With a honey-like sweetness balanced with just the right punch of acidity, homemade bread kvass is a delicious addition to the table. Notes of toasted bread come through in this naturally fermented, traditional Russian drink. Not only does it taste refreshing, but it's a nutrient-rich functional food that you can make with practically no effort. You just need a few scraps of old bread to get you started.
What is kvass?
Kvass is a traditional Eastern European fermented drink typically made with stale, toasted sourdough rye bread. While bread kvass is the most popular, other versions exist including those made with beets and fruit.
It tastes of honey and malt, similar to a cross between a blonde beer and mead; however, it contains much less alcohol than these drinks. Owing to its brief fermentation cycle, it usually contains as much alcohol as other similar drinks, such as kombucha or water kefir, ranging from .3 to 1.5% (1).
Where did it come from?
The earliest recorded reference to kvass dates back to 989 AD. Russian chroniclers describe a celebration held in which newly converted Christians were given food, honey, and bread kvass at the direction of Prince Vladimir (2).
While written references may date back over a thousand years, the drink is undoubtedly older than that, with references to brewing small beers and other fermented drinks made from fermenting spent grains dating to antiquity - particularly in Sumeria and the fertile crescent.
It makes sense, too. Kvass is a natural solution to a few problems of the pre-industrial era: lack of access to clean water coupled with a collective need to minimize food waste. Traditionally, the water for kvass was first boiled and then the hot water would be poured over hard stale bread. Boiling water kills pathogenic bacteria that could sicken people, making kvass a safer drink than water. Further, when food was scarce, preparing kvass also meant creating nourishment out of something that might otherwise go to waste: stale bread.
For many families, turning bread and water into kvass was a daily practice. By the 19th century, kvass making became a thriving cottage industry with kvasniks specializing and selling unique varieties that featured grains such as barley, mint, and other herbs, or fruit such as apples and berries. Today, kvass continues in popularity throughout Eastern Europe and is rising in popularity in the U.S.
What's in it?
The ingredients for bread kvass are simple and uncomplicated. You need day-old sourdough rye bread, water, a source of sweetener such as honey, and a yeast-based starter culture. To this basic mix, you can add spices, herbs, and fruit for flavor as it suits you.
- Stale sourdough rye bread is the foundation of the drink. To prepare the bread for fermentation, you'll first chop or tear the bread into chunks and then toast them until dark.
- A sweetener gives the kvass flavor, and it also helps feed the bacteria and yeast in the starter culture that are responsible for transforming stale bread and water into kvass. Honey is the most traditional option; however, sugar, molasses, and maple syrup work too.
- A starter culture inocculates the bread and water with yeast (and if using a natural starter) lactobacillus bacteria. This culture kickstarts the fermentation process and helps the drink to ferment safely.
- Spices, herbs and fruit can improve the flavor of kvass. Coriander, caraway, lemon verbena, mint, apples, pears, and berries are common additions.
How to make kvass
Making kvass is a four-step process. While the fermentation process takes several days, you'll only spend a few minutes of active time in the kitchen. Instead, the bacteria and wild yeast responsible for transforming sourdough bread and water into a bubbly fermented beverage will do most of the work for you.
- Preparing your ingredients. You'll toast stale bread, gather your spices (we use coriander and caraway), and whichever source of yeast you're planning to use.
- Soaking the bread. After toasting the bread, you'll toss it into a jar, cover it with water, and let it soak or steep for up to 3 days. In hotter temperatures, you may only need to let it soak for a day, while colder temperatures require more time. A large (2-quart) mason jar works well for this purpose.
- Fermentation. During the initial fermentation, you'll strain the liquid (called the wort) through a cheesecloth, disiscarding the bread. Combine the wort with other seasonings (such as mint or fruit), honey, and a source of wild yeast. Allow this yeast mixture to ferment for one to two days.
- Bottling. After the initial fermentation, you'll strain the resulting kvass into bottles and let it ferment one more time. This technique, called bottle conditioning, is also used to brew beer or make kombucha. Sometimes, an additional source of sugar is added to the bottle, such as honey, to increase the fermentation which results in more bubbles.
