The Back Story
Kombucha is a really delicious, complex fermented drink. Complex in terms of the flavours you can create, rather than being complex to make. It is a fermented tea drink and the fermentation occurs thanks to the Kombucha SCOBY (symbiotic community of bacteria and yeasts), the visible manifestation of which floats around in the liquid like a mother-ship.
The visible SCOBY (which is made by cellulose-producing bacteria) is not actually essential in the making of Kombucha, but the probiotic bacteria and yeasts that migrate from it and then flourish in the liquid, are. That is why, when making a new batch of Kombucha, we “backslop” some of a previous batch into the new batch to “seed” it with the bacteria and yeasts we want to encourage. I keep my floating SCOBY too, because it is a totally fascinating thing to watch develop. And with each brew, it will form more baby SCOBYs, which will always grow to fit the exact shape of the vessel you put it in.
So far as I can discern, Kombucha mainly consists of the following bacteria and yeasts:
Gluconacetobacter – feed on the nitrogen in the tea and produces acetic and gluconic acid;
Lactobacillus – make lactic acid;
Acetobacter – make acetic acid and gluconic acid. And helps build the visible SCOBY;
Zygosaccharomyces – yeasts which produce alcohol and carbonation and contribute to building the SCOBY.
These microbes use the tea and the added sugar to ferment, thereby creating Kombucha. Once bottled (anaerobic environment) the alcohol content of this drink can rise, so bear this in mind if feeeding to children. Kombucha will also contain caffeine from the tea used to make it.
No one is totally sure from where Kombucha originated, some think it came from Russia, but it is older than recorded history, so all we can do is speculate. We do know that Kombucha is a delicious tea-based fermented drink that contains bacteria and yeasts, along with their metabolic by-products, many of which may benefit your digestive system.
The known by-products of this fermentation process are Butyric Acid, Caprylic Acid, Gluconic Acid, Lactic Acid, Alcohol and carbon dioxide. Kombucha also contains vitamin C, various B vitamins and, if you use green teas to make it, a powerful antioxidant from green tea – a catechin called EGCG, which has been shown to protect against cell damage and inflammation.
Making Kombucha is an aerobic process – oxygen is required, so don’t shut the lid on it until the bottling stage!
It is really worth experimenting with what tea you use. Your Kombucha SCOBY prefers tannin and polyphenol rich teas – black teas, green teas and white teas. The choice you make will affect the flavour of your Kombucha. Herbal teas are ok, but only if mixed in with the above teas at the same time. Avoid teas that contain oils – such as earl gray or flavoured teas. These images show my Kombucha brewing and Sandor Katz’s SCOBY, which had been in his SCOBY hotel for a while.
There is plenty of information on the internet on varying styles and approaches to fermenting Kombucha. The Wondergut Website Resources Page here at Wondergut has links to the main websites I have used. Have a read. Have a go and discover which style you prefer.
2 x 2 litre kilner jars.
A number of BREWING bottles – Kombucha is not as lively as water kefir but, having had a Kilner bottle of water kefir explode on me once, I now only use BREWING BOTTLES for the shut lid stage (i.e. when there is likely to be a build up of carbon dioxide from the fermenting process). Kilner bottles aren’t strong enough – as I discovered – the hard way!! Having said that, fermenting expert, Sandor Katz, now generally uses plastic bottles to avoid the risk of injury and I am considering doing this myself sometimes, too.
A filter funnel.
Water – ideally filtered (fluoride and chlorine are not great for Kombucha microbes).
Sugar – I use demerara.
Tea – I use tea bags rather than leaves (less hassle) – the tea is a mineral source for the Kombucha microbes.
The Variables Involved In Fermenting Kombucha
Temperature – the warmer it is, the faster it will ferment.
Time – the longer I leave the brew, the less sweet the Kombucha is, because the microbes digest the sugar. I don’t like it too sweet but equally, the longer it is left, the more alcoholic it becomes and if left for weeks and weeks, the acetobacter eventually take over and turn my Kombucha into Kombucha vinegar for me. This is great for dressings but not so good to drink.
Amount of water - ideally filtered water to avoid chlorine.
Amount of sugar – this is the food source for the Kombucha SCOBY.
