kombucha — MikrobenKabinett

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MikrobenKabinett is what I call my fermentation cabinet — a bubbling, living archive.

Here I keep a growing collection of starter cultures that I’ve collected, nurtured, traded, or purchased over the years, along with several ongoing jarred fermentation experiments.

This page is a digital duplicate of the cabinet at home. It serves both as a record of each “member” in the Kabinett, and as a practical manual: If you’ve ever received a culture from me in real life, you’ll likely find its basic ratios and reference recipes here — to help you start your own fermentation journey!

Welcome to explore！
Xijing Xu
info@xijingxu.com
https://xijingxu.com
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Kombucha

A probiotic drink

unnamed

I got a piece of scoby from a girl in Berlin that I connected with on xiaohongshu in the winter of 2024.

Tea Kombucha

Feeding ratio

0.5-1:10:10:90
tea leaves(depending on the tea variety) : fermented liquid : sugar : water
+ a piece of SCOBY

For example:
Brew 8g of black tea leaves with around 900g of water. Keep tasting the tea to make sure the flavor doesn’t go off.
Dissolve 100g of sugar into the hot tea.
Once it cools down to room temperature, add 100g of pre-fermented liquid and a piece of SCOBY.

Tea brewing

As kombucha becomes more and more trendy in the Western world, there’s been a growing wave of recipes that experiment with fruits, herbs, or juices—sometimes skipping tea altogether.

Meanwhile, in China, some people who call themselves kombucha orthodox insist on using only high-quality tea leaves. They see kombucha as an extension of the tasting culture surrounding traditional tea ceremonies.

Personally, I also enjoy making kombucha solely with tea, partly because it’s more accessible to me, but also because I believe the quality of the tea determines everything. If you know how to brew a good cup of tea, you can be sure the resulting kombucha will taste fantastic.

When brewing tea for kombucha, I always check the TDS level of the water—either filtering tap water or using bottled water with low mineral content. I’ve tried brewing large batches in a big pot, but I always end up going back to the traditional gaiwan method. It gives me better control over the brewing time for each infusion, and thus the flavor. Plus, it helps me avoid that slight metallic taste that sometimes comes from stainless steel pots.

Brewing with Gaiwan

The color change before and after the fermentation

Coffee Kombucha

Feeding ratio

1:10:10:10
coffee bean : fermented liquid : sugar : water

For example:

Grind 100g of coffee beans and let them sit in 900g of cold water in the fridge for 24–48 hours.
Dissolve 100g of sugar in 100g of boiling water.
Once the coffee is ready, strain out the grounds and mix in the sugar water.
When everything has cooled to room temperature, add your starter liquid and a SCOBY.

Coffee brewing

I find that coffee kombucha tastes best when the coffee is cold brewed. Hot brewing, at least with the beans I use, tends to produce a slightly smoky flavor — which actually makes an interesting vinegar for cooking, but not quite what I want in a drink.

That said, this method uses a relatively large amount of coffee beans, so I’m always a bit hesitant about whether I should keep making it.

I’m not a coffee expert (just a regular cappuccino drinker), so maybe this is something better explored by someone more deeply into coffee — especially with different types of beans.

Someone I met in Changsha once recommended trying to brew kombucha using whole coffee beans, without grinding them. A friend from Colombia, who’s building his own coffee brand, told me that in some of the farms he visited, people even make kombucha with the flesh of the coffee fruit. These are flavors I can only try to imagine!

Feeding schedule

Once per 5-14 Days, depending on the room temperature and the taste you want to achieve.