Seltzer Experiments

Requirements:

• Glass or metal only - no plastic, or very little plastic in touch with the liquid. Plastic touching gas or solids is more acceptable.
• Cost should be lower in the long run than either buying consumer bottles or siphon chargers or even SodaStream supplies if possible.
• Keep seltzer cold if possible.

Research:

• Explored existing systems and settled on using home brewing equipment.
  • Cost is similar in initial outlay to Penguin Sodastream
  • Long-term costs are much cheaper. Costs $15 - $20 to refill/exchange a sodastream 60L cartridge. Costs $15 - $20 to refill a 5 lb CO2 tank (Produces ~600 gallons of seltzer depending on usage patterns)
  • See Ask Metafilter question and answers for more details
• 2015 experiment with citric acid and baking soda stimulated by Metafilter question
  • Experimental answer.

First, my BEST experience was a recipe (that should easily be able to be scaled up) consisting of:
- 5/32 tsp baking soda
- 1/4 tsp citric acid crystals
- 1/4 cup water

And it wasn't very good. Quality of this batch was low. Factors:
- Taste was both sour and basic (indicates reaction is not complete). Possible improvement could be using warm water for the mixture and then cooling in the freezer afterwards, but my tongue and stomach can't stand further trials.
- While foaminess on initial mix was effervescent, foaminess after a minute had turned towards sudsy (indicates that not all of baking soda was consumed - other trials where citric acid was clearly in excess - sour! - had foaminess but not sudsiness).
- As indicated above, not all the baking soda had visibly dissolved.

Notes for recipe:
1) I would experiment with weighing out the ingredients instead of using fractional volume-based measurements. Assuming you have a small enough scale, the measurements would probably be more reliable.
2) Based on my taste and texture preferences, it's better to have an excess of unreacted citric acid. The foaminess stays foamy instead of heading toward sudsy land, and it's still present when you have unreacted baking soda, so you avoid the sweet-sour taste of that situation.
3) The recipe nanook posted is 2 parts baking soda to one part citric acid. That recipe IS nasty. It was so nasty that I stopped increasing the relative proportion of baking soda when I got to that ratio, because I could tell that adding more baking soda would just get more and more miserable, tasting and feeling more like soap.
4) I would also recommend using a higher ratio of water and figuring out the best ratio of water to the other ingredients. It was my sense that 1/4 cup water was just enough to make everything react to the degree it was going to react, but tastes were way too concentrated.
5) If you were going to start at my best recipe and tweak it, certainly explore both increasing and decreasing baking soda, but my guess would be you'd want to decrease it from there, likely by a miniscule amount.
6) After all's said and done, you'll want to move on to considering flavorings and probably a little dab of sugar. From further reading it looks like sugar helps mask the tastes of the unreacted citric acid and baking soda.

• After acquiring equipment from Oak Barrel Winecraft set about figuring out the best method for pressurizing/dispensing.
  • Oak Barrel salesperson described complicated method:

1. 1. 1. COLD water, fill corny keg with 2.5 gallons.
      2. Set regulator at 30 psi, quick connect to keg.
      3. Roll and slosh keg around at 30 psi for 1 - 5 minutes.
      4. Disconnect tank line, close tank and purge tank line with valve on regulator.
      5. Purge pressure in keg with keg valve.
      6. Set regulator at 2 psi, quick connect to keg.
      7. Dispense at 2 psi until keg is empty.
      8. Disconnect tank, close tank, purge tank line, purge keg with keg valve.
      9. Repeat step 1 for new tank.

• • MeFi user pwb503 suggested a simpler method:

1. 1. 1. COLD water, fill corny keg with 2.5 gallons.
      2. Set regulator at 60 psi, quick connect to keg.
      3. Roll and slosh keg around at 60 psi for 1 - 5 minutes.
      4. Disconnect tank line
      5. Store keg in fridge to keep cold
      6. Attach tap and dispense at 60 psi of initial charge.
      7. Let sit to equilibrate and maximize bubbliness/taste.
      8. Recharge with relatively high pressure if the keg does not empty with initial charge.

• • MeFi user ttrendel suggested method more like Oak Barrel, but dispensing at 30 psi.
  • Discussion with pwb503 indicates that experimentation is probably necessary to get the right behavior I want.
  • Note-taking and experimentation on Google Drive spreadsheet
  • Some indication picnic tap was either not tightened properly or faulty. Troubleshooting.
    • First step: make sure top threaded "lid" is screwed down tightly.