Sugar Content

My wife was wondering how much sugar was in her Kombucha. So I measured it with my hydrometer and ended up with a 1.020. We were going to compare this with a commercial batch but we had ran out the night before. I am more curious than anything else but what readings are "normal" and what are others getting? Thanks.

My limited understanding is that gravity is not going to play as big a part in Kombucha/wild fermentations as it would in a more controlled Sach fermentation. Reason being that you have many microbes that are converting alcohol to acetic acid for one, or are not "heterofermentive" meaning (overall, not individually) they do not produce a predictable or consistent output of alcohol/co2/acid/etc. On top of that, I've read/heard (right or wrong) that certain bacteria's (and we know enzymes do this) job is to merely convert sugar-types from one to another. So in other words, know how much sugar you put into it and that's all you're probably going to really get. without some sort of proper chemical analysis.

I'm also fairly certain some scientist will come on here and school all of us, which I welcome.

Thanks. Learned something new. I really appreciate the lesson.

This link says to take a volume of 'buch, boil it down by half, dilute up to the original volume, then take your reading (say, 1.003) and do this math to get sugar density: (1003-1000)*2 = 6 grams per liter.

http://www.happyherbalist.com/hydrometer.aspx

I'm not sure where they got their data, though.

This paper says that 65% to 85% of the sugar gets consumed:
http://onlinelibrary.wiley.com/doi/10.1111/1541-4337.12073/full

So if you start with 1 cup of sugar per gallon (236g per gallon, or 236g per 3.785 liters, or 62g per liter, or a 6.2% w/v), you can expect your result to be between 9g/L and 22g/L (if I did my math correctly).

Doing the boil and dilute method, including multiplying by 2, mine came out 30g/L.

As a point of reference, CocaCola is 108g/L.

This paper says that they got 50% conversion after 21 days on a 25% solution of sugar (but the recipes I've seen are more like 6% solutions).
http://omicsonline.org/ArchiveJMBT/2009/December/01/JMBT1.72.pdf

This post has got me very confused. I have always known its 1 cup of sugar but I never knew about measuring the amount of sugar in my batch.

Adam_Trainor101 said:

This post has got me very confused. I have always known its 1 cup of sugar but I never knew about measuring the amount of sugar in my batch.

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Sugar content is important if you want brew it in your desire taste,the same reading SG is critical also.Here are people who always tended to use hygrometer to measure the context.But the handed brix refreactometer would be better choice as supposed,which is very easy to use and would never waste compared hygrometer.Only 2-3drops will get the accurate reading!
I personally suggest after my research,here we design brand new KETOTEK brix refractometer,which will measure the SG and the sugar content at the same time!