Like just about any old-world fermented food, making kvass is simple and fuss-free. These recipes and techniques are uncomplicated. Remember, it comes from a time when homemakers didn't have time to make elaborate or fussy meals; rather, ingredients needed to be simple and affordable while techniques needed to be easy to follow and require minimal effort. That said, there are a few things you'll need to keep in mind when you brew your first batch.
- Toast your bread until it's dark. Those toasty, toffee-like notes come through and give the kvass body and flavor. They pair beautifully with honey, too.
- Use hot water, but it doesn't have to be boiling. Traditionally the water for kvass was boiled first. Since you have (most likely) have access to clean water, you only need to warm it up a bit. It should be about as hot as a cup of tea.
- Use clean equipment, but don't worry about sterilizing. Clean bottles and clean jars just out of the dishwasher work fine.
- Use a caloric sweetener. This recipe calls for honey to sweeten the kvass (and feed all the good microbes during fermentation); however, you can use another sweetener. Noncaloric sweeteners inhibit fermentation since they lack enough carbohydrate to feed bacteria and yeast.
- Pay attention to temperature. Kvass will ferment faster in warm temperatures and take more time in cold kitchens.
- Burp your jars and bottles if you're concerned about the build up of carbon dioxide. Carbon dioxide is a natural byproduct of fermentation and it's what makes fermented drinks, such as kombucha, beer, and kvass, naturally fizzy.
Homemade Kvass Recipe
Toasting the bread.
- Heat the oven to 400 F, and line a baking sheet with parchment paper.
- Arrange the bread onto the parchment paper, and bake for 20 to 30 minutes or until dark brown.
- Drop the toasted rye bread into a jar with a tight-fitting lid, cover with water, and then dd the caraway and coriander seeds. Seal tightly. Allow the kvass to ferment for 3 days in a warm spot in your kitchen way from direct light.
- Strain through a fine-mesh sieve or square of cheesecloth, pressing the liquid from the bread to extract as much as possible. Return the liquid to the jar, discarding the spent bread. Add the mint, honey, and sourdough starter.
- Seal the jar and allow it to ferment for 2 days in a warm spot in your kitchen, away from light and direct heat.
- Transfer the kvass into flip-top bottles, and let them ferment 1 day more. Then transfer to the fridge where it will keep up to 5 days. Serve cold with a sprig of mint.
Which type of yeast should you use for kvass?
Traditionally, bread kvass is fermented with the addition of yeast-based starter culture. This speeds up the fermentation process and also ensures a level of uniformity from one batch to the next. A mixture of flour and water similar to a sourdough starter would be used, but you have a few options.
Sourdough starter is a good option as it contains both lactobacillus bacteria and yeast. The lactobacillus bacteria give the kvass its characteristic sour undertone, while the yeast gives the drink its fizz. Here's how to make a sourdough starter.
Wild yeast (yeast water) is a good alternative, and it's made soaking dried or fresh fruit in water for a few days. In those few days, the naturally occurring yeast on the surface of the fruit will start to multiply. Get the recipe for wild yeast here.
Kombucha tea contains both acetobacter (the same kind that produces vinegar) and yeast. Like the lactobacillus in sourdough, acetobacter will give the kvass a distinct sour flavor.
Ginger bug is a wild-fermented starter for fermented drinks and it contains naturally occurring yeast and beneficial bacteria. It's not a traditional option for kvass-making, but it works well and gives your drink a gingery undertone. Get the ginger bug recipe here.
Kvass from a previous batch also works fine as a starter. So, if you've already made a good batch that you enjoy, keep a little (especially the yeasty sediment at the bottom of the jar) to start your next brew.
Commercial yeast works as well and is popular in many home kitchens since you can find it in any grocery store and it doesn't require the maintenance of sourdough starter. This can be the same yeast brewers use or even the active dry yeast you might use for baking.
Lemon verbena makes a nice substitute for fresh mint, giving the kvass a lemony, herbal flavor.
