Thursday, March 7, 2013

Making a Secondary Ferment for Water Kefir and Kombucha

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Blueberry lemon water kefir
So you started making kombucha or water kefir because you know just how important it is to be having probiotics on a regular basis, and wanted to save money and make it yourself instead of buying expensive store bought kombucha all the time.
But then you wonder- why is it that my kombucha tastes like flat sweet and sour tea, and my water kefir like mildly effervescent mild lemonade- don't they sell falvored fizzy kombucha? Can't water kefir be soda like?

Ah yes. You can definitely have your kombucha and water kefir be various flavors and be very fizzy too- all you have to do is make a secondary ferment!

What exactly is a secondary ferment?

Well, to begin with, I have to explain the science behind making kombucha and kefir, the standard "first ferment".

Water kefir and kombucha are made by putting something called a SCOBY- a symbiotic culture of bacteria and yeast- in water with sugar, and in the case of kombucha, with tea. (Here's how to grow your own kombucha mother/SCOBY.)
The SCOBY is filled with a bunch of beneficial probiotic bacteria and yeasts, which eat the sugar in the drink, and convert it to acid, a little alcohol, carbon dioxide, and a few other beneficial substances. At the same time, the bacteria and yeast are busy multiplying and growing in the liquid, as well as being concentrated heavily in the SCOBY.

When you drink the water kefir or kombucha, in addition to getting the liquid, you're also a healthy dose of the probiotics that have grown and now live in the liquid.

So the secondary ferment.

Now that you've got liquid that's packed with probiotic bacteria and yeasts, you no longer need the SCOBY. Strain out the kefir grains, or take out the kombucha mother, and use those to start a new batch of kombucha or kefir.

The liquid that you have filled with probiotics, the kombucha or water kefir, can now be fermented a second time, without the SCOBY, because it already has the probiotics inside.
Because there is no SCOBY in it, you can play around with the ferment and do things to it that you wouldn't be able to do if the SCOBY were inside and you were worried about contamination or of killing the SCOBY.

This playing around can give you all sorts of delicious flavors.

Most place I read say that for a secondary ferment, you just stick some dried fruit inside your kefir or kombucha, and let it ferment some more.

I don't do that.

I want the most bang for my buck, the most fermented drink possible in as little time as possible.

To make my secondary ferment, I usually take a container and fill it half way with my kombucha or kefir.

I then fill it the rest of the way with fruit juice or sugar water, etc... and then add spices if I want to. The sugars in this second half also get digested by the probiotics inside, and you now have twice as much kefir as you did when you finished the first half- making the first ferment.

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Left to right- mango kombucha, apple spice kombucha, blueberry lemon water kefir
My favorite way of fermenting is filling half a container with water kefir, the rest with apple juice, and then sticking in a few spices, like whole cloves, cinnamon sticks, star anise, and ginger (dried or fresh), and then letting it ferment some more. Kombucha made that way as a secondary ferment is also really yummy!

Other ferments I've made- water kefir mixed half half with water, jaggery, blueberries, and freshly squeezed lemon juice (really yummy!), water kefir mixed with more sugar and ginger, to make a yummy gingerale type drink, kombucha secondary fermented with lemon and ginger (really great!), and water kefir mixed with orange juice and mango juice (delicious!).

I tried making a mango kombucha secondary ferment but wasn't in love by the results, nor did I really like the orange kombucha. The persimmon water kefir I made was fine, but nothing oh so special either.

You can play around with flavors and do it how you want. All you need to do is start with at least 50% of the fermented drink, mix it with more liquid and sugar and flavor, and you're good to go. You can make it with juices, with spices, with dried fruit, with fresh fruit, etc...

Below- left- apple spice secondary ferment, right- blueberry lemon secondary ferment.
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So, now I got to how to make the flavor. But how do you actually make it be fizzy like soda?

Well, a byproduct of making the kombucha and kefir is carbon dioxide. The probiotics make carbon dioxide as their waste.
When in an uncovered jar, the carbon dioxide escapes.
But when you trap the drink in a closed container, the carbon dioxide can't escape, and instead, it carbonates the water, making it nice and fizzy.
When there is too much pressure built up inside from all the carbon dioxide, though, the container can explode.
Very dangerous.

