The drink is made by mixing tea with sugar adding the Scoby in a sealed jar and allowing it to ferment in a warm environment.
The bacteria and yeast of the Scoby convert the sugar into ethanol and acetic acid, which keeps out harmful bugs and gives the kombucha its distinctive sour taste.
Rory McCoy, director of Little Duck The Picklery, Dalston, East London, said: “Kombucha is growing in popularity. Our best selling flavours are tea with with peach, raspberry, rhubarb and we have a herbal one with sage.
“I think making kombucha is a very creative thing to do. It takes about seven to 14 days to brew a batch but you have got to be careful.
“You are fermenting bacteria and there is bad bacteria in everything. The key to a good kombucha is that it must look appealing. you should not drink it if it’s too dark and brown or the Scoby is mouldy and spotty.”
His firm does not sell Scobys to consumers but he sells them to the catering trade.