Sure I can do it but will it taste bad?
May 8, 2015 7:19 AM   Subscribe

My quest to sate my wife's appetite for carbonated water, along with a scene in a BBC documentary about pharmacies, has led me to the idea of using citric acid and baking soda to carbonate our own. Setting aside the risk of bottle bombs, I'm curious as to if the quantities needed to make a fizzy beverage will impart a strong or unpleasant taste, or any taste at all for that matter. Any first hand experience with this sort of thing?

First and foremost let me reiterate that I'm not here to talk about the safety risk associated with carbonation in improper containers or via careless measures. I've brewed my own beer, alcoholic and root, and I've both bottle carbonated wine and beer as well as kegs for that matter. The words chemistry, stoichiometry, and partial pressure are not unfamiliar to me.

That's not to say that I don't welcome some casual discussion about levels of carbonation as it regards to taste as well as some math gut-checks (not unlike this one) but once I get my hands on the materials (mostly the food grade, no additives citric acid as I already have plenty of baking soda) I'll both do the proper due diligence on the math side as well as on the common sense verification side by using smaller amounts and working my way up.

Gut checks regarding the recomended daily allowance of the trisodium citrate in the output is also welcome as I'm not completely sure that it's a non-issue at the moment.

But, back to the point, the main question is about taste. That link I posted mentions that the resultant trisodium citrate has a, expectedly, "tart, slightly salty taste" and if this method is only going to be useful in making lemonade tasting water then it may not be worth the effort to begin with.


ps - One of the main draws to this method is the simplicity and low cost. We're not looking to buy any extra countertop devices, setup my CO2 tank and regulator, nor make a plastic bottle powered device. One bottle, one beverage is part of the appeal here.
posted by RolandOfEld to Grab Bag (25 answers total) 2 users marked this as a favorite
I went with the CO2 tank and regulator. I did not do the citric acid/baking soda route but it's certainly a traditional approach.

I wouldn't worry about the bottle bomb issue. Plastic bottles for carbonated beverages are rated around 100 PSI, and you are unlikely to get that amount of pressure from a chemical reaction.

For taste, you have to experiment and find out. Find a recipe and then vary it a little to see what tastes right to you.

You might also consider a CO2 charger in a siphon, which can be a pretty way to do it, but it does of course generate waste in the form of the charger cartridges.
posted by kalessin at 7:23 AM on May 8, 2015

I wouldn't worry about the bottle bomb issue.

Yea, I'm really, really not.

You might also consider a CO2 charger in a siphon

Nah, I hate the idea of wasting those little things, and if the chemical route turns out to be a non-starter then I'll just wait until our next move is complete then setup my beer carbonation (read: CO2 tank and regulator) kit and use that rather than purchase widgets in the meantime. Money's tight.
posted by RolandOfEld at 7:31 AM on May 8, 2015

To my tastes, citric acid is just a tart flavor, and baking soda is slightly soapy. Any imbalance in your recipe will probably tilt the flavor towards one of the two. But it doesn't sound like you'd have any problems with the chemistry.

The baking soda will increase your wife's dietary sodium intake. You didn't mention it as a concern, but she may want to take it into account in planning her diet.
posted by Wilbefort at 7:51 AM on May 8, 2015

I don't see why you wouldn't try it! The ingredients don't seem difficult to find or expensive. It probably won't taste like "plain" carbonated water.

So, I'm also a cost-conscious bubbly-water addict. From my casual math, the CHEAPEST overall way is the CO2 tank route. After that, maybe store-brand seltzer bottles. The siphon and cartridges doesn't work out to a whole lot cheaper than buying bottles. Neither does a SodaStream, but I'll admit that I eventually went with that and it's totally convenient.
posted by jeweled accumulation at 7:55 AM on May 8, 2015

If you ever get sick of all the damned simplicity and low cost, you can carbonate individual beverages with dry ice. Fun for special occasions, what with the chill mists pouring over the cuplip and all. And the drinks get cold.
posted by Don Pepino at 8:06 AM on May 8, 2015

I have citric acid and baking soda. Want me to try it out? I can't guarantee my tastes are the same as yours, but I also have a tank and keg system so I can compare and contrast. :)
posted by kalessin at 8:16 AM on May 8, 2015

