©David B. Fankhauser, Ph.D.
Professor of Biology and Chemistry
U.C. Clermont College
Batavia OH 45103
Ingredients collected
First posted 28 June 1996, rvsd: 19 Mar 97, 3 July 97,  29 June 00, 7 Aug 00
This page has been accessed  Counter times since 26 July 2000.
Adding the extract

[NOTE: I have found uncredited copies of this (and other of my pages) posted on the web as if it were the work of the poster. PLEASE give credit where it is due. And to friends of my pages: please let me know if you believe others are plagiarizing this body of work.  Here is a letter I sent to "Hubpages" asking that they correct the situation.]

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 makiing 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 is 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)

(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.)

powdered baker's yeast (1/4 teaspoon)  (Yeast for brewing would certainly work at least as well as baking yeast.)

cold fresh water


1) Assemble the necessary equipment and supplies
2) With a dry funnel, add in sequence:

1 level cup of table sugar (cane sugar) (You can adjust the amount to achieve the desired sweetness. Cutting the sugar in half still produces adequate carbonation with much less sweetness.)

[I get MANY questions about an artificially sweetened version.  Know that some sugar is a must for carbonation, but if you want to reduce sugar to a tablespoon per 2 liters, and add artificial sweetener, it is your choice.  I confess that I do not trust artificial sweeteners.  Call me a luddite...]

3) Add: 1/4 teaspoon powdered baker's yeast ( fresh and active)

(Fleischmann's or other brand)

Some have suggested that using champagne yeast may produce less of a yeasty flavor.  I don't mind the complexity of this recipe,. and have not tried varying the yeast used.  If you find a significant improvement with more esoteric yeasts, let me know.
4) You can see the yeast granules on top of the sugar.
5) Shake to distribute the yeast grains into the sugar.
6) Swirl the sugar/yeast mixture in the bottom to make it concave (to catch the extract).
7) Add with funnel:

1 Tbl of root beer extract (I prefer Zatarain's, but Hires, etc. will work.)

on top of the dry sugar
8) The extract sticks to the sugar which will help dissolve the extract in the next steps.  If you shake it, it will further help it to dissolve.
9) Half fill the bottle with fresh cool tap water (the less chlorine, the better since yeast does not like chlorine).  You can diminish the amount of chlorine by drawing water the night before, placing in a large pot, and letting it "exhale" the chlorine overnight.

Rinse in the extract which sticks to the tablespoon and funnel. Swirl to dissolve the ingredients.
10) Q.s. [fill up] to the neck of the bottle with fresh cool tap water, leaving about an inch of head space, securely screw cap down to seal. Invert repeatedly to thoroughly dissolve.
If you leave it in a warm temperature longer than two weeks, you risk an explosion...
11) Place at room temperature (RT)about three to four days until the bottle feels hard to a forceful squeeze. Move to a cool place (below 65 F). refrigerate overnight to thoroughly chill before serving. Crack the lid of the thoroughly chilled root beer just a little to release the pressure slowly.

NOTE: Do not leave the finished root beer in a warm place once the bottle feels hard. After a couple weeks or so at room temperature, especially in the summer when the temperature is high, enough pressure may build up to explode the bottle! There is no danger of this if the finished root beer is refrigerated.

12) Move to a refrigerator overnight before opening.

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.

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