The antimicrobial efficacy of plant essential oil combinations and interactions with food ingredients

Abstract

1The objective of this study was to evaluate the efficacy of plant essential oils (EOs) in 2 combination and to investigate the effect of food ingredients on their efficacy. The EOs 3 assessed in combination included basil, lemon balm, marjoram, oregano, rosemary, sage 4 and thyme. Combinations of EOs were initially screened against B. cereus, E. coli, L. 5 monocytogenes and P. aeruginosa using the spot-on-agar test. The influence of varying 6 concentrations of EO combinations on efficacy was also monitored using E. coli. to be a function of ingredient manipulation. Starch and oils concentrations of 5% and 10% 21 had a negative impact on the EO efficacy. On the contrary, the EOs were more effective 22 at high concentrations of protein, and at pH 5, by comparison with pH 6 or 7. This study 23 3 suggests that combinations of EOs could minimize application concentrations and 1 consequently reduce any adverse sensory impact in food. However, their application for 2 microbial control might be affected by food composition, therefore, careful selection of 3 EOs appropriate to the sensory and compositional status of the food system is required. 4This work shows that EOs might be more effective against food-borne pathogens and 5 spoilage bacteria when applied to ready to use foods containing a high protein level at 6 acidic pH, as well as lower levels of fats or carbohydrates. 7 8

Combined application of origanum vulgare l. essential oil and acetic acid for controlling the growth of staphylococcus aureus in foods

“…Combination of essential oils with existing physical or chemical treatments (Hurdle Technology concept) could rise as an effective approach for reinforcing their natural antimicrobial effects. The addition of small amounts of other natural preservatives may be a way to provide the balance between sensory acceptability and antimicrobial efficacy (17,29).…”

Microbiological quality and other characteristics of refrigerated chicken meat in contact with cellulose acetate-based film incorporated with rosemary essential oil

“…The pH of a product can also have an influence on the activities of active agents because the pH can modify the extent of ionization (dissociation/ionization) of certain compounds and consequently affect their activity (28). Gutierrez et al (27) described studies using essential oils of oregano and thyme in which a pH of 5 was favorable for the activities of the oils.…”

Efecto del almacenamiento sobre las propiedades físicas de las películas de quitosano con inclusión de aceites esenciales de tomillo y romero

“…Se observó un aumento del diámetro de inhibición con la inclusión de la mezcla de aceites esenciales de romero e tomillo, además que el efecto fue mas eficaz para las cepas de S. aureus. Este fenómeno se presenta porque las combinaciones de TEO y REO presentan una actividad sinérgica en la película de quitosano [6], además que las bacterias Gram-positivas son más sensibles a los agentes antimicrobianos [18].…”

“…Estos han sido incluidos en matrices poliméricas de CH para mejorar sus propiedades antimicrobianas y antioxidantes. Los principales componentes del aceite esencial de romero son eucaliptol (39,6%), alcanfor (19%), α-pineno (4,8%), timol (52,9%) y p-cimeno (34%), mientras que los principales componentes del aceite esencial de tomillo son timol (52,9%) y p-cimeno (34%) [6]. Estos componentes pueden inhibir el crecimiento de microorganismos.…”