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Thermal Properties of Starch from Exotic-by-Adapted Corn (Zea mays L.) Lines Grown in Four Environments

¹Graduate 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. ²Currently, Food Technologist, Tate and Lyle, Decatur, IL 62525. ³Research geneticist, USDA-ARS, Corn Insects and Crop Genetics Research Unit, Department of Agronomy, Iowa State University, Ames, IA 50011. ⁴Corresponding author. Phone: (515) 294-9688. Fax: (515) 294-8181. E-mail: pjwhite@iastate.edu

The effect of four growing environments (two at Ames, IA; one at Clinton, IL; and one at Columbia, MO) on the thermal properties of starch from five exotic-by-adapted corn inbred lines (Chis37, Cuba34, Cuba38, Dk8, Dk10) and two control lines (B73 and Mo17) were studied using differential scanning calorimetry (DSC). The variations in thermal properties within environments were similar for the exotic-by-adapted lines and control lines. Missouri was the warmest environment and generally produced starch with the greatest gelatinization onset temperature (T_oG), the narrowest range of gelatinization (R_G), and the greatest enthalpy of gelatinization (ΔH_G). Illinois was the coolest environment and generally resulted in starch with the lowest T_oG, widest R_G, and lowest ΔH_G. These differences were attributed to higher temperatures in Missouri during grain-filling months either increasing the amount of longer branches of amylopectin or perfecting amylopectin crystalline structure. The Ames 1 environment produced starch with thermal properties most similar to those of Illinois, whereas the Ames 2 environment produced starch with thermal properties most similar to those of Missouri. Ames 2, located near a river bottom where temperatures tend to be warmer, likely had temperatures most similar to those found in Missouri during grain filling.