Merck dehydrated culture media are, apart from a few exceptions, produced in granular form.

The individual components of each batch are mixed and ground together producing a homogeneous, finely powdered mixture which is then subjected to the granulation process. Here the powered mixture binds together to form small granules.

Granular culture media offer several advantages when compared with the customary powder culture media:

?  Considerably less dust is formed when handling the media, the dangers of allergic reactions and inhalation of toxic substances are thus largely eliminated.

?  Better flow properties, the media do not adhere to the walls of vessels or apparatus and are thus easier to weigh out.

?  Better coating of the granulate with water reduces the time required for suspending and dissolving the media, formation of clumps which are hard to dissolve is thus prevented.

?  Homogeneous distribution of the package contents is ensured even after long storage, the components do not therefore separate out.

?  Larger shelf life due to

- low water content

- homogeneous distribution of the contents.

Some culture media form very fine granules as a result of their composition. The advantages listed above also apply here, particularly as regards the flow properties and the homogeneous distribution of the contents.