Effect of Ground Beef Irradiation on Annual Nontyphoidal Salmonella and Escherichia coli O157 Burden and Direct Healthcare Costs in the United States: A Simulation Study.

Over 20% of E. coli O157 illnesses and over 5% of Salmonella illnesses are estimated to be attributable to beef consumption in the United States. Irradiating ground beef is one possible method to reduce disease burden. We simulated the effect of ground beef irradiation on illnesses, hospitalizations, deaths, and direct healthcare costs from ground beef-associated E. coli O157 and Salmonella illnesses in the United States. To estimate the fraction of illnesses, hospitalizations, deaths, and direct healthcare costs preventable by ground beef irradiation, we multiplied the disease burden attributable to ground beef; the estimated percentage of ground beef sold that is not currently irradiated; the percentage of unirradiated ground beef that would be irradiated; and the percentage reduction in risk of illness after irradiation. We multiplied this fraction by estimates of burden and direct healthcare costs to calculate the numbers or amounts averted. Model inputs were obtained from the literature and expert opinion. We used Monte Carlo simulation to incorporate uncertainty in inputs into model estimates. Simulation outcomes were summarized with means and 95% uncertainty intervals (UI). Irradiating 50% of the currently unirradiated ground beef supply would avert 3,285 (95% UI: 624-9,977) E. coli O157 illnesses, 135 (95% UI: 24-397) hospitalizations, 197 (95% UI: 34-631) hemolytic uremic syndrome cases, 2 (95% UI: 0-16) deaths, and $2,972,656 (95% UI: $254,708-$14,496,916) in direct healthcare costs annually. For Salmonella, irradiation would avert 20,308 (95% UI: 9,858-38,903) illnesses, 400 (95% UI: 158-834) hospitalizations, 6 (95% UI: 0-18) deaths, and $7,318,632 (95% UI: $1,436,141-$26,439,493) in direct healthcare costs. Increasing ground beef irradiation could reduce E. coli O157 and Salmonella burden in the United States. Additional studies should assess whether targeted irradiation of higher-risk ground beef products could prevent similar numbers of illnesses with less total product irradiated.

Development and evaluation of a point-of-use UV appliance for fresh produce decontamination.

In-house treatment strategy for fresh produce decontamination has not been emphasized as much as industrial washing. The most common treatment for fresh produce decontamination and cleaning at home and other point-of-use places such as cafeteria is rinsing and/or soaking in a sink. In this study, an appliance utilizing UV and agitated water to decontaminate fresh produce was developed and its effectiveness was investigated in an aim to identify optimum processing parameters. Grape tomato and spinach representing two different surface smoothness were dip-inoculated in a four-strain Salmonella cocktail to reach a final population of 5-8 log CFU/g and air-dried. The produce samples were then washed in 1 gallon tap water under varying conditions, water agitation speed (0-190 RPM), sample size (50-400 g), UV intensity (0-30 mW/cm2) and treatment time (2, 5 and 10 min). In general, increasing the agitation speed and UV intensity enhanced Salmonella inactivation for both grape tomato and spinach. Sample size significantly affected the UV inactivation of Salmonella on grape tomato, but not on spinach. The effect of extending treatment time from 2 to 10 min was insignificant for almost all the UV treatments and the controls. The effect of UV intensity and treatment time on inactivation of Salmonella on spot-inoculated grape tomato and spinach was also determined. The most severe treatment used in this study, 30 mW/cm2 UV for 10 min, resulted in >4 log reductions of Salmonella dip- or spot-inoculated on grape tomato (200 g sample size and 190 RPM agitation speed) and 3.5 log reductions of Salmonella dip- or spot-inoculated on spinach (100 g sample size and 110 RPM agitation speed). We foresee that the UV appliance developed and evaluated in this study could be further fine-tuned and optimized to eventually construct a point-of-use UV appliance that can be used at home, cafeteria, restaurants, and hospitals for fresh produce decontamination and cleaning. The UV appliance could be an inexpensive and effective tool to improve fresh produce safety.

Catalytic intense pulse light inactivation of Cronobacter sakazakii and other pathogens in non-fat dry milk and wheat flour.

