Kvass (from the word kvassit) is a traditional Russian drink with a volume fraction of alcohol not exceeding 1.2%, made as a result of wort fermentation. The first mention of kvass in Russian written sources dates back to 989: after baptism, Prince Vladimir I Svyatoslavich ordered to distribute "food, honey and kvass" to the people.
It is interesting that until the XII century, kvass in Russia was stronger and thicker than modern beer. Kvass was considered an alcoholic drink, and the word "drunkard" in the language of that time was "kvassnik". It is believed that the emergence of vodka led to a change in the technology for making kvass. It was no longer necessary to chase after the fortress, so they began to pay more attention to taste and quality, and brewed kvass much lighter, its fortress dropped from about 8 to 4% alcohol and below.
The profession of "leavening" was very widespread in Russia. Kvasniki usually specialized in certain varieties of kvass and were often called barley, pear, apple, etc. Kvassniki were sold each in their own specific area, going beyond which was fraught with troubles.
An interesting fact, kvass according to the classification of the organization BCP, which trains and certifies judges for holding beer tasting competitions, kvass is a beer, and belongs to the category "Beer historical, traditional, local".
Nowadays, many synthetic surrogates for kvass are also commercially produced, consisting of soda, sweeteners and a simulant of the taste of kvass, and are sold in plastic bottles.
Kvass is good for health, it regulates the activity of the gastrointestinal tract and the cardiovascular system, improves metabolism, prevents the development of pathogens, and raises the tone.