Cold atmospheric gas plasma disinfection of chicken meat and chicken skin contaminated with Listeria innocua

Gas plasmas generated at atmospheric pressure and ambient temperatures offer a possible decontamination method for poultry products. The efficacy of cold atmospheric gas plasmas for decontaminating chicken skin and muscle inoculated with Listeria innocua was examined. Optimization of operating conditions for maximal bacterial inactivation was first achieved using membrane filters on which L. innocua had been deposited. Higher values of AC voltage, excitation frequency and the presence of oxygen in the carrier gas resulted in the greatest inactivation efficiency, and this was confirmed with further studies on chicken muscle and skin. Under optimal conditions, a 10 s treatment gave > 3 log reductions of L. innocua on membrane filters, an 8 min treatment gave 1 log reduction on skin, and a 4 min treatment gave > 3 log reductions on muscle. These results show that the efficacy of gas plasma treatment is greatly affected by surface topography. Scanning electron microscopy (SEM) images of chicken muscle and skin revealed surface features wherein bacteria could effectively be protected from the chemical species generated within the gas plasma. The developments in gas plasma technology necessary for its commercial application to foods are discussed

Statement on safety of cannabidiol as a novel food: data gaps and uncertainties

The European Commission has determined that cannabidiol (CBD) can be considered as a novel food (NF), and currently, 19 applications are under assessment at EFSA. While assessing these, it has become clear that there are knowledge gaps that need to be addressed before a conclusion on the safety of CBD can be reached. Consequently, EFSA has issued this statement, summarising the state of knowledge on the safety of CBD consumption and highlighting areas where more data are needed. Literature searches for both animal and human studies have been conducted to identify safety concerns. Many human studies have been carried out with Epidyolex(R), a CBD drug authorised to treat refractory epilepsies. In the context of medical conditions, adverse effects are tolerated if the benefit outweighs the adverse effect. This is, however, not acceptable when considering CBD as a NF. Furthermore, most of the human data referred to in the CBD applications investigated the efficacy of Epidyolex (or CBD) at therapeutic doses. No NOAEL could be identified from these studies. Given the complexity and importance of CBD receptors and pathways, interactions need to be taken into account when considering CBD as a NF. The effects on drug metabolism need to be clarified. Toxicokinetics in different matrices, the half-life and accumulation need to be examined. The effect of CBD on liver, gastrointestinal tract, endocrine system, nervous system and on psychological function needs to be clarified. Studies in animals show significant reproductive toxicity, and the extent to which this occurs in humans generally and in women of child-bearing age specifically needs to be assessed. Considering the significant uncertainties and data gaps, the Panel concludes that the safety of CBD as a NF cannot currently be established

Variability in the Post-hatching Growth Trajectory of Alligator Hatchlings Incubated with and without the Eggshell

Our project investigated the importance of two putative roles of the calcareous eggshell in eggs of the American alligator: eggshell as a reservoir of calcium for embryonic development and growth, and eggshell as a barrier to bacterial infection. Using a novel experimental approach – peeling the eggshell and incubating the eggshell-less eggs, we tested three hypotheses: (1) alligators without eggshell show reduced skeletal maturity at hatching; (2) inhibition of carbonic anhydrase enzyme has the same effect as peeling the eggshell; and (3) bacterial inoculation results in greater embryonic mortality in the absence of the eggshell. Our (preliminary) results suggest that the eggshell is an important source of calcium, but is not required to prevent infection of egg contents

V.: A distributed architecture for enforcing norms in open mas

Abstract. Norms have been promoted as a coordination mechanism for controlling agent behaviours in open MAS. Thus, agent platforms must provide normative support, allowing both norm-aware and non normaware agents to take part in MAS controlled by norms. In this paper, the most relevant proposals on the definition of norm enforcement mechanisms have been analysed. These proposals present several drawbacks that make them unsuitable for open MAS. In response to these problems, this paper describes a new Norm-Enforcing Architecture aimed at controlling open MAS

Implementation of an individual-based model for microbial colony dynamics

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Influence of composition and processing of Frankfurter sausages on the growth dynamics of Listeria Monocytogenes under vacuum

