Combined application of essential oils from Origanum vulgare L. and Rosmarinus officinalis L. to inhibit bacteria and autochthonous microflora associated with minimally processed vegetables

Abstract

This study assessed the occurrence of an enhancing inhibitory effect of the combined application of Origanum vulgare (OV) and Rosmarinus officinalis (RO) essential oils against bacteria associated to minimally processed vegetables using the determination of Fractional Inhibitory Concentration (FIC) index, kill-time assay in vegetal broth and application in vegetable matrices. Moreover, it was determined chemical composition of the essential oils and their effects alone and in mixture on sensory characteristics of minimally processed vegetables. Carvacrol (66.9 g/100 g) was the most prevalent compound in OV essential oil, while for RO was 1.8-cineole (32.2 g/100 g). OV and RO essential oil showed MIC in a range of 1.25-5 and 20-40 μL/mL, respectively. FIC indices of the combined application of the essential oils were 0.5 against Listeria monocytogenes, Yersinia enterocolitica and Aeromonas hydrophilla suggesting a synergic interaction. Only for Pseudomonas fluorescens FIC index was 0.75 purposing additive effect. Application of the essential oils alone (MIC) or in mixture (¼ MIC + ¼ MIC or ¼ MIC + ½ MIC) in vegetable broth caused significant decrease (p b 0.05) in bacterial count over 24 h. Mixture of essential oils reduced (p b 0.05) the inocula of all bacteria in vegetable broth and in experimentally inoculated fresh-cut vegetables. Similar efficacy was found to reduce the autochthonous microflora in vegetables. Sensory evaluation of vegetables sanitized with essential oils revealed that the scores of the most evaluated attributes fell between like slightly and neither like nor dislike. The combination of essential oils at sub-inhibitory concentrations could mean an interesting approach to sanitize minimally processed vegetables.

Chemical Composition and Antimicrobial Activity of Cinnamon, Thyme, Oregano and Clove Essential Oils Against Plant Pathogenic Bacteria

“…Cimanga et al (2002) reported the high antibacterial efficacy of thyme essential oil and its major components, which are α-pinene, p-cymene, carvacrol and thymol against post-harvest pathogens. In comparison to the previously reported results (de Azeredo et al, 2011;Hosseini Nezhad, 2012) the isolates tested in this study are less sensitive to used essential oils. Usually is problematic to compare outcomes achieved in different studies, because of authors used the various testing methods, numerous bacterial strains and several sources of tested antimicrobial substances.…”

Evaluación de la vida útil de quesos semimaduros con recubrimientos comestibles utilizando aceite esencial de jengibre (Zingiber officinale) como agente antimicrobiano.

“…En efecto, se han reportado distintos trabajos (Alves de Azeredo et al, 2011;Ramos-García et al, 2010;Zheng, Young-Min, Kyu-Seok, Sunggi, & Sun-Young, 2013, entre otros) orientados a preservar frutas y hortalizas mínimamente procesadas, para lo cual desarrollaron películas comestibles impregnadas con aceites esenciales extraídos de distintas plantas. También, se han realizado ensayos preliminares para la utilización de este tipo de recubrimientos en la conservación de quesos de distinto tipo.…”

Essential Oil from Origanum vulgare Linnaeus: An Alternative Against Microorganisms Responsible for Bad Perspiration Odor

“…Found carvacrol (66.9 g/100 g) as being the most prevalent compound 37 in the essential oil of O. vulgare, which also presented high content of p-cymene (13.9g/100 g) and γ-terpinene (7.8 g/100 g). The authors suggest that phenolic active compounds, such as carvacrol, sensitize the cell membrane of the bacteria by complexation to available targets (amino acids and proteins) in the cells.…”