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Changqing Wu - One of the best experts on this subject based on the ideXlab platform.
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application of pulsed light pl surfactant combination on inactivation of salmonella and apparent quality of Green Onions
Lwt - Food Science and Technology, 2015Co-Authors: Wenqing Xu, Haiqiang Chen, Changqing WuAbstract:Abstract In our previous study using pulsed light (PL) and PL-sanitizer/surfactant to inactivate Escherichia coli O157:H7 on Green Onions, the combination of PL and 1000 ppm of surfactant (sodium dodecyl sulfate, SDS) was more effective than single treatments. In this study, whether PL-surfactant combination would provide similar inactivation efficacy of Salmonella on Green Onions was tested. Different surfactants (SDS and Tween 80) as well as different concentrations (10, 100 and 1000 ppm) of each surfactant combined with PL were tested. Survival populations of Salmonella and quality of Green Onions (color and texture) were evaluated after treatments as well as during storage (15 days) at 4 °C. The results showed that PL-SDS and PL-Tween 80 combinations at various surfactant concentrations provided synergistic inactivation efficacy on Green onion leaves (2.6–2.9 log10 CFU/g and 2.4–2.7 log10 CFU/g, respectively), but not on their stems (0.4–1.0 log10 CFU/g and 0.3–0.6 log10 CFU/g, respectively). PL-1000 ppm SDS combination negatively impacted color and texture of Green Onions during 15 day storage at 4 °C. To consider both safety and quality of Green Onions, PL-10 ppm SDS was selected since it showed similar Salmonella inactivation on Green Onions as PL-1000 ppm SDS but did not affect quality of Green Onions during shelf-life.
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decontamination of salmonella enterica typhimurium on Green Onions using a new formula of sanitizer washing and pulsed uv light pl
Food Research International, 2014Co-Authors: Wenqing Xu, Changqing WuAbstract:Abstract Pathogenic bacteria such as Salmonella and Shigella flexneri have been linked to Green onion contamination. This study was conducted to evaluate decontamination of Salmonella Typhimurium using a new formula of sanitizer washing (0.4 mg/mL thymol and five new formula sanitizers including 300 ppm H 2 O 2 + 4% SDS, 2 mg/mL citric acid + 4% SDS, 0.2 mg/mL thymol + 4% SDS, 0.2 mg/mL thymol + 2 mg/mL citric acid and 0.2 mg/mL thymol + 2 mg/mL acetic acid), pulsed UV light (PL) as well as synergy between the sanitizer wash and PL. New formula sanitizers based on decontamination efficacy of single washing solutions (organic acids, hydrogen peroxide (H 2 O 2 ), essential oil or surfactant) were applied to decontaminate spot inoculated Green Onions. PL, the novel technique, alone has been applied to inactivate Salmonella on both dip and spot inoculated Green Onions. Salmonella inactivation of PL–new formula sanitizer combinations on dip inoculated Green Onions was investigated for their potential synergy. As a result, for spot inoculated Green Onions, 0.4 mg/mL thymol individually and the five new formula sanitizers all achieved higher log reduction of Salmonella (4.5–5.3 log 10 CFU/g reduction) than the 200 ppm chlorine washing. These new formulas of sanitizer would be potential alternatives to chlorine. The 5 s dry PL (4.6 log 10 CFU/g) or 60 s wet PL treatment (3.6 log 10 CFU/g) was better or comparable as chlorine washing. The sanitizer combinations did not provide significantly higher log reduction than PL, and PL has the potential of being used in the Green onion industry for decontamination purpose. For dip inoculated Green Onions, none of our treatment provided > 0.8 log 10 CFU/g (0.6–0.8 log 10 CFU/g) reduction of Salmonella . As a result, the PL–new formula sanitizer combinations had no or minimal synergy to inactivate Salmonella dip inoculated on Green Onions.