© 2015 Elsevier Ltd. Ready-to-eat (RTE) meat products, such as Frankfurter sausages, are often linked to cases of listeriosis, which is a disease caused by the foodborne pathogen Listeria monocytogenes. Frankfurter sausages vary, from manufacturer to manufacturer, in many aspects: (i) composition, (ii) physicochemical characteristics, (iii) background flora, (iv) processing technology and (v) organoleptic characteristics. Some of these factors have been widely investigated for their effect on L. monocytogenes on food products. However, studies on the specific effect of composition and processing technology on L. monocytogenes dynamics between two sausages are lacking. In this study, the growth dynamics of L. monocytogenes on two types of Frankfurter sausages, fresh and in brine, were studied at constant storage temperatures (4, 8 and 12°C). Additionally, the physicochemical and compositional characteristics of both types of sausages were analysed. In order to study the isolated effect of preservatives, L. monocytogenes growth dynamics, at 4°C and 30°C, were studied in two types of liquid systems. These were prepared with the same level of preservatives as in the two types of sausages. Results indicated no major significant differences in physicochemical characteristics for the two types of sausages; but, statistically significant variability was detected in the concentration of preservatives. In liquid systems, the maximum specific growth rate (μmax) remained unaffected by the effect of preservatives, but the lag phase was longer in the system mimicking fresh sausages. In sausages, the 'in brine' type had two-fold higher μmax at all temperatures and shorter lag phase at 4°C. The presence/absence of sausage skin, which was found to be impermeable from L. monocytogenes cells and was present in the fresh sausage, could explain those differences. In conclusion, this study highlighted the influence of processing factors, and specifically of the sausage casing on L. monocytogenes growth dynamics. Therefore, an edible membrane, which is heat resistant and impermeable to the cells, could be a hurdle strategy to control the microbiological food safety. monocytogenes growth dynamics can vary in different types of Frankfurters. monocytogenes growth on Frankfurters. monocytogenes growth on Frankfurters. monocytogenes cells.publisher: Elsevier articletitle: Influence of composition and processing of Frankfurter sausages on the growth dynamics of Listeria monocytogenes under vacuum journaltitle: Food Research International articlelink: http://dx.doi.org/10.1016/j.foodres.2014.12.047 content_type: article copyright: Copyright © 2015 Elsevier Ltd. All rights reserved.status: publishe

An individual-based modeling approach to simulate the effects of cellular nutrient competition on Escherichia coli K-12 MG1655 colony behavior and interactions in aerobic structured food systems

Traditional kinetic models in predictive microbiology reliably predict macroscopic dynamics of planktonically-growing cell cultures in homogeneous liquid food systems. However, most food products have a semi-solid structure, where microorganisms grow locally in colonies. Individual colony cells exhibit strongly different and non-normally distributed behavior due to local nutrient competition. As a result, traditional models considering average population behavior in a homogeneous system do not describe colony dynamics in full detail. To incorporate local resource competition and individual cell differences, an individual-based modeling approach has been applied to Escherichia coli K-12 MG1655 colonies, considering the microbial cell as modeling unit. The first contribution of this individual-based model is to describe single colony growth under nutrient-deprived conditions. More specifically, the linear and stationary phase in the evolution of the colony radius, the evolution from a disk-like to branching morphology, and the emergence of a starvation zone in the colony center are simulated and compared to available experimental data. These phenomena occur earlier at more severe nutrient depletion conditions, i.e., at lower nutrient diffusivity and initial nutrient concentration in the medium. Furthermore, intercolony interactions have been simulated. Higher inoculum densities lead to stronger intercolony interactions, such as colony merging and smaller colony sizes, due to nutrient competition. This individual-based model contributes to the elucidation of characteristic experimentally observed colony behavior from mechanistic information about cellular physiology and interactions.publisher: Elsevier articletitle: An individual-based modeling approach to simulate the effects of cellular nutrient competition on Escherichia coli K-12 MG1655 colony behavior and interactions in aerobic structured food systems journaltitle: Food Microbiology articlelink: http://dx.doi.org/10.1016/j.fm.2014.05.003 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.status: publishe

The metabolism of Escherichia coli as a multiparametric programming problem

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Critical assessment of the Time-To-Detection method’s performance to estimate microbial growth parameters

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Effect of cell immobilization on the growth dynamics of Salmonella Typhimurium and Escherichia coli at suboptimal temperatures

Predictive microbiology has recently acknowledged the impact of the solid(like) food structure on microbial behavior. The presence of this solid(like) structure causes microorganisms to grow as colonies and no longer planktonically as in liquid. In this paper, the growth dynamics of Salmonella Typhimurium and Escherichia coli were studied as a function of temperature, considering different growth morphologies, i.e., (i) planktonic cells, (ii) immersed colonies and (iii) surface colonies. For all three growth morphologies, both microorganisms were grown in petri dishes. While E. coli was grown under optimal pH and water activity (aw), for S. Typhimurium pH and aw were adapted to 5.5 and 0.990. In order to mimic a solid(like) environment, 5% (w/v) gelatin was added. All petri dishes were incubated under static conditions at temperatures in the range [8.0°C-22.0°C]. Cell density was determined via viable plate counting. This work demonstrates that the growth morphology (planktonic vs. colony) has a negligible effect on the growth dynamics as a function of temperature. The observation of almost equal growth rates for planktonic cultures and colonies is in contrast to literature where, mostly, a difference is observed, i.e., μplanktonic cells≥μimmersed colonies≥μsurface colonies. This difference might be due to shaking of the liquid culture in these studies, which results in a nutrient and oxygen rich environment, in contrast to the diffusion-limited gel system. Experiments also indicate that lag phases for solid(like) systems are similar to those for the planktonic cultures, as can be found in literature for similar growth conditions. Considering the maximum cell density, no clear trend was deducted for either of the microorganisms. This study indicates that the growth parameters in the suboptimal temperature range do not depend on the growth morphology. For the considered experimental conditions, models previously developed for liquid environments can be used for solid(like) systems.publisher: Elsevier articletitle: Effect of cell immobilization on the growth dynamics of Salmonella Typhimurium and Escherichia coli at suboptimal temperatures journaltitle: International Journal of Food Microbiology articlelink: http://dx.doi.org/10.1016/j.ijfoodmicro.2015.05.011 content_type: article copyright: Copyright © 2015 Elsevier B.V. All rights reserved.status: publishe