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Changqing Wu - One of the best experts on this subject based on the ideXlab platform.
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Similar Reduction of Salmonella enterica Typhimurium on Grape Tomatoes and Its Cross-Contamination in Wash Water by Washing with Natural Antimicrobials as Compared with Chlorine Treatment
Food and Bioprocess Technology, 2014Co-Authors: Yingjian Lu, Rolf Joerger, Changqing WuAbstract:Thymol (THY), a generally recognized as safe (GRAS) compound found in thyme oil, has inhibitory effects against foodborne pathogens including Salmonella . Hydrogen peroxide (H_2O_2) is another GRAS agent to effectively inactivate Salmonella . The aim of the current study was to develop a GRAS wash solution containing THY (or H_2O_2) and other GRAS antimicrobials (organic acids and food surfactants) that would effectively reduce Salmonella enterica on Grape Tomatoes and minimize cross-contamination in washing water. A systematic approach including minimum inhibitory concentration and minimum bactericidal concentration tests, inhibition zone tests, and small-scale and scaled-up tomato washing tests was used to develop such wash solutions. Grape Tomatoes surface-inoculated with S. enterica Typhimurium were washed with selected solutions containing combination of 0.2 mg/ml THY, 5 % sodium dodecyl sulfate (SDS) and 2 mg/ml acetic acid (AA), 800 ppm H_2O_2, combination of 200 ppm H_2O_2 with 4 % SDS, or 200 ppm chlorine for 2 min. THY 0.2 mg/ml + SDS 5 % + AA 2 mg/ml, 800 ppm H_2O_2, or 200 ppm chlorine achieved around 7.5 log reductions of Salmonella on the Tomatoes as compared to the control in tests involving 10 or 100 g Tomatoes. More than 5.0 log reductions in the spent washing solutions (0.2 mg/ml THY + SDS 5 % + 2 mg/ml AA; 800 ppm H_2O_2) was observed. None of these antimicrobial washes changed the color, pH, texture, sensory quality of the Tomatoes during 16-day storage at 4 and 22 °C. These treatments also achieved a 1.3 log reduction of total aerobic bacteria. Thus, washing with 0.2 mg/ml THY + SDS 5 % + 2 mg/ml AA and 800 ppm H_2O_2 as alternative to chlorine-based washing could be an effective method to inactivate Salmonella on Tomatoes and reduce the transmission of pathogens from Tomatoes to washing solutions.
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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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reduction of salmonella enterica on Grape Tomatoes using microwave heating
International Journal of Food Microbiology, 2011Co-Authors: Yingjian Lu, A Turley, X Dong, Changqing WuAbstract:Abstract Grape Tomatoes were surface inoculated with Salmonella enterica serovars Typhimurium, Senftenburg, Kentucky and Enteritidis and heated for 10, 20, 30, 40 and 50 s using a household microwave oven at two different power levels (medium and high). Following heating, viable counts, temperature measurements and quality measurements were performed on the Tomatoes. At high power level, more than 2 log reduction of Salmonella enterica was detected on Grape Tomatoes after 50 s but the texture were damaged. Three heating treatments, 40 s heating at high power level, 40 and 50 s heating at medium power level, could achieve more than 1.45 log reduction of Salmonella enterica on Grape Tomatoes, and all the treatments except for 50 s at high power level did not affect the color, pH value and nutritional quality of Grape tomato after heating (p > 0.05). However, 40 s heating at medium power was the only treatment among the three that did not affect the texture quality of Grape tomato. Therefore, it might be a potential way for consumers to use microwave heating at medium power level (700 W) for 40 s to reduce Salmonella population on water immersed Grape Tomatoes.