Sounds like Fizzies tablets
posted by Sophont at 8:24 AM on May 8, 2015

Here, by the way, is a discussion of the chemistry of the reaction. Assuming a 100% completeness - I was unable to confirm that the kinetics run this way but it's probably a reasonable assumption, these are the calculations you need to use for relative proportions of each ingredient. If you do this in a bottle (i.e. a sealed reaction chamber), there may be kinetics effects that prevent full, complete consumption of the limiting reagent from the partial pressure of the gas in the bottle's headspace. I rate this as unlikely but you'll need to do some minimal experimentation to figure out how to get a complete reaction - it may just happen, or it may require jostling.
posted by kalessin at 8:26 AM on May 8, 2015

Carbonated water already tastes slightly acidic, but I don't think most people even detect that as a flavor. Adding another acidic salt won't likely change the overall flavor for most people, but it may taste more sour. Some people may also taste the salt.

I'd worry less about the RDA of sodium citrate than the plain sodium content and the effect of lots of soda water on tooth enamel.
posted by zennie at 8:34 AM on May 8, 2015

I have citric acid and baking soda. Want me to try it out?

Sure, that'd be awesome. This isn't really about my taste buds either. My wife's are quite a bit different than mine so any report from yours regarding, for lack of a better word, intensity of any flavors would be quite useful. Many thanks.

I swore I had some citric acid sitting around as well, from a cheese making kit, but I think said wife admitted to throwing it out.

Carbonated water already tastes slightly acidic, but I don't think most people even detect that as a flavor.

Yea, she does. Double blind mini-studies (she's a scientist-statistician after all) have proven she can, I can't.

I'd worry less about the RDA of sodium citrate

Right, I'm not so much worried about that except for completeness sake.

than the plain sodium content

Between us we drink about a 12 pack of cans of soda water a week, more or less. Combine that with alot of cooking at home and not being super heavy handed on the salt and I suppose we're in the 'lower than average' bracket but honestly this didn't even come into mind for me with regards to comparing the experimental self carbonated batch with commercial soda water from the store.

the effect of lots of soda water on tooth enamel.

Wat!? *goes off to internet to probably add one more thing to the list of things we're doing that are unhealthy*
posted by RolandOfEld at 9:03 AM on May 8, 2015

I remember finding an article debunking the bit about soda water and tooth enamel. I'll look for it. Noodling around with citric acid and baking soda will likely need to wait until this afternoon, but I'll get to it and report back.
posted by kalessin at 9:58 AM on May 8, 2015

What I meant regarding tooth enamel was the relatively low pH of soda water. It can have an effect that may be significant in susceptible people. So if soda is largely replacing plain water, it's just something to consider.
posted by zennie at 10:46 AM on May 8, 2015

I know it isn't really carbonated water, but if flavoring is okay, you might consider brewing some traditional fizzy beverages instead, like water kefir or kombucha (I'm a big fan of mineral water myself and these sorts of beverages definitely scratch the same itch for me).
posted by veery at 12:38 PM on May 8, 2015 [1 favorite]

I happened to have food grade citric acid and baking soda lying around, and hey, fizzy water! So I made up a glass using this recipe. Preliminary tasting is just awful. Really awful, salty, baking sod-ey, unpleasant. So much so that I am no way inclined to bother tweaking the recipe for better results. YMMV.
posted by nanook at 1:37 PM on May 8, 2015 [2 favorites]

So even though that didn't give good results, people do get reasonably palatable lightly fizzy water through acid base reactions; that's what the "Emergen-C" products do. Their ingredient list has a variety of weak bases, and a few weak acids (citric acid, malic acid, and ascorbic acid). Dunno how it would taste without the additional flavoring, and it does only make water lightly fizzy, but it does show the concept is viable.
posted by aubilenon at 2:38 PM on May 8, 2015

I used to do this when I was a kid, from a recipe in one of my mother's cookbooks. I could always taste a bit of residue from the baking soda, and only found it pleasant when mixed with super sweet strong flavours, like berries and a ton of sugar.
posted by lollusc at 5:45 PM on May 8, 2015

Yesterday I didn't experiment because all I could find for a formula was this experiment. Which looks like it gives a useful experimental range but would be a lot of work to mess about with. Still I may try it later.

