Preparation and physicochemical characterization of starch/pectin and chitosan blend bioplastic films as future food packaging materials

Abstract

Currently, petroleum-based plastics are widely used for food packaging applications, but their non-biodegradable nature has created serious environmental concerns. Here, we have used starch/pectin biopolymers as matrix and chitosan as co-biopolymer together with tartaric acid (TA)/citric acid (CA) as natural plasticizers to fabricate their bioplastic films by covalent ester/amide linkages between carboxyl and hydroxy/amine groups in the crosslinked network accompanied by intermolecular hydrogen bonding interactions. The FTIR analysis confirmed the successful formation of amide/ester linkages and non-covalent hydrogen bonding interactions, while the broad XRD bands indicated the amorphous characteristics of the obtained bioplastics. Their swelling ratio ranged between 510 to 620 ± 50% and the mass loss from 44 to 76 ± 5%, which was susceptible to acid-facilitated hydrolysis after 24 h incubation in water. The young modulus values ranged between 0.5 ± 0.1 to 7.5 ± 0.5 MPa, which was highest for starch/TA film (7.5 ± 0.5 MPa), attributed to comparatively lower plasticization effect of TA than CA. All the samples showed complete biodegradation (97 ± 2.5%), after 3 days dipping in soil and were ecofriendly by ecotoxicity assay. Therefore, these pure biobased films could be greener renewable materials for the future food packing industry.