Antimicrobial and biodegradable chitosan/cellulose acetate phthalate/ZnO nano composite films with optimal oxygen permeability and hydrophobicity for extending the shelf life of black grape fruits.

Film-forming biopolymers possessing antimicrobial activity and biodegradability are of great interest on account of their potential use in food packaging applications. The present study deals with the fabrication and characterisation of chitosan (CS) - cellulose acetate phthalate (CAP) films incorporated with ZnO nanoparticles (nano ZnO). CS-CAP films with varying ratios of nano ZnO reinforcement were prepared by solvent casting method. The thermal stability and barrier properties of the fabricated films increased with increasing amount of nano ZnO in the range of 2-7.5% (w/w). CS-CAP film loaded with 5% (w/w) nano ZnO showed the most optimal tensile strength and stiffness to be utilized as a food packaging material. Water contact angle measurements showed the prepared nano composite films to have low surface wettability and high contact angle value up to 90°. Biodegradability of the nano composite films ranged from 30 to 50% in 28 days. The CS-CAP film loaded with 5% (w/w) nano ZnO had extended the shelf life of black grape fruits up to 9 days. The demonstrated barrier and food protection characteristics of the CS-CAP-ZnO films attested its suitability as a primary food packaging material that can be used to increase the shelf life of black grape fruits.