From the ear to ethanol via enzymes

Want to see how your science students can work with ag-related fermentation and distillation? Jerry Vydra, a biology teacher at Mogadore High School, is a Feed the World workshop alumnus and an Ohio Corn & Wheat grant recipient. Here’s how he used Feed the World lessons and materials in his biology and environmental science classes.

In our biology classes we learn how cells convert the energy in food molecules into energy the cells can use. Cellular respiration, in which oxygen is required, is the most efficient way that cells can convert energy into a usable form. However, there are certain organisms, and sometimes eukaryotic cells, that must use fermentation as a way to extract energy from food molecules, especially glucose.

Perhaps the most significant lesson and activity related to cellular respiration was the distillation of ethanol. However, before we distilled a drop, we had lessons and activities that helped the students understand this process.

The first topic we discussed was the power of enzymes. Students learned that enzymes are specialized proteins that speed up chemical reactions, essential for almost every chemical reaction in organisms.

To help demonstrate the effectiveness of enzymes we conducted several interesting experiments. The first was to observe the effectiveness of lactase, the enzyme that breaks down lactose, which is one of the sugars in milk. Students could see that lactase was necessary for breaking down lactose and it helped them understand lactose intolerance.

We then experimented with amylase in saliva. Students added saliva to cornstarch to observe how amylase catalyzes the reaction of starch breaking down into glucose.

When we reached the topic of cellular respiration and fermentation, the accelerated biology class made ginger beer. Authentic ginger beer is a carbonated drink made from ginger root and sugar, and a little bit of lemon. To help demonstrate that carbon dioxide is one of the products of fermentation, we allowed our ginger beer to become naturally carbonated.

The first step is to make a ginger bug. This bug is used as a concentrated source of flavor and yeast. It is a mixture of shredded ginger root, water, and sugar. An additional important ingredient, but not obviously added, is the naturally occurring yeast growing on the ginger root. This yeast is extremely important as it not only adds carbon dioxide, or carbonation, to the ginger beer, but it also produces ethanol, the alcohol that we eventually distilled in a later activity.

The ginger bug is placed in a dark area and fed every day by adding more sugar and shredded root. After three days, the liquid portion of the ginger bug is added to an additional mixture of sugar and ginger root. It is then bottled and allowed to ferment. After a period of time, we opened the bottles to see how we did. Success is claimed if the drink is palatable and carbonated. Carbonation is important for students to observe because carbon dioxide is one of the products of fermentation.

With a background knowledge of enzymes and fermentation, we moved on to ethanol production. Ethanol production requires enzymes, yeast, water, and sugar. When these ingredients are combined, the yeast can convert the sugar into ethanol by way of fermentation.

Ethanol has a variety of uses, including use as a fuel additive to make gasoline more environmentally friendly. The materials, lessons, knowledge, and equipment used for this activity were largely provided through a grant from Ohio Corn & Wheat . Topics such as agriculture, fermentation, fuel efficiency, and enzymes are included in the lessons on their website.

Students created a corn mash that was used as a base to be fermented into ethanol. The students learned that the starch in corn needs to be broken down into glucose to increase the yeast’s food supply and increase the efficiency of ethanol production. The starch is broken into glucose using heat and two types of enzymes. Each of these enzymes are found naturally in the digestive system of humans and other organisms. Once the enzymes have had a chance to do their job, yeast is added to begin the conversion of glucose into alcohol and carbon dioxide.

After a period of a few days, the fermented liquid is filtered and placed into the distillation vessel. The distillation apparatus allows us to separate ethanol from water and other liquids. In addition to the distillation equipment that we were able to purchase through the grant from Ohio Corn & Wheat, a water pump was added to cool our distillation equipment without wasting water.

Students were able to observe the distillation of ethanol as it dripped from the cooling tube. To prove that ethanol is indeed produced, we burned the ethanol in a watch glass and powered a Stirling engine.

I also used the materials and equipment from the corn grant with the environmental science class. The purpose of these lessons was to demonstrate fuel production for transportation, air pollution and global warming from burning fossil fuels, and careers related to agriculture.

Before the environmental science class made ethanol, we discussed the extraction, use, and burning of fossil fuels. These ideas were integrated with our understanding of the history of the Industrial Revolution, transportation and energy needs, and the cause of air pollution and global warming,

We also learned about the internal combustion engine, one of the major causes of our atmospheric challenges. To help them understand how the internal combustion engine works, I acquired donations of two lawn mowers from local repair shops. We disassembled the mowers to learn how the mower works and how the engine supplies the necessary power. The students then tore into the motor to observe the parts of an engine and how they function. Terms related to engines such as cylinders, cams, valves, and cubic inches and cubic centimeters were made more clear by actually seeing the inside of an engine and its parts.

Once the students were able to understand how fuel is combusted in the engine, we made ethanol fuel. We talked about careers related to agriculture, and transportation, and also about alternative fuels and future careers related to alternative energy.

Mogadore High School greatly appreciates Ohio Corn & Wheat. The lessons, experiences, materials, and equipment we received have greatly improved the way that we learn science. These activities bring practical and hands-on applications to the classroom to help stimulate students’ interest in science and science-related careers.

Join us for the summer Feed the World workshop and learn more about these resources and lessons!