© 2018 American Chemical Society. The technique of extrusion has been applied to plasticized starch and starch products to induce radical physicochemical changes to the semi-crystalline polymer complex in the native granules, such as destructurization, amorphization and homogenization. The addition of small molecular components such as plasticizer, water or supercritical CO2 in the pressurized melt creates the condition for the formation of widely expanded foam with a unique structure, by rapid decompression at the nozzle. The melted polymer compound has also been used as a reaction medium to perform chemical modifications.