Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: hades_ibex on 27/05/2005 23:36:06
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OK so I have a champagne bottle, a closure, some wine and some dry ice. I want to make sparkling wine. I thought I would put the wine in the bottle leaving a couple cm. headspace at the top, drop in a measured amount of dry ice and quickly cork it. I shouild be able to get the right level of carbonation this way.
My concern is that the rate that the CO2 sublimes would be greater that the rate that it dissolves in the liquid. The pressures would build up in the neck of the bottle and it will explode. Is this a valid concern?
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Yes. Champagne bottles do explode, about one in a thosand in most vineyards. This is why wine waiters wear white gloves, as occasionaly champagne bottles have tiny shards of glass on the outside from their neighbours that exploded over them in the racks at the vineyard. I would advise you didn't try this at all, as their is every chance your seal might be stonger than the bottle. As glass is a ceramic, covered in tiny cracks of a variety of sizes the pressure at which the bottle will explode is essentialy random, dependent on the size of the cracks, and decreases with handling.
On the matter of explosions I should also add that an exploding gas bottle is hundreds of times more dangerous than an exploding liquid bottle. The energy of the explosion is stored in the compression of the fluid inside. You can compress gas a lot, hence a big, dangerous bang, whereas liquid is essentialy non-compressable, so very little energy is stored, see any bottle rocket experiment. Thus the headspace you were suggesting is probably the most dangerous element.
The dissolved gas is also going to contribute to the power of any explosion. You are either going to dissolve much more gas in the liquid than is usual for champagne. Or, since I don't know what the usual concentration of gas in champagne is, you will dissolve a lot less gas, and have very naff sparkling wine. I suggest if you want to make sparkling wine you do it the old fashioned way by fermentation in the bottle and get some advice from a winemakers newsgroup.
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Thanks Anthony for your response. I am a member of several winemakers groups. This is where I got the idea! Also I am looking for a faster way of carbonation than bottle fermentation.
I tried using dry ice in the bottle, but I let it all sublime away before corking. This resulted in mildly carbonated wine. It wasn't very satisfactory. But I will take your advice and not consider the dry ice method anymore. (Although maybe down the road I will using plastic bottles.)
I think for my next kick at the cat, I am going to pressurize the wine in a keg and then use a counter-pressure bottle filler to fill the bottles under pressure. I will definitely build some kind of shield however.
One point that you made I would like to follow up on. Are you suggesting that, say, 3 volumes of CO2 in a bottle without liquid would be more dangerous in the event of an explosion than the same 3 volumes of CO2 in the bottle with wine?
And one more question. Do you think brass fitting on these bottle fillers will be OK with wine (low pH)? I'm thinking of corrosion here.
Thanks.
Mike
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Yes definitely use plastic bottles, You would have difficulty blowing one of those up with CO2 as long as you don't add it too fast. And if you wear some ear protection and eye protection it shouldn't do you too much harm even if it does blow up.
Anthony is right in saying that an empty bottle at 3Bar is more dangerous than a full bottle at 3Bar, as there is less gas at the pressure, however if you add an extra 3l of gas to an empty 2l bottle it will reach 1.5Bar whereas a 7/8 full one will reach 12Bar, so leave an air gap at the top so if the gas is being released faster than it can dissolve it has somewhere to go.
A litre of CO2 weighs about 1.5g so if you start off by adding dry ice in units of about this it should be safe - I would play with water first as this is cheaper than wine.
What you really want is to add the dry ice in a little boat, and then invert the bottle so the dry Ice meets the water. - or you could just leave it to sublime slowly itself.
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I have to admit that I am having a hard time visualizing what happens in that bottle. I've been told that I need 4 volumes of CO2 (3L in a 0.75L bottle), and I've also been told that I need 4 atmospheres of pressure. I can certainly understand that these two are equivalent in an empty (no liquid) bottle. Are they not the same thing in a full bottle? By "full" I mean there is some headspace.
I also would carbonate at around 0C which will drop the pressures and help the CO2 dissolve, but I'll probably store the wine at close to room temp.
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Apologies in advance, I probably don't have time for a complete reply.
Lots of gas is frequently dissolved in water. If you leave tap water out a few bubbles often form after 15 minutes or so on the edge of the glass. If you were to "degas" water in a vacuum you may loose a volume of gas from the water close to the original volume of the water. Of course, the volume of the water would change very little in the process, almost immeasurably. So the take home message is under higher pressures, and with more soluble gases, like carbon dioxide, we can dissolve many volumes of gas in one volume of water. This is all very simplistic, but a good start.
I think your experiments have already shown that the CO2 sublimes at a much faster rate than it dissolves. So the pressure increases if the bottle is sealed. The question is, at room temperature, what is the pressure at which the solid CO2 will stop subliming, as this is essentially the maximum pressure that can be achieved in the system. Answering that properly involves having the data at your fingertips, which I don't have. But my impression is that this is likely to be higher than exploding pressure for most bottles.
Having a large headspace, as Dave says, will decrease the maximum pressure you may achieve in the system, so long as the solid CO2 is limited and not in excess. Limiting your solid CO2 seems like an important safety factor then.
---Out of time, gotta dash---
Your pH question. Don't worry, brass is chemically quite resistant. More importantly the pH of the carbon dioxide system won't keep dropping indefinately with more dissovled CO2, but tends to level off somewhere around pH 4. It is not an agressive acid like hydrochloric.
Solid carbon dioxide isn't used by the drinks companies to make carbonated drinks, they do use gas under pressure. Which is what your system reduces down to since the CO2 sublimes faster than it dissolves. Except you have less control over the rate of flow and pressure. My girlfriend, who reads over my shoulder, recommends you check out, www.sodastream.co.uk, though this may not be as much fun.
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I had the pleasure of visiting some Australian vineyards last weekend, including the Seppelt vineyard - famous for it's sparkling Shiraz. In talking to the guide there he confirmed the explosive dangers of Champagne and other sparkling wines, professionals handling the bottles are never allowed to handle more than one bottle in each hand at a time and wear leather gauntlets, sleeves, aprons and polycarbonate faceshields while handling the wine. Apparently a large stack of pallettes of bottles collapsed recently and blew out the wall of the steel shed they were sitting in.
The tasting afterwards certainly exemplified the taste differences between two alternative routes to making champagne, the German Transfer Method and the traditional French method. My new appreciation of the dry and yeasty flavour of the traditional champagne would lead me to suggest you might get more pleasure as a winemaker through that approach...