title: 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.
authors.affiliation: Embrapa FortalezaCE Brazil Embrapa, Fortaleza, CE, Brazil.
authors.forename: Terezinha Feitosa
authors.initials: TF
authors.lastname: Machado
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas Universidade Federal do Ceará FortalezaCE Brazil Departamento de Análises Clínicas e Toxicológicas, Universidade Federal do Ceará, Fortaleza, CE, Brazil.
authors.forename: Nádia Accioly P
authors.initials: NA
authors.lastname: Nogueira
authors.affiliation: Embrapa FortalezaCE Brazil Embrapa, Fortaleza, CE, Brazil.
authors.forename: Rita
authors.initials: R
authors.lastname: de Cássia Alves Pereira
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas Universidade Federal do Ceará FortalezaCE Brazil Departamento de Análises Clínicas e Toxicológicas, Universidade Federal do Ceará, Fortaleza, CE, Brazil.
authors.forename: Cívita Teixeira
authors.initials: CT
authors.lastname: de Sousa
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas Universidade Federal do Ceará FortalezaCE Brazil Departamento de Análises Clínicas e Toxicológicas, Universidade Federal do Ceará, Fortaleza, CE, Brazil.
authors.forename: Valéria Chaves Vasconcelos
authors.initials: VC
authors.lastname: Batista
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D003470:Culture Media / Q000737:chemistry; D004347:Drug Interactions; D005504:Food Analysis; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D032411:Lippia / Q000737:chemistry*; D008089:Listeria monocytogenes / Q000254:growth & development; D008826:Microbial Sensitivity Tests; D009822:Oils, Volatile / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D009822:Oils, Volatile
keywords: antimicrobial; essential oil; food ingredient