Probiotic Soda

I do a lot of fermentation—sourdough, wine, beer, and vegetables like sauerkraut. I wanted something similar to kombucha but a little different. While kombucha is easy to start and maintain, it usually involves gallon-sized batches and post-fermentation flavoring. I was looking for a smaller-batch option that was simple to flavor, and that’s when I came across probiotic sodas made with a ginger bug.

Making probiotic sodas is a lot like working with kombucha or sourdough: you create a starter, use it to make a batch, and keep feeding it for future batches. The starter here is a ginger bug, made by mixing fresh ginger from your local grocery store with water and a bit of cane sugar. Here’s one simple method for making a ginger bug—this is a straightforward approach for creating a ginger bug.

Equipment needed

• Mason jar or container large enough to hold ~1L
• Venting lid or cheese cloth to cover the jar but let it vent.
• Flip/swing top bottle, growler or a ~1 gallon homebrew keg to make a batch.
  • I like using a small keg which I will connect to my kegerator for serving
  • If you have one and need a large batch, you could use a corneilius
  • Flip tops containers are nice to release the CO2 developed during fermentation.
  • The container you use should be able to hold CO2 pressure but also easy to release some.
• Funnel
• Blender
• Strainer
• Iodophor for sanitizing.
  • You can do without this but could get a batch with wild yeast and bacteria not found in your ginger bug.
  • Just need enough to give a tint to water to fill what you want to sanitize.

Making a batch

Making a batch is simple and requires no heating. I usually mix everything in my blender pitcher, then pour it through a strainer into my keg. If you’re using swing‑top bottles or growlers, you can skip straining, but for a keg the solids can clog the beer-out tube if you leave them in.

The recipe below is for a 1 L blueberry–lime soda fermented in a bottle or growler; for a keg, just scale it up. You can swap the blueberries for raspberries, mixed berries, your favorite frozen fruit, or extra ginger. I like frozen fruit because it’s always easy to find and consistently high quality, but fresh fruit works as well, and you can even experiment with vegetables like cucumbers or peppers. The finished soda usually has an alcohol content similar to kombucha, typically under 1% ABV.

• 1 L water
• 1 8 oz bag of frozen blueberries.
• Juice of one lime
• 1/2 to 3/4 C cane sugar
  • Depend on how much sugar the fruit or other ingredients add. Less for sweeter fruit.
• 2 tbls ginger bug – refreshed and actively fermenting

1. Add everything except the ginger bug to the pitcher of your blender.
2. Blend until smooth.
3. Strain into your container if needed.
4. Add the ginger bug to the container. Try to get mostly ginger bug liquid, if you are using a keg you should strain it to get out any ginger pieces.

Once your bottle or keg is filled, close it and leave it at room temperature in a dark place, such as a cupboard. Let it sit for a few days, but don’t forget about it. Check the carbonation daily by briefly opening the bottle or pulling the keg’s pressure‑release valve—you should feel or hear some pressure. After the first day, open carefully, as it can become quite fizzy and even erupt; I once had a raspberry batch partially redecorate my kitchen. If you leave it too long without checking, there is a real risk that a bottle could burst.

As a general guideline, let it ferment at room temperature for about 3 days, then move it to the refrigerator for another 2 days before tasting. When you first try it, if it is still very sweet or only lightly carbonated, let it ferment longer; you may need to take it out of the fridge for a day or two to speed things up again. When I’m using a keg, the fermentation usually produces enough natural carbonation that I don’t need to add extra CO₂ for serving.