Effects of Sugars and Sugar Alcohols on the Gelatinization Temperatures of Wheat, Potato, and Corn Starches

The gelatinization temperature (T_gel) of starch increases in the presence of sweeteners due to sweetener-starch intermolecular interactions in the amorphous regions of starch. Different starch botanical sources contain different starch architectures, which may alter sweetener-starch interactions and the effects of sweeteners on T_gels. To document these effects, the T_gels of wheat, potato, waxy corn, dent corn, and 50% and 70% high amylose corn starches were determined in the presence of eleven different sweeteners and varying sweetener concentrations. T_gels of 2:1 sweetener solution:starch slurries were measured using differential scanning calorimetry. The extent of T_gel elevation was affected by both starch and sweetener type. T_gels of wheat and dent corn starches increased the most, while T_gels of high amylose corn starches were the least affected. Fructose increased T_gels the least, and isomalt and isomaltulose increased T_gels the most. Overall, starch T_gels increased more with increasing sweetener concentration, molar volume, molecular weight, and number of equatorial and exocyclic hydroxyl groups. Starches containing more short amylopectin chains, fewer amylopectin chains that span through multiple clusters, higher number of building blocks per cluster, and shorter inter-block chain lengths exhibited the largest T_gel increases in sweetener solutions, attributed to less stable crystalline regions.

Keywords: gelatinization; starch; sugar; sugar alcohols; sweeteners.