What is the science behind the fact that I can't SodaStream my lemonade?

March 19, 2018 2:50 PM

Why can't I have carbonated lemonade on demand?

I love my SodaStream, and I love lemonade. I understand that it's dodgy at best to use anything other than water with the machine. (I tried unsweetened tea once and it didn't even work that well.)

I find myriad entries via Google either warning me to use only water or explaining the shitshow that will occur if I don't, but nothing seems to tell me WHY.

Can someone explain to an American Studies major the science behind why liquids with more sugar in them can't be carbonated? I'm going to make a guess that it's something to do with carbon and oxygen molecules and what they can or can't bond with, but that vague statement approaches the limit of my scientific understanding, so ...

posted by mccxxiii to Food & Drink (22 answers total)

Mostly I'm here as an American Studies prof in solidarity with you... but my assumption was always simply that the sugar gunks up the workings of the SodaStream.

(I look forward to more scientific explanations.)
posted by correcaminos at 2:57 PM on March 19, 2018 [3 favorites]

I don't have a SodaStream, but I do have a carbonator setup, and have carbonated lemonade before. It's great, but the only problem is that it fizzes and foams up all over the place when you open the bottle. For this reason I like to carbonate water, then add lemonade (or other juices) to it.
posted by suedehead at 2:59 PM on March 19, 2018 [7 favorites]

I also don't have a SodaStream, but do have a carbonator setup and watching how much water ends up in the clear tube has kept us from carbonating anything but water - it would be a real pain in the ass to clean out if it were anything else.
posted by I'm Not Even Supposed To Be Here Today! at 3:01 PM on March 19, 2018

Not a chemist or food science. But two things jump out at me

(1) Sugary liquids are more likely to leave a gummy residue in the works and might clog little injector nozzles

(2) Some liquids will hold actual bubbles very well so that when you try to carbonate them you end up with a frothy mess exploding out of the thingie instead of carbonated fluid.

(you can still have carbonated lemonade any time you want -- make a lemonade syrup by cooking down some lemon juice and sugar-or-other-sweetener, add a little to a glass, and then pour in some carbonated water)
posted by GCU Sweet and Full of Grace at 3:01 PM on March 19, 2018 [7 favorites]

They absolutely can. I used to make up a keg of bubbly vodka lemonade and keep it on tap during the summer. I've seen hard root beer being made, and it was far more carbonated than beer. Or, obviously, look at any commercial soda. Tons of sugar, super bubbly.

I don't have a sodastream, so I can't tell you why horrible things happen when you try to carbonate other things with it. But it's not due to limits of chemistry.
posted by booooooze at 3:01 PM on March 19, 2018 [2 favorites]

Previously.

It's a viscosity thing. My first batch, I skipped the instructions and added the syrup first and everything went kaboom when I took the bottle out and I ended up with syrupy water on the ceiling. It was never that intense when I carbonated just plain old water.
posted by mochapickle at 3:02 PM on March 19, 2018 [5 favorites]

Agreed, there's no particular science to it (otherwise Coca-Cola would be in trouble), it's purely the SodaStream workings which have trouble if they would need to be cleaned. I have a DIY rig that's little more than "Canister, regulator, tube with quick-snap adaptor valve" and it's made fizzy margaritas just fine.
posted by CrystalDave at 3:02 PM on March 19, 2018 [1 favorite]

If/when you try to carbonate lemonade, bubbles will nucleate around millions of tiny solids and it will foam up quite dramatically.

Nerds are getting around this by purifying the juice with a centrifuge. It can then be carbonated and added to a drink which will cost you seventeen US dollars.
posted by ftm at 3:02 PM on March 19, 2018 [10 favorites]

Best answer: I have a good explainer for this! It's tailored to cocktails, not specifically juice, but it covers the basics. Briefly: sugar increases surface tension of liquid, liquid gets extra-foamy, liquid goes FOOM. You can carbonate higher-sugar liquids like lemonade -- you can even carbonate wine! -- but it'll carbonate more quickly and more... aggressively.
posted by halation at 3:03 PM on March 19, 2018 [17 favorites]

OK, I was a women's studies major and wondered the same thing!

