Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2003
Publication Date: 6/8/2004
Citation: Ji, Y., Pollak, L.M., Duvick, S.A., Seetharaman, K., Dixon, P.M., White, P.J. 2004. Gelatinization properties of starches from three successive generations of six exotic corn lines grown in two locations. Cereal Chemistry. 59:-64. Interpretive Summary: We have developed several exotic x adapted new corn lines that have unusual starch properties. Our objective in this study was to gain information about the changes in the functional properties and molecular starch structures of the starch from the new lines, see if the changes persisted as we kept developing the lines, and establish how the functional properties and molecular starch structures were related. We found that as we kept developing the lines by self pollination, the frequency of our desired starch traits increased as long as we kept selecting for that trait. The starch granules in our new lines had different shapes and sizes than typical corn starch. Molecular structure analysis showed that the starch molecules had more branching with a greater number of branches than typical corn starch. The results of this research are important to breeders because they show that selection for unusual starch structures is possible by selecting for the starch's function. This is important because starch function is much easier to analyze than starch structure. The lines may be important for the starch industry because they may be valuable raw ingredients for new food and industrial products.
Technical Abstract: The objectives of this research were to evaluate functions and structures of starches from exotic x adapted inbred lines and exotic lines, to confirm the advancement of functional traits into the next generation of core, and to establish relationships between the fine structure and functional properties of the starches. Several lines were characterized from the forth and fifth successive generations of exotic crosses and from the third generation of exotic inbreds containing kernels with unusual and potentially useful, thermal properties as measured by a differential scanning calorimetry (DSC, gelatinization onset temperature < 60oC or range of gelatinization temperature > 14oC). The frequency of these traits increased with succeeding generations, when selection of the plants was based on the desired trait. Significant differences were observed in starch-granule size distributions and shape distributions of the selected starches. 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 to 24 and/or a greater normalized concentration of chains with a dp of 6 to 12. Overall, chains with a low ToG had a greater relative concentration of branch chains shorter than dp 13 than did normal starch. Strong correlations were found between DSC and RVA properties and the granular structure (granular size distribution and branch-chain-length distribution of amylopectin).