Amylose Determination of Native High‐Amylose Corn Starches by Differential Scanning Calorimetry

Abstract

Abstract Differential scanning calorimetry (DSC) was investigated as an alternative method to more conventional iodine‐binding methods for determining starch amylose in a maize breeding program, because it requires fewer steps. In addition, many current DSC instruments are now equipped with sampling robots for performing automated analysis. The iodine‐binding method and a recently described DSC method for amylose determination were compared using five commercial starch samples. In addition, two sets (Set 1 and Set 2) of germplasm samples obtained from a high‐amylose breeding program were examined using each method. Correlation coefficients ( r 2 ) between the two methods for the commercial starch samples, Set 1 and Set 2 were found to be 0.99, 0.89 and 0.82, respectively, suggesting a good correlation but with greater discrepancy between them with increasingly higher amylose values. The DSC method appeared to have an improved repeatability, because its associated CV value was lower (4.1%) compared to the iodine‐binding method (5.8%). It was concluded that the DSC method should be effective in discriminating high‐amylose genotypes in a breeding program specifically designed to identify maize starches with amylose values at or above 70%.