Stop! Don’t let the word “fermented” scare you.
What you should think when you hear that word is: “healthy” and “easy.”
Lacto-fermentation simply means that we will introduce some good bacteria into our honey-sweetened strawberry rhubarb juice. These good bacteria will eat up some of the honey and fruit sugars and in turn make lactic acid and the byproduct CO2, which is what will make our soda “fizz.”
Additionally, these bacteria will grow in population and when we drink our soda, we will get a good dose of health-promoting probiotics.
Sounds pretty cool, right?
Lacto-fermenting has taken place for centuries, and was once a very important part of food preservation. The reason is that an environment full of lactic acid is an environment that bad bacteria can’t live in. No bad bacteria eating up the goods = food preserved.
Honey is a great sugar to use for lacto-fermentation. The good bacteria love it just as much as we do! Honey and lacto-fermentation have been a great pair for thousands of years.
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Step 1: Ingredients & Equipment
4 cups sliced rhubarb
2 cups strawberries
8 cups clean water
¾-1 cup raw honey
2 Tbs liquid from a yogurt container
knife and cutting board
four-quart pot with lid
wire mesh strainer
glass jug with stopper (demijohn)
airlock or a balloon
rubber stopper bottles
Step 2: Extracting Flavor From the Fruit
Fermentation is a fight between the good and bad bacteria.
We want the good to prevail and take over the ferment. Use only fresh, clean produce for fermenting. Anything moldy or starting to turn rotten or mushy can introduce the wrong type of bacteria and ruin your product.
To get the most beautiful pink color in your soda, try to select the stalks of rhubarb that have the most red on them. Cut them into ¼” to ½” slices, measure out four cups and place them into a large pot.
Add in two cups of strawberries (fresh or frozen, whole or sliced… anything is fine) and then pour in the eight cups of water.
*A note about the water. You will want to use water that is non-chlorinated (or at the most, very lightly chlorinated). Chlorine is put in water to kill bacteria. We don't want it to kill the good bacteria we are trying to grow!
Cover the pot with a good fitting lid (we don’t want to loose any water!) and simmer gently over low to medium heat for about 30 minutes. You will know when it is finished because the fruits will have become pale and the water will be blushing red.
Step 3: Adding the Honey and Cultures
Allow the mixture to cool for 15-20 minutes and then use a mesh strainer to separate the mushy fruit from the liquid. Avoid “pressing” the fruit into the strainer to get the last bits of juice out, and instead just give it plenty of time to drain. Pressing the fruit will push particles into your liquid and make chunky soda.
“Chunky” isn’t really a word I want to describe my beverages… :)
While the mixture is still a little warm (but not hot!) stir in the honey until dissolved. Now, taste the mixture. The good bacteria will eat up some of the honey, so you want to start with a liquid that is overly sweet in order to finish with soda that is perfectly sweet.
Feel free to add more honey if you’d like yours sweeter. You will also have an opportunity to control the sweetness by monitoring how long you let the soda ferment.
Finally, stir in two tablespoons of liquid (whey) from a container of plain yogurt. I find that I get more whey from a yogurt container if I remove some of the yogurt (as in, I eat some...) and then let the container sit in the fridge for a couple hours. The whey collects in the cavity where I removed the yogurt from.
Step 4: Let the Fermentation Commence!
Transfer your liquid into a very clean glass jug (a demijohn) with a tight fitting stopper and airlock. I like a clear glass jar so I can see what is going on inside. We want to let some of the gasses that will be produced escape, but not let any new air into the jug, which is what the airlock mechanism will allow.
You can get these things online, at health food stores, or wine and beer-making shops. They are very inexpensive and will last a long time! This jug and airlock cost $7 total.
If you don’t have an airlock, you can also try using a balloon. Take a regular birthday-type balloon and use a pin to poke a small hole in the top. Pour the soda liquid into a regular-mouth mason jar or into your demijohn and stretch the balloon over the top of the container.
Place your jug in a room-temperature to slightly warm location, and not in direct sunlight. Putting it in a closet or covering the jug with a towel will help keep the direct sun out.
The temperature at which your jug is stored will help determine the rate at which your soda ferments. The warmer it is, the faster the bacteria will multiply, the faster they will eat up the sugars, and the faster the soda will ferment. But a too hot environment (like in direct sun) can kill the bacteria.
A nice room-temperature is perfectly adequate.
I recommend tasting your soda in progress every day, or even twice a day to learn about how fast it ferments and how it is changing. It is really fascinating and educational!
Once your soda has become fizzy and tastes good (2.5-3 days seems to be the magic number for me), you’ll want to slow the fermentation process way down- which can be accomplished by bottling it and keeping it in the fridge.
Step 5: Bottling & Drinking
When your soda tastes perfect and delicious to you, you should immediately bottle it and get it into the refrigerator. It will be slightly sweet, slightly tart, and have a great mild fizz to it!
You can drink it at anytime now, and it should last for at least a week in the fridge, possibly two. It will very slowly continue to ferment as it sits, so it will slowly become less sweet and more sour as it ages.
A funnel is helpful for bottling, but if you don’t have one just use a cup or bowl with a pour spout (like a Pyrex measure cup) and a steady hand.
Rubber gasket stopper bottles are perfect for bottling your soda. The gasket keeps in the carbonation but doesn’t allow the bottle to explode. Plus, they’re just really cool!
Imagine popping open a cold refreshing bottle of your home-brewed healthy Strawberry-Rhubarb soda. It’s only three days away! What a great way to put your summer rhubarb crop and local, raw honey to use!