Abstract: A process and device for producing a foamed product or foam made of unmodified starch is provided in which the starch is introduced through a feed opening into a treatment chamber containing a conveying device. The conveying device conveys the starch from the feed opening in an axial direction through the treatment chamber. The conveying device has an increasing effective cross section so that by increasing the volume, or by expansion foaming and/or break down of the starch is achieved. An outlet is provided at the other end of the treatment chamber for extruding the product.