Effect of oxygen glow plasma on supramolecular and molecular structures of starch and related mechanism

The effect of oxygen glow plasma (OGP) on the supramolecular structures (fractal, lamellar, and crystalline characteristics) and molecular characteristics (molecular weight, mean square radius of gyration) of potato and corn starches were investigated, and the related mechanism was explored. Compared with native corn starch, native potato starch possessed more compact scattering objects which however displayed a weaker resistance to OGP. For both starches, while the OGP treatment simultaneously influenced the crystalline and amorphous materials, there was a higher degree of destruction to the amorphous materials at the initial period. Both starches displayed a typical positive deviation from Porod's law. Interestingly, potato starch suffered a higher degree of destruction to both of its supramolecular and molecular characteristics (particularly, a higher degree of decrease in the molecular weight). This can be attributed to the large amount of inter-helical water molecules which could be induced by OGP, and to the fracture of the glycoside bonds in the solid starch granules which happened in a non-random way and close to the chain center.