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

In this review, antimicrobials from a range of plant, animal, and microbial sources are reviewed

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The study was supported by Novartis.

SummaryThere is a diverse range of microbiological challenges facing the food, healthcare and clinical sectors. The increasing and pervasive resistance to broad-spectrum antibiotics and health-related concerns with many biocidal agents drives research for novel and complementary antimicrobial approaches. Biofilms display increased mechanical and antimicrobial stability and are the subject of extensive research. Cold plasmas (CP) have rapidly evolved as a technology for microbial decontamination, wound healing and cancer treatment, owing to the chemical and bio-active radicals generated known collectively as reactive oxygen and nitrogen species. This review outlines the basics of CP technology and discusses the interactions with a range of microbiological targets. Advances in mechanistic insights are presented and applications to food and clinical issues are discussed. The possibility of tailoring CP to control specific microbiological challenges is apparent. This review focuses on microbiological issues in relation to food-and healthcareassociated human infections, the role of CP in their elimination and the current status of plasma mechanisms of action.

bAtmospheric cold plasma (ACP) is a promising nonthermal technology effective against a wide range of pathogenic microorganisms. Reactive oxygen species (ROS) play a crucial inactivation role when air or other oxygen-containing gases are used. With strong oxidative stress, cells can be damaged by lipid peroxidation, enzyme inactivation, and DNA cleavage. Identification of ROS and an understanding of their role are important for advancing ACP applications for a range of complex microbiological issues. In this study, the inactivation efficacy of in-package high-voltage (80 kV [root mean square]) ACP (HVACP) and the role of intracellular ROS were investigated. Two mechanisms of inactivation were observed in which reactive species were found to either react primarily with the cell envelope or damage intracellular components. Escherichia coli was inactivated mainly by cell leakage and low-level DNA damage. Conversely, Staphylococcus aureus was mainly inactivated by intracellular damage, with significantly higher levels of intracellular ROS observed and little envelope damage. However, for both bacteria studied, increasing treatment time had a positive effect on the intracellular ROS levels generated.A tmospheric cold plasma (ACP) refers to nonequilibrated plasma generated at near-ambient temperatures and pressure. ACP is composed of particles, including free electrons, radicals, and positive and negative ions, but it is low in collision frequency of gas discharge compared to that with equilibrated plasma (1, 2). ACP technologies have widely been applied for many surface treatments and environmental processes. Recently, they have been studied for food sterilization and plasma medicine (2-5).ACP provides inactivation effects against a wide range of microbes, mainly by the generation of cell-lethal reactive species (6-8). By discharging in air, groups of reactive species are generated, such as reactive oxygen species (ROS), reactive nitrogen species (RNS), UV radiation, energetic ions, and charged particles (5). However, the inactivation efficacy can be varied by changing the working gases, which results in different types or amounts of reactive species generated (9-11). ROS are often identified as the principal effecting species, with a relatively long half-life and strong antimicrobial effects, which are generated in oxygen-containing gases (12).ROS generated during plasma discharge in air or oxygen-containing mixtures are assemblies of ozone, hydrogen peroxide, and singlet and atomic oxygen, while ozone is considered the most microbicidal species (13). With strong oxidative stress, cells are damaged by lipid peroxidation, enzyme inactivation, and DNA cleavage. The generation of plasma in air or a nitrogen-containing gas mixture can also generate NO x species. However, higher inactivation efficacy has been reported with the combined application of NO and H 2 O 2 on Escherichia coli than that with a treatment with NO or H 2 O 2 alone (14). Reactive nitrogen species are highly toxic and can lead to cell death by increas...

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Atmospheric cold plasma (ACP) represents a potential alternative to traditional methods for non-thermal decontamination of foods. In this study, the antimicrobial efficacy of a novel dielectric barrier discharge ACP device against Escherichia coli, Salmonella enterica Typhimurium and Listeria monocytogenes inoculated on cherry tomatoes and strawberries, was examined. Bacteria were spot inoculated on the produce surface, air dried and sealed inside a rigid polypropylene container. Samples were indirectly exposed (i.e. placed outside plasma discharge) to a high voltage (70kV RMS) air ACP and subsequently stored at room temperature for 24 h. ACP treatment for 10, 60 and 120 s resulted in reduction of Salmonella,