Kvass Bubbly Probiotic Beverage Recipe

Almost every culture has found a way to use stale bread. Traditional kvass is a way to turn it into a delicious, bubbly probiotic beverage that’s satisfying and very slightly alcoholic (0.5-1%).

It’s a traditional drink in eastern Europe that dates back to the middle ages. Historically, kvass was made with rye bread, fruit, honey, and herbs to add flavor. People would also add beets for flavor, which is how we got a more westernized version that skips the bread and only uses beets for the process.

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Kombucha has become popular as a probiotic drink, and you can find many lightly fermented beverages labeled as kvass. Still, very few of them actually follow the methods of the traditional drink.

We’ll show you how to make homemade kvass the traditional way so that you can enjoy a satisfying bubbly, probiotic beverage whenever you want!

How to Choose a Sweetener for Your Kvass

If you want a stronger drink and to balance out the sour notes from the probiotic culture, you’ll want to add some sweetener to your kvass. Traditionally, you make kvass using birch syrup or sap, but maple syrup and honey are also good choices. You can also use white or brown sugar in a pinch.

Birch beer, which is a similar drink to kvass, is made with birch sap like kvass but without the bread. The birch sap is believed to have medicinal properties—we recommend using commercial birch syrup to sweeten your kvass. It’s not difficult to find, and it has a very distinct (and delicious) flavor.

How to Make Homemade Kvass Without Yeast

The health benefits of drinking kvass come from the long and slow fermentation process that slowly breaks down the stale bread’s nutrients. If you add a couple of spoonfuls of commercial yeast, it will completely overpower the natural cultures. You’ll get a fizzy drink quickly, but it’s not an ideal solution.

Using yeast for your kvass is also very untraditional and results in a much harsher drink. Traditional kvass cultures started similarly to how we make sourdough starts, so unsurprisingly, a spoonful of sourdough starter is the best way to start your kvass.

A white sourdough starter works fine, but a rye sourdough starter will give you a more traditional kvass flavor. You can make your own or buy a sourdough starter from your local grocery store or even Amazon!

If you can’t get a sourdough starter in time to make your kvass, you can use yogurt with active cultures along with a tiny pinch of beer or bread yeast.

How to Make Homemade Kvass

Kvass fermenting in a glass jar

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The first step in making homemade kvass is toasting your bread. Here’s why:

  • It caramelizes the sugars, making them easier for the microbes to digest.
  • It creates a more flavorful kvass with a darker color.
  • It helps kill any mold spores that might be growing on the bread’s surface.

If your bread is sliced, you can put it in the toaster until golden (but don’t burn it!). You can turn the slices into small cubes with your hands after toasting.

If you have a loaf of stale bread, you can bake it at 350 for around ten minutes until it’s dry and toasted.

Then, place the cubed bread in a large bowl or mason jar and add in the remaining ingredients (sourdough starter, sweetener, and other flavorings). Cover the bowl or mason jar loosely and let it sit out for 2-7 days.

Homemade Kvass Recipe


  • Six cups of water
  • Four to six cups of toasted, cubed stale bread
  • ½ cup to ¾ cup of your choice of sweetener
  • Two to four tablespoons of sourdough starter OR
    • Two tablespoons of yogurt + a pinch of beer or bread yeast
  • Fruit or herbs for seasoning (optional)


  • Boil the water, sweetener, and seasonings.
  • Stir until the sweetener is dissolved, and turn off the heat.
  • Allow the liquid to cool to room temperature.
  • Place your sourdough starter or yogurt mixture and the toasted, cubed bread into a half-gallon mason jar.
  • Pour the liquid into the mason jar (if the water is over 90 degrees, it will kill the cultures—make sure it’s cool enough!).
  • Loosely cap the mason jar and allow the mixture to ferment for 2-7 days at room temperature.
  • Filter it with a fine mesh strainer, bottle the kvass, and store it in the fridge.
  • Enjoy your homemade kvass within ten days!
  • How to Know When Your Kvass Is Ready

    When you make kvass at home, you need to ferment it long enough to get fizz and flavor, but not so long that it gets overly sour. Traditionally, kvass is lightly carbonated—it’s not going to have as much carbonation as modern drinks like sodas.

    Depending on your home’s temperature, the activity in your sourdough starter, and the amount of sweetener you use, your kvass will be ready in 2-7 days. You’ll want to give it a taste after the first two days.

    You’ll know it’s ready when it tastes a little sweet, a little sour, and slightly carbonated. You’ll also notice slight malty notes from the bread. For a more tangy flavor, you can allow it to ferment an extra day or two. Once the flavor is to your liking, you’ll want to strain it using a fine-mesh strainer before bottling it.

    How to Bottle Your Homemade Kvass

    A swing-top bottle for storing kvass

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    After your kvass is finished, you’ll want to bottle it to build more carbonation and keep it from becoming too sour from over-fermenting. The easiest way to bottle kvass is in mason jars; you can strain it straight into the jar, leave about 1” of space on top, seal it, and refrigerate it.

    With a tight seal and refrigeration, your kvass will slowly build more carbonation, and it will keep well for up to ten days.

    For a more elegant presentation, you can also bottle your kvass like kombucha by using reusable Grolsch bottles. Either way, store them in a cool basement or the refrigerator so that they don’t over carbonate or over ferment.

    Looking for a premade probiotic drink instead of making your own? Try our probiotic shots—an easy (and delicious) way to get the health benefits of natural probiotics!

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