nailing siphon carbonation I

(Putting a preemptive ‘I’ on this, because I still don’t feel like I’ve totally nailed it.)

Almost every bar I’ve ever worked in has had a housemade ginger beer. The recipes have varied, but the one thing they all had in common was that they were dispensed through a siphon. Pouring out a glass, they never really maintained a stable carbonation though. All I ever seemed to get was a giant glass of foam, and waiting for it to settle took about as long as pouring a warm diet coke (ugh, whyyy). Afterward there never really seem to be many bubbles rising upwards. Eventually I learnt that carbonating a liquid in a siphon and then opening the canister to pour the liquid out gently instead of using the dispense nozzle reduced the loss of carbonation. (Personally I like using a cream siphon, because the opening is much larger and you can release the excess gas/increase the pressure inside, without losing any liquid. Not entirely sure, but I have this funny feeling that the companies that make the siphons would warn against using CO2 in a siphon designed for N2O, and vice versa, so consider this a disclaimer..). So I’m in territory now where I’m carbonating and bottling on a small scale and things are still fizzy for real, which is pretty exciting. Like actual soda. There are a few concepts that have helped me once I got my head around them.

Why the soda loses carbonation when it’s squirted from the dispense nozzle: agitation. Squirting the soda from the siphon agitates the liquid and lets the CO2 escape from the liquid much faster. Pouring gently gives it less opportunity to break the surface tension of the liquid. (Scientific American)

Why does cream taste sour when you accidentally charge it with CO2 instead of N2O: dilute carbonic acid. When you charge water (H2O) with soda cartridge (CO2) they bond to form H2CO3 (carbonic acid). Basically, carbonic acid is the name for carbon dioxide that has dissolved into water, and it’s an acid, so it tastes sour. (N2O is more stable and mixing it into water or cream doesn’t create new molecules. In thick substances, like cream, it just gets trapped in there and hangs out. In thin substances, like water, it doesn’t get trapped, so no gas bubbles stick around.) (Seasoned Advice)

Why does soda carbonate better when it’s cold: Le Chatelier’s Principle. Here we’re getting a bit beyond the limits of my scientific education, but as I understand it, Le Chatelier’s Principle is about maintaining equilibrium. So if you apply a stress to one part of system, the system will adapt to balance it. Lowering the temperature and increasing pressure are stresses that increase the saturation point of the liquid and the solubility of the CO2. They encourage the CO2 to dissolve into the liquid. (I’m still reading about this principle, because I’d really like to compare it to something like making a saline solution/brine or sugar syrup. Saturation points make sense to me in those circumstances, because increasing the temperature of the water increases the amount of salt or sugar that you can dissolve into it…)

One more link, and the best of them all… (Carbonating at Home)