Congratulations! You're now a proud owner of some of my kombucha tea. These instructions should help you build a nice strong culture.
I saved a bottle from my last first fermentation. You should have about 400 ml of tea there. It's pretty strong, I brewed for a bit over 2 weeks so it's nice and tart and should get you off to a good start. I also added a bit of sugar to keep the culture going.
Do not put this in the fridge. the culture will go dormant and will take time to wake back up, and you might end up developing mould in your brew as a result. Until you use the starter culture, keep it at room temperature, and just burp the bottle (open it) daily to let the gas out. Ideally you should use this within a week or so, but you can keep it going for longer by adding some freshly brewed black tea and a couple of teaspoons of sugar. Let it cool down to room temp before adding it to your starter culture otherwise you'll burn it!
I'm not sure I gave you enough starter culture to make a massive batch of kombucha in your first brew. So what I'd recommend is doing half of my recipe for your first brew, and then add in half more sweet tea and brew again. This way you can ensure that the tea grows up nice and strong, daddy-o.
So brew some sweet tea. I recommend a litre of water, 100g of sugar (golden works best anecdotally), and about 4/5 black tea bags, or the equivalent amount of loose leaf tea. Brew this and let it cool to room temperature. I recommend using ice if it takes too long, or just using hot but not boiling water. You should leave it for at least 30 minutes though.
- Do not mix hot tea with your culture as this will kill the poor mites
- It's best to cool it so that it's about lukewarm to the touch.
- I normally sterilise my gear during this time, if I haven't done it in a while.
- Black tea is best for getting a strong brew, since it has all the tanins in it. Later on you can experiment with mixing green tea for extra tartness.
Once it's at room temperature, get the liquid into your starter culture (if you're using loose leaf, make sure to strain out the leaves). Then you can add your starter culture to it, give it a bit of a mix and you're good to go! Pop the cloth on top, elastic band to hold it in place, and then let it do its thang.
You should absolutely sterilise your brewing vessel (and your 2nd fermentation bottles) before use. Easiest way is to clean the inside with vinegar and water, then drip drain it, then pop it into the oven at 120 celcius (ish) for about 10-15 minutes. Then just let it cool to room temperature (important) before using it. BTW if you use swing top bottles, remember to remove the lids first otherwise they'll melt.
Hands, utensils, etc can just be cleaned with vinegar and hot water.
Why not washing up liquid? er... because it's anti bacterial. not the name of the game here. you want the bacteria!
Over the first few days, try to avoid moving your brew vessel too much, as the pellicle (the flabby bit) will be growing on top. You should place your brew vessel somewhere warm, and somewhere that doesn't get a lot of foot traffic (dust etc kicked up). But don't keep it in a cupboard, it needs fresh air to brew and not get mouldy! I use my desk, it's kinda cute, a bit like those sea monkey things I had as a kid...
The top of the brew will start looking a bit scummy and horrible. That's your pellicle growing!
After about 7-10 days, start tasting your kombucha, with a straw, or a spoon or whatever (clean it first obvs). If it has a nice tang to it and doesn't taste like tea, you're good to go! Brew another litre of sweet tea as before, and add it in (and stir). You should be able to brew a nice strong first batch (should take anywhere between 10-14 days).
This is where the fizzing happens. Wilko do really nice swing top bottles for not too much money. or try your friendly homebrew dealer for some fermentation grade bottles. the IKEA ones and the ones in TK Maxx are shit. they're decorative and will probably explode under the pressure.
For regular unflavoured kombucha, just pour in liquid from your brewing vessel into the bottle, leaving a few cm of headspace (room at the top of the bottle). You can also add a tea spoon of sugar to help get the fizz up a bit more.
Fill them up but leave like 400-500ml of your brewed tea in your brew vessel. This will be the starter for your next tea. You can throw away layers of your pellicle too if you like, it;'s mainly just flab that takes up space in your jar. I normally keep a bit as it's a nice physical barrier from the nasties in the world.
This is the point where you can mess around with your flavourings too. If I flavour my kombucha, I'll normally shift the tea over to another bottle after 2/3 days so I don't over infuse the tea with whatever leaves/zests I'm using. Burp your bottles every couple of days or so if you're worried about them exploding. Although I never wait long enough so they end up being a bit flat. It's a risk we all take.
Good luck!