The outbreaks of Cronobacter sakazakii, Salmonella spp, and Bacillus cereus in powdered foods have been increasing in worldwide. However, an effective method to pasteurize powdered foods before consumption remains lacking. A prototype Intense Pulsed Light (IPL) system was developed to disinfect powdered foods under different IPL and environmental conditions. Synergistic effect of IPL and TiO2 photocatalysis on microbial inactivation was studied. The results show that high energy intensity of each pulse, high peak intensity, and short pulsed duration contributed to a high microbe inactivation. With TiO2 photocatalysis, one additional log10 reduction was achieved, bringing the total log reduction to 4.71 ± 0.07 (C. sakazakii), 3.49 ± 0.01 (E. faecium), and 2.52 ± 0.10 (B. cereus) in non-fat dry milk, and 5.42 ± 0.10 (C. sakazakii), 4.95 ± 0.24 (E. faecium), 2.80 ± 0.23 (B. cereus) in wheat flour. IPL treatment combined with the TiO2 photocatalysis exhibits a strong potential to reduce the energy consumption in improving the safety of powdered foods.

Selection for Antimicrobial Resistance in Foodborne Pathogens through Exposure to UV Light and Nonthermal Atmospheric Plasma Decontamination Techniques.

This study was aimed at assessing whether the repeated exposure of 12 strains of Salmonella spp., Escherichia coli, and Listeria monocytogenes to alternative nonthermal decontamination techniques with UV light (UV-C) and nonthermal atmospheric plasma (NTAP) may cause the emergence of variants showing increased resistance to clinically relevant antibiotics (ampicillin, cefotaxime, ciprofloxacin, gentamicin, streptomycin, tetracycline, erythromycin, vancomycin, and colistin). UV-C and NTAP treatments were applied on the surface of inoculated brain heart infusion (BHI) agar plates. Survivors were recovered and after 24 h of growth in BHI broth were again subjected to the decontamination treatment; this was repeated for 10 consecutive cycles. A total of 174 strain/decontamination technique/antibiotic combinations were tested, and 12 variant strains with increased resistance to one of the antibiotics studied were identified, with the increases in the MICs in Mueller-Hinton broth ranging from 2- to 256-fold. The variant strains of Salmonella spp. isolated were further characterized through phenotypic screenings and whole-genome sequencing (WGS) analyses. Most changes in susceptibility were observed for antibiotics that act at the level of protein synthesis (aminoglycosides, tetracyclines, and glycylcyclines) or DNA replication (fluoroquinolones), as well as for polymyxins. No changes in resistance to ß-lactams were detected. WGS analyses showed the occurrence of sequence alterations in some antibiotic cellular targets (e.g., gyrA for ciprofloxacin-resistant variants, rpsL for a streptomycin-resistant variant), accompanied by variations in stress response regulators and membrane transporters likely involved in the nonselective efflux of antibiotics, which altogether resulted in a low- to medium-level increase in microbial resistance to several antibiotics.IMPORTANCE The emergence and spread of antibiotic resistance along the food chain can be influenced by the different antimicrobial strategies used from farm to fork. This study evidences that two novel, not yet widely used, nonthermal microbial decontamination techniques, UV light and nonthermal atmospheric plasma, can select variants with increased resistance to various clinically relevant antibiotics, such as ciprofloxacin, streptomycin, tetracycline, and erythromycin. Whole-genome analysis of the resistant variants obtained for Salmonella spp. allowed identification of the genetic changes responsible for the observed phenotypes and suggested that some antimicrobial classes are more susceptible to the cross-resistance phenomena observed. This information is relevant, since these novel decontamination techniques are being proposed as possible alternative green techniques for the decontamination of environments and equipment in food and clinical settings.

Efficacy of pulsed-ultraviolet light for inactivation of Salmonella spp on black peppercorns.