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reduction of salmonella enterica contamination on Grape Tomatoes by washing with thyme oil thymol and carvacrol as compared with chlorine treatment
Journal of Food Protection, 2010Co-Authors: Yingjian Lu, Changqing WuAbstract:In recent years, multistate outbreaks of Salmonella enterica serovars were traced to Tomatoes and resulted in serious economic loss for the tomato industry and decreased consumer confidence in the safety of tomato produce. Purified compounds derived from essential oils such as thymol and carvacrol had wide inhibitory effects against foodborne pathogens including Salmonella. The objective of this study was to determine the antimicrobial activities of thymol, carvacrol, and thyme oil against Salmonella on Grape Tomatoes. Surface-inoculated Grape Tomatoes were washed with 4% ethanol, 200 ppm of chlorine, or one of six washing solutions (thymol [0.2 and 0.4 mg/ml], thyme oil [1 and 2 mg/ml], and carvacrol [0.2 and 0.4 mg/ml]) for 5 or 10 min. There was no significant difference in the reduction of S. enterica serovars when different washing times were used (P > 0.05). Thymol (especially at the concentration of 0.4 mg/ml) was the most effective (P < 0.05) among the three natural antimicrobial agents, which ach...
Kimberly J B Sokorai - One of the best experts on this subject based on the ideXlab platform.
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Advanced oxidation process for the inactivation of Salmonella typhimurium on Tomatoes by combination of gaseous ozone and aerosolized hydrogen peroxide.
International Journal of Food Microbiology, 2019Co-Authors: Kimberly J B Sokorai, Joshua B GurtlerAbstract:Abstract Fresh produce-associated outbreaks of foodborne illnesses continue to occur every year in the U.S., suggesting limitations of current practices and the need for effective intervention technologies. Advanced oxidation process involves production of hydrogen radicals, which are the strongest oxidant. The objective of the present study was to evaluate the effectiveness of advanced oxidation process by combining gaseous ozone and aerosolized hydrogen peroxide. Grape Tomatoes were inoculated with a 2-strain cocktail of Salmonella typhimurium on both stem scar and smooth surface. Gaseous ozone (800 and 1600 ppm) and aerosolized hydrogen peroxide (2.5, 5 and 10%) were separately or simultaneously introduced into a treatment chamber where the inoculated Tomatoes were placed. During the 30 min treatments, hydrogen peroxide was aerosolized using an atomizer operated in two modes: continuously or 15 s on/50 s off. After the treatments, surviving Salmonella on the smooth surface and stem scar were enumerated. Results showed that ozone alone reduced Salmonella populations by
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Quality deterioration of Grape tomato fruit during storage after treatments with gaseous ozone at conditions that significantly reduced populations of Salmonella on stem scar and smooth surface
Food Control, 2019Co-Authors: Lin Wang, Kimberly J B Sokorai, Joseph SitesAbstract:Abstract Gaseous ozone was evaluated for its effectiveness in reducing populations of Salmonella and native microorganisms on Grape Tomatoes and its impact on sensory and nutritional quality of the fruit. Grape Tomatoes with Salmonella enterica serovar Typhimurium inoculated onto stem scar and smooth surface were treated with 1.71, 3.43 and 6.85 mg L−1 gaseous ozone for 2 or 4 h. For quality studies, non-inoculated Tomatoes were treated with gaseous ozone under the same concentrations and durations and stored at 10 °C for 21 d. Sensory properties (appearance and off-odor), total plate count (TPC), mold and yeast count, instrumental color, firmness, and lycopene and vitamin C content were measured on d 1, 7, 14, and 21 of storage. Results showed that 6.85 mg L−1 ozone for 2 and 4 h treatments reduced Salmonella populations by approximately 2 log CFU fruit−1 on both smooth surface and stem scar area of Tomatoes. Other treatments did not significantly reduce the populations of Salmonella. Significant reductions on TPC were observed on fruit treated with 6.85 mg L−1 ozone for 2 and 4 h and 3.43 mg L−1 for 2 h on d 1 and 7 of storage. However, mold and yeast counts were not consistently affected by the gaseous ozone treatments. Ozone at 3.43 and 6.85 mg L−1 for 4 h negatively impacted the ratings of appearance and off-odor. In addition, the same treatments significantly reduced firmness and decreased lycopene and vitamin C contents. Overall, our results indicated that gaseous ozone that achieved significant reductions of Salmonella populations caused deteriorations in the quality of Grape Tomatoes.
