The thickness of pure chitosan (CG0) and chitosan-based composite films (CG1, CG2, CG3) are presented in Table 2. As noted from Table 2, the thickness of chitosan-based composite films prepared from the same amount of casting solution, increased from 27.9 0.7 to 55.5 0.5mm with the addition of increasing amounts of GFSE from 0 to 1.5% v/v. The increase in thickness was possibly due to the presence of cross-links formed by high
molecular weight phenolic compounds in GFSE [18], consequently leading to an increase in spatial distance within the chitosan matrix. Similar trend of an increase in the thickness of films with the addition of GFSE was also reported for soy protein edible film and barley bran protein–gelatin composite film [13,18].