Today is going to be a big family thing with lots of minding my elderly Dad. So experimenting will wait until Sunday, sorry.

I majored in chemistry and have some graduate school experience in p chem. Given nanook's and lollusc's testimonies, either the proportions aren't quite right and the measuring needs more accuracy to bias the citric acid as the non-limiting reagent or the kinetics of the reaction need a kick (possibly thermodynamic - the reaction is endothermic and may be reduced in efficiency if the solution as a whole gets too cold), so you might need to start with warmish water to get a total reaction and burn up all the reagents. Or maybe even with tweaking there's only so much you can do with measuring realistic amounts of the ingredients.

If I do experiment, of course I will report back.
posted by kalessin at 6:42 AM on May 9, 2015 [1 favorite]

P.S. two debunkings of the claim that carbonated water is bad for you:
- The Nutrition Diva & Quick and Dirty Tips are both MacMillan published and I found the link via Scientific American.
- If you prefer more crowdsourced, there's also a debunking at
posted by kalessin at 6:54 AM on May 9, 2015

Apologies if this counts as a failure to answer the question as specified, but if you're looking to generate carbonated water without extra flavors, there really is no alternative to getting a CO2 tank, regulator, and a 2L bottle-cap fitting. It's fairly cheap and easy, and the product is far more satisfying than any easy to come by CO2-generating chemical reaction.

For an initial outlay of approximately $150, a few minutes a week shaking bottles, and a trip to the CO2 supplier every year or two, you get nearly free and unlimited carbonated water with no extra flavors. What's more, you can pressurize your bottles at several times the pressure at which commercial seltzer is shipped. I'm not so spoiled by home-made water, store bought seltzer tastes like plain tap water. (Consumer counter-top and in-siphon seltzer makers and all the fizzy dissolvables I've tried don't even come close.)
posted by eotvos at 2:31 PM on May 9, 2015

I don't understand the question. Carbonated water costs about 10¢/litre from the supermarket. Surely that's the cheapest and simplest option?
posted by turkeyphant at 12:36 PM on May 10, 2015 [1 favorite]

Apologies if this counts as a failure to answer the question as specified,

Yea, it's a bit outside the bounds of the question to be honest. I mean, I already have a tank and regulator. I'd just have to setup the 2 liter bottle side of it or dedicate a keg to just water. However, I don't have that stuff with me as it's in storage 7 hours away, we're moving in 2 months, and we don't have room in the place we're living now anyway.

Trust me, I have zero arguments that a kegging or bottling setup is the *best* solution here. It's just not answering my question.
posted by RolandOfEld at 12:38 PM on May 10, 2015

Carbonated water costs about 10¢/litre

Just did the math and it's about 6 times that here for store-brand carbonated water in a 12 pack of cans. Sure it's maybe a bit cheaper by the 2 liter but it goes flat before you can drink all of it.

And honestly the question isn't just based on cost or else, again, it's best to just spend the upfront investment to go home CO2 tap... it's just the idea in general.
posted by RolandOfEld at 12:41 PM on May 10, 2015

My bad - I had focussed on your final statement that "One of the main draws to this method is the simplicity and low cost" and my answer seems unbeatable for that. I fully expect you'll encounter taste issues with your method, a SodaStream (or equivalent) doesn't meet the low cost criterion (as well as being morally unacceptable) while setting up a home CO2 tap certainly isn't a simple solution...
posted by turkeyphant at 1:02 PM on May 10, 2015

Okay, I did a 1-trial-of-each experiment with citric acid and baking soda, and I have a couple of interesting points/discoveries, but I have to say that this is probably not for you, RolandOfEld.

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.

So that's what I have for you. I hope it helps. For what it's worth, I would rather spend the money on the tank-regulator-keg-tap system I have than rely on drinking this stuff. But it's possible you'll come up with a palatable recipe if you work at it.
posted by kalessin at 3:28 PM on May 10, 2015 [1 favorite]

Oops, nanook's is 3 parts baking soda to 2 parts citric acid. That's not AS nasty, but still nasty. :)
posted by kalessin at 3:37 PM on May 10, 2015

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