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in package atmospheric cold plasma treatment of bulk Grape Tomatoes for microbiological safety and preservation
Food Research International, 2018Co-Authors: Brendan A Niemira, Glenn Boyd, Joseph Sites, Kimberly J B SokoraiAbstract:Abstract Effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inactivation of Salmonella and the storability of Grape tomato were investigated. Grape Tomatoes, with or without inoculation with Salmonella, were packaged in a polyethylene terephthalate (PET) commercial clamshell container and cold plasma-treated at 35 kV at 1.1 A for 3 min using a DACP system equipped with a pin-type high-voltage electrode. DACP treatment inactivated Salmonella (p 0.05). DACP treatment inactivated Salmonella uniformly in both layers of the double-layer configuration of the Grape Tomatoes regardless of the position of the Tomatoes in each layer. Salmonella was most efficiently inactivated when the headspace to tomato volume ratio of the container was highest. Integration of rolling of Tomatoes during treatment significantly increased the Salmonella reduction rates from 0.9 ± 0.2 log CFU/tomato to 3.3 ± 0.5 log CFU/tomato in the double-layer configuration of the tomato samples. Rolling-integrated DACP also initially reduced the number of total mesophilic aerobic bacteria and yeast and molds in the double-layer configuration of tomato samples by 1.3 ± 0.3 and 1.5 ± 0.2 log CFU/tomato, respectively. DACP treatment effectively reduced the growth of Salmonella and indigenous microorganisms at 10 and 25 °C, and did not influence the surface color, firmness, weight loss, lycopene concentration and residual ascorbic acid of Grape Tomatoes during storage at 10 and 25 °C. DACP treatment holds promise as a post-packaging process for improving microbial safety against Salmonella and storability of fresh Grape Tomatoes.
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Cold plasma-activated hydrogen peroxide aerosol inactivates Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria innocua and maintains quality of Grape tomato, spinach and cantaloupe.
International Journal of Food Microbiology, 2017Co-Authors: Yunbin Jiang, Kimberly J B Sokorai, Georgios Pyrgiotakis, Philip Demokritou, Xihong Li, Sudarsan MukhopadhyayAbstract:Abstract The purpose of this study was to investigate the efficacy of aerosolized hydrogen peroxide in inactivating bacteria and maintaining quality of Grape Tomatoes, baby spinach leaves and cantaloupes. Stem scars and smooth surfaces of Tomatoes, spinach leaves, and cantaloupe rinds, inoculated with Escherichia coli O157:H7, Salmonella Typhimurium and Listeria innocua , were treated for 45 s followed by additional 30 min dwell time with hydrogen peroxide (7.8%) aerosols activated by atmospheric cold plasma. Non-inoculated samples were used to study the effects on quality and native microflora populations. Results showed that two ranges of hydrogen peroxide droplets with mean diameters of 40 nm and 3.0 μm were introduced into the treatment chamber. The aerosolized hydrogen peroxide treatment reduced S . Typhimurium populations by 5.0 log CFU/piece, and E. coli O157:H7 and L. innocua populations from initial levels of 2.9 and 6.3 log CFU/piece, respectively, to non-detectable levels (detection limit 0.6 log CFU/piece) on the smooth surface of Tomatoes. However, on the stem scar area of Tomatoes, the reductions of E. coli O157:H7, S . Typhimurium, and L. innocua were only 1.0, 1.3, and 1.3 log, respectively. On the cantaloupe rind, the treatment reduced populations of E. coli O157:H7, S. Typhimurium and L. innocua by 4.9, 1.3, and 3.0 log CFU/piece, respectively. Under the same conditions, reductions achieved on spinach leaves were 1.5, 4.2 and 4.0 log for E. coli O157:H7, S. Typhimurium and L. innocua , respectively. The treatments also significantly reduced native aerobic plate count, and yeasts and mold count of tomato fruits and spinach leaves. Furthermore, firmness and color of the samples were not significantly affected by the aerosolized hydrogen peroxide. Overall, our results showed that the efficacy of aerosolized hydrogen peroxide depended on type of inoculated bacteria, location of bacteria and type of produce items, and aerosolized hydrogen peroxide could potentially be used to sanitize fresh fruits and vegetables.
Sudarsan Mukhopadhyay - One of the best experts on this subject based on the ideXlab platform.