Efficacy of pulsed ultraviolet (PUV) to inactivate Salmonella pure culture and on inoculated black peppercorns was evaluated. Black peppercorns inoculated with Salmonella were subjected to PUV treatment (0.28 J/cm2 /pulse) using two different sample holders, on a traditional flat surface or on a wave-shaped surface to increase surface exposure of peppercorns to PUV through light reflection. The temperature change on black peppercorns surface during treatment was recorded, and the effect of cooling period during PUV treatment was studied. PUV treatment of two pulses reduced Salmonella population by more than 6 log CFU/mL in phosphate-buffered saline. Continuous PUV treatment (80 pulses on each side) using a wave-shaped surface was able to reduce Salmonella by 1.9 log CFU/g; same treatment using flat surface reduced Salmonella by less than 1.5 log CFU/g. The temperature on peppercorns surface increased to 65 °C after 80 pulses continuous PUV treatment. Adding 280 s cooling time after every 20 pulses reduced the temperature from 65 to 40 °C and achieved similar Salmonella inactivation (P > 0.05) as the continuous PUV treatment. Results from this study showcase the effectiveness of PUV treatment for reducing Salmonella level on black peppercorns surface and provided insights on the potential implementation of PUV treatment at the industrial level. PRACTICAL APPLICATION: Results from this study showcased the effectiveness of PUV treatment for reducing Salmonella level on black peppercorns surface and provided insights on the potential implementation of PUV treatment at the industrial level.

Radiofrequency-Assisted Thermal Processing of Soft Wheat Flour.

Wheat flour may be thermally processed to improve microbiological safety; however, come-up time for thermal processing of wheat flour is long due to its low thermal conductivity. In the present study, a novel radiofrequency (RF)-assisted thermal processing approach was investigated for reducing the come-up time of soft wheat flour (SWF) and for improving microbiological safety. The temperature and time combinations of 80 °C for 7 and 10 hr, 90 °C for 2 and 3 hr, and 100 °C for 0.75 and 1 hr for RF-assisted thermal processing were selected to achieve a minimum of a 7-log reduction in Salmonella spp. The quality and functional properties of RF-assisted thermally processed SWF was evaluated by solvent retention capacity (SRC), swelling power, sodium dodecyl sulfate sedimentation tests, and rapid-visco-analyzer test, and the values were compared with the untreated (unpasteurized) and commercially pasteurized SWF. All the SRC attributes at 80 °C for 7 hr, 90 °C for 2 hr and 100 °C for 0.75 hr were not significantly different from that of the unpasteurized SWF. The optimum RF-assisted thermal processing conditions of 80 °C for 7 hr and 90 °C for 2 hr were recommended for pasteurization of SWF without any compromise in the quality and functionality. PRACTICAL APPLICATION: Thermal processing of low-moisture foods such as flours and powders through traditional methods is not practical due to extremely long come-up times. Novel radiofrequency-assisted thermal processing is poised to reduce the processing time 89 times for 100 °C. The processing parameters determined in this study will enhance the microbiological safety of wheat flour without compromising the quality and functionality.

Effects of intense pulsed light on Cronobacter sakazakii and Salmonella surrogate Enterococcus faecium inoculated in different powdered foods.

Cronobacter sakazakii and Salmonella spp. are foodborne pathogens associated with low moisture foods. An intense pulsed light (IPL) system is being developed as an alternative novel method to pasteurize powdered food. The aim of the study is to investigate the microorganism inactivation in different powdered foods and a variety of related variables using a vibratory-assisted IPL system. The results showed that C. sakazakii on non-fat dry milk (NFDM), wheat flour, and egg white powder were significantly inactivated by 5.27, 4.92, and 5.30 log10 CFU/g, respectively, after 3 or 4 passes of IPL treatments. For decontamination of E. faecium, 3-4 passes of IPL treatments reduced the E. faecium level on NFDM, wheat flour, and egg white by 3.67, 2.79, 2.74 log10 CFU/g, respectively. These results demonstrated that the enhanced microbiological inactivation can be achieved using this vibratory-assisted IPL system after multiple passes.

Comparative Effects of Thermal, High Hydrostatic Pressure, and UV-C Processing on the Quality, Nutritional Attributes, and Inactivation of Escherichia coli, Salmonella, and Listeria Introduced into Tiger Nut Milk.

HIGHLIGHTS: Thermal and nonthermal methods can support a 5-log CFU reduction of model bacteria introduced into tiger nut milk. Thermal treatment of tiger nut milk results in significant loss of protein, antioxidants, and quality properties. HHP or UV-C treatment of tiger nut milk retains quality and nutritional characteristics. HHP or UV-C are suitable for the pasteurization of tiger nut milk.

Comparison of Water-Assisted Decontamination Systems of Pulsed Light and Ultraviolet for Salmonella Inactivation on Blueberry, Tomato, and Lettuce.

