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ARS Home » Midwest Area » Ames, Iowa » Corn Insects and Crop Genetics Research » Research » Publications at this Location » Publication #134333
Title: FUNCTIONAL AND STRUCTURAL PROPERTIES OF STARCHES FROM NEW CORN LINES

Author
item JI, Y - ISU
item SEETHARAMAN, K - PENN STATE
item WONG, K - ISU
item Pollak, Linda
item Duvick, Susan
item JANE, J - ISU

Submitted to: American Association of Cereal Chemists Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The objective of this study was to evaluate the functions and structures of starches from exotic x adapted inbred lines and exotic breeding crosses (exotic populations x adapted lines), and to establish the relationship between the fine structure and functional properties of the starches. Starches from exotic corn lines were screened for useful and unusual thermal properties with Differential Scanning Calorimetry (DSC). Based on these screenings several lines with thermal properties of potential commercial use were identified and further characterized. All selected starches from the developmental lines had greater peak viscosity, final viscosity and set back values than did starch from normal corn inbreds. All selected starches exhibited a typical A-type X-ray diffraction pattern. Two independent gelatinization transitions, one corresponding to the melting of a peak at a lower temperature approx. 66 deg C and the other to a peak melting at a higher temperature approx. 69 deg C, were found in some starches. The melting characteristics were traced to two separate types of granules within the endosperm, which differentiates these two transitions from those reported in C-type granules. Significant differences were observed in starch-granule size-distributions and shape-distributions of the selected starches. Strong correlations were found between DSC, Rapid Visco Analyser (RVA) properties and proportion of large granules with equivalent diameter. No significant differences were observed in the apparent amylose content and component profiles of starch. Measurements with high-performance anion-exchange chromatography (HPAEC) revealed that all selected unusual starches had a lower normalized concentration of chains with a degree of polymerization (dp) of 15-24 and/or a greater normalized concentration of chains with a dp of 6-12. Overall chains with a low TOG had a higher relative concentration of branch chains shorter than dp 13 than did normal starch. These studies will aid in understanding structure-function property relationships of starches, and in identifying corn lines of interest for commercial breeding.