Manufacturing
Kvass is made by the natural fermentation of bread, such as wheat, rye, or barley, and sometimes flavoured using fruit, berries, raisins, or birch sap collected in the early spring. Modern homemade kvass most often uses black or regular rye bread, usually dried (called plural suhari), baked into croutons, or fried, with the addition of sugar or fruit (e.g. apples or raisins), and with a yeast culture and zakvaska ("kvass fermentation starter").
Commercial kvass, especially less expensive varieties, is occasionally made like many other soft drinks, using sugar, carbonated water, malt extract, and flavorings. Better brands, often made by beer rather than soft drink manufacturers, usually use a variation of the traditional process to brew their products. Kvass is commonly served unfiltered, with the yeast still in it, which adds to its unique flavor as well as its high vitamin B content.
There is only one brewery in the United States that brews kvass year round. That is the Beaver Brewing Company in Beaver Falls Pennsylvania. They make it with the addition of raisins and lemons.
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