Category Archives: Food Technology

Research – Utilizing kitchen steamers to inactivate Listeria monocytogenes and Salmonella enterica on whole cantaloupe melons

Posted on May 14, 2019 by | Leave a comment

Wiley Online

 

Abstract

Cantaloupes contaminated with Listeria and Salmonella have caused large scale of foodborne illness outbreaks in recent years. Prior research has shown that heat treatment can be used to reduce microbial contaminates on fruit surfaces. However, no study has evaluated the use of kitchen steamers for inactivating foodborne pathogens on cantaloupes. The purpose of this study was to test the sanitization efficacy of three models of electrical kitchen steamers (steamer‐A, ‐B, and ‐C) for eliminating foodborne pathogens on cantaloupe surfaces. Fresh cantaloupes were spot‐inoculated with Listeria monocytogens or Salmonella enterica and kept at 4 or 22 °C for a day before steam treatment for ≤100 s. Test results show that the surface of nonrefrigerated cantaloupes can be decontaminated (with ≥5.0 log reduction) within 60 s using any of the tested steamers. For refrigerated fruits (4 °C), however, only two steamers (steamer‐B and ‐C) decontaminated the cantaloupes within 60 s and they were unable to render the pathogens undetected in enriched samples. Salmonella was more susceptible than Listeria to steam treatment. In conclusion, electrical kitchen steamers can be utilized by consumers to sanitize whole cantaloupes prior to consumption. However, fruit temperature and steamer selection can influence the heating time required for surface sanitization.

Practical applications

Melons with netted rind surfaces, such as cantaloupes, likely have caused more outbreaks because their surface shelters pathogens from being eliminated by conventional washing and sanitization. As whole melons marketed at retail stores typically are not treated due to shelf‐life considerations, the safety of untreated melons can be of concern to consumers, especially among at‐risk populations. This study focused on the evaluation of the use of commercially available kitchen steamers in eliminating foodborne pathogens on cantaloupe surfaces. This study showed that kitchen steamers can be utilized to sanitize whole cantaloupes and also at household level, be a highly beneficial for the average concerned consumer to reduce the risk of pathogens on produce before consumption.

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Posted in food contamination, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Safety, Food Technology, Food Testing, Listeria, Listeria welshimeri, Salmonella, Uncategorized

Research – Effects of Package Atmosphere and Storage Conditions on Minimizing Risk of Escherichia coli O157:H7 in Packaged Fresh Baby Spinach

Posted on May 7, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Packaged fresh spinach has been associated with outbreaks of illness caused by Escherichia coli O157:H7. The purpose of this study was to assess the behavior of E. coli O157:H7 in packaged baby spinach in response to storage conditions of temperature and package atmosphere and including effects of inoculation level, spinach leaf damage (cut leaves), internalized or leaf surface contamination, exposure to hypochlorite sanitizer, and package size. Behavior of E. coli O157:H7 inoculated at 2 and 4 log CFU/g on spinach packaged in polymer bags composed of a two-layer laminate (polypropylene and polyethylene) and stored under atmospheres of 20% O2–3% CO2 and 0% O2–15% CO2 (aerobic and anaerobic, respectively) was assessed at 5, 7, 12, and 15°C for up to 14 days. Growth kinetics were calculated using DMFit software. Temperature decreases progressively diminished growth or survival of the pathogen, and an aerobic package atmosphere resulted in longer lag times (4 to 6 days) and lower population levels (0.2 to 1.4 log CFU/g) compared with the anaerobic atmosphere at 15°C. Internalized contamination, leaf cuts, or exposure to 100 ppm of hypochlorite did not result in changes in pathogen behavior compared with controls; however, a growth minimization trend consisting of longer lag times and lower population levels was repeatedly observed in the aerobic compared with the anaerobic package atmospheres. In contrast, growth of indigenous mesophiles and Enterobacteriaceae was unaffected by package atmosphere. Spinach stored at 5 to 7°C in two sizes (5 and 16 oz) of polyethylene terephthalate clamshell packages with ambient air atmospheres was more likely to progress to lower-oxygen conditions in 16-oz compared with 5-oz packages after 7 days of storage (P < 0.05). Practices to maintain aerobic conditions within the package, as well as storage of the package at low temperature, are ways to limit growth of E. coli O157:H7 in packaged spinach.

HIGHLIGHTS

  • Cold aerobic conditions limited survival of E. coli O157:H7 in packaged spinach.

  • Low-oxygen atmosphere increased pathogen risk in temperature-abused packages.

  • Internalization, leaf cuts, and hypochlorite stress did not increase pathogen risk.

  • Large spinach packages trended toward lower-oxygen conditions more than small packages.

  • Maintaining cold aerobic conditions can limit pathogen risk in packaged spinach.