The farthest I got was that the sugar provides extra "nucleation sites" - something about the sugar molecules essentially creates more space for carbonation to happen. And the carbonation happens all over the machinery. Hopefully someone with a science degree will come along to elabaorate!
posted by lunasol at 3:03 PM on March 19, 2018

Best answer: It has to do with the solubility of the CO2 in the water. Liquids with sugar can hold less CO2 than plain water can. One demonstration of this is how plain soda water fizzes like crazy when you mix sugar syrup in: the plain water has a lot of CO2 in it, while the sugar-water can only hold (example) half that much, so the bubbles are released all at once making a big foam, until the CO2 level settles down at the lower amount that the sweet liquid can hold. Both liquids seem very fizzy when we drink them, because we're sensing the saturated liquid releasing bubbles of gas, we're not so sensitive to how much dissolved CO2 is required to put it at the saturation point.

So, if you had perfect control over how much CO2 was being released into your pressure bottle, you could try using half as much gas for a batch of lemonade as you would for a batch of plain water.
posted by aimedwander at 3:08 PM on March 19, 2018 [6 favorites]

Ok, my previous answer was neglecting nucleation. I'm definitely not 100% correct there.
posted by aimedwander at 3:09 PM on March 19, 2018

Another approach: this Sima recipe looks like the one I use from an old Time-Life cookbook. I make it every summer and once, in conjunction with a Bio 101 paper on Saccharomyces cerevisiae, estimated the alcohol content using a hydrometer to be no more than .5% so I think it still qualifies as a soft drink. It is very fizzy.
posted by Botanizer at 3:16 PM on March 19, 2018 [3 favorites]

There are some Sodastream-like carbonators such as the DrinkMate which are designed to be able to carbonate anything.
posted by zsazsa at 3:21 PM on March 19, 2018

I don't know about a Sodastream but if you get something (like a kegging setup for homebrewed beer) that can dial in a lower pressure you should be fine. It won't be quite as fizzy as seltzer but it will still be carbonated. I have made soda (lemongrass, basil, cucumber) to serve out of my draft system that I normally use for beer and it works just fine. The foam of large bubbles did surprise me but it was no problem at all using 10 psi of CO2 pressure from a cold keg, same as I use for beer.
posted by exogenous at 3:51 PM on March 19, 2018

Yep it explodes. Been there, done that.
posted by fshgrl at 3:51 PM on March 19, 2018

Yeah, so I accidentally carbonated some water with lime flavoring in it in my SodaStream last week and it spewed water eeeeeeverywhere. There wasn't any sugar involved whatsoever, so I assume the issue is that bubbles can nucleate on the flavor molecules/particles, and they do that rather than dissolving, resulting in a volcano. It was a mess.
posted by Cygnet at 4:24 PM on March 19, 2018

Easier solution in case you're serious about this being the end goal: They make lemonade concentrate. It'll be in the freezer section of your grocery store in little cylinders. Thaw it out and put it in a container in your fridge, ideally a plastic squeeze bottle for ease of use. Add an appropriate amount to taste to each SodaStream bottle after you carbonate, or by the glass; in the summer I'll keep at least a lemonade and a limeade available.
posted by Sequence at 4:29 PM on March 19, 2018 [4 favorites]

My Dad, who is an engineer and generally very smart guy, also generally believes he is too smart to need to read instructions. So when I gave him a sodastream he merrily went ahead and put the flavouring into the water beforehand, and ended up with a face full of sticky fizzy mess. (This is now the thing I quietly picture to myself whenever he implies that I have done soothing foolish) But yea, it just makes the whole thing foam up.
posted by 5_13_23_42_69_666 at 7:13 PM on March 19, 2018 [5 favorites]

This is not what you're asking, but I keep a bottle of lemon juice and a bottle of simple syrup in the fridge, and then just mix them with fizzy water on demand. Alternately, you could mix the lemon juice and simple syrup together and then just mix it with fizzy water on demand. And you can make simple syrup by mixing equal parts water and sugar in a jar on the counter, shake well, and then let it sit until the sugar dissolves. No heat needed.
posted by leahwrenn at 7:58 PM on March 19, 2018 [1 favorite]

I tried to make sparkling lemonade with real, pulp-containing lemon juice in my expensive Penguin Sodastream and it fizzed so much it hit the ceiling and it has never been the same since.
posted by wnissen at 2:22 PM on March 20, 2018

As someone who regularly makes carbonated sweetened beverages with natural fermentation rather than artificial carbonation, I can tell you that what you are trying to do is quite possible, so long as you release the pressure slowly the first time.

Crack the top a little & let the gas out gently until the liquid no longer forms a rising foam on top. Once you can open the top without the liquid rising & spilling, close the top & you will be able to open it safely subsequently.
posted by HiroProtagonist at 7:09 PM on March 22, 2018