Fresh produce are vulnerable to pathogens during pre- and postharvest stages. Most fresh vegetable and fruits are consumed directly or merely washed with chlorine. We investigated two emerging decontamination technologies, pulse light (PL) and ultraviolet (UV), in combination with washing (referred as water-assisted PL [WPL] and water-assisted UV [WUV]). Blueberries, grape tomatoes, and iceberg lettuce shreds were tested in this study to represent fresh vegetables and fruits with smooth and rough surfaces. Salmonella spp. were used as a model microorganism due to its prevalence in outbreaks. Spot-inoculation and dip-inoculation were used to simulate potential contaminations during irrigation, harvest, transportation, and processing. Two intensity levels of PL (∼0.15 and 0.3 J/cm2 per pulse; 3 pulses/s) and UV (∼13 and 28 mW/cm2 ) were tested for 1 and 2 min. For all three types of fresh produce, blueberries, grape tomatoes, and iceberg lettuce shreds, WPL and WUV showed similar Salmonella inactivation effects on fresh produce. For spot-inoculated fresh produce, WPL and WUV treatments reduced 4.5 to 5.7, 4.4 to 5.4, and 1.9 to 3.1 logs of Salmonella on blueberries, tomatoes, and lettuce shreds, respectively. For dip-inoculated fresh produce, WPL and WUV treatments reduced 1.8 to 2.3, 1.9 to 2.5, and 1.9 to 2.6 logs of Salmonella on blueberries, tomatoes, and lettuce shreds, respectively. The majority of the WUV and WPL treatments could eliminate Salmonella in the wash water for blueberries and tomatoes, but not for lettuce. PRACTICAL APPLICATION: Two light systems, pulsed light and UV, for decontamination of fresh produce were evaluated and compared. Results demonstrated that the two systems showed similar decontamination effect on fresh produce, demonstrating that the UV system could be used to replace the pulsed light system to reduce equipment cost.

Inactivation of Listeria monocytogenes and Salmonella spp. on cantaloupe rinds by blue light emitting diodes (LEDs).

This study evaluated the potential of blue light-emitting diodes (LED) of wavelength 405 and 460 nm in combination with sodium chlorophyllin to inactivate Listeria monocytogenes and Salmonella spp. on cantaloupe rind. A cocktail culture of L. monocytogenes or Salmonella spp. strains was surface inoculated onto cantaloupe rinds to reach a final concentration of 4 log CFU/cm2 and dip-treated in a 100 µM sodium copper chlorophyllin solution. The cantaloupe samples were then exposed to 405 or 460 nm LEDs at a total dose of 1210 J/cm2 and 5356 J/cm2, respectively, at 4 and 20 °C. Results showed that the antibacterial efficacy against both pathogens on cantaloupe rinds between LED alone and LED with the chlorophyllin were statistically similar with bacterial inactivation ranging from 1.1 to 3 log CFU/cm2 in most of the cases or the difference was only minimal. A similar inactivation of 3 log CFU/cm2 was obtained in the case of L. monocytogenes and Salmonella spp. when illuminated by 405 nm LEDs while the inactivation of L. monocytogenes was higher than Salmonella spp. when illuminated by 460 nm LED. The δ value, a modified Weibull model parameter defined as the time (h) taken to reduce the bacterial population by 90%, was computed to compare the inactivation rates of the conditions. It was inferred that illumination with 405 nm LED required a lower δ value than 460 nm LED illumination (P < 0.05) for the inactivation of L. monocytogenes at 20 °C and Salmonella spp. at 4 °C. Thus the findings of this study indicate a promising application of blue LEDs to inactivate these pathogens on the surface of cantaloupe, minimizing the risk of listeriosis and salmonellosis by consumption of cantaloupe.

Evaluation of inactivating Salmonella on iceberg lettuce shreds with washing process in combination with pulsed light, ultrasound and chlorine.

