Cereal Chem 54:436 - 443.  |  VIEW ARTICLE
Gelatinization of Starch in Extruded Products.

B.-Y. Chiang and J. A. Johnson. Copyright 1977 by the American Association of Cereal Chemists, Inc. 

Some of the important factors affecting starch gelatinization during extrusion of wheat flour, such as moisture content of raw materials, temperature, screw speed, and die nozzle size were investigated. The interaction of temperature and moisture significantly affected starch gelatinization. Increasing extrusion temperatures increased starch gelatinization when moisture contents were between 18 and 27%. Moisture contents did not significantly affect starch gelatinization at low temperatures (65 and 80 C), but affected gelatinization at high temperatures (95 and 110 C). Increasing shear rate (screw speed) decreased starch gelatinization. Increasing the die nozzle size decreased starch gelatinization. Results showed that the (2-1) glycosidic bonds of sucrose and raffinose and the (1-4) glycosidic bonds of malto-oligosaccharides and starch are broken when cereal products are extruded.