Amount of Kombucha SCOBY – both from Kombucha Mother and from backslop – see later.
Mineral supply – what type of tea you choose to use and how much
If things don’t quite work out and I don’t like how my Kombucha tastes, then the chances are one of my variables needs tweaking.
Oxygen - the microbial activity involved in Kombucha is aerobic so it is important to ensure that, until you bottle your finished product, the lid of your vessel remains open. I just secure a muslin over the opening with an elastic band to avoid any unwanted additions (such as flies).
Cleanliness - I am not obsessing about the cleanliness of utensils. I either hand wash them in hot water or wash them in the dish washer.
2 litres of cold filtered water.
100g of demerara sugar.
Approx 125 ml of Kombucha tea from previous batch (called backslop) (or if none, use shop-bought – unpasteurised Kombucha or you can use 60 ml of raw apple cider vinegar).
4 tea bags – I am currently using a mix of green tea and white tea. The last batch I did was with green Pukka Mint Matcha and white tea and the flavour was fabulous.
A Kombucha SCOBY
Pour 1 litre of the water into a saucepan and bring to the boil.
Pour the other litre of water (which remains cold) into a clean 2 litre Kilner jar.
Add the 125 ml backslop of previous brew Kombucha (or bought Kombucha/raw vinegar) to the litre of cold water.
Once the water in the saucepan has boiled, turn off the heat and stir in the 100g of sugar to dissolve it.
Add the tea bags to the saucepan and leave to steep and to cool.
Once steeped and cooled, remove the tea bags and pour this sugary tea into the Kilner jar. Because it is now mixing with the cold water and backslop, it will ensure that the concoction is not too hot for the Kombucha SCOBY.
Slip your Kombucha SCOBY into the Kilner Jar.
Cover with a muslin or breathable cloth and put somewhere safe for around 7 days. This prevents unwanted flies e.t.c paying a visit to your lovely Kombucha.
I like to label my jar so I know what tea I used and what date I made it. It is easy to forget!
After around 7 days, start tasting your Kombucha – you want to catch it at a point where it is a delicious balance between sweet and tart.
At this point, you are ready to bottle your ready-to-drink Kombucha. It is drinkable now or you can add further flavourings.
Filter your ready-to-drink Kombucha through a filter funnel into brewing bottles or plastic bottles so that it becomes carbonated.
At this stage, I like to flavour my Kombucha further, so I pop some fruit or herbs into the bottle with the Kombucha – some berries maybe, or some lemon and ginger, passionfruit is delicious. The choices are endless.
Then refrigerate (to minimise further fermentation) and DRINK! Remember to burp the bottles and remember, the longer you leave Kombucha, the higher the alcohol content it may contain. The more sugar you use, the more potential for alcohol. As far as I can gather, the range of alcohol content is from around 0.5% to 2.5% but if you want almost no alcohol, drink it soon after bottling.
To keep a continuous supply of Kombucha, as you embark on Stage 2, simultaneously begin Stage 1 again, which then allows you, as your last batch becomes ready to drink, to use it to backslop your new batch and you can just slip your Kombucha SCOBY straight from your last batch to your new batch.
If you don’t want to make Kombucha so regularly, you can just put your SCOBY into a Stage 1 brew and put it in the fridge. It will survive there indefinitely in what some call a “SCOBY Hotel”!
Remember that your SCOBY Mother will get thicker and thicker with time. You can either keep the older layers of SCOBY and just keep brewing with a thicker and thicker visible SCOBY. This will eventually affect the levels of oxygen that can reach your Kombucha liquid and this will afffect your end product. I tend to peel the oldest layers off and either keep them in a SCOBY Hotel for future use, give them to friends or feed them to the dog – who ADORES eating them.
To me, Kombucha is a delicious tonic – I don’t drink gallons of the stuff – just one or two small glasses a day if I fancy it.
We are all individual – this is the basics of my practice but this wonderful process is totally interactive and involves each of us working out what volume/rate/fermentation time/flavor best suits us and the environment in which we are doing it. That takes a bit of experimenting and it involves trusting our senses of taste and smell and adjusting our process to suit us.
There is so much information online – enjoy falling into the internet black hole that is fermenting websites!! You will see that there are so many different ways to ferment Kombucha – enjoy finding your own.