risk of being knocked over, an event that would severely compromise the entire study.

Hint: The less you open them, the more the results will be in your favor. See if you can change the protocol to every other or even every third day.

[zippy]

I think we'll probably have to do at least a round two experiment after all of this. Maybe I could just drop a Mentos in her bottle without her seeing.

[curiousuburb]

Surface area of the liquid/air boundary should have an influence, logically.

Bottles upright will have only the cross sectional area of the bottle as a state boundary.

Bottles on their side will have a larger surface area boundary. Worse, I would think.

I squeeze the extra air out (which mashes the bottle in and limits surface area). Seems to work, but YMMV.

Sounds like one for the Mythbusters. As long as they can make it explode at the end.

[zippy]

We won't do the open-and-pour-a-new-glass test until this evening, but after about 8 hours, the bottle that had all the air squeezed out, is almost completely back to original shape - meaning much air has escaped the soda. The bottle that did not have the air squeezed out, has that nice, firm, pressurized feel. Obviously some air has escaped, but how much is unknown.

I would say that Majost's suggestion about waiting longer than one day to test would help my theory, but after seeing the bottles this morning, I'm feeling pretty confident that once a day will be sufficient to prove my theory. Besides, it may be more of a real-world test this way.

[joveblue]

You can't have done the lids up very tightly if it's nearly back to original shape?

[alcimedes]

Actually if he did the lid tightly it would be back to the original shape, as escaping CO2 from the soda would repressurize the bottle. If the top weren't on tightly, the CO2 gas would escape from the top, and not be pushing against the walls of the bottle, and wouldn't make it reform.

[zippy]

Trust me, the lids are on tight - I'm not a small fella, and I cranked them down pretty hard. And alcimedes is right, it's the tightness that is keeping the CO2 from escaping.

[drewprops]

You're right, this is TOTALLY Mythbusters!!!

[EmC]

Colder liquids can hold more gas dissolved in them.

[julesstoop]

- Keep the air in;
- keep it as cool as possible but not subzero;
- put it in glas or metal or some other less permiable container: plastic will leak.

[Banana]

You know, this would make a great "As seen on TV" product" if someone made a 2-liter container you could pour your carbonated beverages in, and recompress with your hand (e.g. push the lid down) and it had a mean to hold the re-compressed air space without leaking carbon dioxide. No moving or mechnical parts would make it quite practical and cheap.

[psmith2.0]

Originally Posted by curiousuburb Sounds like one for the Mythbusters. As long as they can make it explode at the end.

And as long as Kari can do the testing in her bathing suit. Or something.

Unfortunately, I think that show is hitting a wall here lately. Don't enjoy it like I used to.

I quit buying two-liter beverages a long, long time ago because of the fizzy/flat problem. I get the 12-16oz. bottles of Dr. Pepper. Or even the cans.

[zippy]

I'm coming to realize the true humanitarian importance of this endeavor. As such, I have decided to invest a proportionate sum of money and order one of these thingies:


I plan to sell enough of my current investments to free up the requisite $2.79 plus shipping. Of course I will share the results with everyone here even before I am published in some fancy schmancy scientific magazines.

[johnq]

After opening and pouring a drink...

1. Insert deflated balloon in bottle.
2. Inflate balloon as much as possible.
3. Tie and stuff the end into the bottle.
4. Recap the bottle.


EDIT: or buy the above thingy.

Hey, are we talking science experiment or practicality?

EDIT 2: Or how about this? (Less spittle this way)
1. Insert deflated balloon in bottle.
2. Inflate balloon as much as possible.
3. Tie the end. No need to cap.

[zippy]

Ooohh, Bonanza!

I also found this little number:


Hmm.. both for $5.78 plus shipping. I'll need to consult with my accountant, but this is just too damn important to pass up. My fellow ANers at the very least are in dire need of proper info - right?

OK, stop twisting my arm, I'll do it.

I'm headed for financial ruin. There's no question.

Results just wouldn't be accurate without also getting this little unit:


That's another $5.99 plus shipping.

Damn you Amazon.......................

Edit: Damn you auto post merging....................

Originally Posted by johnq After opening and pouring a drink... 1. Insert deflated balloon in bottle. 2. Inflate baloon as much as possible. 3. Tie and stuff the end into the bottle. 4. Recap the bottle. EDIT: or buy the above thingy. Hey, are we talking science experiment or practicality? EDIT 2: Or how about this? (Less spittle this way) 1. Insert deflated balloon in bottle. 2. Inflate baloon as much as possible. 3. Tie the end. No need to cap.

