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Soft drinks from Russia, Belarus, Ukraine, Baltic states, Poland

Fermented birch sap (berezovitsa, birch kvass)березовица (berezovitsa)

Birch sap, tapped in spring, holds about 1–2 % sugar and spoils within a day at room temperature. Set with oats, malt, rye bread or raisins, it ferments into a sour drink kept in barrels. In parts of NW Russia most sap is now drunk fresh and only what is left is fermented.

Fully documentedSoft drinks

Recipe

No fixed amounts recordedHousehold tradition with no fixed amounts.
Fresh birch sapAbout 1–2 % sugar, mostly sucrose[fernandez2025]
Oats laid on top (Lithuania), or malt, rye bread, beans or wax (Russia)[prakofjewa2024][shikov2017][belichenko2021]
Raisins, citrus slices, mint or blackcurrant leaves (modern Belarus)[prakofjewa2024]
Starteroats laid on the sap (Lithuania); raisins sometimes added to start the fermentation (Pskov Oblast)
Start
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What changes: Sap drips from a tapped birch into a container

Step 1 of 4
Tap the sap in spring
Time
Not documented
Temperature
Not documented
Salt
None given
Acidity
Not documented
Which microbes the steps name, step by step
Lactic acid bacteria
L. reuteri

Output: fresh sap.

Flavour
Not documented
Texture
Not documented
Colour
Not documented

Microbes at work in this step

Not documented for this step.

Method

Measured measured in a studySet fixed by a specification or tested recipeReported one source reports itTypical a general value, not sourced for this fermentUnconfirmed not yet checked against a source

At a glance

Birch sap, tapped in spring, holds about 1–2 % sugar and spoils within a day at room temperature. Set with oats, malt, rye bread or raisins, it ferments into a sour drink kept in barrels. In parts of NW Russia most sap is now drunk fresh and only what is left is fermented. Limosilactobacillus reuteri does most of the fermenting.

Key numbers
AciditypH 6 → 3.18Measured[semjonovs2014]Let it sour

What makes this one different

Fermented birch sap starts from a thin tree sap with only about 1–2 % sugar instead of grain or fruit juice. Birch kvass replaces the water of bread kvass with sap.

Related ferments

Variants

  • Birch sap kvassSap fermented with barley malt bread or rye bread.
  • Oat-crust birch sap (Lithuania)Oats laid on the sap sprout into a crust that covers it while it sours.

Safety

Fresh sap spoils fast, in about a day at room temperature, so tap and process it quickly and keep it cold. Bacterial counts in sap rise late in the tapping season.

History and sources

Every number is labelled with how it is known. How this atlas is made

Birch sap has been drunk fresh and fermented in Lithuania for centuries and was widely tapped in eastern Poland in the 19th century. In the 1970s and 1980s a technology for sterilised birch sap appeared in NW Russia, and some lemon or orange started to be added.

  1. [semjonovs2014] Semjonovs P., Denina I., Fomina A. et al. 2014, Development of birch (Betula pendula Roth.) sap based probiotic fermented beverage, International Food Research Journal 21(5):1763–1767paper
  2. [bilek2016] Bilek M., Pytko J., Sosnowski S. 2016, Badania trwałości soków drzewnych brzozowych (shelf life of birch sap), Polish Journal for Sustainable Development 20:7–14paper
  3. [sancho2022] Sancho A.I., Birk T., Gregersen J.M. et al. 2022, Microbial safety and protein composition of birch sap, Journal of Food Composition and Analysis (abstract)paper
  4. [fernandez2025] Fernandez de Ullivarri M., Buttimer C. et al. 2025, Cold induced expression of a novel levansucrase gene sacB1 enhances exopolysaccharide production and stress resilience in Leuconostoc mesenteroides, Scientific Reportspaper
  5. [prakofjewa2024] Prakofjewa J., Sartori M., Šarka P. et al. 2024, Knowledge in motion, temporal dynamics of wild food plant use in the Polish-Lithuanian-Belarusian border region, Journal of Ethnobiology and Ethnomedicinepaper
  6. [shikov2017] Shikov A.N., Tsitsilin A.N., Pozharitskaya O.N. et al. 2017, Traditional and current food use of wild plants listed in the Russian Pharmacopoeia, Frontiers in Pharmacologypaper
  7. [belichenko2021] Belichenko O., Kolosova V., Melnikov D. et al. 2021, Language of administration as a border, wild food plants used by Setos and Russians in Pechorsky District of Pskov Oblast, NW Russia, Foods 10(2):367paper