Kvass
What it is
A lightly fermented, mildly tangy, low-alcohol beverage of the Slavic world, traditionally made from stale rye or black bread. Cloudy, brown, gently fizzy, and faintly sweet-sour. Included here for its dual life as a drink and a cooking liquid. (See also the grains-and-breads section, where its bread base is treated.)
How it's made
Stale dark rye bread is toasted, steeped in water, sweetened (sugar, honey, or fruit), and fermented briefly with yeast and lactic bacteria — often from a starter — until lightly carbonated and tangy, with very low alcohol. Raisins, mint, or fruit are common additions.
Flavor profile
Earthy, bready, malty, and lightly sour with a gentle sweetness and a soft effervescence; the alcohol is negligible. Refreshing and distinctly rye-forward.
Culinary uses
Drunk cold in summer, and used as the souring liquid base for cold soups — most famously okroshka — where it stands in for stock or broth. A culinary as well as a thirst-quenching ingredient.
Regional variations
Bread kvass is the classic; beet kvass (next entry) is a separate vegetable ferment. Fruit and herb kvasses abound across Russia, Ukraine, Poland, the Baltics, and beyond.
Cultural & historical context
Kvass is one of the oldest and most democratic beverages of the Slavic world — historically the everyday drink of rich and poor alike, a thrifty use of stale bread, and a fixture of street carts in summer.
Reference notes
Tags: `fermented`, `beverage`, `bread-based`, `slavic`, `low-alcohol`, `vegan`. Vegan (contains gluten). Related ingredients: Rye bread, Beet kvass, Okroshka. Related cuisines: Russian, Ukrainian, Baltic. Suggested links: Beet Kvass, Sourdough Starter, Okroshka.