I was sent a sample of a new carbonation device called the Bonne O, and in trying it out I had a lot of questions about how it worked. That lead me to learn a bunch of new (or needing repetition) facts about it.
The Bonne O carbonator is different from a Soda Stream carbonator in two fundamental ways:
- Instead of a CO2 tank, it takes tablets that work like giant Alka-Seltzer tablets to create CO2
- You can carbonate more than just water. With Soda Stream (at least the current models), you carbonate only water and then add syrup to it to make soda. With this device you can add other ingredients into the carbonating chamber.
But I was confused as to how specifically it works. You add most of the liquid and any solid ingredients to the bottle that will be carbonated, then on the base of the machine the fizzing tablet to one chamber, and the sweetening/flavoring syrup to a separate chamber. That last part particularly confused me.
So I emailed with Bonne O inventor Darren Hatherell. He explained to me (and also did a good job of it on this blog post, from where I stole most of these images), and now I'll explain to you.
The Stuff You're Carbonating Must Be Cold, But the Chemical Reaction Should be Warm
For maximum carbonation, you must have cold liquids, as cold liquids hold more carbon dioxide in solution. However, the particular acid-base Alka-Seltzer-style fizzing reaction in the Bonne O works best when the liquid added to the fizzing tablet is warm. (To verify this, try adding Alka-Seltzer to warm vs cold water and see how much longer it takes to fizz.)
They way they got around needing both cold and warm liquid is: The device takes the temperature of the liquids in the bottle (it sucks some into the machine from the top), and if it's too warm for effective carbonation, it just beeps at you and won't even try to carbonate. If it's nice and cold, however, it sucks in that liquid and heats it to an ideal temperature before sucking it into the carbonation chamber with the fizzing tablet.
This warm liquid (and dissolved tablet) doesn't go back into the bottle. It stays in the chamber and you dump it out at the end. Keep reading for how and why...
Sugar Makes Foam And That's Bad
The main reason you don't put syrup flavors into the Soda Stream is that when you carbonate syrupy water, it foams up and out of the bottle, then will clog up the gas system, perhaps only to explode later. Sugary things make foam.
The Bonne O gets around this by holding the syrup in a separate flavor chamber (you can add flavors to the bottle, including solid ingredients like strawberries, but the stuff in the bottle ideally shouldn't be super sugary).
When you hit the button to turn it on, the Bonne O sucks in liquids from the top of the bottle into the carbonation chamber where it fizzes and creates CO2 gas, and pushes out the syrup or other liquid from the flavor chamber (along with the newly-created CO2 gas) into the bottom of the bottle. So the space in the bottle from the stuff that was sucked out is replaced with the syrup or other stuff from the flavor chamber. Thus the flavor chamber always has to be full, even when you're not flavoring your liquid.
So if you're just carbonating water, you add cold water to the bottle and water to the flavor chamber. (Same if you're carbonating a bottle of tequila, which I did live at Tales of the Cocktail - you put tequila in both the bottle and the flavor chamber.)
If you're carbonating a soda or cocktail like a Gin & Tonic using tonic syrup, you add the gin and water to the bottle and the tonic syrup to the flavor chamber. If you were going to carbonate a cocktail with a liqueur like a Margarita, you might want to put the liqueur into the flavor chamber instead of mixing up the full cocktail first. I haven't experimented with adding something syrupy to the bottle to see what happens.
The Downside To Both
The downside to a Soda Stream is that you ultimately add carbonated water to syrup, which will reduce its overall carbonation.
The downside to the "keep the syrup separate" model of the Bonne O is that if you're a perfectionist you have to do some math to get your cocktail right: Some of the liquid in the bottle will be sucked out and discarded to be replaced by the syrup, so you have to control for the change in volume.
The bottle holds 750ml
The flavor chamber holds 142 ml
Thus, you need 142 ml extra un-sweetened liquid that will be discarded from the bottle.
Let's Do Math!
For example, if you used Strong Tonic syrup to make a carbonated G&T, the brand recommends 1 part syrup to 2 parts gin to 4 parts water. For the final 750 ml that you will make, that means each "part" is 1/7th of 750 ml:
107 ml syrup
214 ml gin
428 ml water
But not all of that goes into the bottle- remember the syrup goes into the flavor chamber. The flavor chamber holds 142 mls, so you can add the full 107 ml of syrup to it, and then top it off gin and water. But how much? We need 35 ml total of non-syrup to get to our 142 ml.
So the total of non-syrup (that's the gin and water combination) will be 750ml (that's what fits in the bottle) + 35ml extra for the flavor chamber = 785 ml of gin/water.
So 785 ml of gin/water in a proper 1:2 ratio is:
262 ml gin
524 ml water
Checking our math on actual quantities used in final drink:
Flavor Chamber: 107 ml syrup + 35 ml gin/water in 2:1 combo (12 ml gin and 24 ml water)
Bottle: 750 ml gin/water in 2:1 combo (250 ml gin and 500 ml water)
But remember that 142 ml of the bottle is discarded. 750 - 142 = 608 ml gin/water combo will actually go into the drink, plus everything in the flavor chamber, which makes our total of each ingredient:
Syrup: 107 ml
Gin from flavor chamber = 1/3 (35ml) = 12 ml
Gin from bottle = 1/3 x (750-142 = 608) = 203 ml
Gin total = 215
Water from flavor chamber = 2/3 (35ml) = 24 ml
Water from bottle = 2/3 x (750-142 = 608) = 405 ml
Water total = 429 ml water
So our final recipe is:
Mix 262 ml gin and 524 ml water and make sure the combo is very cold. Fill Bonne O bottle to top with this combination.
Add: 107 ml Strong tonic syrup to flavor chamber plus rest of gin/water combo (35ml) to flavor chamber.
Add carbonating tablet to carbonation chamber and press the button to carbonate the liquid.
Science is fun!