|Dintzis, Frederick - USDA-ARS-NCAUR (RETIRED)|
Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 27, 1997
Publication Date: N/A
Interpretive Summary: Starch is an abundant byproduct of corn processing. In order to develop and improve end use, starch-containing products methodology is needed to better characterize the components of starch and how they are affected by processing. The main component of starch is a very high molecular weight material called amylopectin. In some applications, such as food processing gand paper coating, starches are cooked and the quality of the product can be affected by the molecular weight characteristics of the resulting cooked amylopectin. It has been very difficult to characterize these amylopectins. This research has demonstrated a better way to characterize the molecular weight of such materials. This information will be useful to starch processors who need to have suitable methods to maintain the quality of their products.
Technical Abstract: A hydrodynamic column packed with solid beads chemically bonded with sorbitol amine residues has been used with 90% DMSO-H2O mobile phase as part of a chromatographic system to characterize jet-cooked waxy maize starch. Software calculations based on signals from refractive index and dual angle light scattering detectors indicated the column could fractionate molecular weights up to about 5 x 10**8 D. Calculated molecular weight values for the highest molecular weight sample was greatest at the lowest flow rate of 0.1 ml/min. Values of molecular weights and radii of gyration determined by the in-line dual angle light scattering detector were significantly less than those determined with an off-line multi-angle light scattering detector that examined samples that had not traveled through the hydrodynamic column. This work has demonstrated the feasibility of using a hydrodynamic column to characterize ewaxy maize amylopectins. However, considerations of sample shear sensitivity and questions of in-line light scattering detection show that further efforts are required to develop and optimize a chromatographic system to characterize very high molecular weight amylopectins.