This study was conducted to investigate the Salmonella inactivation effects of washing in combination with pulsed light (PL), ultrasound, and chlorine on lettuce shreds. First, the effect of washing combined with PL and chlorine on the inactivation of Salmonella on lettuce and in wash water was evaluated in a small-scale study with clear tap water and turbid tap water containing lettuce extract and silicon dioxide. In general, water wash combined with PL (PL wash) and chlorine wash combined with PL (PL-Cl) were significantly more effective on killing Salmonella on lettuce than the chlorine wash and water wash regardless the wash water quality and inoculation method. We then tested washing combined with PL, ultrasound and chlorine using a large-scale UV setup with turbid wash water. Increasing the sample size decreased the decontamination efficacy of all the treatments. All the treatments resulted in <2 log reductions of Salmonella on lettuce shreds. For both small- and large-scale studies, treatments involving chlorine could keep the Salmonella population in wash water under the detection limit of 2 CFU/mL for almost all the replicates. Taking everything into consideration, we concluded that the combined PL-Cl treatment could be a better alternative to the chlorine wash for lettuce decontamination since it was in general more effective on inactivating Salmonella on lettuce than chlorine wash and could maintain the Salmonella level in wash water under the detection limit of 2 CFU/mL regardless the inoculation method, water quality and sample size, preventing the potential cross contamination through wash water.

Strategies to enhance fresh produce decontamination using combined treatments of ultraviolet, washing and disinfectants.

This study investigated the effect of a water-assisted ultraviolet system (WUV; samples were treated by UV while being immersed in agitated water) on the inactivation of Salmonella on baby spinach, iceberg lettuce, blueberry, grape tomato, and baby-cut carrot. The Salmonella inactivation effect of the WUV system was tested in two scales, and three disinfectants, chlorine, peroxyacetic acid (PAA) and hydrogen peroxide (H2O2), were tested in combination with the system to see whether the Salmonella inactivation effect could be enhanced. The fresh produce samples were dip-inoculated with a Salmonella cocktail to final concentrations of 4.6-7.6 log CFU/g. To simulate the washing process in the industry, fresh produce extracts and/or silicon dioxide were added in the wash water to adjust chemical oxygen demand to ~2000 mg/L and turbidity to >60 NTU. In general, the decontamination efficacy of WUV treatments followed this order: Tomato > Carrot > Lettuce ≈ Blueberry > Spinach. In the small-scale study, WUV alone was able to achieve 0.9, 2.6, >3.6, 1.7, and 2.0 log CFU/g reductions of Salmonella on fresh produce for spinach, lettuce, tomato, blueberry, and carrot, respectively. For all fresh produce items, WUV combined with PAA could achieve significantly (P < 0.05) higher Salmonella reduction on fresh produce than chlorine wash and PAA wash. The WUV treatments combined with chlorine or PAA were able to keep residual Salmonella in wash water below the detection limit (2 CFU/mL) for almost all the replicates. Similar Salmonella reductions on fresh produce and in wash water were found in the large-scale study. Considering the decontamination efficacy on fresh produce, the ability to disinfect the wash water, and the cost, we recommend chlorine wash for baby spinach, WUV alone for grape tomato and WUV combined with PAA for iceberg lettuce, blueberry and baby-cut carrot.

UV-C inactivation of foodborne bacterial and viral pathogens and surrogates on fresh and frozen berries.

Outbreaks of foodborne illness associated with berries often involve contamination with hepatitis A virus (HAV) and norovirus but also bacteria such as Escherichia coli O157:H7 and parasites such as Cyclospora caytanensis. We evaluated the applicability of UV-C to the inactivation of pathogens on strawberries, raspberries and blueberries. Our three-step approach consisted of assessing the chemical safety of UV-C-irradiated berries, evaluating the sensory quality after UV-C treatment and finally studying the inactivation of the target microorganisms. Treatments lasting up to 9 min (4000 mJ cm-2) did not produce detectable levels of furan (<5 µg/kg), a known photolysis product of fructose with genotoxic activity and thus were assessed to be toxicologically safe. No effect on taste or appearance was observed, unless treatment was excessively long. 20 s of treatment (an average fluence of ~ 212 mJ cm-2) reduced active HAV titer by >1 log10 unit in 95% of cases except on frozen raspberries, while 120 s were required to inactivate murine norovirus to this extent on fresh blueberries. The mean inactivation of HAV and MNV was greater on blueberries (2-3 log10) than on strawberries and raspberries (<2 log10). MNV was more sensitive on fresh than on frozen berries, unlike HAV. Inactivation of Salmonella, E. coli O157:H7 and Listeria monocytogenes was poor on all three berries, no treatment reducing viable counts by >1 log10 unit. In most matrices, prolonging the treatment did not improve the result to any significant degree. The effect was near its plateau after 20 s of treatment. These results provide insight into the effectiveness of UV-C irradiation for inactivating bacterial and viral pathogens and surrogates on fresh and frozen berries having different surface types, under different physical conditions and at different levels of contamination. Overall they show that UV-C as single processing step is unsuitable to inactivate significant numbers of foodborne pathogens on berries.

