The fermentation process is divided into two stages namely

Upstream and downstream processing both of these processes can be discussed taking an example of citric acid production. 

Typical activities               Typical Activities                       Typical Activities

$\bullet$Cell line-section,         $\bullet$Scale-up of seed                   $\bullet$ Harvesting 

genetic manipulation         culture                                 $\bullet$ lsolation 

and characterisation      $\bullet$ Process monitoring                $\bullet$ Concentration

$\bullet$Media purification,          and control                           $\bullet$ Purification

formulation,                  $\bullet$ Optimisation of                      $\bullet$ Polishing

optimisation and                culture conditions                  $\bullet$ Formulation/

sterilisation                                                                       Packaging

The upstream processing in biotechnology involves identifying a material. This forms the initial process of fermentation. It deals with inoculum preparation, preparation of culture media, scale up of the entire process and inoculation.

When the products are subjected to a series of processes including separation and purification of the product, it is collectively known as downstream processing, It deals with the post-harvest product, i.e., recovery-clarification, purification, polishing and formulation
till the packaging of the desired product.