Overstocked, and accumulated a stockpile of old coffee grounds at home? In our fifth episode of Coffee On, we collaborated with Singapore's 'Prince of Fermentation' Ding Jie Tan, founder of Starter Culture to discover creative ways to repurpose old coffee grounds.

If naturally fizzy coffee 'soda' is something you might like, then this recipe is for you!

Coffee Kombucha Recipe

Ingredients
Makes 1litre
900ml water
100ml Kombucha starter
100g coarse-ground coffee
80g raw cane sugar/honey/white sugar

Equipment
Glass jar (at least 1000ml)
Paper filter
Kitchen towel or clean cloth
Rubber band 

Instructions

Step 1: Brew the coffee
Steep coarse-ground coffee in 700 ml of water for 10 hours at room temperature. Strain with a paper filter to remove sediments and oils. 

Step 2: Add Kombucha starter
Dissolve 80 g raw cane sugar in 200 mL water. Combine and mix the sugar syrup, kombucha starter, and cold brew coffee in a large glass jar.

Step 3: Ferment for 5 to 7 days
Cover with a clean kitchen towel and secure it with a rubber band. Leave it in room temperature. Label and monitor the fermentation process over 5 to 7 days. Reserve 100ml of your fermented coffee as a starter for your next batch of coffee konbucha!

Step 4: Bottle for 3 to 4 days 
Transfer to an air-tight bottle and top up with sugar (1g sugar of per 100ml of kombucha). Refrigerate when bubbles are observed at the surface. Once it's chilled, you can pour and enjoy your naturally fizzy and fruity coffee ‘soda’!

Which coffee did you use for this recipe? Let us know in the comments below!