The word rhubarb (Rheum rhabarbarum) is likely to date back to the fourteenth century, deriving from old French rubarbe, which came from the Latin rhabarbarum, meaning ‘from the barbarians beyond the river Rha’. In China, rhubarb has been used as a medicinal plant for thousands of years. Its leaves are packed with toxic oxalic acid, but the stalks are full of sugar, the roots can soothe stomach ailments, and eating the stalk regularly could lower cholesterol, aid digestion and improve liver health.
Young blackberry shoots (Rubus fruticosus) emerge in mid-March; they are tender and packed with all the nutrients the plant is shooting through its roots. They are rich in vitamin C, calcium, vitamin K, magnesium and iron. They also contain powerful plant compounds like tannins and antioxidant flavonoids.
Blackberry shoots must be picked before they start to produce spines. Once home, fold them into a clean towel and bruise them to help release enzymes, as though working on a bread dough. Soon after, dry them by placing them close to a window in direct sunlight, or if you have a dehydrator, dry them at 35ºC inside a tray with hot steaming water.
Kombucha (makes 3 litres)
Kukicha tea, 10g
Dried blackberry shoots 20g
Spring water, 2.5l
Unrefined cane sugar, 300g
Unpasteurised kombucha (or the liquid that comes with a packed scoby), 500ml
1 scoby
Fermented rhubarb
Fresh rhubarb, 500g
Unrefined cane sugar, 200g
How to prepare the kombucha
3l jar, open on the top
A cheesecloth
An elastic band
The jar needs to be sterilised with hot water for a couple of minutes. Once cooled, add the scoby and the unpasteurised kombucha, cover the top with the cheesecloth and tighten with the elastic band.
Have two pans ready, one in which you will keep the Kukicha and dry blackberry shoots ready to brew and a second in which to bring 300ml of water and 300g of sugar to a gentle simmer.
Once ready, pour the simmering syrup on the herb mix, cover with a lid and leave it brewing for 12 minutes.
After brewing, filter the tea through a fine filter bag and add 2.2L of cold water, bringing the temperature down to around 30ºC.
Pour everything into the jar with the scoby and the unpasteurised kombucha.
Make sure there is an inch gap left at the top of the jar, and cover again tightly with the cheese cloth.
The kombucha will take 7 to 10 days to ferment, depending on storing temperature.
A perfect brew requires a constant temperature between 26–29ºC but anything less will just take longer, the important thing is to keep away from the sun and bright light. I usually try my kombucha on the fifth day to check how it is progressing. Especially if you don’t have a regulated heating system, fermentation time will change depending on the season. It’s important to understand the sweet spot, where sweet starts to flip into sour, and taste it every day from that point on until you find your best desired flavour.
Fermented rhubarb
Cut the rhubarb into small pieces, place into an airtight container, add the sugar, cover with the lid and wait for the magic.
As with the kombucha, it will take between 7–10 days to ferment, depending on room temperature. Make sure you stir the mix from time to time to avoid any mould formation.
Bottling your kombucha
You need five 500ml bottles with swing-top lids.
After the fermentation process has finished, pour 100ml of the fermented rhubarb syrup into each bottle. Top with the blackberry shoot kombucha, leaving an inch gap at the top. Close the lid and store in a cool place for 2–3 days for a second fermentation. This time, the CO2 produced will stay trapped into the bottle creating a natural, effervescent fizziness. Store in your fridge soon after and treat as an unpasteurised product.
Rhubarb Collins
Fermented rhubarb syrup, 25ml
Lemon juice, 25ml
Gin of your choice, 50ml
Rhubarb kombucha, enough to top the glass
In a tumbler glass add all the ingredients apart from the kombucha and stir well. Add ice, then top with the rhubarb kombucha. Garnish with rhubarb left over from the fermentation process.
Antonio Curcetti is mixologist at the East London restaurant Pidgin, and founder at Mind Blowing Kombucha.