Carbonator Soda Pop – Why no one needs to buy soda from the store anymore

introduction to force carbonation

After inheriting a CO2 Tank & Kegerator from one of my dear friends for our beer brewing operation I’ve quickly become obsessed with force carbonation. For one, I hate bottling, so it was the next logical step putting all of our beer into 1 container rather than 30. Most of all, it saves a lot of time waiting for the beer to naturally carbonate, which takes about a week. We’ve also discovered that this process can take a lot longer if you don’t add priming sugar to the beer before bottling – like 6 months longer if you’ve got a really good strain of yeast that can actually keep eating the more complex sugars…

Aside from natural carbonation, the only other way to get something carbonated is to force it. The idea behind force carbonation, and I won’t go into to many scientific details (too lazy to find sources), is to pump CO2 into a liquid at a high pressure (25-40 psi). The part that’s always a little counter-intuitive is when you realize that by shaking the liquid while it’s under pressure, it will actually continue to absorb the CO2 until its completely super-saturated. Also, with 5 gallons, it’s best to leave the pressure up for a few days to allow for full saturation. This would also be a good time to learn how to control the mix of CO2 in order to come up with the appropriate level of carbonation based upon what is being made. Some beers taste better with more carbonation than others. I haven’t learned how to measure the CO2 level yet, so I’ll drop off here.

the carbonator

After kegging, the next logical step is to figure out how to transport a carbonated beverage without having to carry the entire keg. I’ve taken my 5-gallon keg w/CO2 tank to a party before and it wasn’t the easiest thing to bring into the kitchen. A 2-liter bottle, recycled, is much better but would allow the beer to go flat without added CO2 pressure. Enter “the carbonator.” I’ve found a few articles out there with directions on how to build a homemade version of this, but I can honestly say that this is one of the few things that’s worth going to the brewstore and purchasing.

Finally we’re getting somewhere. The carbonator adds the ability to force carbonate a 2-liter. -I wasn’t that impressed at first either, let’s break this down:

  1. Ability to take a small sample of homebrew (uncarbonated), carbonate it, and taste the future in about 5 minutes, rather than wait a few days.
  2. Ability to re-charge and save beer that has already been poured – especially when transporting to a friends house.
  3. Ability to force carbonate other liquids on a small scale..

Item 3 is what got me. I had this carbonator sitting around for about 4 months before it dawned on me that I could make club soda with it.

the problem with american soft drinks

I was in the grocery store with my girlfriend giving her shit for buying soda pop with a lot of sugar in it. Like many other people out there, I’m really fed up with all the corn sugar in EVERYTHING we buy these days. So we decide that the real reason behind buying this stuff is the carbonation, not the sugar. So why is it that club soda costs so much money if its just carbonated water.. and then the idea finally came.. we can make our own! I got really excited at that point.

When I got home, I started researching homemade soft drinks using the force-carbonation method. Sure enough, other people felt the same way. Buying a 5 lb. CO2 tank, regulator, adapters + carbonator costs somewhere between $150 – $200. The 5 lb. CO2 tank will last quite a while, only needing a refill once or twice a year and refills cost about $10-$20. The cost/benefit analysis was almost done.

soda extracts

The local brewstore carries a lot of different extracts for making soda. The major brand to check out is Gnome Soda. They have their own recipes with each extract. A 4oz package is enough extract for 10 gallons and cost about $5-$6.

more cost/benefit analysis

  • 10 gallons * 3.6 liters/gallon = 36 liters / 2-liter bottle = 18 2-liter bottles
  • $6 / 18 = $0.33 per 2-liter
  • cost of sugar is about $6.50 for 10 lb. — Gnome recipe recommends 8 lb. sugar for 10 gallons = 8 * $6.5/10 = $5.2 / 18 = $0.29 per 2-liter. This raises the total cost of a homemade 2-liter to $0.62 (IF you follow the Gnome recipe, which I don’t)
  • typical 2-liter at the store costs anywhere from $1-$2
  • So, what if you cut the sugar content down to save money. We can do this now because we’re in control, not Coca-Cola. Where Gnome would recommend about 1 1/8 cups per 2-liter, I use about 2/3 cup. So for 10 gallons, thats 12 cups (6 lbs), where as Gnome would recommend 16 cups (8 lbs). back to some math:
  • 6 lb. sugar for 10 gallons = 6 * $6.5/10 = $3.9 / 18 = $0.22 per 2-liter, bringing the total cost down by 7cents per 2-liter

