Moisture sensitivity can lead to spontaneous, rapid and uncontrolled decomposition of the material (5, 12). The physicochemical properties of the bilayer film obtained based on PuOC/Zein, moisture content, total soluble matter and swelling, during four weeks of storage, are presented in Figure 2. A slight decrease in moisture content (Figure 2a) during the storage period was observed. The percentage of total soluble material decreased after the first week and then remained stable during storage time (Figure 2b). The swelling percentage also decreased during the storage period and after four weeks it was three times lower than in the initial week (Figure 2c). These results show that during the storage period at ambient conditions, PuOC/Zein-based films likely lose moisture and lead to the formation of new bonding and cross-linking. Figure