Does a bottle of kvass become alcoholic if you leave it for long?

Question by Captain G: If you leave a bottle of kvass long enough, does it become alcoholic?
For the unfamiliar, kvass is an old Russian beverage made from sugar, fruit, and bread ingredients like malted rye and yeast. It is a fermented drink that tastes like a sweet, bready “almost beer” but has no alcohol to it. I was wondering whether it would turn into alcohol if it was allowed to sit long enough, or if it would just spoil instead.
Clarification: Yes, it does have some alcohol to it… so little though that it’s not even noted on the bottle and it’s drunk regularly by children. I guess what I’m asking is whether it will gain alcohol content if left long enough, or whether there’s something about brewing beer that causes it to “stop”. I know this stuff is similar to an unfinished beer… I just wasn’t sure if it was possible to “finish it” or if it is what it is and never would get any ‘harder’.

Answers and Views:

Answer by Richard English
If it is a fermented drink then it already has alcohol in it.

Answer by Stevko
Depends. Homemade kvas gets pretty strong in a week or two if you just let it be. Bought, industrially pasteurised or even with preservatives added, doesn’t change. It isn’t prone to spoiling either.

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