Activity of chitosan films enriched with the essential oil of Alpinia malaccensis rhizome against S. aureus, E. coli and C. Musae

Abstract

In this paper, the in vitro antimicrobial activity of Alpinia malaccensis rhizome oil was investigated in its pure form and incorporated into chitosan films, against Colletotrichum musae, Staphylococcus aureus and Escherichia coli. Dry rhizome oil of A. malaccensis was extracted using steam distillation. Chitosan films enriched with the oil were prepared by casting as a potential bio-based food packaging film. The major constituent of A. malaccensis oil was identified as 1,8-cineole by GC-MS. The antifungal activity of the essential oil (EO) was tested using the disk diffusion method. The minimum inhibitory concentration (MIC) and the minimum lethal concentration (MLC) for C. musae was 100.0 and 300.0 μg μL-1, respectively. A liquid bioassay method was used to determine the antifungal efficacy of the oil enriched chitosan films against C. musae. More than 50 % inhibition of the growth of the fungus was achieved when the oil concentrations in EO-chitosan films was between 0.08 – 0.40 μg mm-2. The antibacterial activity of the oil and the oil enriched films was determined by measuring the optical density of the cultures at 610 nm. The optical density (OD610) values of S. aureus and E. coli cultures showed a sharp and gradual reduction, respectively with increasing oil concentration. The growth of S. aureus was negligible at oil concentrations higher than 5.0 μg μL-1. The oil enriched films showed a lower inhibition of the growth of both bacteria.