This is a very simple technique that makes an extra tasty batch of kombucha. By adding fruit juice after the ten day fermentation period you get a fizzier drink, which means there is more alcohol. This drink is very much like a grape soda, but good for you!
I have been making kombucha lately with honey , and I have found that over time the mushroom looses it’s potency. I have a batch of regular black tea kombucha  getting started this morning because I have a flurry of people requesting kombucha babies (SCOBY) via the www.kombu.de  website. Since I have been making it with honey, I need to make up a potent batch before I can spread that good kombucha love.
Concord Grape Kombucha Soda
- Double batch black tea kombucha 
- 2 lb (1kg) fresh concord grapes
- 1 apple (optional)
Quick video howto on kombucha making here .
Once your kombucha has finished brewing, juice your concord grapes and apple. Fill the bottom of your jars (I use litre sized jars from Avalon or from my olive oil bottles). I usually fill them about 2 inches with the fresh juice before adding in the fresh kombucha tea.
It is a good idea to strain your grape and apple juice through a fine strainer or there will be a large amount of sediment in the bottom of the kombucha.
Allow the grape kombucha to sit at room temperature for another 48 hours or more depending on how you like your juice. As I make a large batch of about 6 jars, I like to put three in the fridge after about 48 hours and let the other three sit out another 24 hours. This makes a quite potent fizzy brew. Other juices can be used as well, or you can also add ginger while juicing, which is also lovely.
Before drinking you may need to remove another tiny kombucha culture that forms on the top.