Amino acids are either produced by fermentation or chemical synthesis.
The products produced by chemical synthesis are produced
as racemic mixtures, the D- and L- form of the amino acids. Today in
commercial practice all amino acids except sulphur-containing amino
acids (methionine) sources are produced by fermentation. This is due
to the fact that fermentation only produces the L-isomeric form that is
utilizable within animal organisms. For methionine sources the D-isomer
is also utilizable and thus DL-methionine sources are produced
by chemical synthesis.
9.1. Fermentation
The generalised flow diagram for the production of all amino acids by
fermentation is shown below. Advanced modern biotechnology has
allowed rapid progress to be made in the selection of specialised microorganisms
that transform carbohydrates such as starch and sugar,
through fermentation to amino acids in a highly efficient and sustainable
manner. Sufficient quantities of nitrogen and a range of micro nutrients
must also be supplied during the process. Hygiene and control
of the conditions with the fermenter are critical; they are continuously
monitored to ensure optimal production and product quality. After fermentation,
the microorganisms are inactivated and further processing
steps take place to produce the various end products (Figure 13). A
detailed list of the main amino acids products available on
9.2. Chemical Synthesis
Starting from petrochemical derived raw materials a complex multistep
chemical process transforms these small molecules into methionine
or its analogue. This process is performed in large scale facilities
under optimally controlled reaction conditions, ensuring a highly efficient
process. These products can be in dry or liquid form and can be
further reacted or coated to produce additional products