Use of gamma radiation for inactivating Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes in tahini halva.

Tahini halva is a traditional sweet product that is consumed with bread in different countries. It is a low water activity (aw) product basically made by mixing and cooking tahini, sugar, citric acid and Saponaria officinalis root extract together. Tahini halva maybe contaminated with foodborne pathogens during any stage of production from tahini and other raw ingredients, workers, environment or contact surfaces. The objectives of the study were to i) investigate the efficacy of gamma radiation to inactivate Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes in tahini halva, ii) evaluate the effect of pre-irradiation storage (0, 7 and 30 days at 21 °C) of tahini halva on the sensitivity of these microorganisms toward gamma radiation, and iii) evaluate the effect of post-irradiation storage of tahini halva for up to 6 months on the their survival characteristics. Tahini halva samples were inoculated with Salmonella spp., E. coli O157:H7 and L. monocytogenes separately then stored at 21 °C for 0, 7 and 30 days prior to irradiation at 0-4 KGy and for up to 6 months after irradiation at 4 KGy. Salmonella spp. were the most irradiation resistance among the tested microorganisms. Irradiation (0.8-4.0 KGy) reduced the bacteria in samples stored for 0, 7 and 30 days pre-irradiation in the range of 0.43-2.11, 0.45-2.68 and 0.52-2.7 log10 CFU/g for Salmonella spp., 0.55-3.08, 0.66-3.00 and 0.60-2.80 log10 CFU/g for E. coli O157:H7, and 0.69-2.96, 0.86-4.30, 0.62-3.29 log10 CFU/g for L. monocytogenes, respectively. The D10-value, the irradiation dose needed to inactivate 1 log10 of pathogen, was 1.83, 1.47 and 1.50 KGy for Salmonella spp., 1.28, 1.32 and 1.48 KGy for E. coli O157:H7, and 1.33, 0.94 and 1.27 KGy for L. monocytogenes in pre-irradiation stored samples for 0, 7 and 30 days, respectively. Post-irradiation storage was efficient in decreasing the levels of the microorganisms ca. ≥2 log10 CFU/g in the first month and to undetected level after the second month of storage but enrichment results showed that Salmonella spp. and L. monocytogenes were detected in the samples until of the end of storage period. The study demonstrates that gamma radiation can be applied to inactivate of foodborne pathogens in tahini halva. Irradiation dose at 4 KGy can reduce Salmonella spp., E. coli O157:H7 and L. monocytogenes in tahini halva by 2-3 log10 CFU/g. Storage of tahini halva before or after irradiation may reduce the risk of foodborne pathogens in the product.

Thermal inactivation of Listeria monocytogenes and Salmonella spp. in sous-vide processed marinated chicken breast.

The heat resistance of a cocktail of five Salmonella strains and five L. monocytogenes strains was determined in teriyaki-marinated chicken breasts. Inoculated meat, packaged in bags, were completely immersed in a circulating water bath and cooked to a final temperature of 55, 57.5 or 60°C in 1h, and then held for predetermined times. The surviving Salmonella and L. monocytogenes cells were enumerated by surface plating on XLD agar and Palcam agar, respectively. D-values, determined by linear regression, of Salmonella in chicken breast ranged from 47.65min at 55°C to 7.48min at 60°C; the values for L. monocytogenes ranged from 54.81min at 55°C to 10.39min at 60°C. Marination rendered the pathogen more sensitive to the lethal effect of heat. The results of this study will assist the food industry in ensuring microbiological safety of sous-vide processed marinated chicken breasts.

Advanced Oxidation Process sanitization of hatching eggs reduces Salmonella in broiler chicks.

