Ethanol Fermentation - The Chemical Process of Fermentation of Glucose

The Chemical Process of Fermentation of Glucose

The chemical equations below summarize the fermentation of sucrose (C12H22O11) into ethanol (C2H5OH). Alcoholic fermentation converts one mole of sucrose into four moles of ethanol and four moles of carbon dioxide, producing two moles of ATP in the process.

The overall chemical formula for alcoholic fermentation is:

C6H12O6 + Zymase → 2 C2H5OH + 2 CO2

Sucrose is a dimer of two glucose molecules. In the first step of alcoholic fermentation, the enzyme invertase cleaves the glycosidic linkage between the two glucose molecules.

C12H22O11 + H2O + invertase → 2 C6H12O6

Next, each glucose molecule is broken down into two pyruvate molecules in a process known as glycolysis. Glycolysis is summarized by the equation:

C6H12O6 + 2 ADP + 2 Pi + 2 NAD+ → 2 CH3COCOO− + 2 ATP + 2 NADH + 2 H2O + 2 H+

The chemical formula of pyruvate is CH3COCOO−. Pi stands for the inorganic phosphate.

As shown by the reaction equation, glycolysis causes the reduction of two molecules of NAD+ to NADH. Two ADP molecules are also converted to two ATP and two water molecules via substrate-level phosphorylation.


  • Glucose depicted in Haworth projection

  • Pyruvate

  • Acetaldehyde

  • Ethanol

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