Essential oils as antibacterial agents against food-borne pathogens: are they really as useful as they are claimed to be ?

Original articleMost studies evaluating the use of essential oils (EO) as antibacterial agents focus mainly on minimal inhibitory concentrations (MIC) rather than minimal bactericidal concentrations (MBC). In this work, we compared MICs and MBCs of EO from condiment plants commonly used in Mediterranean Europe, namely Origanum vulgare, Salvia lavandulaefolia, Salvia officinalis, Salvia sclarea and Rosmarinus officinalis, aiming to evaluate their application as disinfecting agents in minimally processed produce. Outbreaks-related pathogens such as Listeria monocytogenes, Pseudomonas aeruginosa and Yarrowia lipolytica were used. Results showed that all EO were able to reduce bacterial growth in all bacterial strains tested, particularly O. vulgare. However, fewer EO exhibited bactericidal activities, and were only effective against one or two bacterial strains, hence eliminating the possibility to use them as broad range disinfectants. Furthermore, the necessary concentrations were too high for food application. Hence, our work suggests the need to evaluate MBC rather than MIC and questions EO usefulness in controlling undesired microorganisms. Overall, and despite the large volume of data published on EO, results obtained were not very encouraging for a realistic application on produce and question the viability of EOs as disinfecting agents in foodinfo:eu-repo/semantics/publishedVersio

Characteristics of oleuropeinolytic strains of Lactobacillus plantarum group and influence on phenolic compounds in table olives elaborated under reduced salt conditions

The technological characteristics of five oleuropeinolytic strains of the Lactobacillus plantarum group selected within 135 isolates from table olives were investigated. The metabolism of phenolic compounds during elaboration of green (cv. Chalkidikis) and black (cv. Kalamata) olives under reduced salt conditions was evaluated. Olives of both cultivars were fermented in two different kinds of brine (Brine A containing 2.3% NaCl, 32.3mM Ca-acetate and 33.9mM Ca-lactate and Brine B containing 4% NaCl, pH 5.0 in both brines) by five selected strains of L.plantarum group. After 60 days of fermentation, the analysis of phenolic compounds was performed by HPLC and nine compounds were identified and quantified: oleuropein, hydroxytyrosol, tyrosol and vanillin and the phenolic acids protocatechuic, caffeic, p-hydroxybenzoic, vanillic and p-coumaric acid. The study can lead to the development of starter culture potentially active in biological debittering of olives during fermentation in order to unify the debittering and fermentation process during elaboration of table olives