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nisin based organic acid inactivation of salmonella on Grape Tomatoes efficacy of treatment with bioluminescence atp assay
Journal of Food Protection, 2020Co-Authors: Armarynette Berriosrodriguez, Sudarsan Mukhopadhyay, Dike O Ukuku, Modesto Olanya, Jenifer Cassidy, Lynette E Orellana, Brendan A NiemiraAbstract:ABSTRACT The antimicrobial activity of a new nisin-based organic acid sanitizer (NOAS), developed in our laboratory, was tested against viable aerobic mesophilic bacteria and Salmonella populations...
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Cold plasma-activated hydrogen peroxide aerosol inactivates Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria innocua and maintains quality of Grape tomato, spinach and cantaloupe.
International Journal of Food Microbiology, 2017Co-Authors: Yunbin Jiang, Kimberly J B Sokorai, Georgios Pyrgiotakis, Philip Demokritou, Xihong Li, Sudarsan MukhopadhyayAbstract:Abstract The purpose of this study was to investigate the efficacy of aerosolized hydrogen peroxide in inactivating bacteria and maintaining quality of Grape Tomatoes, baby spinach leaves and cantaloupes. Stem scars and smooth surfaces of Tomatoes, spinach leaves, and cantaloupe rinds, inoculated with Escherichia coli O157:H7, Salmonella Typhimurium and Listeria innocua , were treated for 45 s followed by additional 30 min dwell time with hydrogen peroxide (7.8%) aerosols activated by atmospheric cold plasma. Non-inoculated samples were used to study the effects on quality and native microflora populations. Results showed that two ranges of hydrogen peroxide droplets with mean diameters of 40 nm and 3.0 μm were introduced into the treatment chamber. The aerosolized hydrogen peroxide treatment reduced S . Typhimurium populations by 5.0 log CFU/piece, and E. coli O157:H7 and L. innocua populations from initial levels of 2.9 and 6.3 log CFU/piece, respectively, to non-detectable levels (detection limit 0.6 log CFU/piece) on the smooth surface of Tomatoes. However, on the stem scar area of Tomatoes, the reductions of E. coli O157:H7, S . Typhimurium, and L. innocua were only 1.0, 1.3, and 1.3 log, respectively. On the cantaloupe rind, the treatment reduced populations of E. coli O157:H7, S. Typhimurium and L. innocua by 4.9, 1.3, and 3.0 log CFU/piece, respectively. Under the same conditions, reductions achieved on spinach leaves were 1.5, 4.2 and 4.0 log for E. coli O157:H7, S. Typhimurium and L. innocua , respectively. The treatments also significantly reduced native aerobic plate count, and yeasts and mold count of tomato fruits and spinach leaves. Furthermore, firmness and color of the samples were not significantly affected by the aerosolized hydrogen peroxide. Overall, our results showed that the efficacy of aerosolized hydrogen peroxide depended on type of inoculated bacteria, location of bacteria and type of produce items, and aerosolized hydrogen peroxide could potentially be used to sanitize fresh fruits and vegetables.
