Carbonation Consternation

[Adam]

I am curious; how do you carbonate your kombucha? Also, if you DID
want to add some kind of fruit juice, at what point would you add the
juice so as not to adversely affect the salutary value of the 'buch?

[Jared Englund]

Carbonation, oh carbonation. For hundreds, maybe thousands of years,
Kombucha has been enjoyed only lightly carbonated by the CO2 gas
trapped in the tea by the SCOBY covering the surface. When Kombucha
became a bottled beverage, it was then able to be bottle-fermented to
make it a super carbonated soda-pop like drink. There is some
evidence to show that regularly drinking carbonated beverage can have
negative affects on bone health, so if you're drinking Kombucha every
day, maybe the ultra bubbly stuff isn't the best...

But if you just crave that champagne-like pop of cracking open a fizzy
bottle of booch, here's how you do it.
When you brew Kombucha, use only tea, dried herbs (optional), and
sugar. Keep it simple in the brewing vessel (so no juice with the
SCOBY). After this primary fermentation, bottle your Kombucha and to
make it fizzy, add another sugar source to cause a secondary or
"bottle fermentation." This can be in the form of fruit juice, dried
fruit, ginger, honey or just plain sugar. Let the bottles sit in a
warm place for a few days. Don't add too much! Bottle explosions are
a real problem if you're using air-tight lids. We prevent this
problem by using plastic lids that leak carbonation if there's too
much buildup. We add a teaspoon of lemon juice and a teaspoon of
ginger juice, let the bottles sit at 75º for three or four days, and
our Kombucha fizzes pretty good when the bottle is cracked open.

[Adam]

I understand entirely. I also have a question about hydrometers. I am
beginning to move into a commercial operation in my Queen City of the
Plains, and am in the midst of a slew of shelf-life tests. What
devices/methods do you use to measure the alcohol content of your
stuff?

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[Jared Englund]

We send our Kombucha to a lab (Exova) for alcohol testing.
Hydrometers won't work - they are for yeast-only ferments. The
bacteria in Kombucha convert the alcohol and the hydrometer will not
take this into consideration. Though the hydrometer does make a very
good, simple point. More sugar = more alcohol. I'll save you time,
frustration, and money by telling you that 2/3 cup sugar per gallon
will result in about 0.4% alcohol. A secondary "bottle ferment" will
raise that by 0.1-0.2%, so if you want to make bubbly Kombucha and
keep it under the limit, you'll have to use even less sugar, like 1/3
cup per gallon.

If this sounds crazy, talk to House Kombucha in San Francisco. I
think they use around 1/4 cup sugar per gallon, add things like dried
fruit for a secondary ferment, and their Kombucha is very popular.
They are also very very great, nice people and I'm sure would answer
any questions you have of them.

Thanks for the questions!

[Adam]

Thank you for your answers and for your help-full attitude. It is most
encouraging. I am planning a trip to your City of Roses in July; while
there I would love to meet you and perhaps attend one of your classes.
I will be in touch closer to that date. Again, many thanks.

-Adam Didier

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[good...@gmail.com]

Hello
I came across this thread searching for help with kombucha carbonation. I'm doing everything as told. Letting it ferment then bottling and letting it sit on the counter. At first I was just letting it sit for 2 days after bottling and last batch I let it sit on the counter for 7 days. It still wasn't carbonated! Any tips?

[Jared Englund]

Sometimes carbonation can take a long time.  It depends heavily on the amount of sugar in the Kombucha and also temperature (among other things such as oxygen, pH, etc.)

Add a little sugar before bottling.  Then keep the bottles in a warm spot (75 degrees + ) for over a week.  That should do it...

[sdmi...@gmail.com]

Hi,

Sorry to revisit such an old post but I found this info to be really intriguing and had a few questions.  I've been brewing using 1cup of sugar per gallon.  You're saying that you're 2/3 cups and that House only uses 1/4 cup yet everything that I've read says that you'll starve your SCOBY or cause it to mold if you use too little sugar.  Have you had that issue or how do you prevent it?  Will kombucha take less time to ferment if you're using less sugar? 

Also, I'm trying to keep the sugar content of my kombucha low.  When you add sugar for a 2nd fermentation in the bottle, does that sugar get eaten during the 2nd fermentation or will the kombucha remain sweet?

[Jared Englund]

Hey there,

A great question!  Let me start from the top.
When you make Kombucha you are growing yeast and bacteria.  The good stuff you want comes from the bacteria, but the bacteria need the yeast to get the nutrients they need.  When you add sugar to Kombucha it feeds the yeast, then those yeast feed the bacteria.  If you don't use enough sugar (or leave your brew in sunlight, or if it's too cold) there will not be enough yeast growth to grow the good bacteria.  This can increase the chances of mold or other less desireable microorganisms.

We have found that 1/2 cup sugar per gallon is the lowest amount of sugar you can use to make healthy Kombucha.  The less sugar you use, the more important it is that your Kombucha be warm so that the yeast can grow strong.  The yeast and bacteria life cycles are about the same no matter how much sugar you use, so it will take about the same amount of time to ferment.

Bacteria need oxygen to thrive.  When you add sugar to bottle carbonate, you seal the bottle so there is not much oxygen.  The yeast eat the sugar and make CO2 and alcohol, but the bacteria don't do much so your Kombucha will either be sweet and flat, or it will be carbonated and slightly alcoholic.

The best idea I have for you is to use a siphon to fill your Kombucha bottles (this helps preserve the natural carbonation), then use a minimal amount of sugar to carbonate (about 1-2 tbsp per gallon) so you make sure your final product is not too sweet and not too alcoholic.

I hope that helps!  Best of luck on your Kombucha adventures,
Jared