Cereal Chem 66:69-73   |  VIEW ARTICLE

Role of Sodium Bicarbonate and Trapped Air in Extrusion.

C. S. Lai, J. Guetzlaff, and R. C. Hoseney. Copyright 1989 by the American Association of Cereal Chemists, Inc. 

Addition of sodium bicarbonate or sodium carbonate to wheat starch improved expansion of the extrudate but weakened its structure and caused browning. The added bicarbonate or carbonate appeared to react with the acids formed from oxidation of starch during extrusion. Addition of acidulants to bicarbonate further improved the expansion of the extrudate and eliminated the browning problem caused by the bicarbonate. Trapped air appears to provide the major nucleation sites for the bubbles formed during extrusion.