How do I care for my kombucha culture?

SCOBYs like it warm and acidic. There are two absolute NO-GOs:

Do NOT store your SCOBY in the refrigerator!

While kefir grains are best kept in the refrigerator to slow down fermentation, the same does not apply to a kombucha SCOBY. It thrives in an acidic environment. The easiest way to keep it happy is to set up a SCOBY hotel (see below).

Storing your SCOBY in the refrigerator can increase the risk of mould.

Do NOT wash your SCOBY!

You often read that SCOBYs should be rinsed – unfortunately, that simply isn’t good advice. Your SCOBY likes an acidic environment. Washing it raises the pH at its surface and can make the culture more vulnerable to mould.

SCOBYs sometimes develop rather unattractive brown strings. You can simply pull them off if they bother you. They are usually yeast strands and other fermentation material – perfectly normal signs of an active culture.

What is a SCOBY hotel and how do I make one?

Simply proceed as you would when brewing a regular batch of kombucha. Make tea, sweeten it and add your SCOBYs. Make sure to add some starter liquid as well.

Cover the vessel with a cloth and keep it in a cool place – but not in the refrigerator.

The most important thing is to prevent your SCOBY hotel from drying out. Check it regularly to make sure there is enough liquid to cover and feed all your SCOBY babies.

Twice a year, your hotel guests will appreciate a thorough clean. Over time, dead yeast and sediment accumulate at the bottom of the jar and should be removed.

Simply prepare a fresh batch of sweetened tea as usual and move your SCOBYs into their new hotel. Add plenty of clear liquid from the old hotel, but leave the yeast sediment at the bottom of the old jar behind.

How much SCOBY do I need for how much tea?

A SCOBY roughly the size of your palm is enough to brew several litres of kombucha.

Far more important than the size of the SCOBY is using enough starter liquid: 10% of the total volume, which means 100 ml per litre.

Which tea is best?

We use caffeinated tea for our kombucha.

Herbal teas can work too, but we find the results less interesting.

The kombucha culture benefits from compounds such as the polyphenols found in tea, and the transformation of the tea’s bitter compounds also plays an important role in the final flavour.

Can I ferment coffee with a SCOBY?

Yes.

Which sugar is best?

Ferments like things natural. The less refined the sugar, the more interesting we find the resulting kombucha. Refined sugar works perfectly well, but less refined sugars can contribute additional flavour.

Honey can also be used as a sugar source. Kombucha traditionally fermented with honey is known as Jun.

For Jun, we recommend using a culture accustomed to fermenting sweetened tea made with honey rather than suddenly switching a regular kombucha culture to honey.

How much sugar do I need? Do I need sugar at all?

Yes. Sugar is the microorganisms’ food source. Without fermentable sugar, there is no kombucha fermentation.

Compared with many conventional soft drinks, finished kombucha can contain relatively little residual sugar because part of the sugar is metabolised during fermentation.

We recommend starting with no more than around 8% sugar, or 80 g per litre of tea. Higher sugar levels can encourage greater alcohol and carbon dioxide production – and potentially turn your bottle into a geyser.

Follow our recipe and you’ll end up with a pleasantly dry kombucha with relatively little residual sweetness.

Do I need a second fermentation?

Not necessarily.

Two things usually happen during the second fermentation: the kombucha is flavoured with fruit, spices or other ingredients, and natural carbonation develops in the sealed bottle.

If you don’t want a carbonated drink, you can drink your kombucha after the first fermentation. In that case, there is no need to build up pressure in a tightly sealed bottle.

Which bottles are best?

Use only high-quality bottles designed to withstand pressure, or suitable PET bottles.

The carbon dioxide produced during bottle fermentation – particularly when more sugar is present – can generate considerable pressure. Unsuitable glass bottles can break or even explode.

Always chill your kombucha thoroughly before opening it.

Treat your kombucha like Champagne: only shake it if you’re planning to christen a boat with it.

