In spite of modern improvements in slaughter hygiene and food production techniques, food safety is an increasingly important public health issue. Essential oils (EOs) are aromatic oily liquids obtained from plant material. An estimated 3000 EOs are known, of which about 300 are commercially important. Besides antibacterial properties, EOs or their components have been shown to exhibit antiviral, antimycotic, antitoxigenic, antiparasitic, and insecticidal properties. In vitro studies have demonstrated antibacterial activity of essential oils against Listeria monocytogenes, Salmonella typhimurium, Escherichia coli O157:H7, Shigella dysenteria, Bacillus cereus and Staphylococcus aureus at levels between 0.2-10 μl ml-1. Gram-negative organisms are slightly less susceptible than Gram-positive bacteria. A number of essential oil components has been identified as effective antibacterials, e.g. carvacrol, thymol, eugenol, perillaldehyde, cinnamaldehyde and cinnamic acid, having minimum inhibitory concentrations of 0.05-5 μl ml-1 in vitro. A higher concentration is needed to achieve the same effect in foods. Studies with fresh meat, meat products, fish, milk, dairy products, vegetables, fruit and cooked rice have shown that the concentration needed to achieve a significant antibacterial effect is around 0.5-20 μl g-1 in foods and about 0.1-10 μl ml-1 in solutions for washing fruit and vegetables.

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