Kansas Corn: Fermentation in a Bag

Seed to STEM
Grade Level: Middle School

In this experiment, students investigate the process for fermentation in resealable bags with yeast, warm water, enzymes, and various sources of sugars from plants.   Students will observe and measure the inflation of the bag as the reaction produces gas (CO2) during the production of ethanol.  Students will set up several bags to compare how yeast ferments simple sugars, starch, and complex carbohydrates.  Students can compare the rates of ethanol productions and the effects of different enzymes using the inflation of the bag, inflation of balloons, water, or breathalyzers.  This lab is used to explore and understand the process of ethanol production as a biofuel.

Ethanol is a renewable source of fuel for vehicles that is widely produced from corn. Ethanol production is reliant on anaerobic fermentation of corn sugars by yeast. Scientists and industry professionals are always working to make the fermentation procedure more efficient. Different enzymes are added to the corn to break the starch into simple sugars that the yeast can process into ethanol. This lab allows students to experiment with different variables in the fermentation process to determine their effect.

When a fuel, such a gasoline, is burned, carbon is released into the atmosphere in the form of carbon dioxide.  Burning fossil fuels adds extra carbon dioxide to the atmosphere.  This extra carbon dioxide traps heat from the sun and is a major contributing factor in climate change.

Ethanol made from corn also releases carbon dioxide into the atmosphere, but unlike burning fossil fuels, corn plants have already absorbed the CO2 from corn grown last season.  This means that by using ethanol we can cycle carbon dioxide between the plants and atmosphere, as opposed to releasing fossilized carbon from oil.