The two key components of a fermentation system are the organism and its feedstock.
In general, the desirable effect of microbial activity may be caused by its biochemical activity.
Microbial enzymes breaking down carbohydrates lipoids, proteins and other food components can improve food digestion in the human gastrointestinal tract and thus increase nutrient uptake.
Organisms that live in environments lacking oxygen are called anaerobes. The anaerobic extract energy from nutrients using a metabolic process called fermentation that occurs in the cytoplasm.
ATP is formed by ‘substrate level’ phosphorylation because it is associated with redox transformation between organic compounds.
Fermentations occurs in anaerobic environment, includes glycolysis plus one or two reactions in which pyruvic acid is converted either to lactic acid or to alcohol ethanol and carbon dioxide.
C6H12O6 + Yeast ----- 2C2H5OH + 2CO2 +ATP + Heat
Glycolysis is the first stage of fermentation, just as it is for aerobic respiration. Two pyruvate, two NADH and tow ATP form in glycolysis.
In the last stage of fermentation, the pyruvate is converted to other molecules.
Science of Fermentation