Hmm.. good ideas. Methinks non-latex would be safest - just in case we have company. This could be a cheaper solution - depending on how long any of the above units last (assuming they work, but then the advertisements say they do, so they must, right?). Removal of the balloon needs to be done with care - a quick pop, might disturb the soda and cause a sudden rush of CO2 release. Also, I wouldn't want shards of balloon floating around. But a carefull Snip right near the knot should allow for a slower release, and complete removal of the balloon.

[Banana]

Originally Posted by pscates2.0 And as long as Kari can do the testing in her bathing suit. Or something..

I presume this is one of 26,000 valid reasons to not run for any political positions?

"Mr. President, amid the controversy over a GIF of Sheryl Crow making a suggestive gesture and asking you to call her allegedly made by you, an undisclosed source claims that you recruited your all-female cabinet for ulterior motive. Is this true?"

"Well, they're a bunch of great girls. They know their job. Of course if they get out of line, we have ourselves a little spanking session, but I assure you, they're fantastic. Now, we were talking about domestic policy?"

I dunno. Seems more like a reason to run rather not to.

Anyway, we're supposed to be talking fizzs, not foxes.

[billybobsky]

Originally Posted by curiousuburb Surface area of the liquid/air boundary should have an influence, logically. Bottles upright will have only the cross sectional area of the bottle as a state boundary. Bottles on their side will have a larger surface area boundary. Worse, I would think. I squeeze the extra air out (which mashes the bottle in and limits surface area). Seems to work, but YMMV. Sounds like one for the Mythbusters. As long as they can make it explode at the end.

That will only be true if we are talking about kinetics of CO2 release, but we're not... These bottles are at equilibrium.

[johnq]

1. Insert deflated balloon in bottle.
2. Inflate balloon as much as possible until soda doesn't rise anymore.
3. Put a twist tie on the end. No need to cap.

I think this would work. But I haven't tested it in the field.

OR: (If you are near a water source)

1. Insert deflated balloon in bottle.
2. Fill balloon with water.
3. Put a twist tie on the end. No need to cap.

All we are trying to do is replace the missing volume of liquid (and hence pressure) from the bottle, right? So it doesn't NEED to be a gas we are using, right?

Keep in mind I'm bad at basic science.

I always said soda should come in toothpaste-like tubes so you can squeeze it and force the soda to be in a smaller area to the top as you go. The interior of the tube could be lined with a substance that uses the Van der Waals force so it stays joined after you squeeze.

Okay...patent time.

™ & © and patent pending - 2007 johnq

[ast3r3x]

I have like 6 soda kegs in my basement that are normally used for beer (smaller, so you can fit two in a kegerator instead of 1! Why don't I just buy several gallons of coke and stick them in that…it'll stay carbonated, and I can dispense it like a fountain soda then.

[AsLan^]

What if you just put the lid on normally and store the bottle upside down?

[Enki]

Originally Posted by johnq 1. Insert deflated balloon in bottle. 2. Inflate balloon as much as possible until soda doesn't rise anymore. 3. Put a twist tie on the end. No need to cap. I think this would work. But I haven't tested it in the field. OR: (If you are near a water source) 1. Insert deflated balloon in bottle. 2. Fill balloon with water. 3. Put a twist tie on the end. No need to cap. All we are trying to do is replace the missing volume of liquid (and hence pressure) from the bottle, right? So it doesn't NEED to be a gas we are using, right? Keep in mind I'm bad at basic science. I always said soda should come in toothpaste-like tubes so you can squeeze it and force the soda to be in a smaller area to the top as you go. The interior of the tube could be lined with a substance that uses the Van der Waals force so it stays joined after you squeeze. Okay...patent time. ™ & © and patent pending - 2007 johnq

The water in teh balloon would work, but not the air. Compressibility of air kills that.

[zippy]

Originally Posted by AsLan^ What if you just put the lid on normally and store the bottle upside down?

I've heard that one before, but I really don't see how that would be any different than putting the lid on and leaving it right-side up

Originally Posted by Enki The water in teh balloon would work, but not the air. Compressibility of air kills that.

Good point. I think the key is whether you could get the air in the balloon in such a way that it already had more pressure than just the standing air in a bottle that was simply re-capped. After thinking about it, I'm honestly not sure whether you could be successful at this or not.

The water ideal may work better, but what a pain in the butt.

[FFL]

The air in the balloon would indeed work. It's at a higher pressure, AND it's a sealed system of its own. The soda would have to release enough CO2 to physically compress the sealed balloon, and that's not gonna happen.

This engineer gives your idea Two Thumbs Up, johnq. I think you might want to add a balloon bottle to your test, zippy.

[cosus]

Why not just buy cans of soda and rid yourself of this excess labor?