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Effects of UV-C treatment on inactivation of Salmonella enterica and Escherichia coli O157:H7 on Grape tomato surface and stem scars, microbial loads, and quality ☆
Food Control, 2014Co-Authors: Sudarsan Mukhopadhyay, Dike O Ukuku, Vijay K JunejaAbstract:The purpose of this study was to investigate the effectiveness of ultraviolet-C (UV-C) light inactivation as affected by the location of pathogens on the surface and at stem scars of whole Grape Tomatoes. A mixed bacterial cocktail containing a three strain mixture of Escherichia coli O157:H7 (C9490, E02128 and F00475) and a three serotype mixture of Salmonella enterica (S. Montevideo G4639, S. Newport H1275, and S. Stanley H0558) were used. Tomatoes were spot inoculated using approximately 100 μL of inocula to achieve a population of about 107±1 CFU/tomato. Additionally, the effects of treatment on color, texture, lycopene content, and background microbial loads during post UV-C storage at 4 °C for 21 days were determined. Results showed that UV-C doses of 0.60–6.0 kJ/m2 resulted in 2.3–3.5 log CFU per fruit reduction of E. coli O157:H7 compared to 2.15–3.1 log CFU per fruit reduction for Salmonella on the surfaces. Under the same conditions, log reductions achieved at stem scar were 1.7–3.2 logs CFU for E. coli O157:H7 and 1.9–2.8 logs CFU for Salmonella. The treatment was effective in controlling native microbial loads during storage at 4 °C as the total aerobic mesophilic organisms (PCA) and anaerobic lactic acid bacteria (LAB) counts of treated Tomatoes were significantly (p
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efficacy of integrated treatment of uv light and low dose gamma irradiation on inactivation of escherichia coli o157 h7 and salmonella enterica on Grape Tomatoes
Journal of Food Science, 2013Co-Authors: Sudarsan Mukhopadhyay, Dike O Ukuku, Vijay K JunejaAbstract:The study evaluated the efficacy of integrated ultraviolet-C light (UVC) and low-dose gamma irradiation treatments to inactivate mixed strains of Escherichia coli O157:H7 and Salmonella enterica on inoculated whole Grape Tomatoes. A mixed bacterial cocktail composed of a 3 strain mixture of E. coli O157:H7 (C9490, E02128, and F00475) and a 3 serotype mixture of S. enterica (S. Montevideo G4639, S. Newport H1275, and S. Stanley H0558) was used based on their association with produce-related outbreaks. Spot inoculation (50 to 100 μmL) on tomato surfaces was performed to achieve a population of appropriately 107–8 CFU/tomato. Inoculated Tomatoes were subjected to UVC (253.7 nm) dose of 0.6 kJ/m2 followed by 4 different low doses of gamma irradiations (0.1 kGy, 0.25 kGy, 0.5 kGy, 0.75 kGy). The fate of background microflora (mesophilic aerobic) including mold and yeast counts were also determined during storage at 5 °C over 21 d. Integrated treatment significantly (P 5 log) per fruit was accomplished by combined UVC treatment with 0.5 kGy and 0.75 kGy irradiation, respectively, for all tested pathogens. Furthermore, the combined treatment significantly (P < 0.05) reduced the native microflora compared to the control during storage. The data suggest efficacious treatment strategy for produce indicating 5 or higher log reduction which is consistent with the recommendations of the Natl. Advisory Committee on Microbiological Criteria for Foods.
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Efficacy of Integrated Treatment of UV light and Low‐Dose Gamma Irradiation on Inactivation of Escherichia coli O157:H7 and Salmonella enterica on Grape Tomatoes
Journal of Food Science, 2013Co-Authors: Sudarsan Mukhopadhyay, Dike O Ukuku, Vijay K JunejaAbstract:The study evaluated the efficacy of integrated ultraviolet-C light (UVC) and low-dose gamma irradiation treatments to inactivate mixed strains of Escherichia coli O157:H7 and Salmonella enterica on inoculated whole Grape Tomatoes. A mixed bacterial cocktail composed of a 3 strain mixture of E. coli O157:H7 (C9490, E02128, and F00475) and a 3 serotype mixture of S. enterica (S. Montevideo G4639, S. Newport H1275, and S. Stanley H0558) was used based on their association with produce-related outbreaks. Spot inoculation (50 to 100 μmL) on tomato surfaces was performed to achieve a population of appropriately 107–8 CFU/tomato. Inoculated Tomatoes were subjected to UVC (253.7 nm) dose of 0.6 kJ/m2 followed by 4 different low doses of gamma irradiations (0.1 kGy, 0.25 kGy, 0.5 kGy, 0.75 kGy). The fate of background microflora (mesophilic aerobic) including mold and yeast counts were also determined during storage at 5 °C over 21 d. Integrated treatment significantly (P 5 log) per fruit was accomplished by combined UVC treatment with 0.5 kGy and 0.75 kGy irradiation, respectively, for all tested pathogens. Furthermore, the combined treatment significantly (P < 0.05) reduced the native microflora compared to the control during storage. The data suggest efficacious treatment strategy for produce indicating 5 or higher log reduction which is consistent with the recommendations of the Natl. Advisory Committee on Microbiological Criteria for Foods.
Joshua B Gurtler - One of the best experts on this subject based on the ideXlab platform.
