is shown in Table 2. The amount of phenolic compounds was measured by Folin-Ciocalteu method. Table 2 shows the impact of incorporating TP on the total phenolic content of PPF/TP composite films, and it's based on the calibration curve (y = 0.0208x+0.0001, R2 = 0.9994). Incorporation of TP had a significant change on the total phenolic content (p < 0.05), increasing from 8.12 mg g−1 of GAE for the PPF films to 38.26 mg g−1 of GAE for the PPF/TP composite films with 20% TP. Total phenolic content observed in the PPF films might be ascribed to the presence of amino acid residues like tyrosine and histidine, which were able to react with Folin−Ciocalteu reagent (Aewsiri et al., 2009). The above results showed that antioxidant activity of the PPF films significantly increased (p < 0.05) with increasing TP concentration. Similar results were also found by Wang et al. (2013) and Liu et al. (2015).