Vol. 22, May/June 2010 Journal of Essential Oil Research/283 Received: May 2008 Revised: September 2008 Accepted: November 2008 Effect of Some Essential Oils as Natural Food Preservatives on Commercial Grated Carrots Flora V. Romeo, Serena De Luca, Amalia Piscopo, Emanuela De Salvo and Marco Poiana,* BIOMAA - Department of Biotechnologies for Agricultural Food and Environmental Monitoring, Mediterranean University of Reggio Calabria, Feo di Vito 89060 (RC), Italy Abstract In the present work, the effects of lemon verbena (Lippia citriodora), cypress (Cupressus sempervirens) and lemon-balm (Melissa officinalis) essential oils against the growth of three microorganisms (potentially dangerous to the safety of foods) were evaluated. The three oils were chosen and tested on grated carrots inoculated with bacteria and stored at 8°C until 8 days to simulate the market sale. The most resistant of the three strains against all the tested oils was Escherichia coli, while Listeria strain was the most easily influenced. An important interaction was revealed with the packaging type: oxygen diffusion greatly influenced the bacteria survival at the end of the experiment. Key Word Index Carrots, Melissa officinalis, Lamiaceae, Lippia citriodora, Verbenaceae, Cupressus sempervirens, Cupressaceae, essential oil composition, a-pinene, d-3-carene, citronellal, geranial, neral, preservatives. 1041-2905/10/0003-0283$14.00/0—© 2010 Allured Business Media *Address for correspondence Introduction There has been considerable emphasis on studies involving essential oils, extracts and decoctions of spices on inhibiting the growth of microbes (1). Examinations of the growth-inhibitory effects of essential oil components on microorganisms has been studied (2). In fact, many authors have reported antimicrobial, antifungal, antioxidant and radical-scavenging properties of spices and oils (3). The bacteria Listeria monocytogenes, Staphylococcus au- reus and Escherichia coli are important foodborne pathogens because of their ability to grow at a wide range of temperature, pH and high salt content. Since Listeria spp. is an ubiquitous microorganism, post-process contamination of cooked product is a major concern and has been reported during the packaging stage of production (4). Some components of oils can be used as antilisterial materials; most of this antimicrobial activity appears to derive from phenolic compounds (5). It has been shown that some pathogens are able to survive and grow to significant numbers on refrigerated foods (6), thus making post-process contamination a significant concern. Moreover, the problem of preserving food is becoming more complex, with the introduction of new products requiring an even longer shelf-life and a higher degree of protection against pathogenic microorganisms (7). Fruits and vegetables are eco- logical niches for a diverse and changing microflora. Fresh raw produce contains a complex mix of bacteria, fungi and yeasts that are characteristic of that fruit or vegetable, and whose population and kinds are highly variable (8). To prolong the shelf-life of fresh fruits and vegetables, the growth of microbial populations must be controlled, and hence several post-harvest processes are employed to reduce initial high counts (9). The food industry has been reducing the use of chemi- cal preservatives due to increasing pressure from consumers to either completely remove them or to adopt more natural alternatives for the extension the shelf life of foods (10). To reduce health hazards and economic losses due to foodborne microorganisms, particular interest has been focused on the potential application of essential oils, spices and herbs that have been shown to possess antimicrobial activities (11). Most stud- ies have been conducted using oils in vitro on microbiological media (12–14); consequently, little is understood about their effectiveness when applied to food. The use of oils, however, may be limited due to their flavor, since effective antimicrobial doses may exceed acceptable levels from an organoleptical point of view (9). Their antimicrobial action depends on the type, composition and concentration of the oils, type and concentration of the target microorganism, composition of the substrate, processing and storage conditions (14,15). Moreover, to improve the shelf-life of the packaged food, an active packaging material could be created by adding an oil as an active compound to the wax formulation before coating of the pack material (16). The present work studied the application of three oils as natural preservatives against some pathogens on fresh foods like grated carrots. Poiana et al.