Co-extrusion is an extrusion process used to obtain a product that combines two textures : one material is extruded and continuously filled with another to form a single product. For example, a crispy cereals outer envelope can be co-extruded with a sweet or savory filling basis.
How does the co-extrusion process work ?
co extrusion schéma
Co-extrusion involves the use of an extruder to create the outer envelope and an auxiliary system for injecting a filling. This is called co-extrusion or co-injection.
Co-extrusion should not be confused with “true co-extrusion” which implies two extruders connected together to extrude two products simultaneously and form only one. The “true co-extrusion” is used for example in the case of pet food treats when the viscosities of coextruded materials are high.