Publication no. C-2002-1204-05R |  VIEW ARTICLE

Jet Cooking of Waxy Maize Starch: Solution Rheology and Molecular Weight Degradation of Amylopectin.

Jeffrey A. Byars (1). (1) Cereal Products and Food Science Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, USDA, Peoria, IL 61604. Phone: 309 681 6330. Fax: 309 681 6685. <byarsja@ncaur.usda.gov> Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. Cereal Chem. 80(1):87-90. Accepted August 22, 2002. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. American Association of Cereal Chemists, Inc., 2003.

The effect of processing conditions in an excess steam jet cooker on the degradation of waxy maize starch was studied. The temperature of the steam, the flow rate of the starch slurry, and the concentration of starch were determined to influence the extent of degradation. The viscosity of concentrated solutions of the jet-cooked product and the intrinsic viscosity of dilute solutions were used as measures of the extent of molecular degradation. The viscosity decreased at higher reaction temperatures, and at higher steam-to-starch ratios. Multiple passes through the jet cooker decreased the viscosity dramatically for the first two passes, but little additional change was observed for further passes. The results show that mechanical and thermal degradation effects are both important in the jet cooking of waxy maize starch, although the primary effect is due to mechanical degradation.