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Difficulty: MediumIndustrial Chemical Processes and Biotechnology Applications

In the industrial biotechnology process of ethanol production from sugar molasses, fermentation is carried out using yeast. Which of the following best explains why the fermentation vessel must be kept anaerobic (oxygen-free) and maintained at a temperature below 40∘C40^\circ\text{C}?

  1. To prevent the microbial oxidation of ethanol into ethanoic acid and protect the yeast enzymes from heat denaturation.Answer
  2. B
    To shift the position of dynamic equilibrium toward the products by altering reaction enthalpy.
  3. C
    To convert the glucose substrate into a concentrated alkanoic acid via an esterification mechanism.
  4. D
    To ensure that the ethanol produced undergoes immediate polymerization into synthetic addition polymers.

Answer

The fermentation vessel must be kept anaerobic to prevent ethanol from being oxidized into ethanoic acid, and maintained below 40°C to prevent thermal denaturation of yeast enzymes.
The option identifying microbial oxidation prevention and enzyme protection is correct because yeast enzymes (zymase) denature and lose catalytic activity at elevated temperatures above 40°C. Furthermore, anaerobic conditions prevent aerobic bacteria from further oxidizing the formed ethanol into ethanoic acid.

Step-by-Step Solution

1
Analyze the biological role of yeast enzymes during industrial fermentation.
Yeast secretes enzymes such as invertase and zymase, which hydrolyze sucrose and ferment glucose into ethanol (C2H5OHC_2H_5OH) and carbon(IV) oxide (CO2CO_2).
Enzymes are protein molecules that require an optimal temperature range (typically 25°C - 37°C); temperatures above 40°C cause irreversible denaturation.
2
Determine the necessity of anaerobic (oxygen-free) conditions in ethanol synthesis.
In the presence of atmospheric oxygen, aerobic microorganisms oxidize ethanol into ethanoic acid (CH3COOHCH_3COOH), spoiling the alcoholic yield.
Anaerobic respiration ensures glucose is converted to ethanol rather than carbon dioxide and water or ethanoic acid.

Key Concept

Industrial Biotechnology and Enzymatic Fermentation Conditions
Estimated Time:1m 0s
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Topics

Industrial Chemical Processes and Biotechnology Applications