The antimicrobial efficacy of Lippia alba essential oil and its interaction with food ingredients

Abstract

The objective of this study was to evaluate the antimicrobial potential of Lippia alba essential oil (EOLa) and to investigate the effect of food ingredients on its efficacy. The antimicrobial potential of the oil was determined by the presence or absence of inhibition zones, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Escherichia coli, Listeria innocua, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella choleraesuis and Staphylococcus aureus. The effect of food ingredients and the pH on the antimicrobial efficacy of oil was assessed by monitoring the maximum growth rate of Listeria monocytogenes in model media. The model media included potato starch (0, 1, 5 or 10%), beef extract (1, 5, 3, 6 or 12%), sunflower oil (0, 5 or 10%) and TSB broth at pH levels of 4, 5, 6 or 7. The EOLa showed efficacy at all concentrations (50%, 25%, 6.25%, 3%, 1.5%, 0.8%, 0.4% and 0.2%) evaluated, against all bacterial species, Gram-positive and Gram-negative. The antimicrobial efficacy of EO was found to be a function of ingredient manipulation. Proteins and lipids had a negative impact on the oil effectiveness, indicating the protective action of both on the microbial specie tested. On the contrary, at the highest concentration of starch (10%), the lower rate growth of L. monocytogenes was detected, therefore indicating a positive effect of carbohydrates on the oil effectivenes. Regarding the pH, the studies showed that the rate of microbial growth increased with increasing pH. It was concluded that the use of EOLa is more effective control pathogenic and spoilage bacteria when applied to starchy foods under an acidic pH.

Antioxidant activity of essential oils from condiment plants and their effect on lactic cultures and pathogenic bacteria

“…Citral was the major component in the essential oil from L. alba (59.43%=geranial 33.8%+neral25.63%). This result was consistent with the one recorded for citral chemotype by JEZLER et al 2011 (MACHADO et al, 2014;MARQUES et al, 2018).…”

Plant essential oils as fish diet additives: benefits on fish health and stability in feed

“…According to the authors, EOs (Lippia alba, Origanum vulgare, Syzygium aromaticum, T. vulgaris) might be more effective against food-borne pathogens and spoilage bacteria when applied to foods containing a high protein level at acidic pH and lower levels of fats or complex carbohydrates. In addition, high levels of water and/or salt appear to facilitate the action of EOs (Burt 2004;Gutierrez et al 2008Gutierrez et al , 2009Machado et al 2014;Witkowska et al 2014). However, due to variability in the chemical composition of the EOs, the above noted criteria to ensure greater effectiveness can also vary depending on the particular chemical characteristics of each oil.…”

Modulatory Effect of Lippia alba Essential Oil on the Activity of Clinically Used Antimicrobial Agents on Salmonella typhi and Shigella dysenteriae Biofilm

“…Machado et al [17] demonstrated LaEO activity over S. choleraesuis ATCC 10708, E. coli ATCC 10536, L. innocua ATCC 19115, L. monocytogenes ATCC 33090, P. aeruginosa ATCC 9027, and S. aureus ATCC 6538P strains, and obtained as the main constituent e-citral (31.57%), neral (25.50%), d-limonene (14.07%), germacrene D (5.47%), b-elemol (5.37%), g-terpinen (4.09%), and p-cymene (1.56%).…”

“…The pharmacological potential of Lippia alba essential oils has been widely described in the literature [13,17,32]; however, its action on Gram-negative bacteria of medical importance has been little explored. The present study demonstrated the excellent antimicrobial potential of this oil on strains causing gastrointestinal infections.…”