How Quickly Yeast Utilizes Lactose in Comparison to Common Sugars

Abstract

Every year dairy farms produce millions of pounds of excess whey that is chock full of lactose. Lactose, which is found in whey, can be used for fermentation but is not a common sugar used for fermentation. In this experiment we measured just how well yeast thrives off of lactose in comparison to sucrose, dextrose, and starch. Using CO₂ emissions to measure the respiration rate, we found that out of all our sources the most CO₂ emissions came from sucrose, the second most came from glucose, the third most came from lactose, and the fourth most, or the least, came from starch. Our hypothesis of the lactose sample producing less CO₂ than the other sugars is partially supported; it produced less CO₂ than glucose and sucrose, but more than starch. Glucose performed the best overall.