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different efficiency of ozonated water washing to inactivate salmonella enterica typhimurium on Green Onions grape tomatoes and Green leaf lettuces
Journal of Food Science, 2014Co-Authors: Wenqing Xu, Changqing WuAbstract:Ozonated water washing is one of the emerging techniques to inactivate foodborne pathogens on produce, and limited information is available to optimize processing parameters (treatment time, temperature, and pH) to improve ozone efficacy on Salmonella inactivation for different produce. The efficacy of ozonated water washing for inactivation of Salmonella enterica Typhimurium on Green Onions, grape tomatoes and Green leaf lettuces were studied in our research. Surface inoculated fresh produce were washed by ozonated water for 1, 5, or 10 min at room temperature and pH 5.60 ± 0.03. Then efficacy of ozonated water washing at mild heated (50 °C) and refrigerated (4 °C) temperature for 5 min with pH 5.60 ± 0.03 was investigated. Salmonella inactivation efficacy under pH 5.60 ± 0.03 and 2.64 ± 0.02 with 5 min washing at room temperature were also compared. Our results showed that Salmonella inactivation by ozonated water was time-dependent for 3 fresh produce. Mild heated temperature (50 °C) and pH 2.64 ± 0.02 improved efficacy of ozonated water to inactivate Salmonella on tomatoes and lettuces, but not on Green Onions. It is suggested that different surface structures of fresh produce significantly impact the antimicrobial efficacy of ozonated water washing operated under various parameters (time, temperature, and pH). Practical Application Washing is the essential step for Green Onions and lettuces in the packinghouse and grape tomatoes in the restaurants and grocery stores having salad bars. Ozonated water can be used as disinfectant to reduce microbial contamination (FDA). The effectiveness of this disinfectant depends on the type of product and treatment conditions, such as water temperature, acidity, contact time. Our study showed that Salmonella inactivation by ozonated water washing was time-dependent. Mild heat and low pH improved inactivation efficacy on tomatoes and lettuces, but not on Green Onions. Processors should consider adjustments that are most appropriate for their produce.
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decontamination of escherichia coli o157 h7 on Green Onions using pulsed light pl and pl surfactant sanitizer combinations
International Journal of Food Microbiology, 2013Co-Authors: Wenqing Xu, Yaoxin Huang, Haiqiang Chen, Changqing WuAbstract:Abstract Imported Green onion has been associated with three large outbreaks in the USA. Contamination has been found on both domestic and imported Green Onions. The objective of our study was to investigate Escherichia coli O157:H7 inactivation efficacy of pulsed light (PL) as well as its combination with surfactant and/or sanitizers on Green Onions. Green Onions were cut into two segments, stems and leaves, to represent two different matrixes. Stems were more difficult to be decontaminated. Spot and dip inoculation methods were compared and dipped inoculated Green Onions were found to be more difficult to be decontaminated. Results showed that 5 s dry PL (samples were not immersed in water during PL treatment) and 60 s wet PL (samples were immersed in water and stirred during PL treatment) treatments provided promising inactivation efficacy (> 4 log 10 CFU/g) for spot inoculated stems and leaves. For dip inoculated Green Onions, 60 s wet PL treatment was comparable with 100 ppm chlorine washing, demonstrating that PL could be used as an alternative to chlorine. To further increase the degree of microbial inactivation, combined treatments were applied. PL combined with surfactant (SDS) was found to be more effective than single treatments of PL, SDS, chlorine, citric acid, thymol, and hydrogen peroxide, and binary combined treatments of PL with one of those chemicals. Addition of chlorine or hydrogen peroxide to the PL–SDS combination did not further enhanced its microbial inactivation efficacy. The combination of PL and 1000 ppm of SDS reduced the E. coli O157:H7 populations dip inoculated on the stems and leaves of Green Onions by 1.4 and 3.1 log 10 CFU/g, respectively. Our findings suggest that PL could potentially be used for decontamination of E. coli O157:H7 on Green Onions, with wet PL added with SDS being the most effective PL treatment.
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Decontamination of Escherichia coli O157:H7 on Green Onions using pulsed light (PL) and PL–surfactant–sanitizer combinations
International Journal of Food Microbiology, 2013Co-Authors: Wenqing Xu, Yaoxin Huang, Haiqiang Chen, Changqing WuAbstract:Abstract Imported Green onion has been associated with three large outbreaks in the USA. Contamination has been found on both domestic and imported Green Onions. The objective of our study was to investigate Escherichia coli O157:H7 inactivation efficacy of pulsed light (PL) as well as its combination with surfactant and/or sanitizers on Green Onions. Green Onions were cut into two segments, stems and leaves, to represent two different matrixes. Stems were more difficult to be decontaminated. Spot and dip inoculation methods were compared and dipped inoculated Green Onions were found to be more difficult to be decontaminated. Results showed that 5 s dry PL (samples were not immersed in water during PL treatment) and 60 s wet PL (samples were immersed in water and stirred during PL treatment) treatments provided promising inactivation efficacy (> 4 log 10 CFU/g) for spot inoculated stems and leaves. For dip inoculated Green Onions, 60 s wet PL treatment was comparable with 100 ppm chlorine washing, demonstrating that PL could be used as an alternative to chlorine. To further increase the degree of microbial inactivation, combined treatments were applied. PL combined with surfactant (SDS) was found to be more effective than single treatments of PL, SDS, chlorine, citric acid, thymol, and hydrogen peroxide, and binary combined treatments of PL with one of those chemicals. Addition of chlorine or hydrogen peroxide to the PL–SDS combination did not further enhanced its microbial inactivation efficacy. The combination of PL and 1000 ppm of SDS reduced the E. coli O157:H7 populations dip inoculated on the stems and leaves of Green Onions by 1.4 and 3.1 log 10 CFU/g, respectively. Our findings suggest that PL could potentially be used for decontamination of E. coli O157:H7 on Green Onions, with wet PL added with SDS being the most effective PL treatment.
