Polysaccharide functionality through extrusion processing

Extrusion processing is a technology applied in the food and pharmaceutical industry for affecting product microstructure, product chemistry or the macroscopic shape of products. Starch based products are often extruded to break down the starch granule to render it digestible and to produce a shaped product. Encapsulation of flavors, nutrients and drugs is another frequent application of extrusion processing. This short review article is concerned with the use of extrusion processes to modify polysaccharide functionality. Extrusion processes are applied to polysaccharides for specific purposes such as physical modification or chemical modification (reactive extrusion), manufacture of confectionary gels and encapsulation of flavors or drugs. Non-starch polysaccharides and confectionary gels have also been extruded. Another application area is in the field of dietary fibers, obtained through extrusion processing of by- or waste-products of the food industry. The focus of this article is on extruding starch and other polysaccharides as an ingredient rather than as part of a final food product obtained by extrusion processing. It concludes with a discussion on extrusion as microstructure generating process and the relevance of this application to taste perception in semi-liquid foods.