Measuring the Fermentation Rate in Yeast

Introduction: As bread yeast breaks down glucose it produces carbon dioxide gas and alcohol.

The pH of the solution should change as the production of these products increases.

 

Objective: To measure the fermentation rate of yeast over time by measuring the change in pH in the solution.

 

Materials: bread yeast, warm water, sucrose, Vernier pH probe, iMac DV, LoggerPro software for Mac,

standard solutions of pH 4, ph 7 and pH 10. Six beakers.

 

Procedure:

1) Test the calibration of the Vernier pH probe with the standards: pH 4, pH 7 and pH 10. *NOTE: We found that you had to have all the peripheral equipment (probe and loggerpro) connected prior to turning on the iMac DV.

2) Make a yeast solution by adding 1 teaspoon of yeast in 150 ml of warm water. Add a pinch of sugar to the solution.

3) Set the sampling rate in the software for one sample taken every 15 minutes for and 8 hour period.

4) Insert the pH probe into the yeast solution and begin sampling.

 

Results