ABSTRACT
Material and energy balances imply stoichiometry,
which is the science concerned with the quantitative com-
position of chemical compounds and conversion in chemi-
cal reactions. It is one of the fundamentals of reaction
engineering together with thermodynamics and kinetics.
Stoichiometric calculations require knowledge of the
mechanisms and the balance of major compounds.
Normally, it could be applied to all compounds. But gen-
erally for conservating properties, only macrobalances are
used. Indeed it is difficult to apply it to fermentation as
several hundred components are involved in the whole
metabolism (Figs. 2 and 3). But specific microbalances
can be used. The main problem in applying stoichiometry
to fermentation arises from the complex network of meta-
bolism. Due to high complexity, the approach is made
simpler by using the concept of yield. But this macroscopic
variable cannot be considered as a biological constant.
