Sept - Using Cellular Respiration to Make Root Beer!

Simple Sugar
Glucose

This month, I got to teach a class on cellular respiration, or how cells make energy.  Cellular respiration is the process of breaking down sugars into ATP (Adenosine triphosphate), what we call energy.  Cells can use Aerobic or Anaerobic pathways for breaking down sugars into energy.  Aerobic means 'with oxygen' while Anaerobic means 'without/lacking oxygen'.  Although a cell can use both pathways to produce energy, the efficiency of ATP production is greatly affected in a non-oxygen environment compared to when oxygen is present for the process.  For comparison, a single glucose (sugar) molecule will produce only 2 ATP in the fast paced and wasteful anaerobic process, while the aerobic process can produce 34-38 ATP from the same, single sugar molecule.  

The complicated process of how a cell makes energy

Our class experimented with yeast to see how the process works in real time.  We couldn't, of course, see the cellular processes taking place, but we could see the release of by products being formed from the cellular process.  

In aerobic respiration, the by products formed along with ATP are carbon dioxide and water.  Bakers yeast, once activated, will produce energy in order for the yeast to grow and work properly in a recipe, but as that energy is made, it release a lot of carbon dioxide into the air.  In our experiment, we trapped and measured the carbon dioxide (via the foam produced) once the yeast was activated.  by changing some variables like temperature and energy source, we saw some interesting differences in our experiments. 

Our Yeast Experiment

Once we discussed the results from our experiments, we talked about industries that have harnessed some of these 'by-products' to make products we use at home.  One we can make specifically from yeast is Root beer! 

Experiment. Using Cellular Respiration to Craft Homemade Root Beer

Supplies:

¨ 1 Cup Table Sugar

¨ 1 Tablespoon Root Beer Extract

¨ 1/4 Teaspoon Powdered Baker’s Yeast

¨ 1 Two Liter Bottle

¨ 1 Funnel

¨ Cold (Op. Filtered) Water

 

Directions:

1. Sterilize anything that will touch your Root Beer.  May include pots, funnels, tubes/siphons, measuring cups, and bottles.  You can boil these items or simply run them through the dishwasher (high temperatures will kill any unwanted bacteria).  Wash your hands too!

 

2. Using a clean bottle and a dry funnel, add the ingredients in sequence.

à Add 1 level cup sugar.  The amount may be adjusted up/down for sweetness preference.

à Measure 1/4 teaspoon powdered baker’s yeast and place down funnel.  Yeast should be FRESH and ACTIVE, any brand.

3. Cap bottle and shake well to distribute the yeast grains evenly into the sugar.

4. Swirl the sugar/yeast mixture in the bottom.  This should cause a concave pouch in the middle that will enable it to catch the extract in the middle.

5. Replace the funnel and add 1 Tbsp of root beer extract on top of the dry sugar.  Notice that the extract will stick to the sugar and this will help dissolve the extract. 

6. Fill the bottle halfway with fresh, cool tap water that has little or no chlorine.  Pour through the funnel. Rinse the extract stuck to the funnel and tablespoon.

7. Swirl to dissolve all ingredients.

8. Fill the bottle to the neck with fresh water, leaving only about an inch of head space.  Secure the bottle cap.  Invert bottle repeatedly to thoroughly dissolve contents. 

9. Place the sealed bottle at room temperature for about three or four days. 

10. Eventually, the bottle should feel hard to a forceful squeeze.  Refrigerate overnight to thoroughly chill before serving.  Crack the lid of the bottle just a little to release the pressure slowly. 

We had mixed feelings about the root beer, but overall it turned out pretty yummy! 

For the full Cellular Respiration Lesson, please check out our Newest STEM Kit - Cellular Respiration by reserving it on our website.  Until then - Happy STEMing!