Comparative study on the interaction between native corn starch and different hydrocolloids during gelatinization.

The effect of hydrocolloids (Arabic gum, guar gum, xanthan gum) on the thermal, rheological, and microstructural changes of corn starch during gelatinization was studied by combining multiple analytical techniques. Arabic gum located in the continuous phase had no significant delaying effect on starch gelatinization. A two phase system could be directly observed by scanning electron microscopy. The analysis of variance suggested that xanthan gum could restrict the swelling of starch granules and the destruction of granule structure more effectively than other hydrocolloids tested. Morphologies of corn starch granules formed with hydrocolloids showed that xanthan gum promoted the association between starch granules. Compared to xanthan gum, starch granules were more swollen in the presence of guar gum during heating, thus the increase in hydrocolloid concentration in the continuous phase results from an excluded volume effect was more pronounced. Overall, the results suggest that hydrocolloids could effectively restrict the swelling of starch granules, depending on hydrocolloid type, owing to the efficient thickening property. A synergistic increase in paste viscosity occurred as a result of a combination of intermolecular interactions and phase separations. These findings may thus provide a useful basis for the study of other types of starch/hydrocolloid mixtures and concentrations.