"Food extrusion has been primarily an art and only within the last ten years has any serious effort been made to apply rigorous principles to this complicated process. This statement is not to condemn the art, for it has been the trial and error approach coupled with a keen sense of observation which has lead to the many successfid applications of food extruders."
This statement by Dr. Judson Harper in his two volume text Extrusion of Foods is, I believe, particularly appropriate today. For while we in the flavor industry have seen significant changes in our products and in the technology associated with their development over the last decade, like the artists that have pioneered food extrusion, we know that trial end error coupled with careful observation are two constants that have remained.
The first food extenders were used in the meat industry to stuff sausages. I suppose an old fashioned meat grinder could also be considered an early form of screw type food extruder. In the early 1900s extruded paste came into existence and represented one of the first forms of extruded cereal grain products.