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Make Your Own Soda (Fermentation 101)

August 8, 2009

There are many reasons to try experimenting in the kitchen. In this case, making your own soda is cheaper, more nutritious, and offers a greater flavor variety than store-bought sodas. Basically, this just water with some bubbles and flavor, and is a lot of fun to make!

The bubbles in store-bought sodas are made by adding carbon dioxide gas to a flavored based under high pressure. The gas dissolves into the liquid – you can get a similar effect at home using one of these seltzer makers. However, I like to use a trick that has been around for thousands of years: yeast. Yeast makes bubbles in beer, and yeast can also make bubbles in your homemade soda.

How does this work? Yeast, like humans, obtain energy from breaking down sugar molecules. This requires oxygen, and is known as aerobic respiration. If there is no oxygen around, humans will die. Yeast however, have a metabolic trick that allows them to survive: in the absence of oxygen, yeast can derive energy from sugar in a process known as anaerobic respiration, or fermentation. The two byproducts of yeast fermentation are ethanol (alcohol) and carbon dioxide (fizzy bubbles). When making soda at home, we will let our mixture ferment for ~24 hours. This is enough time for the yeast to produce a lot of bubbles, but only a tiiiiiny trace of alcohol:

yeast.gif

Materials you will need:

2-liter plastic soda bottle
Water
Sugar (or honey, turbinado sugar, agave nectar………)
Flavorings (herbs, fruit, syrups)
Yeast – preferably champagne yeast from a store that carries brewing supplies. Baker’s yeast will do in a pinch.

Steps:

1. Clean your equipment. For making soda, you don’t need to sterilize everything with bleach (like you would for homebrewing beer or wine), but make sure everything is clean.

2. In a pot, add ~1.75 liters of water, and all of the flavorings you plan to use. Bring the mixture up to a simmer, and let it bubble for 30 seconds. Turn off the heat and let the mixture cool.

3. In a separate bowl, dissolve 1.4 teaspoon of yeast into a small amount of warm water. When the yeast is dissolved, add it to the cooled soda base.

4. Pour the completed soda base into the 2-Liter bottle, and close the cap tightly. Let the bottle sit for 24 to 48 hours. The amount of time is variable, depending on the temperature of your kitchen, etc. At first, the carbon dioxide we be produced as a gas, and will increase the pressure in the bottle. Once enough pressure has been built up, newly produced carbon dioxide will begin to dissolve into the soda base.

You can monitor the fermentation by squeezing the bottle – it should start to feel firm, just like a commercial soda bottle would. Enjoy!

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Note 1: When you open the soda bottle, there will be a lot of initial fizz. However, if you pour a glass out, and the soda is pretty flat, don’t worry. All this means is that the yeast needs more time. Put the cap back on, and let it go another day. Play around and have fun – since yeast are alive, some days they will produce more bubbles than other days.

Note 2: If you use fruit puree or other “chunky” ingredients, you can filter the cooled soda base through a cheesecloth if you wish. The resulting soda will be smoother. Just like buying orange juice, you can choose pulp or no pulp.

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Recently I made a Blueberry-Ginger-Lemon Sparkler. In a pot I combined:

1.75 L water, 1 cup frozen blueberries (pureed in blender), 1 inch chunk of ginger (grated), 1/4 cup sugar, and 1/2 lemon (whole). I brought the mixture to a simmer – behold the cauldron…..

cauldron.gif

Then, I added 1/4 tsp champagne yeast which I dissolved first in a little warm water. I added the yeast to the *cooled* soda base (minus the lemon half) and pour into a clean 2 L soda bottle. I went to sleep, and the yeast went to work. The next day, I had:

bottle.gif

glass.gif

More fermentation resources:

NOVA’s blog has a post on 45-million year old beer

Matt’s blog Brew and Bake had wonderfully detailed instructions for making your own beer!

Craftzine offers a cool video for making soda using a similar technique.

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2 Comments leave one →
  1. August 8, 2009 12:31 pm

    Can you tell me who did your layout? I’ve been looking for one kind of like yours. Thank you.

    • Jill permalink
      August 8, 2009 12:55 pm

      Hi Josh,
      I used a free theme from WordPress called Vigilance. I designed the header by myself using Adobe Illustrator. I’m new to blogging, so that’s about all I could handle. I like your website!! I’m very interested in Biofuels. My alma mater, UW – Madison has a great biofuels research project http://www.greatlakesbioenergy.org/

      Good luck with your blog!

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