Does Kefir Soda Have Alcohol?

If you make your own fermented beverages, especially if you make homemade kefir soda, you may wonder if it has alcohol in it, and if so, how much? You won’t believe all the steps it took to finally get a solid answer on this question, thankfully my brother-in-law Kevin, who is a chemist, jumped in to help…

First, to make sure we’re all on the same page:

So why does it matter, anyway?

This past summer I took some of my bottled kefir soda when we were meeting my family (siblings, nieces & nephews) at Mom’s pool. Our kids love our homemade pop and I couldn’t wait for the family to try it, hoping I could get them, by some miracle, to start making and drinking this instead of pop. (Regular soda pop is full of the heart-killer sugar, high fructose corn syrup, as well as other mystery chemicals to add fizz, preservatives, etc. Scary stuff! Note: artificially sweetened soda pops are just as bad! Read more: Are you addicted to liquid candy?)

They weren’t impressed.

First they couldn’t believe I was making homemade soda pop in the first place. Then they couldn’t get over the alcoholic smell, and joked about what Aunt Kelly was doing to all the nieces and nephews, we had some good laughs over that! It does have a little fermented taste and smell (because, HELLO!, it’s fermented!), but not a lot in my opinion. Next, they thought it was a little bland. Keep in mind that most of them drink Mountain Dew or other sodas regularly, so a drink that’s not overpoweringly sweet is going to taste more bland to them. As I said, my kids loved it! (But they don’t even get juice regularly, let alone pop, so they thought it was a big treat – don’t let the secret out that it’s actually good for them…)

Many have speculated about the alcohol content in kefir soda pop, but I wanted to know for sure so I could tell my family, lest they think I’m turning my kids into boozers. My step-Dad, Carl, was convinced it had at least 4% alcohol, but online most sources guess it at more like 1%.

So I was going to figure this out.

I started out on my own, assuming it couldn’t be that tricky. After some internet research, I bought a hydrometer at the beer-making store, and made another trip when I realized I didn’t have the right container to float it in. Then I had the right equipment, but when I was finally ready to take my readings, I realized our cute little 4 year old had broken the hydrometer while looking it over one day. So it was back to the beer-making store for another one (thankfully they’re only $5) and I could finally get started. (See the hydrometer floating in this container?)

I got a new batch of kefir soda going for my “before” readings, and the next day I finished a batch, bottled it and let it set like normal before I took my “after” readings. But my results weren’t clear.

Thankfully I had someone to call…

My sweetheart brother-in-law, Kevin, is a chemist. Not only that, lucky for me, he also brews his own beer now and then. Kevin had no idea at the time what he was getting into when I first called him about this, but even at about 50 emails into it, he was still saying things like, “I'm having a fun time with this little chemistry experiment!”

He did some research and found a formula for me to follow, which brought me back to my days in chemistry class. He explained that before I could get an accurate “after” reading, I had to boil it down to get rid of the carbonation. But then I had to get it back down to the right temperature, and be sure I was measuring in the same amounts of liquid, so I was comparing apples to apples. I did all this, but my readings still weren’t clear.

So Kevin decided he would like to test this out for himself.

Now, all thanks to him, and after a lot more pooping around that I don’t want to bore you with (as if you’re not sleeping already, although I actually think this is fun!), we finally have a solid number:

The amount of alcohol in kefir soda pop, based on my recipe:

0.64% alcohol by volume

Woohooo!!! Not even close to 4% alcohol, it's more like the amount that's in a non-alcoholic beer!

Kevin’s comments on the taste: “The soda itself wasn't bad. I definitely taste the yeast, and maybe that's what your family is tasting that makes them think of beer.”

Now for you ‘details’ people…

For those of you who are more detailed oriented like I am, I’ll share a few of the email exchanges between Kevin & I. Keep in mind I’m only sharing a few random parts that I thought might be interesting to you, so if something doesn’t jive just right, it’s my fault, not Kevin’s, and it’s also very late right now as I edit this, so cut me some slack.

Kevin:

Okay, I got home tonight and played some more. After another day, my soda was well carbonated. I'll call it “medium” on the carbonation, not quite a can of coke, but plenty for my tastes. I took a sample, heated it in the microwave to get rid of the carbonation, then cooled and measured specific gravity. I get 0.64% by volume (0.50% by weight). Not bad. I think it just took a while for the yeast to kick off. Not sure why, but that happens with beer sometimes too, so it's not surprising.

So I did some investigating and calculating. Here's what I have. This all assumes that little or no alcohol is formed during the initial kefir grain / sugar water fermentation phase. I'm not sure how good of an assumption this is, but my process never formed any alcohol during this phase, and from your spec. grav readings, it doesn't sound like yours did either. So, I assume that the alcohol is only formed in the bottle, and I assume that our final fizziness is about the same as a can of coke (3 volumes of CO2 added per can, according to a couple internet sources). Then, from the chemical reaction that the yeast uses to make alcohol, I know that we get 1 CO2 for each 1 alcohol molecule. This means, that to get 3 volumes of CO2, we would get a MAXIMUM of 0.7% alcohol by volume. Sorry, does that make any sense? Basically, this says that if your Kefir soda is equal or less fizzy than a standard can of coke, then you have less than 0.7% alcohol.

Me:

Just to clarify, you’re saying that the more carbonation, the more alcohol then, right? So should I warn my readers that if they let it set on the counter longer than 18-24 hours, not only are their chances of a kitchen mess (and explosion) more likely, but also their alcohol content will also go up?

Kevin:

You are correct, more carbonation = more alcohol. I would suggest that your readers stick with your initial suggestion and not let the soda stay in the bottle on the counter more than 24 hours. I'm afraid they might explode some bottles if they let it go for 2 days.

A final note:

When I was leaving my bottled kefir soda on the counter for 24 hours, it was fizzing out the top when I opened it and wasting a good share of the soda. I cut it back to 18 hours and this was just right. It still had a good fizz, but most of the time it didn’t go all over.

Now that we know this kefir soda pop is fine for the kids, the next thing I’m making is a nice fermented drink for Momma – I’m ready to try a shot at making wine coolers!

Kevin, are you up for it?

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