Fermentation and Putrefaction

Now there may be a long controversy over spontaneous generation theory but one thing was certain that the presence of microorganisms in organic infusions bring about some chemical changes in the organic infusions itself. These changes primarily are of two kinds: -
i) Fermentation & ii) Putrefaction.

i) Fermentation: - When the organic infusions are of plant origin (i.e. mainly composed of carbohydrates) then their breakdown results in the formation of alcohols & organic acids and are known as fermentation process (in a crude way).
ii) Putrefaction: - When the organic infusions are of animal origin (i.e. mainly composed of proteins) then their breakdown produces ill-smelling compounds and are known as putrefaction process.