The microbial quality of eggs entering the hatchery is an important critical control point for biosecurity, pathogen reduction, and food safety programs in poultry production. Developing interventions to reduce Salmonella contamination of eggs is important to improving the microbial food safety of poultry and poultry products. The hydrogen peroxide (H2O2) and ultraviolet light (UV) Advanced Oxidation Process (AOP) has been previously demonstrated to be effective in reducing Salmonella on the surface of experimentally contaminated eggs. The objective of this study was to evaluate the effect of treating eggs with an egg-sanitizing apparatus using the H2O2/UV AOP on Salmonella contamination during incubation, hatching, and in broiler chicks during grow-out. Experimentally contaminated eggs were treated using the automated H2O2/UV AOP egg sanitizer and incubated for 21 d. AOP sanitization reduced Salmonella up to 7 log10 cfu egg-1 (P < 0.05) from the surface of experimentally contaminated eggs and reduced the number of Salmonella positive eggs by up to 75% (P < 0.05) when treated 1 h post-inoculation. AOP treatment also reduced the number of Salmonella-positive eggs during incubation. Additionally, Salmonella was recovered from more chicks hatched from untreated eggs than from eggs treated using the H2O2/UV AOP egg sanitizer (P < 0.05) through 14 d posthatch. These data suggest reduction of Salmonella contamination on the surface of eggs using the H2O2/UV AOP egg sanitizer prior to incubation may reduce the gastrointestinal colonization of chicks by Salmonella.

Ultraviolet (UV-C) inactivation of Enterococcus faecium, Salmonella choleraesuis and Salmonella typhimurium in porcine plasma.

The objective of this study was to assess the effectiveness of an ultraviolet (UV-C, 254 nm) irradiation system on reducing the load of Salmonella typhimurium (S. typhimurium), Salmonella choleraesuis (S. choleraesuis) resistant to streptomycin and Enterococcus faecium (E. faecium) inoculated in sterile porcine plasma and then subjected to different UV-C irradiation doses (750, 1500, 3000, 6000 and 9000 J/L) using a pilot plant UV-C device working under turbulent flow. Results indicated that UV-C treatment induced a viability reduction of 0.38, 1.18, 3.59, 4.72 and 5.06 log10 S. typhimurium when irradiated at 750, 1500, 3000, 6000 and 9000 J/L, respectively. The observed log10 reduction of S. choleraesuis was 1.44, 2.68, 5.55, 7.07 and 7.97 at 750, 1500, 3000, 6000 and 9000 J/L, respectively. The best-fit inactivation for S. choleraesuis was the Weibull distribution curve, while the best-fit curve for S. typhimurium was the Weibull plus tail model, indicating that around 102 cfu/mL resistant S. typhimurium was detected when the liquid plasma was UV-C irradiated at doses up to 9000 J/L. Viability reduction for E. faecium was 0.44, 1.01, 3.70, 5.61 and 6.22 log10 when irradiated at 750, 1500, 3000, 6000 and 9000 J/L, respectively, with no bacterial resistance observed with UV-C doses of 6000 J/L or higher. The biphasic model was the best fit model for the inactivation curve for E. faecium. For the three microorganisms tested, about a 4 log-unit reduction was achieved when the liquid plasma was irradiated at 3000J/L. Overall results demonstrate the usefulness of the UV-C system to inactivate bacteria in liquid plasma before spray-drying. We conclude that the UV-C system can provide an additional biosafety feature that can be incorporated into the manufacturing process for spray-dried animal plasma.

Inactivation of Salmonella spp., pathogenic Escherichia coli, Staphylococcus spp., or Listeria monocytogenes in chicken purge or skin using a 405-nm LED array.

Raw poultry are sometimes contaminated with foodborne pathogens, which can lead to illness in humans. In recent years research has focused on a variety of light technologies to decontaminate food and food contact surfaces during meat and poultry processing. In this study we evaluated the ability of 405-nm light generated from an LED array to inactivate multi-isolate cocktails of either Salmonella spp., pathogenic Escherichia coli, Staphylococcus spp., or Listeria monocytogenes suspended in chicken purge or skin. When exposed to 180 J/cm2 405-nm light at two separate light intensities (300 mW/cm2/s or 150 mW/cm2/s) the maximum pathogen reduction on chicken skin was ca. 0.4 log. When the pathogens were suspended in chicken purge the maximum log reductions ranged from 0.23 to 0.68 log (180 J/cm2; 150 mW/cm2/s) versus 0.69 to 1.01 log (180 J/cm2; 300 mW/cm2/s). Log reductions of each pathogen, when they were subjected to heat shock prior to 405-nm light treatment, were reduced, indicating that thermal effects accounted for much of the bacterial inactivation.

