Unlike the store bought sodas, which are, high in sugar, preservative and additives, lacto-fermented soda is much lower in sugar whilst containing enzymes, probiotics and the nutrients of the fruit you wish to use. Even better the longer you let your creating ferment the less sugar in your soda.
Here is a recipe for your lacto-fermented soda:
4 cups of your favourite fruit (eg watermelon)
½ cup of organic cane sugar, sucanat or rapadura
¼ cup whey (alternatively water kefir)
1.8 Litres of water
1/ Boil sugar in water for a few minutes whilst stirring to dissolve. Cool till room temperature.
2/ Roughly cut watermelon and place in a blender till pureed.
3/ Strain the watermelon through a cheesecloth to extract the juice only
4/ Combine the watermelon juice and whey into the cooled sugar water and stir, leave this mixture on your counter to ferment for approx. 3 days. Leaving it for a week will result in considerable less sugar.
5/ Transfer into soda bottles via a funnel
6/ Keep at room temperature and let pressure out of the bottle every day. After a few days they can be stores in the fried (this will slow the fermentation process)