Wenqing Xu - One of the best experts on this subject based on the ideXlab platform.
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application of pulsed light pl surfactant combination on inactivation of salmonella and apparent quality of Green Onions
Lwt - Food Science and Technology, 2015Co-Authors: Wenqing Xu, Haiqiang Chen, Changqing WuAbstract:Abstract In our previous study using pulsed light (PL) and PL-sanitizer/surfactant to inactivate Escherichia coli O157:H7 on Green Onions, the combination of PL and 1000 ppm of surfactant (sodium dodecyl sulfate, SDS) was more effective than single treatments. In this study, whether PL-surfactant combination would provide similar inactivation efficacy of Salmonella on Green Onions was tested. Different surfactants (SDS and Tween 80) as well as different concentrations (10, 100 and 1000 ppm) of each surfactant combined with PL were tested. Survival populations of Salmonella and quality of Green Onions (color and texture) were evaluated after treatments as well as during storage (15 days) at 4 °C. The results showed that PL-SDS and PL-Tween 80 combinations at various surfactant concentrations provided synergistic inactivation efficacy on Green onion leaves (2.6–2.9 log10 CFU/g and 2.4–2.7 log10 CFU/g, respectively), but not on their stems (0.4–1.0 log10 CFU/g and 0.3–0.6 log10 CFU/g, respectively). PL-1000 ppm SDS combination negatively impacted color and texture of Green Onions during 15 day storage at 4 °C. To consider both safety and quality of Green Onions, PL-10 ppm SDS was selected since it showed similar Salmonella inactivation on Green Onions as PL-1000 ppm SDS but did not affect quality of Green Onions during shelf-life.
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decontamination of salmonella enterica typhimurium on Green Onions using a new formula of sanitizer washing and pulsed uv light pl
Food Research International, 2014Co-Authors: Wenqing Xu, Changqing WuAbstract:Abstract Pathogenic bacteria such as Salmonella and Shigella flexneri have been linked to Green onion contamination. This study was conducted to evaluate decontamination of Salmonella Typhimurium using a new formula of sanitizer washing (0.4 mg/mL thymol and five new formula sanitizers including 300 ppm H 2 O 2 + 4% SDS, 2 mg/mL citric acid + 4% SDS, 0.2 mg/mL thymol + 4% SDS, 0.2 mg/mL thymol + 2 mg/mL citric acid and 0.2 mg/mL thymol + 2 mg/mL acetic acid), pulsed UV light (PL) as well as synergy between the sanitizer wash and PL. New formula sanitizers based on decontamination efficacy of single washing solutions (organic acids, hydrogen peroxide (H 2 O 2 ), essential oil or surfactant) were applied to decontaminate spot inoculated Green Onions. PL, the novel technique, alone has been applied to inactivate Salmonella on both dip and spot inoculated Green Onions. Salmonella inactivation of PL–new formula sanitizer combinations on dip inoculated Green Onions was investigated for their potential synergy. As a result, for spot inoculated Green Onions, 0.4 mg/mL thymol individually and the five new formula sanitizers all achieved higher log reduction of Salmonella (4.5–5.3 log 10 CFU/g reduction) than the 200 ppm chlorine washing. These new formulas of sanitizer would be potential alternatives to chlorine. The 5 s dry PL (4.6 log 10 CFU/g) or 60 s wet PL treatment (3.6 log 10 CFU/g) was better or comparable as chlorine washing. The sanitizer combinations did not provide significantly higher log reduction than PL, and PL has the potential of being used in the Green onion industry for decontamination purpose. For dip inoculated Green Onions, none of our treatment provided > 0.8 log 10 CFU/g (0.6–0.8 log 10 CFU/g) reduction of Salmonella . As a result, the PL–new formula sanitizer combinations had no or minimal synergy to inactivate Salmonella dip inoculated on Green Onions.
