Oregano oil has been found to be the most effective antimicrobial, followed by allspice and garlic.
Researchers at Processed Foods Research and Produce Safety and Microbiology units of Western Regional Research Centre from the U.S. Department of Agriculture (USDA) investigated the effectiveness of the oils by incorporating them in thin, tomato-based antimicrobial coatings known as edible films.
In addition to its flavour properties, tomatoes are reported to possess numerous beneficial nutritional and bioactive components that may benefit human health.
Edible tomato films containing antimicrobials may protect food against contamination by pathogenic microorganisms.
The findings revealed that oregano oil consistently inhibited the growth of all three bacteria.
Although garlic oil was not effective against E. coli or Salmonella, but was effective against Listeria.
Vapour tests of oregano and allspice oils indicated that these two oils diffuse more efficiently through the air than through direct contact with the bacteria.
Listeria was less resistant to EO vapors while E. coli was more resistant.
"The results show that apple-based films with allspice, cinnamon or clove bud oils were effective against the three bacteria. The essential oils have the potential to provide multiple benefits to consumers," said lead researcher R. J. Avena-Bustillos.
The study appears in Journal of Food Science.