Which alcoholic beverage is naturally fermented?

Kvass is a traditional fermented beverage originating in Russia and at one point was the most common drink across all classes of society. Kvass can be made with stale rye sourdough bread, beets, or other vegetables. The bread based version tastes somewhat like beer--but without the high alcohol content.

Kombucha, ginger beer, kvass and kefir drinks can contain residual alcohol from the fermentation process used in their manufacture. Kombucha is produced from a mixture of steeped tea and sugar, combined with a culture of yeast strains and bacteria. A nationally coordinated survey by Food Regulators found that many fermented drink products such as kombucha, ginger beer, kvass and kefir contained alcohol. Fermented drinks can contain low levels of alcohol as a by-product of fermentation. In NSW, products with an alcohol content greater than 1.15% ABV are considered to be an alcoholic drink. Drinks that have more than 0.5% alcohol by volume (ABV) are required by the Australia New Zealand Food Standards Code to have a statement of alcohol content on the label. For the kombucha samples tested, around 65% had more than 0.5% alcohol, and for water-based kefir samples tested 74% had more than 0.5% alcohol. The dairy-based kefir samples tested all had less than 0.5% alcohol. For samples of ginger beer and kvass tested, around 31% had more than 0.5% alcohol. Some products tested had an alcohol content greater than 1.15% ABV or an alcohol content greater than that shown on their label.