Fermentation is a natural process by which we can make ethanol from readily available things such as fruits and vegetables. Ethanol is produced when glucose is fermented in the presence of yeast. The condition should be completely anaerobic. Tubers and grains have been fermented into alcoholic beverages for many years. For instance, they have found evidence that ancient Egyptians used to brew beer.
Yeast is the most common organism used for ethanol fermentation. It breaks down complex carbohydrates into simple sugars, so long molecules of carbohydrates can be broken down into smaller sugars and then used to ferment into ethanol.
For the fermentation of ethanol, two types of yeast cells are selected. They are as follows.
- Top fermenter: Saccharomyces cerevisiae
- Bottom fermenter: Saccharomyces calsbergenis
Introduction to the Fermentation Process
Fermentation of alcohol formula
The fermentation of alcohol formula is the chemical equation for the production of ethanol from glucose, which is:
C6H12O6 (glucose) → 2 C2H5OH (ethanol) + 2 CO2 (carbon dioxide)
In this reaction, yeast acts as a catalyst. Moreover, it shows:
- One molecule of glucose produces two molecules of ethanol and two carbon dioxide molecules.
Fermentation is a biochemical process where glucose is converted to carbon dioxide and ethanol by the action of zymase that the yeast produces. Also, fermentation takes place in anaerobic conditions.
The fermentation of glucose to ethanol is possible when oxygen is absent. If this doesn’t happen, then lactic acid is produced rather than producing carbon dioxide and ethanol.
- In addition, enzymes are the protein molecules that act as biological catalysts.
- The yeast’s enzymes break down sugars.
- So, the living organisms’ action is getting this reaction to move forward.
The Fermentation process
- The fermenter is filled up to ¾ portion with fermentation medium.
- The fermentation medium is sterilised by pasteurisation at 147°F.
- Cooling coils are used to cool the medium.
- The inoculum is added.
- The temperature of the medium is maintained up to 30-37°C.
- Addition of ‘N’ source. E.g., Ammonium sulphate.
- The pH of the medium should be 4.8-5.0
- The process takes 70 hours for the production of ethanol.
Fermentation Conditions
- Yeast should be present.
- We need a specific reaction temperature, 37 degrees Celsius, because this is optimum for the enzyme.
- Solid raw materials such as sugar cane, fruits, vegetables, barley, etc., have to be chopped up to improve the surface area for fermentation.
- Oxygen should not be present.
Fermentation reactions
- Fermentation is an exothermic reaction, i.e., the heat energy is released, so this reaction produces bubbles and gas and produces heat.
- Moreover, the exothermic reaction releases heat energy.
- Must ensure that the heat does not increase above 37 degrees, and a higher temperature will deactivate the enzyme, so that’s why we need a specific temperature; because above this, the yeast will die, and the reaction will stop. So, it’s the optimum temperature for fermentation.
Raw materials
Carbohydrates, usually glucose, sucrose, or starch, are used and are starting raw materials for making ethanol. The alcoholic beverage beer traditionally comes from barley grown in fields. The barley is treated to break down the starch into fermentable sugars. Another example is wine, where the source of sugars for the fermentation is grape juice.
- As discussed above, we need microorganisms called yeasts for fermentation.
- They are different from bacteria.
- They produce enzymes that catalyse the conversion of glucose to ethanol and carbon dioxide as a by-product.
- So, when we ferment things, there will always be carbon dioxide gas coming off.
- Moreover, sucrose is a simple sugar containing glucose and fructose, which can be fermented to ethanol.
- In addition, it is an economically possible way of making ethanol by fermentation.
Importance of the Fermentation Process
The product of fermentation, i.e. ethanol, is helpful for various purposes in our lives. Some of them are:
- In all alcoholic beverages
- In industrial alcohol applications
Ethanol can be drained to form ethylene. Moreover, it is an important raw material for petrochemicals.
Further fermentation of ethanol produces acetic acid. It is simply known as vinegar. This vinegar serves several purposes, like cooking or removing stains.
How to Stop Fermentation in Kombucha
There are a few steps on how to stop fermentation in kombucha.
- Firstly, always keep your kombucha in a dark, warm place.
- Secondly, never forget the kombucha in the pantry for more than 2-3 days.
- This is more likely to cause its fermentation. So, always move it to the refrigerator.
- This cold environment will stop the entire fermentation process.
Conclusion
In this article, we have learned all about the fermentation of ethanol. Fermentation of ethanol takes place in anaerobic conditions in the presence of yeast. In this process, glucose is fermented to form ethanol and carbon dioxide. Besides, there are several important uses of ethanol produced by the fermentation process. Ethanol comes to our service: in lab research, fuel, cosmetics, alcoholic beverages, and many more. Finally, in this article, we have provided all the required information on ethanol fermentation. So, students can refer to this article to understand the concept clearly.