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two generally recognized as safe surfactants plus acidulants inactivate salmonella escherichia coli o157 h7 and listeria monocytogenes in suspension or on dip inoculated Grape Tomatoes
Journal of Food Protection, 2020Co-Authors: Joshua B GurtlerAbstract:ABSTRACT: Contamination of fresh produce with the foodborne pathogens Salmonella enterica, Listeria monocytogenes, and Escherichia coli O157:H7 continues to be problematic, resulting in outbreaks of foodborne illness and costly corporate recalls. Various individual concentrations of citric or lactic acids (0.35 to 0.61%) or isopropyl citrate (0.16 to 0.54%) combined with two generally recognized as safe surfactants, 0.025% sodium-2-ethyl-hexyl sulfate and 0.025% sodium dodecylbenzene-sulfonate, were tested against these three pathogens in suspension and when inoculated and dried on the surface of Grape Tomatoes. The efficacy of sodium hypochlorite (NaClO; at 46 ppm) was also evaluated under dirty and clean conditions in suspension after addition of 0.3 or 0.03% bovine serum albumin, respectively, as an organic load. NaClO (46 ppm) inactivated the three pathogens in suspension by <0.76 log CFU/mL after 5 min in the presence of 0.3% bovine serum albumin, whereas 9 and 15 ppm of free chlorine inactivated the pathogens by 0.64 and 2.77 log CFU/mL, respectively, after 5 min under clean conditions. Isopropyl citrate (0.16% acidulant) plus 0.05% total concentration of the two surfactants inactivated the pathogens in suspension by up to 7.0 log CFU/mL within 2 min. When applied to Grape Tomatoes for 2 min, 0.54% isopropyl citrate plus 0.025% concentrations of each of the two surfactants reduced Salmonella, E. coli O157:H7, and L. monocytogenes by as much as ca. 5.47, 4.89, and 4.19 log CFU/g, respectively. These reductions were significantly greater than those achieved with 49 ppm of free chlorine. Citric acid and lactic acid plus surfactant washes achieved greater inactivation than water-only washes, reducing Salmonella, E. coli O157:H7, and L. monocytogenes on Tomatoes by up to 4.90, 4.37, and 3.98 log CFU/g, respectively. These results suggest that these combinations of acidulants and surfactants may be an effective tool for preventing cross-contamination during the washing of Grape Tomatoes, for reducing pathogens on the fruit itself, and as an alternative to chlorine for washing fresh produce. HIGHLIGHTS:
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Two Generally Recognized as Safe Surfactants plus Acidulants Inactivate Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in Suspension or on Dip-Inoculated Grape Tomatoes.
Journal of Food Protection, 2020Co-Authors: Joshua B GurtlerAbstract:ABSTRACT: Contamination of fresh produce with the foodborne pathogens Salmonella enterica, Listeria monocytogenes, and Escherichia coli O157:H7 continues to be problematic, resulting in outbreaks of foodborne illness and costly corporate recalls. Various individual concentrations of citric or lactic acids (0.35 to 0.61%) or isopropyl citrate (0.16 to 0.54%) combined with two generally recognized as safe surfactants, 0.025% sodium-2-ethyl-hexyl sulfate and 0.025% sodium dodecylbenzene-sulfonate, were tested against these three pathogens in suspension and when inoculated and dried on the surface of Grape Tomatoes. The efficacy of sodium hypochlorite (NaClO; at 46 ppm) was also evaluated under dirty and clean conditions in suspension after addition of 0.3 or 0.03% bovine serum albumin, respectively, as an organic load. NaClO (46 ppm) inactivated the three pathogens in suspension by
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Advanced oxidation process for the inactivation of Salmonella typhimurium on Tomatoes by combination of gaseous ozone and aerosolized hydrogen peroxide.
