Biting into a sweet, juicy slice of watermelon on a hot summer day can quench your thirst like no other! But today we’re taking this deliciously sweet fruit and making refreshing fermented watermelon soda like you’ve never tasted.
We love making ginger ale and other fermented sodas using a ginger bug starter, but this one is made by using fermented watermelon juice. Oh my!
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Fermenting Watermelon
Most people have only enjoyed fresh watermelon in chunks or slices. They might have even gone as far as making it into a delicious drink by blending it which we highly recommend. Add some mint leaves and I guarantee you will be sipping this tropical drink with a smile.
There are a lot of recipes for watermelon mint soda that call for club soda to get it fizzy. Watermelon soda is about as fresh a drink as you can possibly get, but did you know instead of using club soda, you can bring this drink to life? If you add a starter culture like a ginger bug, you can kick up the flavor and probiotics of this drink into something quite unique without even adding club soda for the bubbles.
There are other ways to ferment watermelon too. One recipe that blew our minds was when we discovered you could use the entire outside of the fruit and make fermented watermelon rinds! It’s basically like making dill pickles that stay crispy. All those times we threw the rinds away, we could have been making watermelon pickles. Try it some time!
Today though we’re focusing on what’s inside of the watermelon. Like many other homemade lacto-fermented sodas, you start with a soda syrup (or “wort”) and then add life to it. From there the bacteria and yeast feast on the sugar and create a natural soda for you.
You’re basically setting up an environment for the starter culture to have a party and do all the work for you. Let’s get into it.
Fermented Watermelon Soda Recipe Using a Ginger Bug
Makes 1/2 gallon (or 4 bottles)
Equipment:
- 1/2 gallon jars or jugs for Primary Fermentation
- Nut milk bag or cheesecloth <– These would work well
- Fermentation lid <– These silicone lids work well for us
- (3) 16 oz. glass flip-top beer bottles <– We love these
- (1) 16 oz. heavy duty plastic bottle (such as Perrier or a soda bottle)
Ingredients for Watermelon Soda:
- 4 cups fresh watermelon juice, minus pulp (~8 cups watermelon chunks)
- 1/2 cup sugar
- 1/2 cup Ginger Bug starter <– full post & video on how to make one
- Non-chlorinated water, target volume 1/2 gallon (enough to fill jar)
Cut watermelon into chunks. Save the watermelon rind if you’d like to make fermented watermelon rind pickles.
Blend watermelon in a blender to a fine consistency.
Strain watermelon juice through a nut milk bag or cheesecloth to remove the pulp.
Pour the watermelon juice into a 1/2 gallon mason jar and stir in sugar to dissolve.
Add your ginger bug starter, give it a stir, and top with a cloth or a fermentation lid to keep out the oxygen.
Ferment on the counter at room temperature for 1 DAY. This is important because watermelon soda has a tipping point! It tastes amazing when fermented the perfect amount of time, but ferment for just a bit too long and it really starts tasting terrible! Normally for fermented sodas like ginger ale we like to ferment for 3 days in our 72-74 degree house, but at 3 days the flavor of fermented watermelon soda is undrinkable. Feel free to try it longer if you want, but you’ve been warned!
Bottle fermented watermelon soda in flip-top bottles along with a plastic tester bottle to begin the secondary fermentation stage if you want bubbly soda. The tester bottle is also extremely important. Since we’ve only fermented for 1 day, the watermelon soda is VERY active. We recommend only bottling for maybe 4 hours and to keep testing the pressure.
If you go longer, you risk the bottle possibly exploding or soda to go spraying everywhere. Normally we let the ferment settle down before bottling but if we waited for it to settle down, the terrible flavor would make it undrinkable.
WARNING! During this step, make sure one of your bottles is a plastic tester bottle so that you can gauge how much pressure is inside the glass bottles.
What to Expect During Fermentation – Watermelon Soda
During the first 12 hours of fermentation, it’s possible you’ll see bubbles beginning to form as the ginger bug starter begins to work its magic and eat the sugar. The color of your watermelon soda will also be a vibrant pink or red and still smell fresh.
After 24 hours, our jar was very bubbly with champagne-like bubbles rising from the bottom. The color began to turn a little less vibrant as some of the watermelon micro pulp began to settle to the bottom of the jar. We could also see pressure building in the fermentation lid as it bulged at the top with gasses escaping the little hole. It also started to smell more yeasty and fermented.
Once we transferred to our flip-top bottles and plastic tester bottle, we began to feel pressure in the bottle after only one hour of bottling! That’s an active ferment! At four hours our bottle was rock solid. Since we were filming, our bottles ended up at about 8 hours of pressurization which we think was too long. When we opened it, it literally sprayed everywhere with quite a bit of force so watch out!
What’s the Alcohol Content of Fermented Watermelon Soda?
We’ve been dying to know how much alcohol is in ginger ale and other fermented sodas so we finally got ourselves a nice hydrometer to measure the alcohol content! Woohoo!
We measured the gravity of our wort before and after the fermentation process and plugged it into the generally accepted formula:
Alcohol By Volume (ABV) Formula
ABV = (og – fg) * 131.25
Original Gravity (og): 1.04
Final Gravity (fg) (after 32 hours): 1.016
ABV = (1.04 – 1.016) * 131.25 = 3.15% ABV
After only a little over one day, we have a fermented watermelon soda estimated at just over 3% alcoholic content. Wow!
How to Make Watermelon Soda Using a Ginger Bug
Using a ginger bug starter to make fermented sodas is such a fun activity! Every time we mix up our ingredients we feel like we’re kids playing scientists, but instead of dangerous chemicals, we have bubbly creations that we get to enjoy in the end.
Keep in mind that you can use many other types of starter cultures to make watermelon soda including water kefir, whey, or even a kombucha scoby. I’m sure they will all have different outcomes but will probably also taste great as well.
We hope you’ve enjoyed this episode on how to make watermelon soda using a ginger bug. Leave us a comment below and don’t forget to subscribe to our YouTube channel!
