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Thermal Properties of Starch from 62 Exotic Maize (Zea mays L.) Lines Grown in Two Locations¹

¹Journal Paper J-17440, Iowa Agriculture and Home Economics Experiment Station, Ames, IA. Projects 3396 and 3082. ²Graduate student and professor, respectively, Department of Food Science and Human Nutrition and Center for Crops Utilization Research, Iowa State University, Ames, IA 50011. ³Research geneticist and biologist, respectively, USDA-ARS, Corn Insects and Crop Genetics Research Unit, Department of Agronomy, Iowa State University, Ames, IA 50011. ⁴Corresponding author. E-mail: pjwhite@iastate.edu Phone: 515/294-3011. Fax: 515/294-8181.

The variability in thermal properties among 62 S₃ lines derived from a high-yielding exotic corn (Zea mays) population, Antigua 1 (PI 484990), was evaluated by differential scanning calorimetry (DSC). The S₃ lines were grown in Puerto Rico (1990–1991) and Georgia (1994). Separate single-kernel starch extractions for five kernels (five replicates) from each line grown in each location were performed, and the starch was analyzed. The DSC values reported included gelatinization onset (T_oG), range (R_G), enthalpy (ΔH_G), and peak height index (PHI) and retrogradation onset (T_oR), range (R_R), enthalpy (ΔH_R), and percent retrogradation (%R) (an indication of the stability of gelatinized starch after storing at 4°C for 7 days). Significant differences (P < 0.05) were found among the 62 lines of Antigua 1 for T_oG, R_G, and PHI and highly significant differences (P < 0.01) were found for ΔH_G. The starches from plants grown in Georgia (1994) had significantly (P < 0.05) greater T_oG, ΔH_G, and PHI but a significantly lower R_G than those from Puerto Rico (1990–1991). These data suggest that the starch from plants grown in Georgia (1994) might have a greater degree of crystallinity than that from Puerto Rico (1990–1991). None of the retrogradation values were significantly different among starches of the 62 lines of Antigua 1 and the starches from plants grown in the two locations.