Effect of octenylsuccination of pullulan on mechanical and barrier properties of pullulan-chickpea protein isolate composite film

The octenyl succinic anhydride (OSA) modification of pullulan (PU) was applied to improve the blend miscibility, compatibility and water-resistance properties of the PU-chickpea protein isolate (CPI) blend films. For this purpose, the effect of degree of substitution (DS) of the modified PU and also the ratio of CPI to PU-OSA on the physical and mechanical properties of the obtained composite films were evaluated. FTIR and XRD results showed that the molecular interactions between CPI and PU-OSA were more than CPI and PU, indicating that these two polymers had more miscibility because of the hydrophobic nature of PU-OSA which also confirmed by scanning electron microscope (SEM) pictures. The findings indicated that the use of PU-OSA instead of PU can significantly improve the mechanical and water-resistance properties of composite films. In this regard, the octenylsuccination of PU decreased the extensibility, moisture content and water vapor permeability, while increased the tensile strength and water contact angle of the produced composite films. The highest values of the tensile strength (8.90 ± 0.10 MPa) and contact angle (91.48 ± 0.34°) were obtained for CPI50–P3 and CPI70–P3 composite films, respectively. Also, the lowest values of the water solubility (21.23 ± 0.96%), moisture content (15.74 ± 0.47%) and water vapor permeability (2.07 ± 0.06 × 10-10 gm-1s-1pa-1) were obtained for CPI70–P3 blend film. Eventually, it can be deduced that the composite films produced by CPI and PU-OSA with DS of 0.06 are the best and can be used as new biodegradable films with excellent properties. • CPI, PU and PU-OSA were successfully employed to produce novel composite films. • The interactions between CPI and PU-OSA were confirmed by FTIR analysis. • Octenylsuccination improved the mechanical and barrier properties of blend-films. • CPI-PU-OSA composite films were more water-resistant than CPI-PU films. • CPI-PU-OSA films showed better TS than the CPI, PU, PU-OSA and CPI-PU films.