International Journal of Food Microbiology, 2019Co-Authors: Kimberly J B Sokorai, Joshua B GurtlerAbstract:Abstract Fresh produce-associated outbreaks of foodborne illnesses continue to occur every year in the U.S., suggesting limitations of current practices and the need for effective intervention technologies. Advanced oxidation process involves production of hydrogen radicals, which are the strongest oxidant. The objective of the present study was to evaluate the effectiveness of advanced oxidation process by combining gaseous ozone and aerosolized hydrogen peroxide. Grape Tomatoes were inoculated with a 2-strain cocktail of Salmonella typhimurium on both stem scar and smooth surface. Gaseous ozone (800 and 1600 ppm) and aerosolized hydrogen peroxide (2.5, 5 and 10%) were separately or simultaneously introduced into a treatment chamber where the inoculated Tomatoes were placed. During the 30 min treatments, hydrogen peroxide was aerosolized using an atomizer operated in two modes: continuously or 15 s on/50 s off. After the treatments, surviving Salmonella on the smooth surface and stem scar were enumerated. Results showed that ozone alone reduced Salmonella populations by
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Tomato type and post-treatment water rinse affect efficacy of acid washes against Salmonella enterica inoculated on stem scars of Tomatoes and product quality
International Journal of Food Microbiology, 2018Co-Authors: Joshua B Gurtler, Kimberly SokoraiAbstract:Abstract A study was conducted to evaluate the effects of post-treatment rinsing with water on the inactivation efficacy of acid treatments against Salmonella inoculated onto stem scar areas of two types of Tomatoes. In addition, impact on fruit quality was investigated during 21 days post-treatment storage at 10 °C. A four-strain cocktail of Salmonella enterica ( S . Montevideo, S . Newport, S . Saintpaul, and S . Typhimurium) was inoculated onto stem scar areas of Grape and large round Tomatoes. The inoculated fruits were then treated for 2 min with the following solutions: water, 2% lactic acid +2% acetic acid +2% levulinic acid, 1.7% lactic acid +1.7% acetic acid +1.7% levulinic acid, and 3% lactic acid +3% acetic acid. After treatments, half of the fruits were rinsed with water while another half were not rinsed. Non-inoculated Grape Tomatoes for quality analysis were treated with the same solutions with and without subsequent water rinse. Results demonstrated that the acid combinations reduced populations of Salmonella enterica on the stem scar area of Grape Tomatoes by 1.52–1.90 log CFU/fruit, compared with the non-treated control while water wash and rinse removed the bacterium by only 0.23–0.30 log CFU/fruit. On the stem scar of large round Tomatoes, the same acid treatments achieved 3.54 log CFU/fruit reduction of the pathogen. The varying response to the acid washes between Grape and large round Tomatoes seems to be related to the differences in surface characteristics of stem scar areas observed with SEM. Rinsing with water after acid combination treatments did not significantly affect the efficacy of the treatments in either Grape or large round Tomatoes. Acidic off-odor was detected on fruits treated with acid combination without water rinse 1 day after treatment while water rinse eliminated the off-odor. The acid treatments with and without water rinse did not consistently affect appearance, color, firmness, or lycopene or ascorbic acid contents of Tomatoes during 21-days storage at 10 °C. Considering the similarity in antimicrobial efficacy between the fruits with and without water rinse following acid treatments, and the elimination of acidic odor by water rinse, fruits should be rinsed with water after acid treatments. Overall, our results demonstrated that the acids were more effective in inactivating Salmonella on large round Tomatoes than on Grape Tomatoes, and water rinses following acid treatments eliminated the acidic odor without affecting the efficacy of the acids against Salmonella .
Bin Zhou - One of the best experts on this subject based on the ideXlab platform.
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salmonella inactivation and cross contamination on cherry and Grape Tomatoes under simulated wash conditions
Food Microbiology, 2020Co-Authors: Bin Zhou, Samantha Bolten, Ganyu Gu, Sam Van Haute, Pat Millner, Shirley A MicallefAbstract:ABSTRACT Washing in chlorinated water is widely practiced for commercial fresh produce processing. While known as an effective tool for mitigating food safety risks, chlorine washing could also represent an opportunity for spreading microbial contaminations under sub-optimal operating conditions. This study evaluated Salmonella inactivation and cross-contamination in a simulated washing process of cherry and Grape Tomatoes. Commercially harvested Tomatoes and the associated inedible plant matter (debris) were differentially inoculated with kanamycin resistant (KanR) or rifampin resistant (RifR) Salmonella strains, and washed together with uninoculated Tomatoes in simulated packinghouse dump tank (flume) wash water. Washing in chlorinated water resulted significantly higher Salmonella reduction on Tomatoes than on debris, achieving 2-3 log reduction on Tomatoes and about 1 log on debris. Cross-contamination by Salmonella on Tomatoes was significantly reduced in the presence of 25-150 mg/L free chlorine, although sporadic cross-contamination on Tomatoes was detected when Tomatoes and debris were inoculated at high population density. The majority of the sporadic cross-contaminations originated from Salmonella inoculated on debris. These findings suggested that debris could be a potentially significant source of contamination during commercial tomato washing.