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different efficiency of ozonated water washing to inactivate salmonella enterica typhimurium on Green Onions grape tomatoes and Green leaf lettuces
Journal of Food Science, 2014Co-Authors: Wenqing Xu, Changqing WuAbstract:Ozonated water washing is one of the emerging techniques to inactivate foodborne pathogens on produce, and limited information is available to optimize processing parameters (treatment time, temperature, and pH) to improve ozone efficacy on Salmonella inactivation for different produce. The efficacy of ozonated water washing for inactivation of Salmonella enterica Typhimurium on Green Onions, grape tomatoes and Green leaf lettuces were studied in our research. Surface inoculated fresh produce were washed by ozonated water for 1, 5, or 10 min at room temperature and pH 5.60 ± 0.03. Then efficacy of ozonated water washing at mild heated (50 °C) and refrigerated (4 °C) temperature for 5 min with pH 5.60 ± 0.03 was investigated. Salmonella inactivation efficacy under pH 5.60 ± 0.03 and 2.64 ± 0.02 with 5 min washing at room temperature were also compared. Our results showed that Salmonella inactivation by ozonated water was time-dependent for 3 fresh produce. Mild heated temperature (50 °C) and pH 2.64 ± 0.02 improved efficacy of ozonated water to inactivate Salmonella on tomatoes and lettuces, but not on Green Onions. It is suggested that different surface structures of fresh produce significantly impact the antimicrobial efficacy of ozonated water washing operated under various parameters (time, temperature, and pH). Practical Application Washing is the essential step for Green Onions and lettuces in the packinghouse and grape tomatoes in the restaurants and grocery stores having salad bars. Ozonated water can be used as disinfectant to reduce microbial contamination (FDA). The effectiveness of this disinfectant depends on the type of product and treatment conditions, such as water temperature, acidity, contact time. Our study showed that Salmonella inactivation by ozonated water washing was time-dependent. Mild heat and low pH improved inactivation efficacy on tomatoes and lettuces, but not on Green Onions. Processors should consider adjustments that are most appropriate for their produce.
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decontamination of escherichia coli o157 h7 on Green Onions using pulsed light pl and pl surfactant sanitizer combinations
International Journal of Food Microbiology, 2013Co-Authors: Wenqing Xu, Yaoxin Huang, Haiqiang Chen, Changqing WuAbstract:Abstract Imported Green onion has been associated with three large outbreaks in the USA. Contamination has been found on both domestic and imported Green Onions. The objective of our study was to investigate Escherichia coli O157:H7 inactivation efficacy of pulsed light (PL) as well as its combination with surfactant and/or sanitizers on Green Onions. Green Onions were cut into two segments, stems and leaves, to represent two different matrixes. Stems were more difficult to be decontaminated. Spot and dip inoculation methods were compared and dipped inoculated Green Onions were found to be more difficult to be decontaminated. Results showed that 5 s dry PL (samples were not immersed in water during PL treatment) and 60 s wet PL (samples were immersed in water and stirred during PL treatment) treatments provided promising inactivation efficacy (> 4 log 10 CFU/g) for spot inoculated stems and leaves. For dip inoculated Green Onions, 60 s wet PL treatment was comparable with 100 ppm chlorine washing, demonstrating that PL could be used as an alternative to chlorine. To further increase the degree of microbial inactivation, combined treatments were applied. PL combined with surfactant (SDS) was found to be more effective than single treatments of PL, SDS, chlorine, citric acid, thymol, and hydrogen peroxide, and binary combined treatments of PL with one of those chemicals. Addition of chlorine or hydrogen peroxide to the PL–SDS combination did not further enhanced its microbial inactivation efficacy. The combination of PL and 1000 ppm of SDS reduced the E. coli O157:H7 populations dip inoculated on the stems and leaves of Green Onions by 1.4 and 3.1 log 10 CFU/g, respectively. Our findings suggest that PL could potentially be used for decontamination of E. coli O157:H7 on Green Onions, with wet PL added with SDS being the most effective PL treatment.
