Maker’s pride: (double fermented) kombucha

Our first kombucha batch in July 2016 in teensy and badly closing bottles.

Nope, this is not becoming a cooking blog… at the moment. But kombucha is a thing we have been brewing since mid-2016, and, since I recently gave Mara a kombucha culture without much proper explanation, I wanted to leave it properly documented here just in case.

Kombucha… whaaat?

Sooo… if you are Eastern European, it is possible that your grandma – like mine – has been doing her own kombucha for years before hipsters started to sell it to you for 5€ for a tiny bottle. She might have had this weird looking big jar in her kitchen and call it the tea mushroom. At least for me growing up it always was this weird sweet/sour drink that wasn’t cool or desirable in any way. Until I moved far away from my grandma’s kitchen, and Julie introduced me to the possibilities of second fermentation, that is.

My grandma still does only one fermentation and then some infusion maybe, like floating some goji berries in her kombucha bottles.

First fermentation

The whole thing is ‘a symbiotic growth of acetic acid bacteria and osmophilic yeast species in a zoogleal mat [biofilm]‘… or, in laywoman’s terms, a quite yucky mushroom-like sponge thing that eats sweet tea and poops probiotics. And that poop-water makes for a refreshing drink, especially if you are very tired of the false choice between alcohol and fizzy sugar stuff. I am not claiming any miracle properties here, mind you, I simply enjoy it as a welcome additional option besides water, herbal teas and alcohol as my typical ‘grab a glass’ go-tos.

Once established that kombucha is fun, it also has to be established that buying kombucha is pretty stupid. Yeah, maybe, sometimes, in a pinch… I think I have bought kombucha only once, in New York in 2017. Because, once you have made your own, paying top euro for it feels ridiculous. It might just be my mental mechanism, but I feel like this about most cooking I’ve figured out on my own. This includes most soups, curries, smoothies, anything with chia seeds, anything with kale, empanadas, all kinds of bowl food, and, most recently, yogurt.

So, once you are open to adopt a kombucha SCOBY (symbiotic culture of bacteria and yeast), you have to find a donor/vendor, and then make your new sponge friend feel at home. While you can buy one (for example, one of Barcelona’s fermenting references, Ferment 9, will sell you one for 15€), I suggest asking around and getting one for free…

You are very likely to get one for free not only because kombucha people are untiring evangelists of their weirdness, but also because of the central magic of fermentation: bacteria just keep multiplying, so you end up having some more to expand your operation or to give away.

Say hi to your new pet!

You will get your SCOBY in a vessel with a bit of liquid, *keep that liquid*! A SCOBY needs to be wet and smell acidly at all times.

Then just make some sweet tea to accommodate your new pet. As for the sugar/tea/water proportions, we have been using the following as our guidelines: 6 tea baggies or 9gr of loose leaf tea with 100gr of sugar for 2l of water. However, we have learnt that SCOBIES – at least ours – are very resilient. A bit more or less won’t really harm them. And I recommend expanding the whole thing to a little farm and making around 5 liters per week, otherwise the final amount isn’t really worth the fuss, imho.

What tea?

I was told to use only organic black when I got mine… and then, because I don’t really care about strict recipes, we found out that it can also be conventional, or earl gray, or green. Our SCOBIES really don’t care.

As for waste, obviously loose leaf tea will make your kombucha much more zeroish waste. And as for pantry cleaning, feel free to mix and match and use up any stupid gift tea somebody gave you. SCOBY will eat it all.

What sugar?

The most basic! I know, I know, you know that white sugar is poison… but it’s not you who is going to eat it. Give the SCOBY what it wants. For this you definitely don’t wan to use some posh, unrefined and less sweet sugar.


You make your sweet tea, and let it cool down completely. I just use the biggest pot we have, bring the water to boil, turn it off, dump in the sugar and the tea – at 100ºC they dissolve and mix on their own alright – and leave it there until next morning

Then you line up you glass jar(s) containing the SCOBY in its home liquid, strain off the leaves and fill it with that room temperature tea. Give them little babushka hats using fabric napkins or tea towels so that they could breathe but no insects or other debris would fall in it. Keep the jar(s) away from direct sunlight in a place nobody will disturb it. In our place, they recent lost their usual countertop corner to coffee stuff and went into a cupboard. They are doing fine.

Keep them like that until you deem them fermented. For how long? As with all fermentation magic, this depends on many variables: the room temperature (everything ferments much faster when it’s hot), the proportion of sugar and tea to water, how big was you SCOBY and how big the vessel. Around week of fermentation is kind of normal with our recipe, jars, and SCOBY.

If it still tastes very sweet, it’s underfermented. Solution: keep fermenting.

If it smells very acidly from a distance and tastes like vinegar, it’s overfermented. You can use it as a vinegar or mix in a little in your future batches, but it’s unpleasant to drink.

There are people who enjoy their kombucha with just one fermentation. Good for you. As I said, single fermentation with a bit of fruit infusion can be very nice. I highly recommend dropping some cut strawberries in there for a couple of hours, it’s amazing. It’s a great way to deal with the typical aromatic but plastic-tasting Huelva strawberries, btw.

For those who are here for the second fermentation, follow me, my friend!

Second fermentation

So the whole idea is to give the kombucha some more sugar to have fun with, both for taste and for sparkle. Cut or smash your fruit of choice, and fill it in *airtight bottles* with kombucha for another week or so. Fun fact: you will soon find out which of your bottles are airtight after a couple of these experiments…

My fruit favorites are (a) ginger + lemon or lime; (b) strawberries, (c) Sirena’s frozen berry mix… Yep, not always zero waste or seasonal but I’m never buying soft drinks or juices, so the math still probably comes out in my favor, even with this indulgence.

Not that good: apples, oranges, watermelon… You want acid and structured fruit for this, but keep experimenting and let me know about other great combinations.

The fruit layer. Obviously, more fruit means faster fermentation:

The rest of the kombucha:

And peacefully fermenting again:

Now you just observe them for 5-7 days, refrigerate before using and enjoy. There are people who burp them in fear that the bottles will explode. We have never had that in the 3.5 years of having made kombucha. What we have had, though, is it bursting out upon opening like a badly shaken champagne but with fruity bits, especially when there is a lot of fruit matter and it’s not refrigerated before opening. Yep, I’ve had to clean walls in 3m radius, so be careful when opening… I recommend doing it in the sink and veeeery slowly.

Also, keep a strainer handy while pouring to avoid more texture than you asked for.

This is what a nicely fermented kombucha looks and feels like: sparkly and refreshing!

In conclusion, double fermenting kombucha is easy but it takes time and some planning. For the ultimate troubleshooting, you can always put your SCOBY, always covered in sweet tea/kombucha, in the fridge. It will be hibernating there until you have time for it. We have had ours away for 3 months, and it came out fine.

It has long become a staple in our household, a refreshing and fruity alternative to bought crap drinks. And a homemade alternative to the commercial kombucha, made exactly as you like it.


Have you had a SCOBY? Is it still alive? Did your grandma have one? Maybe you have tried the commercial kombucha and decided that it is as incredible crap? Tell me, I’d like to know ♥

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