Kombucha - Alcohol Content

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Buch

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I am fairly certain I have searched to the very end of the Internet and have yet to find an answer to my question. :) How do you accurately test the alcohol content in kombucha? I understand you can use a hydrometer; however, my kombucha goes through a second ferment in which I add fruit juice at the time of bottling. Wouldn't the introduction of new sugars from the juice screw up my before and after readings?

Also, are there ways of ensuring that the alcohol level doesn't reach beyond 0.5% without going the pasteurization route?

Thanks for any help!
 

snarf

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A hydrometer is useless for kombucha, even if you don't add fruit juice!
 
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Buch

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A hydrometer is useless for kombucha, even if you don't add fruit juice!
Snarf, thanks for the info. Is sending samples to a lab my best option you think?
 

snarf

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Without fancy equipment, I don't there's a way to measure the alcohol content of your 'booch.
 

dlgura

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@ snarf - why is a hydrometer useless for kombucha? I've used them before with my batches and it seems that as long as most of the carbonation is shaken out of it you can get an accurate reading. Seems like my brew starts with a 5% sugar content as far as I could tell. Haven't done an after measurement to compare. Would think that you would simply take the difference of your before and after readings to determine how much has turned into alcohol? Though.....if the buch is converting the sugar into vinegar and nonalcoholic buch compounds instead of or alongside converting it to alcohol how would that be reflected differently in a hydrometer reading? Just because there is less sugar than when you started that doesn't mean it's all turned to alcohol....hmmm. Suppose this is why the hydrometer doesn't work other than to tell how dry it is....?
 
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In my research and realizing that to test alcohol content is not gonna happen without expensive fancy equipment.. I sent a sample to a lab that does testing for brewers. My kt was .56%
 

snarf

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@ snarf - why is a hydrometer useless for kombucha?
You've basically answered your own question!!

In beer brewing you essentially work with the this simplified model:
you start with a mixture of water and sugar and after fermentation you have a mixture of water, sugar and alcohol. By measuring the SG before fermentation you can determine how much sugar is in there. By measuring the SG after fermentation you can then determine how much of that sugar has been converted to alcohol. However, the hydrometer can't measuere the sugar and alcohol content directly, so the pre fermentation measurement is essential.

In kombucha brewing also several other major processes take place, which all influence the SG in a different way. Hence the above simple model doesn't work and the final SG gives next to no information...
 

dlgura

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Lol yes I guess I did, but thanks for confirming anyway.
 
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I'm sorry, haven't been on the forum for a week.. I had my Kt checked at White labs in San Diego, Ca.
 

Akhenaten

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Does anyone know about the alcohol cycle during both the first and second fermentations?

Does the alcohol content go up and then down? Or does it increase and then level off?

If sugar is added during secondary fermentation, will that increase alcohol content?
 

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