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Decontamination of Escherichia coli O157:H7 on Green Onions using pulsed light (PL) and PL–surfactant–sanitizer combinations
International Journal of Food Microbiology, 2013Co-Authors: Wenqing Xu, Yaoxin Huang, Haiqiang Chen, Changqing WuAbstract:Abstract Imported Green onion has been associated with three large outbreaks in the USA. Contamination has been found on both domestic and imported Green Onions. The objective of our study was to investigate Escherichia coli O157:H7 inactivation efficacy of pulsed light (PL) as well as its combination with surfactant and/or sanitizers on Green Onions. Green Onions were cut into two segments, stems and leaves, to represent two different matrixes. Stems were more difficult to be decontaminated. Spot and dip inoculation methods were compared and dipped inoculated Green Onions were found to be more difficult to be decontaminated. Results showed that 5 s dry PL (samples were not immersed in water during PL treatment) and 60 s wet PL (samples were immersed in water and stirred during PL treatment) treatments provided promising inactivation efficacy (> 4 log 10 CFU/g) for spot inoculated stems and leaves. For dip inoculated Green Onions, 60 s wet PL treatment was comparable with 100 ppm chlorine washing, demonstrating that PL could be used as an alternative to chlorine. To further increase the degree of microbial inactivation, combined treatments were applied. PL combined with surfactant (SDS) was found to be more effective than single treatments of PL, SDS, chlorine, citric acid, thymol, and hydrogen peroxide, and binary combined treatments of PL with one of those chemicals. Addition of chlorine or hydrogen peroxide to the PL–SDS combination did not further enhanced its microbial inactivation efficacy. The combination of PL and 1000 ppm of SDS reduced the E. coli O157:H7 populations dip inoculated on the stems and leaves of Green Onions by 1.4 and 3.1 log 10 CFU/g, respectively. Our findings suggest that PL could potentially be used for decontamination of E. coli O157:H7 on Green Onions, with wet PL added with SDS being the most effective PL treatment.
Haiqiang Chen - One of the best experts on this subject based on the ideXlab platform.
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high hydrostatic pressure inactivation of murine norovirus and human noroviruses on Green Onions and in salsa
International Journal of Food Microbiology, 2017Co-Authors: Robert Sido, Runze Huang, Haiqiang ChenAbstract:Abstract In this study, high hydrostatic pressure (HHP) was evaluated as an intervention for human noroviruses (HuNoVs) in Green Onions and salsa. To determine the effect of water during HHP treatment on virus inactivation, a HuNoV surrogate, murine norovirus 1 (MNV-1), was inoculated onto Green Onions and then HHP-treated at 350 MPa with or without water at 4 or 20 °C. The presence of water enhanced HHP inactivation of MNV-1 on Green Onions at 4 °C but not at 20 °C. To test the temperature effect on HHP inactivation of MNV-1, inoculated Green Onions were HHP-treated at 300 MPa at 1, 4 and 10 °C. As the temperature decreased, MNV-1 became more sensitive to HHP treatment. HHP inactivation curves of MNV-1 on Green Onions and salsa were obtained at 300 or 350 MPa for 0.5–3 min at 1 °C. All three inactivation curves showed a linear relationship between log reduction of MNV-1 and time. D values of HHP inactivation of MNV-1 on Green Onions were 1.10 and 0.61 min at 300 and 350 MPa, respectively. The D value of HHP inactivation of MNV-1 in salsa at 300 MPa was 0.63 min. HHP inactivation of HuNoV GI.1 and GII.4 on Green Onions and salsa was also conducted. To achieve > 3 log reduction of HuNoV GI.1, HHP treatments for 2 min at 1 °C should be conducted at 600 MPa and 500 MPa for Green Onions and salsa, respectively. To achieve > 3 log reduction of HuNoV GII.4, HHP treatments for 2 min at 1 °C should be conducted at 500 MPa and 300 MPa for Green Onions and salsa, respectively.
