Fermentation has been used by mankind for thousands of years for brewing beer, fermenting wine and raising bread. The products of the fermentation of sugar by baker’s yeast Saccharomyces cerevisiae (a fungus) are ethyl alcohol and carbon dioxide. Carbon dioxide causes bread to rise and gives effervescent drinks their bubbles. This action of yeast on sugar is used to ‘carbonate’ beverages, as in the addition of bubbles to champagne). [Note: In response to many questions I have received, here is a discussion of the small amount of ethyl alcohol which results in this root beer .]
We will set up a fermentation in a closed system and capture the generated carbon dioxide to carbonate root beer. You may of course adjust the quantities of sugar and/or extract to taste. You should be able to find root beer extract at your local supermarket.
Hires and A&W have a long history of making root beer extract. I find Zatarain’s extract especially delicious, but your definition of root beer may include a different assortment of flavors. If you can’t find it, Zatarain’s, a product of New Orleans can be ordered on the web.
Other flavors can be substituted for the root beer extract.
Try using a tablespoon of vanilla instead of the extract for a cream soda, and grated ginger and lemon for ginger ale.
IMPORTANT SAFETY CAUTION: As you follow the following recipe, be sure to refrigerate these bottle-fermented soft drinks as soon as the bottle feels hard. Especially in the summer, after a week or so, there is a risk of explosion!
[SUGAR SUBSTITUTES? Many people have emailed me asking about substituting artificial sweeteners for the sugar in this recipe. The short answer; no.
Sugar is required for yeast to generate carbon dioxide which carbonates the beverage. No sugar, no carbonation.
You might experiment with less sugar, and add a substitute to make up for the lower sweetness. I do not know how little sugar you can add and still get adequate carbonization, but 1/2 cup of sugar/ 2 liters makes plenty of carbonation.]
- Clean 2 liter plastic soft drink bottle with cap.
I do not recommend glass bottles because of the risk of explosive shards of glass.
- 1 cup measuring cup
- 1/4 tsp measuring spoon
- 1 Tbl measuring spoon
- 1 cup table sugar [alias cane sugar or sucrose]
- Zatarains’s Root Beer Extract (1 tablespoon)
- Powdered baker’s yeast (1/4 teaspoon)
Yeast for brewing would certainly work at least as well as baking yeast.
- Cold, fresh water
Note on Zatarain’s Root Beer Extract:
When I could not find it locally, I ordered a case of 12 bottles for $18 from Zatarain’s, New Orleans, LA 70114. Previously, I had used Hires extract.
NOTE: There will be a sediment of yeast at the bottom of the bottle, so that the last bit of root beer will be turbid. It will not hurt you, but you can decant carefully if you wish to avoid this sediment.
A Word about the Alcohol in Home Made Root Beer (or Ginger Ale):
I have received numerous inquiries about whether there might be alcohol in this home made soft drink. The answer is yes, but…
We have tested in our lab the alcoholic content which results from the fermentation of this root beer and found it to be between 0.35 and 0.5 %. Comparing this to the 6% in many beers, it would require a person to drink about a gallon and a half of this root beer to be equivalent to one 12 ounce beer.
I would call this amount of alcohol negligible, but for persons with metabolic problems who cannot metabolize alcohol properly, or religious prohibition against any alcohol, consumption should be limited or avoided. However, there are many high school biology labs who have made this beverage without any problems.
If you are one of these, I am interested to hear about your conclusions.