The results showed that DPPH scavenging activity of the films
significantly increased (p 0.05) with increasing GTE concentration
as shown in Fig. 2. The chitosan films without GTE extract
showed some scavenging activity on DPPH. The scavenging
mechanism of chitosan is related to the fact that free radical can
react with the residual free amino (NH2) groups to form stable
macromolecule radicals, and the NH2 groups can form ammonium
(NH3
þ) groups by absorbing a hydrogen ion from the solution (Park
et al.; Yen et al., 2008). In the films containing GTE, the antioxidant
activity increased in more than 15 folds in relation to the control
samples. As the GTE increased in the film formulation, so did the
expected antioxidant character of the active film