Dielectric barrier discharge and radio-frequency plasma effect on structural properties of starches with different amylose content

The effect of the dielectric barrier discharge atmospheric (DBD) and radio-frequency (RF) cold plasma treatment on the morphology, helical order, and structural stability of starches with different amylose content (30, 50, & 70%) was investigated. The cavities formed after RF plasma treatment allowed the active species to modify the internal structure of the granule, probably reaching its center and expanding to the periphery, where the amorphous regions were damaged and gradually removed by the treatment, increasing the amylose helix order and thermal stability of starch molecule as suggested by the SEM, FTIR, DSC, and TGA analysis. In contrast, DBD treatment promoted a thicker coating deposition and HMDSO functional groups inclusion, which increased both the granular interaction and the decomposition temperature. Overall, active species of HMDSO plasma generated in RF and DBD reactors modified mainly the amylose chains in a distinctive way, favoring the ordering or stability of starch molecules, respectively. These findings could be useful when looking for potential applications in the food industry or in other fields like semiconductors.