Toasted barley is a nice addition either on its own or in addition to rye bread.
Try using molasses or maple syrup in place of honey. While honey is more traditional, both molasses and maple syrup can give the drink a touch of sweetness with deeper, amber-like notes.
Hops is a common addition as well. It lends a bitter note to kvass, just as it does with beer. Hops is traditionally used to support nursing mothers and to encourage restful sleep.
Raisins or other dried fruit are often added during secondary fermentation. They're strained out and discarded before bottling.
Gluten-free versions are often made with buckwheat.
Is kvass good for you?
Like all fermented drinks, kvass is a rich source of beneficial bacteria. Fermented foods and drinks are functional foods, meaning that they convey a greater benefit than nutrition alone. The health benefits of these foods and drinks are well-documented (3, 4).
- Kvass is a rich source of beneficial bacteria and yeasts. While the microbial composition of kvass varies, it generally contains a wide variety of microbes including beneficial strains of lactobacillus and saccharomyces (5). These microbes support not only gut health, but systemic wellness.
- It's loaded with B vitamins, particularly niacin, riboflavin, and thiamin (6).
- It's also has a rich nutritional profile that includes plenty of minerals such as copper, phosphorus, zinc, and potassium (7).
Frequently Asked Questions
Like all fermented drinks, kvass contains trace amounts of alcohol - typically about 1.5%, although some versions can contain up to 2.5%(1).
Kvass contains very little alcohol compared to wine, beer, mead, and hard liquor. So, you would have to drink excessive amounts in order to get drunk. Traditionally, kvass is served to people of all ages, including small children without any limit because the alcohol content is so low.
Kvass is traditionally made with sourdough rye bread; however, you can substitute gluten-free sourdough bread or buckwheat bread if you wish. Other naturally gluten-free alternatives include beet kvass and fruit kvass.
Homemade will keep for about 5 days in the refrigerator.
Kvass will continue to ferment if left at room temperature, and its alcohol content will increase with fermentation. Keep your finished kvass in the fridge, and drink it within about 10 days.
If your kvass smells putrid, takes on a slimy or viscous texture, or has visible signs of mold, you should discard it.
You can make kvass easily without commercial yeast. Traditionally, you'd use a starter culture similar to sourdough bread; however, this method still contains strains of wild yeast.
Kvass needs a starter culture, and sourdough works well. If you don't keep a sourdough starter, try making wild yeast with dried fruit and water. Alternatively, you could use ¼ cup plain kombucha since it also contains yeast, or even ½ teaspoon baker's yeast.
Because fermentation produces carbon dioxide, fermenting drinks can create pressure. While exploding jars and bottles are unusual, they can happen. You can burp your jars and bottles as they ferment to allow excess gas to escape; alternatively, you can place your jars and bottles into a cooler so that in the unlikely event that they do explode, the mess will be safely contained.
Other fermented drink recipes you'll enjoy
- Sergei V. Jargin, Kvass: A Possible Contributor to Chronic Alcoholism in the Former Soviet Union—Alcohol Content Should Be Indicated on Labels and in Advertising, Alcohol and Alcoholism, Volume 44, Issue 5, September-October 2009, Page 529,
- Hornsey, Ian. Alcohol and Its Role in the Evolution of Human Society. Royal Society of Chemistry. (2012)
- Marco, Maria L et al. “Health benefits of fermented foods: microbiota and beyond.” Current opinion in biotechnology vol. 44 (2017)
- Şanlier, Nevin et al. “Health benefits of fermented foods.” Critical reviews in food science and nutrition vol. 59,3 (2019): 506-527.
- Dlusskaya, E., Jänsch, A., Schwab, C. et al. Microbial and chemical analysis of a kvass fermentation. Eur Food Res Technol 227, 261–266 (2008).
- Lidums, I., Karklina, D., Kirse, A. et al. Nutritional value, vitamins, sugars, and aroma volatiles in naturally fermented and dry kvass. Foodbalt (2017)
- Ekin, H., Orhan, D. Kvass: A Fermented Traditional Beverage. Fermented Food Products. (2020)