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application of pulsed light pl surfactant combination on inactivation of salmonella and apparent quality of Green Onions
Lwt - Food Science and Technology, 2015Co-Authors: Wenqing Xu, Haiqiang Chen, Changqing WuAbstract:Abstract In our previous study using pulsed light (PL) and PL-sanitizer/surfactant to inactivate Escherichia coli O157:H7 on Green Onions, the combination of PL and 1000 ppm of surfactant (sodium dodecyl sulfate, SDS) was more effective than single treatments. In this study, whether PL-surfactant combination would provide similar inactivation efficacy of Salmonella on Green Onions was tested. Different surfactants (SDS and Tween 80) as well as different concentrations (10, 100 and 1000 ppm) of each surfactant combined with PL were tested. Survival populations of Salmonella and quality of Green Onions (color and texture) were evaluated after treatments as well as during storage (15 days) at 4 °C. The results showed that PL-SDS and PL-Tween 80 combinations at various surfactant concentrations provided synergistic inactivation efficacy on Green onion leaves (2.6–2.9 log10 CFU/g and 2.4–2.7 log10 CFU/g, respectively), but not on their stems (0.4–1.0 log10 CFU/g and 0.3–0.6 log10 CFU/g, respectively). PL-1000 ppm SDS combination negatively impacted color and texture of Green Onions during 15 day storage at 4 °C. To consider both safety and quality of Green Onions, PL-10 ppm SDS was selected since it showed similar Salmonella inactivation on Green Onions as PL-1000 ppm SDS but did not affect quality of Green Onions during shelf-life.
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decontamination of escherichia coli o157 h7 on Green Onions using pulsed light pl and pl surfactant sanitizer combinations
International Journal of Food Microbiology, 2013Co-Authors: Wenqing Xu, Yaoxin Huang, Haiqiang Chen, Changqing WuAbstract:Abstract Imported Green onion has been associated with three large outbreaks in the USA. Contamination has been found on both domestic and imported Green Onions. The objective of our study was to investigate Escherichia coli O157:H7 inactivation efficacy of pulsed light (PL) as well as its combination with surfactant and/or sanitizers on Green Onions. Green Onions were cut into two segments, stems and leaves, to represent two different matrixes. Stems were more difficult to be decontaminated. Spot and dip inoculation methods were compared and dipped inoculated Green Onions were found to be more difficult to be decontaminated. Results showed that 5 s dry PL (samples were not immersed in water during PL treatment) and 60 s wet PL (samples were immersed in water and stirred during PL treatment) treatments provided promising inactivation efficacy (> 4 log 10 CFU/g) for spot inoculated stems and leaves. For dip inoculated Green Onions, 60 s wet PL treatment was comparable with 100 ppm chlorine washing, demonstrating that PL could be used as an alternative to chlorine. To further increase the degree of microbial inactivation, combined treatments were applied. PL combined with surfactant (SDS) was found to be more effective than single treatments of PL, SDS, chlorine, citric acid, thymol, and hydrogen peroxide, and binary combined treatments of PL with one of those chemicals. Addition of chlorine or hydrogen peroxide to the PL–SDS combination did not further enhanced its microbial inactivation efficacy. The combination of PL and 1000 ppm of SDS reduced the E. coli O157:H7 populations dip inoculated on the stems and leaves of Green Onions by 1.4 and 3.1 log 10 CFU/g, respectively. Our findings suggest that PL could potentially be used for decontamination of E. coli O157:H7 on Green Onions, with wet PL added with SDS being the most effective PL treatment.
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Decontamination of Escherichia coli O157:H7 on Green Onions using pulsed light (PL) and PL–surfactant–sanitizer combinations
International Journal of Food Microbiology, 2013Co-Authors: Wenqing Xu, Yaoxin Huang, Haiqiang Chen, Changqing WuAbstract:Abstract Imported Green onion has been associated with three large outbreaks in the USA. Contamination has been found on both domestic and imported Green Onions. The objective of our study was to investigate Escherichia coli O157:H7 inactivation efficacy of pulsed light (PL) as well as its combination with surfactant and/or sanitizers on Green Onions. Green Onions were cut into two segments, stems and leaves, to represent two different matrixes. Stems were more difficult to be decontaminated. Spot and dip inoculation methods were compared and dipped inoculated Green Onions were found to be more difficult to be decontaminated. Results showed that 5 s dry PL (samples were not immersed in water during PL treatment) and 60 s wet PL (samples were immersed in water and stirred during PL treatment) treatments provided promising inactivation efficacy (> 4 log 10 CFU/g) for spot inoculated stems and leaves. For dip inoculated Green Onions, 60 s wet PL treatment was comparable with 100 ppm chlorine washing, demonstrating that PL could be used as an alternative to chlorine. To further increase the degree of microbial inactivation, combined treatments were applied. PL combined with surfactant (SDS) was found to be more effective than single treatments of PL, SDS, chlorine, citric acid, thymol, and hydrogen peroxide, and binary combined treatments of PL with one of those chemicals. Addition of chlorine or hydrogen peroxide to the PL–SDS combination did not further enhanced its microbial inactivation efficacy. The combination of PL and 1000 ppm of SDS reduced the E. coli O157:H7 populations dip inoculated on the stems and leaves of Green Onions by 1.4 and 3.1 log 10 CFU/g, respectively. Our findings suggest that PL could potentially be used for decontamination of E. coli O157:H7 on Green Onions, with wet PL added with SDS being the most effective PL treatment.
