Different strategies have been developed over the years to improve the safety of foods without compromising on their quality. Ultraviolet (UV) light has shown potential to meet these expectations. ...However, due to environmental and safety concerns regarding the use of UV mercury lamps, UV-light emitting diode (LED) devices have emerged more recently, which may be more suited to applications in the food industry. Thus, further evaluation of UV-LED technology is required.
In this review, challenges involving the application of UV-LED technology as a disinfection strategy in the food chain are described. Stress-related mechanisms induced by UV light exposure in microorganisms and their potential consequences are reviewed. Moreover, other future challenges associated with the inactivation of foodborne pathogens and spoilage microorganisms are considered, together with the impact of the application of UV-LED technology on the quality of food.
UV-LEDs have been shown to inactivate a wide range of foodborne pathogens and spoilage microorganisms. However, there are limited studies assessing the effectiveness of UV-LED on products to enhance food safety. Additionally, further studies are required to explore the impact of sublethal exposure to UV-LEDs and the potential consequences of UV-LED exposure in different microorganisms at various wavelengths. Furthermore, UV-LEDs can negatively affect some physicochemical attributes of food. Thus, more attention should be paid to the underlying mechanism of quality changes induced by UV-LEDs.
•Challenges in applying UV-LED in food for microbial inactivation are reviewed.•The impact of UV-LED on food quality attributes is discussed.•Microbial stress-related mechanisms when exposed to UV-LED light are reviewed.•A better understanding of DNA-repair mechanisms induced by UV-LED is required.•The effect of UV-LED on food safety and quality requires further investigation.
Application of novel decontamination strategies such as Ultraviolet (UV) irradiation are required to mitigate the risks associated with Campylobacter jejuni in food. This study evaluated the use of a ...light-emitting diode (LED) based technology to inactivate C. jejuni NCTC 11168 in Maximum Recovery Diluent (MRD) at wavelengths of 280, 300 and 365 nm and combinations. To assess the survival curves, two linear (Log linear (LL) and Linear and Shoulder) and two non-linear models (Weibull and Double Weibull) were fitted. UV exposures showed different antimicrobial effects where a combination of 280/300 nm was the most effective treatment with a 4Dt value of 5 s observed in a bacterial suspension of 5 log CFU/mL. Moreover, the LL model was the most robust model to describe the inactivation kinetics of Campylobacter when exposed to UV and therefore, modelling tools could be applied to predict the efficiency of UV light in a model solution.
Industrial relevance: Light-based technologies like UV light are identified in the literature as potential alternatives to assure the decontamination of surfaces, liquids and solid food. However, some of these techniques require further investigation. The present study evaluated the use of a LED system and effect of combined wavelengths in the inactivation of Campylobacter through predictive modelling. This technique was observed to predict and explain kinetics of inactivation of Campylobacter and could be key in the scaling-up process of UV light at industrial level.
•The studied UV wavelengths showed Campylobacter reductions of 4 log CFU/mL in MRD.•The combination of 280 and 300 nm for 5 s showed the highest inactivation rate.•Log linear models demonstrated the best fit performance to survival curves.
Campylobacter jejuni is the leading bacterial food-borne pathogen within the European Union, and poultry meat is an important vehicle for its transmission to humans. However, there is limited ...knowledge about how this organism persists in broiler litter and faeces. The aim of this study was to assess the impact of a number of environmental parameters, such as temperature, humidity, and oxygen, on Campylobacter survival in both broiler litter and faeces.
Used litter was collected from a Campylobacter-negative broiler house after final depopulation and fresh faeces were collected from transport crates. Samples were confirmed as Campylobacter negative according to modified ISO methods for veterinary samples. Both sample matrices were inoculated with 9 log
10
CFU/ml C. jejuni and incubated under high (≥85%) and low (≤70%) relative humidity conditions at three different temperatures (20°C, 25°C, and 30°C) under both aerobic and microaerophilic atmospheres. Inoculated litter samples were then tested for Campylobacter concentrations at time zero and every 2 hours for 12 hours, while faecal samples were examined at time zero and every 24 hours for 120 hours. A two-tailed t-test assuming unequal variance was used to compare mean Campylobacter concentrations in samples under the various temperature, humidity, and atmospheric conditions.
C. jejuni survived significantly longer (P≤0.01) in faeces, with a minimum survival time of 48 hours, compared with 4 hours in used broiler litter. C. jejuni survival was significantly enhanced at 20°C in all environmental conditions in both sample matrices tested compared with survival at 25°C and 30°C. In general, survival was greater in microaerophilic compared with aerobic conditions in both sample matrices. Humidity, at the levels examined, did not appear to significantly impact C. jejuni survival in any sample matrix. The persistence of Campylobacter in broiler litter and faeces under various environmental conditions has implications for farm litter management, hygiene, and disinfection practices.
