Antimicrobial and antioxidant capacity of biodegradable gelatin film forming solutions incorporated with different essential oils

Biodegradable film forming solutions prepared by gelatin (4% w/v) and different concentrations of thyme, orange, sage, peppermint and clove essential oils (EOs) were investigated for their antioxidant and antimicrobial activities. Total phenolic contents and the antioxidant activity of EOs and gelatin film forming solutions incorporated with EOs were determined by Folin-Ciocalteau and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays, respectively. Antimicrobial activity of gelatin film forming solutions incorporated with different EOs were tested on yeast Candida albicans, Gram (+) bacteria Staphylococcus aureus and Gram (-) bacteria Escherichia coli. Among the EOs studied, thyme and clove EOs showed the highest values in total phenolic content (279,797 and 251,663 mg/L gallic acid) while sage EO had the lowest total phenolic content (14,533 mg/L gallic acid). Total phenolic content of the gelatin film forming solution combined with EOs increased proportional to the EO concentration. Antioxidant capacities of the EOs were found to be high which is supposed to be directly related to the active chemical substances of the EOs. The antioxidant properties of the tested EOs were correlated with total phenolic content. EOs showed potential antimicrobial activity against tested microorganisms. Antimicrobial capacity of the combination of gelatin film forming solution with EOs increased depending on the EO concentration. The study results revealed out that biological activities of biodegradable gelatin film forming solution may be effectively enhanced by using herbal essential oils that have strong biochemical properties.