New Hobby: Kombucha

For my birthday which was a couple of months ago, my friend Violet (who has Many Hobbies) gave me a layer from her SCOBY and thus initiated me into a new hobby: brewing kombucha.

There are lots of online resources, but if you're not familiar with the process – which I wasn't, until recently – here's a quick summary of how to make this funky fermented tea.

The SCOBY is a living thing, short for symbiotic culture of bacteria and yeast ("yum," said my friend Abbi, when I told her what it stands for). It has the texture of a rubber mat, and typically floats on the surface of the brewing vessel.

Well, I say "typically floats", but when I started my second batch of fermentation, my SCOBY sank partially, ending up suspended halfway down the jar. I looked online to see if it's a bad sign, and found reassuring comments like "Nothing wrong with the scoby sinking!" and my favourite: "Scoby does whatever it wants to do."

Anyhow, now it floats again.

For the first fermentation (F1), you put the SCOBY, water, tea and cane sugar in a jar, cover the mouth with cloth, and let the microorganisms do their thing. I use loose-leaf oolong tea from Fujian province, purchased from NTUC. Here you see the tea being steeped in hot water, before I strain out the leaves and use the liquor for F1.

After about a week of F1, it's technically kombucha, and ready to drink. However, most people do another fermentation step (F2), which is when the drink is flavoured and carbonated.

F2 takes 2–3 days. You simply pour off the kombucha – leaving the SCOBY and a bit of extra liquid in the jar for the next round of fermentation – into a sealable container like a flip-top bottle. Then you add whatever you want to flavour it with, such as fruit juice, purée, herbs or spices, and seal the bottle. These are two bottles from my most recent batch: strawberry and mint (left) and pomegranate (right):

If the flavouring agent has some sugar content – like puréed fruit, which is a popular choice – then that should be enough to carbonate the brew. Otherwise, e.g. if you're just adding herbs or spices, you can add cane sugar for carbonation.

For my first batch, I made two bottles: dragonfruit and grape. Violet said her kombucha is not very fizzy, so I figured mine would be similar. Most people recommend F2 for 2-3 days. I gave it 3 days, to ensure adequate more carbonation. This is what happened when I opened the bottles:

The video on the left (dragonfruit) is playing at regular speed, but the one on the right (grape) is at 3x (I sped it up to fit). I suspect the grape kombucha was less fizzy because after 3 days of F2, I kept it overnight in the fridge, which slows down the fermentation process and also makes the gas more soluble.

I'm lucky the bottles didn't explode – thanks Ikea. Since then, I've reduced F2 to two days, which seems about right. My kombucha is fizzy but not excessively so.

Healthy SCOBY grows thicker with time, forming more layers – so you can peel off a layer and give it to a friend. Violet bought her SCOBY online, but then she gave some to me, and also to our mutual friends Chiok and Guofeng. So now we all make kombucha, experiment with different flavours, and compare notes. I took this pic at a recent tasting session at Chiok and Guofeng's place.

Since then, three more people have asked me for SCOBY. Soon this SCOBY will colonise Singapore, with only the wild boar for competition.