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Easy Sourdough Kvass Recipe

Easy Sourdough Kvass

249kcal
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Prep 15 minutes
Cook 20 minutes
Overnight Rye Starter Fermentation 10 hours
Total 1 day 12 hours
A sweet, naturally carbonated Slavic fermented beverage made with barley malt powder and rye sourdough starter. Probiotic-rich with a complex, refreshing taste reminiscent of traditional old-world kvass.
Servings 3 Liters
Cuisine Eastern European / Slavic

Ingredients

Sourdough Starter (Levain - Night Before)
  • 10 g Sourdough starter
  • 30 g Rye flour
  • 30 g Water
Kvass Base
  • 3 Liters Boiling water
  • 100 g Brown sugar
  • 70 g Barley malt powder
  • 50 g Rye sourdough starter from the stage above

Equipment

  • Digital Kitchen Scale
  • 3-Quart Large Glass Jar or fermentation vessel
  • Watering Can or Funnel
  • Glass or Plastic Flip-Top Bottles built for carbonation pressure

Method

Night Before: Build Rye Starter
  1. Combine 10 g starter, 30 g rye flour, and 30 g water in a small jar. Cover loosely and let ferment for 10–12 hours.
Day 2: Prepare & Primary Fermentation
  1. Boil 3 liters of water. Add 100 g brown sugar and 70 g barley malt powder, stirring very well until completely dissolved.
  2. Allow the liquid to cool down to 36–40°C (97–104°F).
  3. Add 50 g active rye sourdough starter and whisk thoroughly to integrate.
  4. Pour the liquid into a large glass jar, cover tightly with a lid, and place in a warm, dark place for 12 hours.
  5. After 12 hours, you should see active bubbles and gas movement in the liquid.
Bottling & Carbonation
  1. Using a watering can or funnel, carefully pour the liquid into 2–3 glass or plastic bottles, trying to leave as much of the settled flour sediment behind in the jar as possible.
  2. Screw the bottle caps on tightly.
  3. Let the bottles ferment at room temperature for 8–12 hours to build natural carbonation.
  4. Transfer the bottles to the refrigerator to chill thoroughly before serving.

Nutrition

Calories249kcalCarbohydrates59gProtein4gFat1gSaturated Fat0.1gPolyunsaturated Fat0.3gMonounsaturated Fat0.1gSodium63mgPotassium134mgFiber3gSugar33gVitamin A4IUVitamin C0.1mgCalcium69mgIron2mg

Notes

Reusing Starter Sediment: The salvaged flour leftovers left at the bottom of the jar can remain on the counter for up to 1 week. Before crafting your next batch, add 1 tablespoon of rye flour to the sediment—this serves as the active starter replacement for your next batch of kvass.
- **Why Sourdough Starter Trumps Commercial Yeast:** Traditional old-world kvass is a product of dual fermentation, relying on both wild yeasts (for alcohol and gas production) and lactic acid bacteria (for clean, refreshing acidity). Utilizing your active sourdough starter introduces this complex ecosystem naturally, producing a deeply nuanced, health-promoting probiotic beverage that avoids the harsh, bread-like flavor of commercial baker's yeast.
- **The Functional Role of the Floating Raisins:** Raisins serve as a highly reliable visual fermentation indicator. Their wrinkled skins contain concentrated natural sugars that feed the wild yeast, and as the yeast consumes those sugars and releases carbon dioxide gas, the gas bubbles get trapped in the fruit's folds. When the raisins swell and float to the surface, it is your definitive signal that primary fermentation is active and the liquid is ready to be bottled.
- **Carbonation Safety Precautions:**Sourdough fermentation can be highly unpredictable and rapid in warm weather. Always use heavy-duty, fermentation-grade flip-top glass bottles (like Grolsch bottles) or heavy plastic soda bottles. Standard thin glass jars or decorative bottles can explode under the immense pressure built during the secondary carbonation phase. Never leave the bottled kvass at room temperature for more than 48 hours without checking or moving it to the fridge.

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