Kvass (Fermented Bread Drink)

Kvass is the most obscure fermented food on this list and the one with the longest history in Slavic culture — documented in Eastern European records from 996 CE, when Vladimir the Great of Kievan Rus distributed it at public feasts. It is made by fermenting rye bread in water with yeast for 1-3 days, producing a lightly carbonated, slightly sour beverage with approximately 0.5-2.5% alcohol (similar to kombucha). Nutritionally: kvass retains the prebiotic fiber from the rye bread, is rich in B vitamins produced during fermentation, and contains the live Lactobacillus cultures responsible for the lactic acid fermentation. The cultural significance: kvass remains the most widely drunk fermented beverage in Russia, Belarus, and Ukraine — more consumed than beer in rural areas. It is now available commercially in Eastern European food stores in the US and UK, and trivially easy to make at home from stale rye bread, water, sugar, and yeast.