ARS | Publication request: The Effect of Cropping Systems on Starch Structure, Chemistry and Functionality in Developing Sorghum Kernels

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 21, 2008
Publication Date: September 20, 2008
Citation: Kaufman, R.C., Wilson, J.D., Tuinstra, M.R. 2008. The Effect of Cropping Systems on Starch Structure, Chemistry and Functionality in Developing Sorghum Kernels [abstract]. Cereal Foods World. 53:A64.

Technical Abstract: Starch, the largest component of cereal grains, consists of two types of polymer. These polymers are deposited into granules by amyloplast organelles as amylose, a near linear molecule and amylopectin, a highly branched molecule. The objective of this study was to determine if sorghum grown under an irrigated cropping system displayed different starch characteristics, such as granule size distribution and amylopectin structure, than samples grown under a dry-land cropping system. A commercially available sorghum hybrid was grown in an irrigated and a dry-land plot at the Ashland Bottoms Research Farm in 2006; upon reaching the mid-bloom stage in maturity approximately 200 heads were tagged in each plot. Samples were regularly collected beginning seven days after anthesis (DAA) until harvest. The samples were then decorticated and the starch was isolated. The granule size distribution, analyzed by laser diffraction sizing, showed a significant shift as the sorghum kernel developed. The volume percent for the A-type granules ranged from 54.9% to 6.6% in the 28 DAA and 7 DAA samples. Amylose concentrations, measured by Concanavalin A precipitation, ranged from 23.5% to 29.3%. Peak gelatinization temperatures, measured by Differential Scanning Calorimetry, ranged from 71.8°C to 75.4°C. Fluorophore-Assisted Capillary Electrophoresis (FACE) was performed to provide details on the amylopectin chain length distribution and its relationship to starch functionality. The cropping systems and maturity of the sorghum affect the structure and functionality of starch as well as provide some insight into possible new end-uses.