Influence of gelatinization process and HMDSO plasma treatment on the chemical changes and water vapor permeability of corn starch films.

In this study, surface, chemical, physicochemical and barrier properties of films treated with hexamethyldisiloxane (HMDSO) cold plasma were investigated. Normal and high amylose starches were gelatinized at different level to obtain films with different amount of free amylopectin. The obtained films were subjected to HMDSO plasma treatment. XPS analysis indicated chemical changes including substitution and crosslinking of the starch molecule, as reflected by the CSi bond increasing and the C-OH bonds reduction on treated films. These changes modified the thermal transitions (Tm and ΔH). The highest amount of CSi bonds was more noticeable in the TF50 film, suggesting a better interaction between active species of plasma and the free amylopectin released into the continuous phase of the film. Moreover, active species of plasma increased the crystallinity in all films. These results suggested that a higher helical packaging, crosslinking and hydrophobic blocking groups (CSi) of starch molecules resulted in films with improved barrier performance against water molecules.