Keeping kvass going

[viitat1010]

Hi there, this is a two part question about beetroot kvass, and into the science of fermentation.

I love beet kvass, but after multiple attempts I found that the flavour varied too much with each fresh batch. My solution was to have a beet kvass which is now two years old - I have frequently removed the spent beets and replaced them with new ones, but kept a certain amount of the previous liquid (as a starter I suppose). It still tastes fabulous. I did this because Sandor Katz mentions that you can reuse the beets 2-3 times, but then he recommends discarding and starting afresh.

Once I ran out of beets but I didn't want it to die out. I thought 'surely this is just like a kombucha, if I add sugar, the microbes will consume it and keep it going.' So that's what I've been doing the last 3 batches and I can't notice any difference so far.

So my question is, is there anything conceptually 'wrong' with feeding sugar to a kvass culture, instead of raw beets?

I note that in some parts of the world, sugar is derived from beets not from sugarcane anyway: they are a potent sugar source even though industrially processed. Needless to say sugar is much cheaper per kilo than raw organic beetroots.

The problem I can foresee is that eventually (like zeno's axe) there may be no beet flavour left - the microbes will be descendants of the same original, but maybe the flavour will become diluted.

And my second pondering is, how long do the bacteria in kvass (or any ferment) actually live? The Lacto-B consume the sugar and produce acids which give the kvass a tangy taste, but then if the LB run out of sugars and presumably die... it still tastes like kvass but the actual living, prebiotic nature of it is reduced or not at all.

Thoughts welcome. I suspect these questions apply to all ferments not just beet kvass, but that's my entry point.

happy fermenting y'all

Tom

[viitat1010]

Hi - I'm replying to my own post
I can confirm that this technique is not a good idea!

It worked OK for the first few batches, adding a small amount of sugar to keep it going as I didn't have any beetroots in season. However by the 4th batch the taste was noticeably sweet and sickly, more like Ribena or blackcurrant cordial although it was still tangy and acidic like kvass, but with an unpleasant sweetness. By the 5th, really too sweet (I don't have a sweet tooth). I wasn't scientific, I just threw in some sugar without measuring, so my guess is that in one batch the sugar added was so calorific it probably led to a LB overgrowth and die off, leaving a lot of undigested sugars to spoil the taste.

Even though a lot of sugar is industrially processed from beets, the processing evidently removes all of the other compounds and flavours that keep it fermenting healthily and with a pleasant flavour.