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Decontamination of Escherichia coli O157: H7 on Green Onions using pulsed light (PL) and PL-surfactant-sanitizer combinations
International Journal of Food Microbiology, 2013Co-Authors: Wenqing Xu, Yaoxin Huang, Haiqiang Chen, Changqing WuAbstract:Imported Green onion has been associated with three large outbreaks in the USA. Contamination has been found on both domestic and imported Green Onions. The objective of our study was to investigate Escherichia coli O157:H7 inactivation efficacy of pulsed light (PL) as well as its combination with surfactant and/or sanitizers on Green Onions. Green Onions were cut into two segments, stems and leaves, to represent two different matrixes. Stems were more difficult to be decontaminated. Spot and dip inoculation methods were compared and dipped inoculated Green Onions were found to be more difficult to be decontaminated. Results showed that 5s dry PL (samples were not immersed in water during PL treatment) and 60s wet PL (samples were immersed in water and stirred during PL treatment) treatments provided promising inactivation efficacy (>4log10CFU/g) for spot inoculated stems and leaves. For dip inoculated Green Onions, 60s wet PL treatment was comparable with 100ppm chlorine washing, demonstrating that PL could be used as an alternative to chlorine. To further increase the degree of microbial inactivation, combined treatments were applied. PL combined with surfactant (SDS) was found to be more effective than single treatments of PL, SDS, chlorine, citric acid, thymol, and hydrogen peroxide, and binary combined treatments of PL with one of those chemicals. Addition of chlorine or hydrogen peroxide to the PL-SDS combination did not further enhanced its microbial inactivation efficacy. The combination of PL and 1000ppm of SDS reduced the E. coli O157:H7 populations dip inoculated on the stems and leaves of Green Onions by 1.4 and 3.1log10CFU/g, respectively. Our findings suggest that PL could potentially be used for decontamination of E. coli O157:H7 on Green Onions, with wet PL added with SDS being the most effective PL treatment. © 2013 Elsevier B.V.
Kalmia E Kniel - One of the best experts on this subject based on the ideXlab platform.
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inactivation of internalized and surface contaminated enteric viruses in Green Onions
International Journal of Food Microbiology, 2013Co-Authors: Kirsten A Hirneisen, Kalmia E KnielAbstract:Abstract With increasing outbreaks of gastroenteritis associated with produce, it is important to assess interventions to reduce the risk of illness. UV, ozone and high pressure are non-thermal processing technologies that have potential to inactivate human pathogens on produce and allow the retention of fresh-like organoleptic properties. The objective of this study was to determine if UV, ozone, and high pressure are effective technologies compared to traditional chlorine spray on Green Onions to reduce enteric viral pathogens and to determine the effect of location of the virus (surface or internalized) on the efficacy of these processes. Mature Green onion plants were inoculated with murine norovirus (MNV), hepatitis A virus (HAV) and human adenovirus type 41 (Ad41) either on the surface through spot inoculation or through inoculating contaminated hydroponic solution allowing for uptake of the virus into the internal tissues. Inoculated Green Onions were treated with UV (240 mJ s/cm2), ozone (6.25 ppm for 10 min), pressure (500 MPa, for 5 min at 20 °C), or sprayed with calcium hypochlorite (150 ppm, 4 °C). Viral inactivation was determined by comparing treated and untreated inoculated plants using cell culture infectivity assays. Processing treatments were observed to greatly affect viral inactivation. Viral inactivation for all three viruses was greatest after pressure treatment and the lowest inactivation was observed after chlorine and UV treatment. Both surface inoculated viruses and viruses internalized in Green Onions were inactivated to some extent by these post-harvest processing treatments. These results suggest that ozone and high pressure processes aimed to reduce the level of microbial contamination of produce have the ability to inactivate viruses if they become localized in the interior portions of produce.