Antibacterial effect of 405±5nm light emitting diode illumination against Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella on the surface of fresh-cut mango and its influence on fruit quality.

To investigate a potential of 405±5nm light emitting diode (LED) as a novel technology for food preservation, the antibacterial effect of 405±5nm LED on Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella spp. on the surface of fresh-cut mango and its influence on fruit quality were evaluated at different storage temperatures. LED-illumination inactivated 1.0-1.6 logCFU/cm2 of populations at 4 and 10°C for 36-48h (total dose, 2.6-3.5kJ/cm2) regardless of bacterial species, while those on non-illuminated mange remained unchanged or slightly increased during storage. At 20°C for 24h (total dose, 1.7kJ/cm2), non-illuminated E. coli O157:H7 and Salmonella gradually grew, whereas LED-illumination reduced 1.2 log of Salmonella and inhibited the growth of E. coli O157:H7. Unlike these, non-illuminated L. monocytogenes cells rapidly increased to 7.3 log, while illuminated cells reached 4.6 log, revealing that LED-illumination delayed their growth. There were no significant (P>0.05) differences in color, antioxidant capacity, ascorbic acid, ß-carotene, and flavonoid between non-illuminated and illuminated cut mangoes, regardless of storage temperature. These results suggest that 405±5nm LEDs in combination with chilling temperatures could be applied to preserve fresh-cut fruits without deterioration of physicochemical quality of fruits at food establishments, minimizing the risk of foodborne disease.

Antibacterial Mechanism of 405-Nanometer Light-Emitting Diode against Salmonella at Refrigeration Temperature.

The aim of this study was to elucidate the antibacterial mechanism of 405 ± 5-nm light-emitting diode (LED) illumination against Salmonella at 4°C in phosphate-buffered saline (PBS) by determining endogenous coproporphyrin content, DNA oxidation, damage to membrane function, and morphological change. Gene expression levels, including of oxyR, recA, rpoS, sodA, and soxR, were also examined to understand the response of Salmonella to LED illumination. The results showed that Salmonella strains responded differently to LED illumination, revealing that S. enterica serovar Enteritidis (ATCC 13076) and S. enterica subsp. enterica serovar Saintpaul (ATCC 9712) were more susceptible and resistant, respectively, than the 16 other strains tested. There was no difference in the amounts of endogenous coproporphyrin in the two strains. Compared with that in nonilluminated cells, the DNA oxidation levels in illuminated cells increased. In illuminated cells, we observed a loss of efflux pump activity, damage to the glucose uptake system, and changes in membrane potential and integrity. Transmission electron microscopy revealed a disorganization of chromosomes and ribosomes due to LED illumination. The levels of the five genes measured in the nonilluminated and illuminated S Saintpaul cells were upregulated in PBS at a set temperature of 4°C, indicating that increased gene expression levels might be due to a temperature shift and nutrient deficiency rather than to LED illumination. In contrast, only oxyR in S Enteritidis cells was upregulated. Thus, different sensitivities of the two strains to LED illumination were attributed to differences in gene regulation.IMPORTANCE Bacterial inactivation using visible light has recently received attention as a safe and environmentally friendly technology, in contrast with UV light, which has detrimental effects on human health and the environment. This study was designed to understand how 405 ± 5-nm light-emitting diode (LED) illumination kills Salmonella strains at refrigeration temperature. The data clearly demonstrated that the effectiveness of LED illumination on Salmonella strains depended highly on the serotype and strain. Our findings also revealed that its antibacterial mechanism was mainly attributed to DNA oxidation and a loss of membrane functions rather than membrane lipid peroxidation, which has been proposed by other researchers who studied the antibacterial effect of LED illumination by adding exogenous photosensitizers, such as chlorophyllin and hypericin. Therefore, this study suggests that the detailed antibacterial mechanisms of 405-nm LED illumination without additional photosensitizers may differ from that by exogenous photosensitizers. Furthermore, a change in stress-related gene regulation may alter the susceptibility of Salmonella cells to LED illumination at refrigeration temperature. Thus, our study provides new insights into the antibacterial mechanism of 405 ± 5-nm LED illumination on Salmonella cells.