Help! What is floating in my ferment?

Is it brown and stringy? Don’t worry. Brown strands and sediment are usually yeast and fermentation material and are perfectly normal.

Is there a smooth, gelatinous film forming on the surface? Congratulations – you’re becoming a parent. Your kombucha is forming a new baby SCOBY.

What should not be floating on the surface during the first fermentation? Actual mould, tea leaves or pieces of fruit.

Mould typically appears as dry, fuzzy patches that may initially be white and later turn green, blue, grey or other colours. If you have genuine mould, discard the entire batch, including the SCOBY.

In our experience, mould problems can often be traced back to one of the following:

Too little or no starter liquid?
Always use at least 10% sufficiently acidic starter liquid when beginning a new batch. SCOBYs thrive in an acidic environment.

Was the SCOBY stored in the refrigerator?
Don’t do it. Imagine being dragged out of a deep sleep and immediately confronted with an enormous pile of work. Even if that sounds suspiciously like your own life, it doesn’t suit your SCOBY. Keep it at room temperature instead.

Did you wash the SCOBY?
SCOBYs like an acidic environment. Rinsing them can temporarily raise the pH at the surface, while what we actually want at the beginning of fermentation is a rapid drop in pH.

My SCOBY always sinks to the bottom instead of floating. Is that okay?

Yes.

Help! A white skin has formed on top of my kombucha. Is that okay?

Yes. If it is smooth rather than fuzzy, it is most likely a new SCOBY forming at the surface.

That is a normal sign of active fermentation. It would be more unusual if a new pellicle never formed.

What do I do with leftover SCOBYs?

Move them into your SCOBY hotel – see above.

What is starter liquid? Do I need it? How much do I need?

Yes!

Starter liquid is mature, highly acidic kombucha. As a rule of thumb, use 10% starter liquid.

For one litre of kombucha, for example, combine 100 ml starter liquid with 900 ml sweetened tea.

Starter liquid helps lower the pH of a fresh batch quickly and creates favourable conditions for a stable fermentation. This practice of inoculating a new batch with part of a previous fermentation is known as backslopping.

How do I make starter liquid?

Simply allow finished kombucha to continue fermenting.

The easiest method is to leave around 300 ml of kombucha in your fermentation vessel together with the SCOBY. Within one to two weeks, it will become increasingly acidic and can be used as starter liquid for your next batch.

Help, there’s mould!

If dry, fuzzy white, grey, green or otherwise coloured mould develops, discard the entire batch, including the SCOBY.

To reduce the risk of mould during the first fermentation:

• Add at least 10% sufficiently acidic starter liquid.

• Do not add fruit, spices or other solid ingredients that can float on the surface during the first fermentation.

No carbonation – what can I do?

Ferments are like pets. They need a little time to settle into their new home, but afterwards they can become loyal and forgiving companions. If you have just acquired your SCOBY, give it some time.

Also check the following:

• Use starter liquid during the first fermentation.

• Make sure there is still enough sugar available for the second fermentation. Bottle your kombucha while it is slightly sweeter than you ultimately want it to taste.

• Use bottles that seal extremely well – pressure-rated swing-top bottles are particularly suitable.

Wild yeasts naturally occur on untreated fruit. If you have access to an unsprayed fruit tree or berry bush, you can add a small piece of fruit to the bottled kombucha during the second fermentation. A little grated apple can work as well. This can encourage vigorous carbonation.

Does kombucha contain alcohol?

Yes, kombucha can contain alcohol.

The amount varies considerably depending on the culture, temperature, fermentation time, oxygen availability, sugar concentration and any ingredients added during secondary fermentation.

Very ripe, strongly fermented kombucha can reach alcohol levels around 1.5% or potentially higher under certain conditions. A particularly sweet starting tea can encourage greater alcohol production.

Be careful when adding fruit during secondary fermentation as well: the additional fermentable sugars can increase both alcohol and carbon dioxide production.