Question

Ethanol is fermented from which type of source?

(a) Fat

(b) Lipids

(c) Starch

(d) Fiber

This question was posed to me in homework.

My question comes from Anaerobic Bioprocesses topic in chapter Mixed Cultures & Traditional Industrial Bioprocesses of Bioprocess Engineering

Answer 1

The correct answer is:

(c) Starch

Explanation:

Ethanol is primarily fermented from starch and other carbohydrates like glucose and sucrose. Starch, which is found in plants such as corn, barley, and wheat, is converted into glucose by enzymes, and this glucose is then fermented by microorganisms (commonly Saccharomyces cerevisiae, or baker's yeast) to produce ethanol and carbon dioxide in an anaerobic environment.

Here’s why the other options are incorrect:

• Fat (option a) and lipids (option b) are not typically used as a direct source for ethanol production. These molecules are mainly utilized in the body or for the production of biofuels like biodiesel rather than ethanol.
• Fiber (option d) is primarily composed of cellulose, which is not easily fermented into ethanol unless it is first converted into simpler sugars by processes like hydrolysis, typically requiring more advanced biochemical or thermochemical methods.

Therefore, the primary source for ethanol fermentation is starch, which is a polysaccharide made up of glucose units that can easily be converted into fermentable sugars.