Pucker Up: The Effects of Acidity on Carbon Dioxide Production During Fermentation of Saccharomyces cerevisiae

Abstract

Baker's yeast (Saccharomyces cerevisiae) is one of the most popularly used microorganisms by the human population, and uses a process called fermentation to obtain energy. Yeast is very particular when it comes to the conditions that it requires to undergo fermentation. Our team decided that we wanted to analyze how different environmental factors, such as pH levels, will influence that fermentation process. We developed two different experimental groups, one with 2mL of lemon juice added to the growth media, and another with 4mL of lemon juice added to the growth media. We were able to measure the amount of carbon dioxide that was produced over five minutes using a carbon dioxide sensor probe and Logger Pro software. Before running the experiment, our team hypothesized that lowering the pH levels of our growth media would negatively impact fermentation and therefore lower carbon dioxide production. After collecting our results, our control group had an average rate of change of 237.55, experimental group 1 had a rate of 217.33, and experimental group 2 had a rate of 201.4. Our results revealed a pattern signifying that a lowered pH level slowed down the production of carbon dioxide. Our hypothesis appears to be supported by the trends in our data. In our experimental group containing 2ml of lemon juice the yeast fermentation was 10.2% slower than the control, and the yeast fermentation of experimental group containing 4ml of lemon juice was slower than the control group by 17%. By determining the effects of acidity on baker’s yeast we are able to get a more defined concept of the ideal pH level for yeast during commercial utilization in everyday products.)