Kvass seller at Sergiev Posad. Kvass is a fermented beverage made from rye or black bread.
By Russian standards, it is classified as a non-alcoholic drink as the alcohol content is
usually less than 1.2%. It is often flavoured with fruits such as strawberries or raisins,
or herbs such as mint. In Russian, the word kvass means “yeast” or “leaven”.