FERMENTED GRAPE SODA

Fermented Grape Soda image

Provided by Cortney Burns

Yield Makes 1 quart

Number Of Ingredients 4

4 teaspoons finely grated washed unpeeled organic ginger, divided (grate 1 teaspoon at a time over 4 days)
4 teaspoons sugar, divided
3 pounds red seedless grapes
A clean 1-liter plastic soda bottle with cap; cheesecloth

Steps:

Stir 1 teaspoon ginger, 1 teaspoon sugar, and 4 cups water in a 32-ounce canning jar to combine. Cover jar with cheesecloth; secure with a canning jar band (without lid). Let sit 1 day out of direct sunlight at room temperature.
Stir in 1 teaspoon ginger and 1 teaspoon sugar and let sit 1 day. Repeat twice more. Mixture (ginger bug) should have bubbles throughout and release more when agitated.
After 3 days, purée grapes in a blender until smooth. Strain, pressing on solids (you should have about 4 cups juice).
Combine juice and 1/2 cup ginger bug in a large nonreactive bowl. Cover with cheesecloth; secure with a large rubber band. Let sit out of direct sunlight at room temperature, skimming white mold from surface, until mixture is slightly foamy and releases bubbles when stirred, 3-4 days. Strain into bottle, cap, and let sit at room temperature until bottle feels pressurized, about 1 day longer. Chill.
DO AHEAD: Soda can be made 2 weeks ahead. Keep chilled.