Mechanical, barrier, and antimicrobial properties of apple puree edible films containing plant essential oils

Edible films, as carriers of antimicrobial compounds, constitute an approach for incorporating plant essential oils (EOs) onto fresh-cut fruit surfaces. The effect against Escherichia coli O157:H7 of oregano, cinnamon, and lemongrass oils in apple puree film-forming solution (APFFS) and in an edible film made from the apple puree solution (APEF) was investigated along with the mechanical and physical properties of the films. Bactericidal activities of APFFS, expressed as BA(50) values (BA(50) values are defined as the percentage of antimicrobial that killed 50% of the bacteria under the test conditions) ranged from 0.019% for oregano oil to 0.094% for cinnamon oil. Oregano oil in the apple puree and in the film was highly effective against E. coli O157:H7. The data show that (a) the order of antimicrobial activities was oregano oil > lemongrass oil > cinnamon oil and (b) addition of the essential oils into film-forming solution decreased water vapor permeability and increased oxygen permeability, but did not significantly alter the tensile properties of the films. These results show that plant-derived essential oils can be used to prepare apple-based antimicrobial edible films for various food applications.