Antibacterial Activity of Chitosan–Polylactate Fabricated Plastic Film and Its Application on the Preservation of Fish Fillet

Abstract

This research prepared chitosan-PLA plastic films by extrusion, analyzed the physical and mechanical properties and antibacterial activity of the fabricated plastic films, and used them to preserve grouper fillet. We added chitosan (220 kDa, 93% DD) in the weight ratio of 0.5-2% into the PLA to prepare the chitosan-PLA films. With the increasing chitosan dosage, both the water vapor transmission rate and moisture content of chitosan-PLA films increased. Among the three doses of chitosan (0.5%, 1%, and 2%) added to PLA, 0.5% chitosan-PLA film had the highest antibacterial activity. This plastic film had an inhibitory efficiency of over 95% against <i>Escherichia coli</i>, <i>Pseudomonas fluorescens,</i> and <i>Staphylococcus aureus</i>. The action of covering the fish fillet with 0.5% chitosan-PLA film significantly reduced several microbes' counting (i.e., mesophiles, psychrophiles, coliforms, <i>Pseudomonas</i>, <i>Aeromonas</i>, and <i>Vibrio</i>) and total volatile basic nitrogen (TVBN) value in the grouper fillets stored at 4 °C. Thus, such action prolongs the fish fillets' shelf life to up to at least nine days, and this 0.5% chitosan-PLA film shows promising potential for preserving refrigerated fish.