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Grade: Senior
Subject: Science

#1229. Root Beer: Demonstration of fermentation

Science, level: Senior
Posted Mon Aug 2 18:45:35 PDT 1999 by Judith Simmons (

New Braunfels ISD, New Braunfels, TX
Materials Required: see lab materials list on assignment
Activity Time: 30-40 minutes
Concepts Taught: biology, fermentation, respiration

Name:__________________________________ Class:________ Date:____________

Root Beer Lab: Demonstration of Fermentation!

Respiration: The breakdown of sugar (glucose) to form ATP (a form of energy
for an organism). There are two types, aerobic and anaerobic (also called

History of Root Beer: Root beer was made by our fore fathers by soaking
Sasafras (a type of tree) root in water, and adding sugar and yeast (yeast
for carbonation). In the early 1900's however, scientists discovered that
safrole, a chemical found in Sassafras root, was a carcinogen (which means
it is a cancer causing agent.) Now, a mixture of other herbs and spices makes
up "root beer extract" which is what we now use to make homemade root beer.

Background Information: There are two types of respiration: aerobic (requiring
oxygen) and anaerobic (without oxygen.)Yeast cells (a type of fungus) obtain
energy from glucose (sugar) by a specific anaerobic process called fermentation.
There are two types of fermentation, lactic acid fermentation (which occurs in
muscle cells when they are oxygen deprived), and alcoholic fermentation, which
is involved in the making of food products. Alcoholic fermentation begins after
glucose diffuses into the yeast cell. The glucose is broken down into 2, 3 carbon
molecules called pyruvic acid. The pyruvic acid is then converted to CO2, ethanol,
and energy for the yeast cell. Don't get excited, students, there is very little
ethanol in this root beer. :) Fermentation is used to make a variety of food
products, including the making of beer, wine, bread, cheese, sauerkraut, and baked
goods. It is the carbon dioxide produced by the yeasts that give root beer its "fizz."
This fizz is produced in store bought root beer by a carbonation machine that forces
carbon dioxide into the root beer mixture, without the aid of our little yeast friends.

Equation for alcoholic respiration: C6H12O6-->CH3-C-COO --> CO2 + H2O + CH3CH2OH (ethanol)

Purpose: To produce a root beer by the Fermentation of sugar.

Materials: Clean, empty, 2 liter plastic bottles + caps
Large Bowl, funnel, mixing spoon
Water (preferably spring water)
Bakers yeast (the dry kind)
Root beer extract (grocery store brand is fine, although
(Hires and A&W do sell their version of extract for a
hefty price)
Sugar, Measuring spoons and cups

1. Dissolve 1/8 teaspoon of yeast in cup of very warm water.
Let stand for 5 minutes. Being in warm water activates the yeasts, and
wakes them up from being dried out. Spring water, incidently,
makes better root beer than tap water.

2. Using the bowl, combine 1 1/2 - 2 tablespoons of Root beer
extract with 1 1/8 cups of sugar in warm water, to dissolve
the sugar.

3. Add the two mixtures to the bottle and add warm water to bring
the level of the liquid up to two liters. (Be sure to use very warm

4. Fill sterilized bottles within 1 to 2 inches to the top. Close
tightly and hold upside down to check for leaks. Make a label out
of plain white paper, and put your names on it. Tape the label to
the bottle.

5. Age root beer for 3 or 4 days in a warm, dark place. Then store
in a cool, dark place for 2 more days. Refrigeration will stop the
fermentaion process and kill the yeast. Total aging of at least one
week is recommended. Two weeks will improve the flavor. Be sure to
check the bottles every day for tightness, if they get too pressurized,
they will explode. Never use glass bottles!

6. Chill root beer and taste. Students may be surprised at how different
this root beer is from store bought root beer.

Questions with ** should be answered the day root beer is made. All others
should be answered when the root beer is ready.

**1. Describe the appearance of the root beer during the bottling process.

2. Describe the appearance of the root beer after fermentation.
How is it different from #1?

**3. Why were the yeasts necessary in this experiment?

**4. Why was the sugar necessary?

5. Explain how the root beer came to be carbonated.

6. **Explain how commercial (store bought) root beer is carbonated.

7. **What is safrole? Why do we not use it anymore?

8. **List the needed ingredients to make root beer.

9. Why did we put the yeasts in the warm water for 5 minutes?

10. **What is fermentation?