Physical and Structural Properties of Potato Starch Modified by Dielectric Treatment with Different Moisture Content

The altered morphology, amylose content, microstructure, viscosity and thermal properties of potato starch after heating by radio frequency (RF) and microwaves (MW) were studied and contrasted with the native potato starch. The results showed that the MW treatment roughens the starch surface and lowers the amylose content of the starch, even more than the RF-treated starch does. The starch granule size of MW treated was larger than RF treated. RF treatment altered the structure and reduced the crystallinity of the starch, but the MW treatment did not affect the crystal form. The gelatinization temperature of the MW-treated starch was higher than the native potato starch, while the RF-treated starch was lower than the native starch. The results also indicated that the peak viscosity and the breakdown viscosity values of the RF-treated starch consistently surpassed that of the MW-treated starch. The results exposed the facts that RF treated starch showed the same trend on crystal and pasting properties compared with the hot water annealing starches, which suggested RF can be an efficient method for starch annealing.