Gelatinization Characteristics of Starch from du, wx, ae , and ae wx Endosperm of Sweet Corn Inbred la5125

Starch gelatinization in excess water was studied by differential scanning calorimetry for the mutants dull (du), waxy (wx) , and amylose extender (ae) , and the double mutant amylose‐extender, waxy (ae wx) from the Ia5125 sweet corn inbred background. Onset temperature (T o ), peak temperature (T max ), and enthalpy (ΔH) were determined. For du and wx starches T max was within 1°C of the value for the normal starch (T max = 69.4°C). For starches from ae and ae wx mutants, T max was 7–8°C higher than the normal starch. The highest enthalpies were observed for wx (3.26 cal/g) and ae wx (3.39 cal/g) starches; ae (2.93 cal/g) and normal (2.52 cal/g) starches were intermediate, and du (2.32 cal/g) starch had the lowest enthalpy. The endotherm of the ae starch was completed at just above 100°C, in distinction to reports for ae mutants from dent lines. Although the ae wx endotherm occurred at a higher temperature than the wx , the endotherm was sharpened relative to the ae endotherm, and was complete at 90°C.