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Thermal Properties and Paste and Gel Behaviors of Starches Recovered from Accessions Used in the Germplasm Enhancement of Maize Project¹

¹Journal paper 18969 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA. Research project 0178 supported by the Center for Crops Utilization Research, the Iowa Agriculture and Home Economics Experiment Station, and the U.S. Department of Agriculture. ²Graduate research assistant, Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011. ³Professor, Department of Food Science and Human Nutrition, and Director, Center for Crops Utilization Research, Iowa State University, Ames, IA 50011. Corresponding author. E-mail: ljohnson@iastate.edu ⁴Professor, Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011. ⁵Research geneticist, USDA/ARS, Corn Insects and Crop Genetics Research Unit, Department of Agronomy, Iowa State University, Ames, IA 50011.

The objective of this study was to screen starches recovered from the corn accessions used in the Germplasm Enhancement of Maize (GEM) project for unusual thermal properties and paste and gel behaviors, so that they could be exploited in corn breeding programs to enhance traits important to corn utilization. In general, the values for gelatinization temperatures and peak height indices were greater, but heat of gelatinization values were less for the starches recovered from the GEM accessions (particularly BRA 052051 (SE 32)) than for starches from commercial Dent corn hybrids (11.3 vs. 13.6 J/g). Generally, retrogradation properties were similar among the GEM accessions, although there were specific accessions (particularly Lima 13) that possessed modestly lower percentage retrogradation (34 vs. 42%). Generally, peak viscosities, cold paste viscosities, and viscosity breakdowns were greater for the starches of the GEM accessions (particularly ARZM 01150, Antiqua 3, and URZM 01089, respectively) than for the starches of commercial hybrids. Pasting temperatures were about the same for all starches. Both 1-day and 7-day gel strengths were considerably greater for the starches recovered from the GEM accessions (particularly BRA 052051 (SE 32), 21.0 g for 1-day and FS8A(T), 66.2 g for 7-day). Although the differences in starch properties were statistically different, only the higher gel strengths of the starches recovered from the GEM accessions were of practical significance to the starch industry.