Development and Optimisation of Cassava Starch-Zinc-Nanocomposite Film for Potential Application in Food Packaging

Abstract

The improvement of biodegradable film used in the food packaging has been made possible through nanotechnology. This research was carried out to develop and optimize the cassava starch-zinc-nanocomposite films for potential applications in food packaging. The zinc nanoparticles were prepared by sol-gel method and established with the particle sizes ranging from 4 nm to 9 nm. The films were developed by casting the solutions of 24 g cassava starch, 0% to 2% (w/w) zinc nanoparticles and 45% to 55% (w/w) glycerol in plastic mould of 8, 10 and 12 mm depths. The average thickness of the films varied respectively with the depth as 15.14 ± 0.22, 16.21 ± 0.36 and 17.38 µm ± 0.13 µm. Permeability and stability of the films were determined at 27°C and 65% relative humidity and thermal range of 30°C to 950°C, respectively. Also, the mechanical properties were determined using the nano indentation technique. The films were optimised based on their characterized attributes using their desirability functions. The hardness, creep, elastic and plastic works, which determined the plasticity index of the films, decreased with thickness and zinc nanoparticles. The water vapour permeability increased with the concentrations of glycerol, zinc nanoparticles and thickness while the oxygen permeability decreased with the nanoparticles. The degradations of the Nanocomposites at 100°C were in the range of 2%-3%, which may indicate that the films are thermally stable. The optimum film whose desirability function is closer to the optimisation goal gave values of 49.29% glycerol, 17 µm thickness and 2% zinc nanoparticles for maximum thermal and mechanical properties. The low permeability, high thermal stability and low plastic work at higher concentration of zinc nancomposites may be essential in food packaging.