Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 22, 2002
Publication Date: January 1, 2003
Citation: BYARS, J.A. JET COOKING OF WAXY MAIZE STARCH: SOLUTION RHEOLOGY AND MOLECULAR WEIGHT DEGRADATION OF AMYLOPECTIN. CEREAL CHEMISTRY. 2002.v.80.p.87-90 Interpretive Summary: Agricultural commodities presently face the lowest prices in several decades. In order to return acceptable profit margins to agricultural materials, new applications and methods to convert agricultural materials into value-added materials need to be found. Jet cooking has been used for many years to produce a wide variety of products from agricultural materials such as starch. Despite the use of jet cooking as an industrial process, little is known of the actual effects of different processing variables on the jet-cooked starch. A detailed knowledge of these factors would enable better product quality using steam jet cooking, as well as allowing the producer to produce material with predictable physical properties. In the work conducted here, the effects of process variables such as mechanical mixing and heating on the flow properties of starch were established. This work is a part of a larger effort to develop pilot-plant-scale excess-steam jet cooking facilities at NCAUR.
Technical Abstract: 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 for 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 a jet cooker, although the primary effect is due to mechanical degradation.