Evaluation of the antibacterial and antioxidant activities of chitosan edible films incorporated with organic essential oils obtained from four Thymus species.

The aims of this study were to evaluate, (1) the antibacterial properties, (2) the total phenol content and (3) the antioxidant activity, of chitosan edible films incorporated with certified organic essential oils (EOs) obtained from Thymus zygis, Thymus mastichina, Thymus capitatus and Thymus vulgaris. The agar disc diffusion method was used to determine the antibacterial activities of chitosan edible films while for the antioxidant activity, two different analytical assays were used (DPPH and FRAP). As regard antibacterial activity, films containing only chitosan were not effective against any of tested bacteria. Chitosan films containing T. capitatus EO (CH + TCEO) was more effective against Listeria innocua and Alcaligenes faecalis whilst chitosan films containing T. mastichina EO (CH + TMEO) had the highest inhibition halos against Serratia marcescens. For and Enterobacter amnigenus no antibacterial activity was achieved. Chitosan films added with Thymus essential oils showed antioxidant activity, at all concentrations and with all methods assayed. CH + TZEO had the highest antioxidant activity revealed with DPPH assay. However in CH + TCEO showed best antioxidant effect when assessed with FRAP assay. The results showed that chitosan edible films incorporated with organic Thymus EOs could be used as active films in food industry due to its antibacterial and antioxidant activities.