Fermentation Lab
The purpose of this lab is to demonstrate the process of fermentation to the students.
Materials:
Ziploc bag ( sandwich size 1 per group)
Sugar cubes (two cubes per group)
Baker's yeast ( one pkg. per group)
warm water 100 mL
Pipette ( one for each group)
Bromothymol Blue inicator ( one pipette full per group)
Bromothymol indicator turns yellow in the presence of carbon dioxide
Before the students arrive it is helpful to put the yeast packet and sugar cubes into the Ziploc bag
this makes it easy to distribute materials. Also have the warm water readily available, make sure to
look at the package directions for the temperature range for the yeast.
Procedure:
1. Have the students open the Ziploc bag and remove the yeast packet.
2. Open the yeast packet and empty the contents into the Ziploc bag, the bag should still contain
the sugar cubes.
3. Collect 100 mL of warm water in a beaker and carefully pour the warmed water into the Ziploc
bag that contains the yeast and sugar.
4. Working with your partner, carefully compress all the air out of the bag before closing the bag.
5. Shake or gently rub the bag so that all ingredients become thoroughly mixed.
6. Let the bag rest for 15 minutes.
7. Make observations about the changes in the bag.
8. Make predictions about the gas that is in the bag and how that gas got there.
9. Gather some bromothymol Blue indicator into a pipette.
10. Carefully open the corner of the bag and squeeze the bromothymol blue into the yeast mixture.
Record color change.