Campylobacteriosis is one of the most common bacterial infections worldwide causing economic costs. The high prevalence of Campylobacter spp. in poultry meat is a result of several contamination and ...cross‐contamination sources through the production chain. Moreover, survival mechanisms, such as biofilm formation, viable but nonculturable state, and antimicrobial resistance, enable its persistence during food processing. Therefore, mitigation strategies are necessary in order to avoid and/or inactivate Campylobacter at farm, abattoir, industry, and retail level. In this review, a number of potential strategies and novel technologies that could reduce the prevalence of Campylobacter in poultry meat have been identified and evaluated to provide a useful overview. At farm level for instance, biosecurity, bacteriocins, probiotics, feed and water additives, bacteriophages, and vaccination could potentially reduce colonization in chicken flocks. However, current technologies used in the chicken slaughter and processing industry may be less effective against this foodborne pathogen. Novel technologies and strategies such as cold plasma, ultraviolet light, high‐intensity light pulses, pulsed electric fields, antimicrobials, and modified atmosphere packaging are discussed in this review for reducing Campylobacter contamination. Although these measures have achieved promising results, most have not been integrated within processing operations due to a lack of knowledge or an unwillingness to implement these into existing processing systems. Furthermore, a combination of existing and novel strategies might be required to decrease the prevalence of this pathogen in poultry meat and enhance food safety. Therefore, further research will be essential to assess the effectiveness of all these strategies.
Although primarily considered to be a nosocomial infection, there is mounting evidence that food, including beef products, may be a source of Clostridioides (Clostridium) difficile. The objective of ...this study was to investigate the behaviour of this pathogen under atmospheric and temperature conditions that may be encountered in vacuum packaged retail beef. Inoculated steaks were stored in air, in low (950 cm3/m2·d· bar), medium (<47 cm3/m2·d· bar) and high barrier (<3 cm3/m2·d· bar) vacuum packs and under anaerobic conditions at 2 °C and 20 °C. At 2 °C a steady decline in C. difficile concentrations was observed over the 32 days of storage, regardless of oxygen conditions. In contrast, in the temperature abuse scenario, the bacterial counts were significantly (P < 0.05) higher in the medium and high barrier packs and under anaerobic conditions after 2 days and increased up to approximately 5 log10 cfu/g by day 8. It was concluded that under chilled conditions, C. difficile will survive, all-be-it at lower concentrations, for extended periods (up to 32 days) but in a temperature abuse scenario these bacteria will grow on beef steaks stored in medium and high barrier vacuum packs and under anaerobic conditions. Given the increase in community acquired C. difficile infections, the potential role of vacuum packaged steaks as a foodborne source of these pathogens requires further investigation.
•C. difficile survives in vacuum packaged steaks at chilled temperatures.•C. difficile will grow on medium and high barrier vacuum packaged steaks at abuse temperatures.•Vacuum packaged steaks are a potential foodborne source of C. difficile.
Bacterial drug resistance represents one of the most crucial problems in present day antibacterial chemotherapy. Of particular concern to public health is the continuing worldwide epidemic spread of ...Salmonella enterica serovar Typhimurium phage type DT104 harbouring a genomic island called Salmonella genomic island I (SGI-1). This island contains an antibiotic gene cluster conferring resistance to ampicillin, chloramphenicol, florfenicol, streptomycin, sulfonamides and tetracyclines. These resistance genes are assembled in a mosaic pattern, indicative of several independent recombinational events. The mobility of SGI-1 coupled with the ability of various antibiotic resistance genes to be integrated and lost from the chromosomal resistance locus allows for the transfer of stable antibiotic resistance to most of the commonly used antibiotics and adaptation to new antibiotic challenges. This, coupled with the incidence of increasing fluoroquinolone resistance in these strains increases the risk of therapeutic failure in cases of life-threatening salmonellosis. Fluoroquinolone resistance has largely been attributed to mutations occurring in the genes coding for intracellular targets of these drugs. However, efflux by the AcrAB-TolC multi-drug efflux pump has recently been shown to directly contribute to fluoroquinolone resistance. Furthermore, the resistance to chloramphenicol-florfenicol and tetracyclines in DT104 isolates, is due to interaction between specific transporters for these antibiotics encoded by genes mapping to the SGI-1 and the AcrAB-TolC tripartite efflux pump. The potential for the use of efflux pump inhibitors to restore therapeutic efficacy to fluoroquinolones and other antibiotics offers an exciting developmental area for drug discovery.