So, how do you make the drink fizzy without the danger?
Note that the drinks become more fizzy when the bacteria are able to grow. To grow, bacteria like warmth. If you put the drink in the fridge, the rate of growth for the bacteria will slow tremendously.
So, you put the kombucha or kefir (with the flavorings) in a container, close it up, wait some time, and then when it's carbonated, put it in the fridge. You can use a mason jar for this so long as it seals well. You can use glass bottles with champagne type poppers.
Or you can do the cheapskate way and take old soda bottles and fill them with the kombucha or kefir.
Once the drinks are closed up inside, cap the bottle tightly. The bottle should be soft to the touch.
When the drink is fully carbonated, the bottle will be very hard. At this point, put it in the fridge or it will explode if you leave it much longer.
To make sure the bottles don't explode, "burp" them at least once every 24 hours, but ideally 2 or 3 times a day- just unscrew the cover for a second to release pressure, then screw back on.
Recently I made a secondary ferment of apple spice water kefir, and I didn't burp it so that when I finally did open up, bubbles poured out of it like a champagne bottle...

I find kombucha secondary ferments take much longer than water kefir- about 2-3 days to be ready instead of the 12-24 hours before a kefir secondary ferment is ready.

Do you drink kombucha or kefir or make it ever? Have you ever purchased a flavored bottle of kombucha? What flavor was it?
If you make a secondary ferment, how do you make it? What do you flavor it with, and how? What do you do to keep the bubbles? 


  1. We did secondary ferments of water kefir for a long time and loved it! Now, though, due to health concerns, we really limit our carbs because I can't seem to find any information about the carbohydrate content of water kefir. Do you know anything about that?

    1. I was looking into this recently because I'm trying to lose weight and apparently 80% of the sugar is converted. So 1/4 cup sugar = 200 calories, which will be 40 calories by the end (makes 1 quart WK). Of course, adding fruit juice to a 2nd ferment will change this.

  2. do you double check for potentially increased alcohol content. Secondary fermintation can increase your chanCes. I'm just curious. I brew mine in a lead free ceramic water type pitcher (continuous brewing) I bottle what I need for the day the night before in old store bought kombucha bottles and put I'm the frig. I get a fairly "bubbly" drink by morning.

  3. I have to ask... where did you get your jars? I love the tall and skinny one with the Apple Spice Kombucha!

    1. I don't live in the US. I bought them in a local houseware store.

  4. I have to ask... where did you get your jars? I love the tall and skinny one with the Apple Spice Kombucha!

    1. Weck makes a tall jar:

      Williams Sonoma carries some Weck jars, but not this one.

  5. How much sugar, do you find, is necessary to get your secondary ferment to go fizzy?

    I've tried 1tbsp with root beer extract (flat) and am trying 2tbsp with vanilla extract (don't know how that one has turned out yet).

    I don't know if you've found a good combination that works every time.

  6. My root beer is always flat too. Maybe it's the extract? My faves are raspberry with a little sugar and lemon (careful, this one is extremely fizzy) and ginger with lemon, which always carbonates nicely.
    Thankesfor all the great information on your site.

  7. I drink my fruity kefir 50/50 with water and even then I find it very filling. Anyone else feel full after drinking even 4 or 5 oz.?

  8. When ever I get a good fizzy batch of WK after 2nd ferment, I make sure to leave about an inch in the bottom of the Trader Joe's Ginger Brew bottle and add the next batch to it to 2nd ferment. This pretty much guarantees that that get a duplicate fizzy batch to the original.

  9. I never add commercial fruit juice or sugar to my second fermentation. I add fresh ginger slices, fresh lemon, lime or lemonade squeezed juice, or passion fruit, squeezed grated tumeric, lightly squashed blueberries etc and leave on bench for 24 hrs then refrigerate. It might be a week or so before that lot gets used and is always fizzy.

    1. That's a great idea, i also don't like adding more sugar/juices to it as i like drinking water kefir throughout the day, and don't want to increase my sugar intake.


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