Okay, now for the payback rate. We have to see how many 2-liters and how long it would take in order to make up for the initial investment in the CO2 equipment, which was about $200. here’s where i make some assumptions just to see how this would work, so take my numbers lightly:

  • average household buys 8 2-liters per month = $8 * 12months = 96 2 liters or $96/year ($1 per 2-liter)
  • we already know it costs $6 (extract) + $3.90 (sugar) for 18 2-liters ~= $10 per 18 2-liters
  • 96 / 18 = 5.33 * $10 = $53.33, so we save $96 – $53.33 = $42.67
  • $200 / $42.67 ~= 4.7 year playback rate!

Summary of above math: Well, if you skipped to this part, you most likely just want to know what numbers I came up with and aren’t curious about how I arrived at them. The basic conclusion is that you could be saving about $40/year, which would pay off the cost of the CO2 equipment in about 5 years. However, you really should add-in the health benefits due to less sugar intake and general happiness for being in control of what you drink.

the 2-liter recipe

I just realized this is the part I wanted to start with, but took me all the above background to get here. Now that we’re all convinced that this is the way to go, let’s figure out a good recipe and method.

  1. [the day or night before] get an empty 2-liter, fill it 1/3 full of water and put it in the freezer at a low angle without a lid – this is to speed up the cooling down process and get the liquid as cold as possible before carbonation. Also note that the colder the liquid (without actually freezing) the higher saturation we can achieve
  2. [measure water to boil] Use the frozen 2-liter, fill it full of water, then pour this water into a pot and start it boiling. Be sure to put the 2-liter back in the freezer, we only needed it to measure the appropriate amount of water to boil.
  3. [make the simple syrup] once the water is boiling, add 2/3 cup sugar and 2 tsp. extract. Allow to boil for 2-3 minutes
  4. [cool the syrup] turn of the heat and remove the pot from the stove. allow it to cool for about 5-10 minutes
  5. [prep the 2-liter] take out the frozen 2-liter bottle and hit it on a counter-top to break up the ice inside as much as possible. Then, using a funnel, add the hot liquid to the bottle while making sure not to melt the plastic. continue to shake the liquid until most of the ice melts and the temperature is very close to 32 degrees (F).
  6. [the carbonator] screw on the carbonator cap about halfway, squeeze the bottle to bleed off any oxygen, and then finish tightening the cap. make sure it’s on tight.
  7. [hook it up] adjust your CO2 regulator up to 40 psi (yes the 2-liter bottle will hold, no explosions yet anyways), make sure the valve is closed, hook up the CO2 hose to the carbonator cap, then turn on the valve. At this point the bottle should be rock hard with all the pressure.
  8. [shake it up] shake like crazy– you’ll hear the CO2 continue to pour into the bottle the more you shake. I found this quite exhilarating.. the more you shake the faster it absorbs. After about 5 minutes, the liquid should be saturated. You’ll know because the flow of CO2 will cease.
  9. DRINK! You can drink it as soon as its ready, nothing else to say. If you think its too flat, then put the whole bottle back in the freezer for about 30 minutes and try again. Likewise, if after a few days it’s flattened out too much, then hook it back up and re-charge it. there’s no end.

After a few successes, the options seem endless. I’m really looking forward to what soft drinks I’ll come up with. Hopefully I’ll be motivated to continue posting my recipes. I hope to see more people doing the same.

by ryan kilkenny 2010