ABSTRACT
The presence of anaerobic microflora on fresh beef carcass and rump steaks, which may contribute to meat spoilage, was explored in this study. A total of 120 carcass and 120 rump steak swabs ...were collected immediately after slaughtering and boning, respectively from five meat plants, anaerobically incubated and enriched at 4°C for 3 weeks. This was followed by DNA extraction and 16S rRNA amplicon sequencing using the Illumina MiSeq, with subsequent bioinformatics analysis. The enriched microbiota of the samples was classified and grouped into 149 operational taxonomic units (OTUs). The microbiota recovered from both sample types consisted mainly of Carnobacterium, with an average relative abundance of 28.4% and 32.8% in beef carcasses and beef rump steaks, respectively. This was followed by Streptococcus, Serratia, Lactococcus, Enterococcus, Escherichia-Shigella, Raoultella and Aeromonas ranging from 1.5 to 20% and 0.1 to 29.8% in enriched carcasses and rump steak swabs, respectively. Trichococcus, Bacteroides, Dysgomonas, Providencia, Paraclostridium and Proteus were also present ranging from 0 to 0.8% on carcass and 0 to 1.8% on rump steak swabs, respectively. Alpha and beta diversity measurements showed limited diversity between the two sample types, but some differences between samples from the beef plants investigated were evident. This study highlights the presence of potential spoilage bacteria, mainly anaerobic genera on and between carcass and rump steaks, as an indication of contamination on and between these samples.
Microbial spoilage of beef carcass and rump steak cuts.
This study tested 24 Campylobacter isolates for the presence of 35 virulence genes using the polymerase chain reaction. The target genes included those involved in motility (flaA, flaB, flhA, flhB, ...flgB, flgE2, fliM, fliY), chemotaxis (cheA, cheB, cheR, cheW, cheY, cheZ), cell adhesion (cadF, dnaJ, jlpA, pldA, racR, virB11), invasion (iamA, ciaB, ceuE), cytotoxin production (cdtA, cdtB, cdtC, wlaN), capsule (kpsM), multidrug and bile resistance (cmeA, cmeB, cmeC), stress response/survival (katA, sodB), and the iron uptake system (cfrA, fur). The motility genes (with the exception of flaB), the CmeABC efflux system, cdtABC genes, and the sodB gene were commonly distributed among Campylobacter strains while the virB11 and wlaN genes were rarely detected. Interestingly, the findings suggest that flaB is not essential for full motility and C. coli lacking the flhA gene may be highly invasive. This study provides additional information on the distribution of Campylobacter virulence factors and the effect of their presence/absence on adhesion and invasion. It will inform future studies designed to elucidate the exact mechanisms of pathogenesis in Campylobacter.
Transfer of Escherichia coli in bioaerosols to humans during and shortly after the land application of farmyard slurry may pose human health hazards, but it has not been extensively explored to date. ...The present study developed a quantitative risk assessment model for E. coli through the air exposure route. The probabilistic model assessed the predicted number of microorganisms in the air (PNair) to which humans may be exposed. A Gaussian air dispersion model was used to calculate the concentration of E. coli transmitted through aerosols. Human exposure (HE) to E. coli was estimated using a Monte Carlo simulation approach. This research predicted the mean HE as 26 CFU day−1 (95th percentile 263 CFU day−1) and suggests the importance of keeping a distance of at least 100 m for the residential population from land spreading activities. However, the simulated mean daily or annual (once a year application) risk of 2.65 × 10−7 person−1 year−1 due to land application of slurry indicates very low occupational risk for farmworkers not equipped with the personal protective equipment (PPE), who are potentially exposed to E. coli indirectly. The model found that the decay constant of E. coli in air, duration of decay, and bio-aerosolisation efficiency factor (top three) could influence HE to airborne E. coli. Furthermore, this research recommends an average time lag of at least 2.5 h following the application of farmyard slurry to the field before humans access the field again without PPE, allowing the airborne pathogen to decay, thereby ensuring occupational safety. The model suggested that the bio-aerosolisation efficiency factor (E) for other pathogens requires further investigation. The information generated from this model can help to assess likely exposure from bioaerosols triggered by land application of farmyard slurry.
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•Land application of farmyard slurry results in bioaerosols containing E. coli.•Pathogenic E. coli pose significant human health hazards.•A probabilistic mathematical model was developed for this research.•A minimum distance of 100 m from land spreading activities is recommended.•An average time lag of 2.5 h following land application before human access to the field without PPE.
The control of bacterial contaminants on meat is a key area of interest in the food industry. Bacteria are exposed to a variety of stresses during broiler processing which challenge bacterial ...structures and metabolic pathways causing death or sublethal injury. To counter these stresses, bacteria possess robust response systems that can induce shifts in the transcriptome and proteome to enable survival. Effective adaptive responses, such as biofilm formation, shock protein production and metabolic flexibility, require rapid induction and implementation at a cellular and community level to facilitate bacterial survival in adverse conditions. This review aims to provide an overview of the scientific literature pertaining to the regulation of complex adaptive processes used by bacteria to survive the processing environment, with particular focus on species that impact the quality and safety of poultry products like
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