Fermentation of Ethanol

Note: Ethanol is also known as alcohol

Bread, beer, and Bordeaux

Yeast has been used for over thousands of years to make these delicious food and drink items but we only learnt of its existence for in the last 200 years. Yeast is a Eukaryota microorganism that metabolizes simple glucose (C6H12O6) into ethanol (C2H5OH) and carbon dioxide (CO2). The word equation would be glucose+yeast→ethanol+carbon dioxide so the balanced chemical formula for the process would be C6H12O6→CO2 + 2 CO2 making this a decomposition type of reaction. Without yeast, fermentation could not be possible as yeast is a microorganism that contains an enzyme which acts as a catalyst.

Fun Fact: Yeast typically functions under aerobic conditions (in the presence of oxygen), but are also capable of functioning under anaerobic conditions (in the absence of oxygen), and without oxygen, ethanol fermentation occurs in the cytosol of yeast cells.

Fun Fact 2: Most types of yeast will stop reproducing when the alcohol content reaches 15% ethanol by volume, or even earlier, putting a natural limit on the alcohol concentration achieved through fermentation.


Early scientist, upon the invention of the microscope and the discovery of yeast, thought that yeast somehow contributed to fermentation by virtue of its spherical shape rather than any digestive processes. It was believed that the fermentation of food and fruit juices was the result of molecular vibrations caused by the death of the food's cells. It took many years for chemist of the nineteenth century to admit that yeast is a living thing. It was the result of microscopic experiments performed individually by multiple scientists in the 1830s to prove that yeast is actually a microscopic creature that reproduces by budding.

But for the case of ethanol fermentation, scientists could date this process being used back to prehistoric times.

The Good, The Bad, and The Delectable

Ethanol fermentation is what makes bread dough rise, it stops the beer from tasting flat, makes great wine, has good medicinal purposes and is one of the most eco-friendly alternatives to fuel we have for cars today. This has impacted society in a mostly positive way.

Rubbing alcohol has increased the sanitation of public and personal areas ten-fold, as it can kill bacteria, viruses, and fungi. Hospitals use rubbing alcohol all the time on surgical instruments and to even mop their floors with since it proves itself as a great disinfectant.

Ethanol gas is much more environmentally friendly than normal gasoline. It reduces greenhouse gases produced by over 59% compared to gasoline, and every day it replaces about 661,000 barrels of imported oil (meaning fewer oil spills) and to add to it, ethanol is a renewable resource.

Everyone loves bread. No argument there.

Despite what some may think, consuming small quantities of alcohol can actually be beneficial to your health. It decreases the risk of cardiovascular problems, decreases the possibility of lethal heart attack, can sometimes reduce the possibility of some kinds of strokes, and may reduce the danger of diabetes. Although this is in small quantities and not everyone is responsible with their alcohol.

In large quantities, alcohol can cause strokes, cirrhosis, cancer, birth defects, sudden death by cardiovascular problems, and suicidal tendencies. In the U.S. alone, over 88,000 people died a year from excessive alcohol, that includes drunk driving. It has also shortened the life span of many people, leading to the combined loss of 2.5 million years of potential life.