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Publication no. C-2004-0602-06R
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ARTICLE
Rapid Screening to Identify Unusual Thermal Starch Traits from Bulked Corn
Kernels.
E. Lenihan (1,2), S. Duvick (3), and P. White (1,4). (1) Graduate student and
professor, respectively, 2312 Food Sciences Building, Department of Food Science
and Human Nutrition and Center for Crops Utilization Research, Iowa State
University, Ames, IA 50011. (2) Currently, Food technologist, Tate and Lyle
North America, Decatur, IL 62525. (3) Biologist, USDA-ARS, Plant Introduction
Research Unit, Department of Agronomy, Iowa State University, Ames, IA 50011.
(4) Corresponding author. Phone: 515-294-9688. Fax: 515-294-8181. E-mail:
<pjwhite@iastate.edu> Cereal Chem. 81(4):527-532. Accepted February 25,
2004. Copyright 2004 American Association of Cereal Chemists, Inc.
Differential scanning calorimetry (DSC) is used routinely to screen for starch
thermal properties. In early generations of line development, the established
analysis separately evaluates starch extracted from five, single corn kernels. A
thermal property trait carried by a recessive gene would appear 25% of the time;
thus, if five separate kernels were evaluated, the likelihood of detecting an
unusual thermal trait is high. The objective of the current work was to expedite
selection by examining five kernels at a time, instead of one, hypothesizing
that we would be able to detect different thermal properties in this blend. Corn
lines, all from the same genetic background (ExSeed68 or Oh43), with known
thermal functions (amylose-extender, dull, sugary-1, sugary-2,
and waxy) were blended with normal starch (control) in ratios of 0:5,
1:4, 2:3, 3:2, 4:1, and 5:0, and analyzed with DSC. The values for each ratio
within a mutant type were unique (alpha < 0.01) for most DSC measurements,
especially for gelatinization onset temperature, change in enthalpy of
gelatinization, and range of gelatinization. These results support the
five-kernel method for rapidly screening large amounts of corn germplasm to
identify kernels with unusual starch traits.
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