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effect of controlled release chlorine dioxide on the quality and safety of cherry Grape Tomatoes
Food Control, 2017Co-Authors: Bin Zhou, Christopher Ference, Elizabeth A Baldwin, Ken HarrisonAbstract:Abstract The effect of controlled-release chlorine dioxide (ClO2) gas on the food safety and quality of cherry/Grape Tomatoes was investigated. Whole Grape Tomatoes artificially inoculated with either Escherichia coli or Alternaria alternata, or whole cherry Tomatoes inoculated with Salmonella enterica Newport, were packed in 1-lb clamshells, and stored at 20 °C for 14 days. ClO2 pouches were attached under the lids with the following four dosages/release rates: single dose slow-release (S), single dose fast-release (F), fast/slow-release combination (FS), and double dose fast-release (FF). The corresponding equilibrium ClO2 concentration in the headspace was about 2, 4, 6 and 8 ppm, respectively. Treatment with F reduced populations of E. coli and A. alternata by 2.9–4.7, and 1.6 to 4.0 log CFU/g, respectively, within 14 days storage at 20 °C. FS and FF treatments showed little benefit over F. The F and FF treatments reduced population of S. enterica for inoculated cherry Tomatoes by 3.28 and 3.80 log CFU/g, respectively, compared to control after 14 days’ storage at 20 °C. ClO2-treated Grape Tomatoes retained higher firmness and had less weight loss compared to the control. The results indicate that 2 ppm of ClO2 (S) in the clamshells did not adequately control microbial populations; the minimum effective concentration of ClO2 was 4 ppm (F). Higher concentrations provided a small but incremental improvement in ability to control microorganisms. ClO2 released into packages of cherry Tomatoes during storage reduced weight loss, while maintaining firmness.
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Effect of controlled-release chlorine dioxide on the quality and safety of cherry/Grape Tomatoes
Food Control, 2017Co-Authors: Bin Zhou, Christopher Ference, Elizabeth A Baldwin, Ken HarrisonAbstract:Abstract The effect of controlled-release chlorine dioxide (ClO2) gas on the food safety and quality of cherry/Grape Tomatoes was investigated. Whole Grape Tomatoes artificially inoculated with either Escherichia coli or Alternaria alternata, or whole cherry Tomatoes inoculated with Salmonella enterica Newport, were packed in 1-lb clamshells, and stored at 20 °C for 14 days. ClO2 pouches were attached under the lids with the following four dosages/release rates: single dose slow-release (S), single dose fast-release (F), fast/slow-release combination (FS), and double dose fast-release (FF). The corresponding equilibrium ClO2 concentration in the headspace was about 2, 4, 6 and 8 ppm, respectively. Treatment with F reduced populations of E. coli and A. alternata by 2.9–4.7, and 1.6 to 4.0 log CFU/g, respectively, within 14 days storage at 20 °C. FS and FF treatments showed little benefit over F. The F and FF treatments reduced population of S. enterica for inoculated cherry Tomatoes by 3.28 and 3.80 log CFU/g, respectively, compared to control after 14 days’ storage at 20 °C. ClO2-treated Grape Tomatoes retained higher firmness and had less weight loss compared to the control. The results indicate that 2 ppm of ClO2 (S) in the clamshells did not adequately control microbial populations; the minimum effective concentration of ClO2 was 4 ppm (F). Higher concentrations provided a small but incremental improvement in ability to control microorganisms. ClO2 released into packages of cherry Tomatoes during storage reduced weight loss, while maintaining firmness.
