Editing Kvass (section)

==Production==
[[File:Kvas on fridge.jpg|thumb|left|Home fermentation of kvass in glass jars]]

In the traditional method, either dried rye bread or a combination of [[rye flour]] and rye [[malt]] is used. The dried rye bread is extracted with hot water and incubated for 12 hours at room temperature, after which [[bread yeast]] and sugar are added to the extract and fermented for 12 hours at {{convert|20|C|K F}}. Alternatively, rye flour is boiled, mixed with rye malt, sugar, and [[baker's yeast]] and then fermented for 12 hours at {{convert|20|C|K F}}.<ref name="Fermented Food Products"/>

The simplest industrial method produces kvass from a [[wort]] concentrate. The concentrate is warmed up and mixed with a water and sugar solution to create wort with a sugar concentration of 5–7% and [[pasteurization|pasteurized]] to stabilize it. After that, the wort is pumped into a fermentation tank, where [[baker's yeast]] and [[lactic acid bacteria]] culture is added, and the solution is fermented for 12–24 hours at {{convert|12|to|30|C|K F}}. Only around 1% of the extract is fermented out into [[ethanol]], [[carbon dioxide]], and [[lactic acid]]. Afterwards, the kvass is cooled to {{convert|6|C|K F}}, clarified through either filtration or [[centrifugation]], and adjusted for sugar content, if necessary.<ref name="Hornsey">{{Cite book |last=Hornsey |first=Ian Spencer |date=2012 |title=Alcohol and its Role in the Evolution of Human Society |publisher=[[Royal Society of Chemistry]] |isbn=978-1-84973-161-4 |pages=296–300}}</ref>

Initially, it was filled in large containers from which the kvass was sold on streets, but now, the vast majority of industrially produced kvass is filled and sold in 1–3-litre plastic bottles and has a [[shelf life]] of 4–6 weeks.<ref>{{Cite book |editor-last1=Gobbetti |editor-first1=Marco |editor-last2=Gänzle |editor-first2=Michael |date=2013 |title=Handbook on Sourdough Biotechnology |publisher=[[Springer Publishing]] |isbn=978-1-4614-5424-3 |pages=272–274}}</ref>

Kvass is usually 0.5–1.0% alcohol by weight,<ref name="Hornsey 2003 p. 8">{{cite book |last=Hornsey |first=I.S. |title=A History of Beer and Brewing |publisher=Royal Society of Chemistry |series=RSC paperbacks |year=2003 |isbn=978-0-85404-630-0 |url=https://books.google.com/books?id=QqnvNsgas20C&pg=PA8 |access-date=21 March 2022 |page=8 |quote=A similar, low alcohol (0.5–1.0%) drink, kvass… may be a 'fossil beer'}}</ref><ref>{{Cite journal |last1=Dlusskaya |first1=Elena |last2=Jänsch |first2=André |last3=Schwab |first3=Clarissa |last4=Gänzle |first4=Michael G. |date=2008-05-01 |title=Microbial and chemical analysis of a kvass fermentation |url=https://doi.org/10.1007/s00217-007-0719-4 |journal=European Food Research and Technology |language=en |volume=227 |issue=1 |pages=261–266 |doi=10.1007/s00217-007-0719-4 |s2cid=84724879 |issn=1438-2385 |quote=The predominant carbohydrates are maltose, maltotriose, glucose, and fructose, the ethanol content is 1% or less [2]. Kvass is considered to be spoiled if ethanol accumulates to higher levels.}}</ref> but may sometimes be as high as 2.0%.<ref name="gazolsz" />