Effect of Oliveria Decumbens essential oils on microbial characteristics of hamburger

The use of herbal essential oils can inhibit bacterial growth and proliferation. In this investigation, the chemical composition and antimicrobial effects of essential oils of Oliveria decumbens on culture media and hamburger have been studied. GC/MS analysis identified 12 components in the essential oils of Oliveria decumbens. The antimicrobial activity of the essential oils was investigated against Staphylococcus aureus and Escherichia coli using disc diffusion and well plate method. The experiment was a factorial form of a completely randomized design with 3 levels in essential oil concentration (0, 0.32, and 1.25 µl/g) in 4 periods (1, 20, 40, and 60 days) with 3 replications on S. aureus, E. coli, mold, yeast and total count in hamburger. The most important identified compounds in the essential oils of Oliveria decumbens were phenolic and aldehyde compounds. Minimum inhibition concentrations of Oliveria decumbens essential oils against S. aureus and E. coli were 0.32 µl/ml and 0.625 µl/ml, respectively. Besides, the number of microorganisms decreased with increasing concentrations of essential oils of Oliveria decumbens. There was no significant difference between the control and concentrations of 0.32 µl/g in E. coli count but in all types of microorganisms, the highest decrease was observed in the concentration of 1.25 µl/g (p < /em><0.05). The high amount of aldehydes and phenols in Oliveria decumbens essential oils may be a reason for antimicrobial effects of the plant essential oils that can be considered as a natural source of preservative in food.