Waxy maize starch subpopulations with different gelatinization temperatures

The objective of this research was to obtain further evidence that starch preparations contain subpopulations of granules with properties that differ from those of other subpopulations. Waxy maize starch was used in this investigation. Nongelatinized waxy maize starch granules (both chemically modified and unmodified) were recovered after suspensions were heated to different temperatures between the initial and final gelatinization temperatures under conditions that minimized leaching of starch polymer molecules. Nongelatinized starch granules that were recovered after heating to 74 °C had a lower normalized concentration of A chains (DP 6-12) and became less substituted upon hydroxypropylation compared to granules recovered after heating to 70 °C and unfractionated granules. Granules of hydroxypropylated starch that were recovered after heating to higher temperatures in the gelatinization temperature range were less substituted (had lower MS values) compared to granules recovered after heating to lower temperatures and unfractionated granules. Results confirm that subpopulations with different physical and chemical properties exist in waxy maize starch. It is hypothesized that granules which gelatinize at higher temperatures are more crystalline due to a higher percentage of amylopectin A chains.