Despite the poorer-than-usual grape harvest this year, our grapevines yielded plenty, and I was left wondering what to do with them all! Enter fermented grape soda. This homemade fizzy drink is super easy to make, tastes awesome, and is rich in probiotics-unlike the Fanta version!

Our grapevines are one of those little things that make me so thankful that we wound up buying this house, instead of building! I never even knew that I was a grape jelly person, until I made it from scratch. There’s just something so satisfying about completing the whole process by hand, from harvesting the grapes all the way until holding a jar of grape jelly (or in this case, a bottle of your own fermented grape soda!)

However, you can still totally make this if you don’t grow your own grapes! Just buy 100% unsweetened grape juice and skip through the “making the juice” portion. The instructions for “making the soda” start with unsweetened grape juice, so you can just jump in there!

pouring fermented grape soda — The fizz is real!

Table of Contents

How Do You Ferment Soda?

The “starter culture” for this fermented grape soda is whey. You do have to make your own whey: this is the liquid byproduct of raw (non-homogenized) milk when it separates (think “little Miss Muffet sat on her tuffet, eating her curds and whey”). This is not the same as whey protein or anything similar you might find in the grocery store.

Whey is a highly effective starter culture and can be used in lots of other fermentation recipes, like to make Lacto-Fermented Vegetables. In that case, you have the option to use all salt if whey isn’t readily available. In fact, the reason I did not use whey as the starter culture in my vegetable post was because I assumed that for most, salt was much easier to come by than whey! In this case, however, I don’t know of any effective substitute for the whey.

To make whey, I simply fill a jar with whole raw milk, close it tightly, and let it sit on the counter for 4-5 days or so, until it is completely separated, then run it through a cheesecloth or strainer. The liquid is the whey: it will be kind of a cloudy/milky white. The solids are the curds. I’m sure there are all sorts of fun ways to use the curds: I haven’t experimented with that bit much yet!

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Tools & Equipment for Fermented Grape Soda

Large mixing bowl
Stock pot
Potato masher
Cheesecloth or jelly strainer
Colander (if using cheesecloth)
Whisk
Funnel
Bottles or jars, to ferment and store soda: these should be able to seal tightly. You can use the size of your choosing, I use these

Ingredients for Fermented Grape Soda

100% juice (unsweetened) grape juice. To make this from grapes, follow the instructions below
Whey
Granulated sugar

The Process

Making your grape juice

First, I should point out that we’re talking about Concord grapes here, not table grapes! Most likely, you won’t encounter Concord grapes at the grocery store, though you can buy them from growers.

First, wash your grapes, and remove the stems. In a large mixing bowl, use a potato masher to mash the grapes down. You may want to do this in a couple batches, if you have a large amount of grapes. Once mashed, the grapes will be kind of lumpy and pulpy. You don’t need to worry about smashing them down extremely well.

Place your mushed grapes in a large stock pot, and add enough water just to cover the grapes. Bring the grapes to a boil on the stove, then reduce the heat and simmer for 10 minutes, stirring frequently. Choose your utensils carefully: the grape juice will stain some materials.

Strain your grapes. I do this by lining a colander with cheesecloth, then placing the colander over a large mixing bowl. Pour the entire contents of the stock pot into the cheesecloth and allow to strain fully (I leave this overnight).

Once fully strained, discard your cheesecloth and the contents- seeds, skins, etc.

Your juice is now ready to use! If you’re not ready to use it yet, you can store it, either in a jar in the fridge or you can freeze it until you’re ready to continue.

Making your soda

Sterilize your bottles. I do this by placing my bottles in a clean sink, boiling water in the electric kettle, and pouring the boiling water over the bottles. Another option is to fill the sink with boiling water first, and then submerge your bottles. Once your bottles have cooled enough, remove to a clean surface.

Whisk together your grape juice, whey, and sugar until fully dissolved.

Use a funnel to pour your juice mixture into your prepared bottles. Seal your bottles tightly.

Leave on the counter to ferment. You will probably begin to see signs of fermentation (little bubbles rising) after a day or so. I typically leave my soda to ferment for 2.5-3 days. You can leave yours for longer, but the soda will progressively become less sweet.

During the fermentation process, “burp” your bottles to remove just the initial excess gas once a day.

Once you are ready for fermentation to stop, move your bottles to the fridge.

Enjoy chilled!

fermented grape soda w scoop of vanilla ice cream

FAQ’s

How Should I Serve Fermented Grape Soda?

My two favorite options: 1.) Just sip it chilled, or 2.) As a Purple Cow (AKA a root beer float, but with grape soda).

How Should I Store Fermented Grape Soda?

In the fridge, tightly closed! I wouldn’t freeze it, due to the carbonation. Also, this hasn’t ever lasted terribly long in my home, so it’s hard to speak to exactly how long you could store it. Most lacto-fermented items can be stored for several months, though I’m not sure if you’d still get as much fizz at that point.

Can I Substitute The Sugar?

You need some sort of sugar in this, to give the bacteria something to eat. Theoretically, other types of sugar (honey, maple syrup, agave, brown sugar) would also work. I cannot, however, speak to how they would affect the taste of your soda.

Yield: 1 quart