Extrusion

Extrusion is a manufacturing process, common in many industries. As a unit operation it can be regarded simply as a shaping process where infinitely long fibres or semi-continuous anisotropic structures are formed, from a block or compacted dispersion. In the metals and plastics industry both “hot drawing” and “cold drawing” are performed. Both of these are known in the kitchen, where the equivalent of “hot drawing” is the formation of cheese fibres in a fondue, and “cold drawing” is the piping of icing sugar as cake decoration, or pasta production from dough. Forming into appealing shapes has also become part of the processing repertoire of ice cream, chocolate and dairy products.