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Comparative Uptake of Enteric Viruses into Spinach and Green Onions
Food and Environmental Virology, 2013Co-Authors: Kirsten A Hirneisen, Kalmia E KnielAbstract:Root uptake of enteric pathogens and subsequent internalization has been a produce safety concern and is being investigated as a potential route of pre-harvest contamination. The objective of this study was to determine the ability of hepatitis A virus (HAV) and the human norovirus surrogate, murine norovirus (MNV), to internalize in spinach and Green Onions through root uptake in both soil and hydroponic systems. HAV or MNV was inoculated into soil matrices or into two hydroponic systems, floating and nutrient film technique systems. Viruses present within spinach and Green Onions were detected by RT-qPCR or infectivity assays after inactivating externally present viruses with Virkon^®. HAV and MNV were not detected in Green onion plants grown up to 20 days and HAV was detected in only 1 of 64 spinach plants grown in contaminated soil substrate systems up to 20 days. Compared to soil systems, a drastic difference in virus internalization was observed in hydroponic systems; HAV or pressure-treated HAV and MNV were internalized up to 4 log RT-qPCR units and internalized MNV was shown to remain infectious. Understanding the interactions of human enteric viruses on produce can aid in the elucidation of the mechanisms of attachment and internalization, and aid in understanding risks associated with contamination events.
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uv light inactivation of hepatitis a virus aichi virus and feline calicivirus on strawberries Green Onions and lettuce
Journal of Food Protection, 2008Co-Authors: Viviana R Fino, Kalmia E KnielAbstract:A majority of illnesses caused by foodborne viruses are associated with fresh produce. Fruits and vegetables may be considered high-risk foods, as they are often consumed raw without a specific inactivation step. Therefore, there is a need to evaluate nonthermal treatments for the inactivation of foodborne pathogens. This study investigates the UV inactivation of three viruses: feline calicivirus (a surrogate for norovirus), and two picornaviruses, hepatitis A virus and Aichi virus. Three produce types were selected for their different surface topographies and association with outbreaks. Green Onions, lettuce, and strawberries were individually spot inoculated with 107 to 109 50% tissue culture infective doses (TCID50) of each virus per ml and exposed to UV light at various doses (≤240 mW s/cm2), and viruses were eluted using an optimized recovery strategy. Virus infection was quantified by TCID50 in mammalian cell culture and compared with untreated recovered virus. UV light applied to contaminated lettu...
Peter Fodor - One of the best experts on this subject based on the ideXlab platform.
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bioavailability of selenium from selenium enriched Green Onions allium fistulosum and chives allium schoenoprasum after in vitro gastrointestinal digestion
International Journal of Food Sciences and Nutrition, 2007Co-Authors: Emese Kapolna, Peter FodorAbstract:Three sample preparation methods—proteolysis to determine the initial species distribution, and an in vitro gastric and gastrointestinal digestion to assess the bioavailability of selenium—were applied to extract the selenium from selenized Green onion and chive samples. Ion exchange chromatography was coupled to a high-performance liquid chromatography–ICP-MS system to analyze the selenium species of Allium samples. The difference in the selenium accumulation capability of Green Onions and chives was significant. Chive accumulated a one order of magnitude higher amount of selenium than did Green onion. After proteolysis of both types of Allium plants, high amounts of organic selenium species such as MeSeCys, SeCys2 and SeMet became accessible. In the case of Se(VI)-enrichment, selenate was the main species in the proteolytic extract. After simulating the human digestion, the organic species were just slightly bioavailable compared with the results from proteolysis. The inorganic selenium content of the s...
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speciation analysis of selenium enriched Green Onions allium fistulosum by hplc icp ms
Microchemical Journal, 2006Co-Authors: Emese Kapolna, Peter FodorAbstract:Abstract Green Onions (Allium fistulosum) enriched with 10 or 100 μg mL− 1 Se(IV) or SeMet were analyzed for total selenium and species distribution. Anion and cation exchange chromatographies were applied for the separation of selenium species with mass spectrometric detection. Two different sample preparation methods (NaOH and enzymatic) were compared from the Se extraction efficiency point of view. Total selenium concentration accumulated by the Onions reached the 200 μg g− 1 level expressed for dry weight when applying SeMet at a concentration of 100 μg mL− 1 as the source of Se. Speciation studies revealed that both in onion bulbs and leaves the predominant form of organic selenium is Se-methyl-selenocysteine (MeSeCys). When Se(IV) was applied for Se-enrichment at a concentration level of 100 μg mL− 1 both onion leaf and bulb contained a significant amount of inorganic selenium. An unknown compound was also detected.
