ISBN 978-3-8439-1640-0

978-3-8439-1640-0, Reihe Verfahrenstechnik

Stefan Kraus
About the mechanism of microwave induced expansion of starch-based, extruded products under vacuum

163 Seiten, Dissertation Karlsruher Institut für Technologie (2014), Softcover, A5

Zusammenfassung / Abstract

Third generation snacks, also known as “half products” or pellets provide an alternative to fully prepared puffed snack foods. For the production only "half" of the process is completed to prepare not expanded "pellets". Generally these are starch-based pellets which can be formed via an extrusion process at high moisture contents above 30 %, moderate barrel temperatures and moderate applied shear stress. The final structure is created by intensive heating of the pellets, e.g. via microwave power input. Thereby the water inside the pellets is vaporized and the resulting steam pressure is the driving force for the bubble growth. During this expansion process moisture is removed and the pellets are dried to reach the end product moisture. In this study pellets containing corn starch were end-dried and expanded by a microwave vacuum drying process. The influence of process parameters, e.g. microwave power and system pressure and product parameters, e.g. degree of starch gelatinization and rheological properties of the matrix on expansion were examined in detail.