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Posted in E.coli, E.coli O157, E.coli O157:H7, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Poisoning, Food Safety, Food Technology, Food Testing, Food Toxin, Uncategorized

Research – Antibacterial Effects of Phytic Acid against Foodborne Pathogens and Investigation of Its Mode of Action

Posted on May 6, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

This study investigated the antimicrobial mechanism of phytic acid (PA) and its antibacterial effects in combination with ethanol. The MIC of PA on Escherichia coli ATCC 11229, Staphylococcus aureus ATCC 6538P, Bacillus subtilis ATCC 6633, and Salmonella Typhimurium CICC 27483 were 0.24, 0.20, 0.26, and 0.28% (w/w), respectively. E. coli ATCC 11229 and S. aureus ATCC 6538P were selected to investigate the mechanism of PA by analyzing its effects at 1/2MIC and at MIC on the cell morphology, intracellular ATP, and cell membrane integrity. Environmental scanning electron microscope images revealed that PA was able to change the cell morphology and disrupt the intercellular adhesion. PA retarded bacterial growth and caused cell membrane dysfunction, which was accompanied by decreased intracellular ATP concentrations. Flow cytometry analysis further revealed that almost all the bacterial cells were damaged after treatment with PA at its MIC for 2 h. Moreover, PA has a synergistic antimicrobial ability when used in combination with ethanol. These results suggested that PA is effective in inhibiting growth of foodborne pathogens mainly by the mechanism of cell membrane damage and to provide a theoretical basis for the development of natural antimicrobial agents in the food industry.

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Posted in Bacillus Subtilis, E.coli, Food Micro Blog, Food Microbiology Blog, Food Pathogen, Food Technology, microbial contamination, Microbiology, Pathogen, pathogenic, Salmonella, Staphylococcus aureus, Technology, Uncategorized

Research – Response to Questions Posed by the Food and Drug Administration Regarding Virulence Factors and Attributes that Define Foodborne Shiga Toxin–Producing Escherichia coli (STEC) as Severe Human Pathogens

Posted on May 5, 2019 by | Leave a comment

Journal of Food Protection

EXECUTIVE SUMMARY

The National Advisory Committee on Microbiological Criteria for Foods (NACMCF or Committee) was asked to report on (i) what is currently known about virulence and pathogenicity of Shiga toxin–producing Escherichia coli (STEC) and how they cause illness in humans; (ii) what methods are available to detect STEC and their specific virulence factors; and most importantly (iii) how to rapidly identify foodborne STEC that are most likely to cause serious human disease. Individual working groups were developed to address the charge questions, as well as to identify gaps and give recommendations for additional data or research needs. A complete list of Committee recommendations is in Chapter 4.

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Posted in E.coli, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Poisoning, Food Safety, Food Technology, Food Testing, Shigatoxin, STEC, STX 1, STX 2, Uncategorized

Research – Evaluation of Inactivating Norovirus, Hepatitis A, and Listeria monocytogenes on Raspberries by Sanitizer Spray

Posted on May 5, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Reducing the risk of contamination with foodborne pathogens is paramount in maintaining safety of produce. The raspberry industry uses chlorine spray as a control measure before conveying freshly picked red raspberries into individually quick frozen units. However, the efficacy of sanitizer spray treatment to inactivate norovirus, hepatitis A virus (HAV), and Listeria monocytogenes on raspberries has not been characterized. In this study, a laboratory-scale spray bar device was fabricated to simulate industrial settings. Fresh raspberries were spot inoculated with murine norovirus (MNV, a norovirus surrogate), HAV, or L. monocytogenes and sprayed with 50 ppm of chlorine or 80 ppm of peroxyacetic acid (PAA). Surviving pathogens were enumerated after spray or postspray frozen storage at −20°C for 1 and 24 h. Chlorine and PAA spray treatments reduced MNV and L. monocytogenes from raspberries by 0.2 and 0.6 log but had no effect on HAV. During frozen storage after spray treatment, the residual PAA on the fruit surfaces further reduced MNV and L. monocytogenes, achieving a total reduction of approximately 0.6 and 3.0 log, respectively. HAV levels were not affected by frozen storage after PAA or chlorine spray treatment. The findings were supported by the sanitizer decay results showing that PAA decayed more slowly than active chlorine on raspberry surfaces. Submerging washes conducted as comparisons showed higher reduction of pathogens from raspberry surfaces than similar respective sanitizer spray treatments. The results suggest that PAA could contribute to raspberry postharvest sanitation, aiding in risk reduction of pathogen contamination prior to entering an individually quick frozen unit.

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Posted in food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Poisoning, Food Safety, Food Technology, Food Testing, Hepatitis A, Listeria, Listeria monocytogenes, Norovirus, Technology, Uncategorized

Research – Growth of Salmonella and Other Foodborne Pathogens on Inoculated Inshell Pistachios during Simulated Delays between Hulling and Drying

Posted on May 4, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

During harvest, pistachios are hulled, separated in water into floater and sinker streams (in large part on the basis of nut density), and then dried before storage. Higher prevalence and levels of Salmonella were previously observed in floater pistachios, but contributing factors are unclear. To examine the behavior of pathogens on hulled pistachios during simulated drying delays, floater and sinker pistachios collected from commercial processors were inoculated at 1 or 3 log CFU/g with cocktails of Salmonella and in some cases Escherichia coli O157:H7 or Listeria monocytogenes and incubated for up to 30 h at 37°C and 90% relative humidity. Populations were measured by plating onto tryptic soy agar and appropriate selective agars. In most cases, no significant growth (P > 0.05) of Salmonella was observed in the first 3 h after inoculation in hulled floaters and sinkers. Growth of Salmonella was greater on floater pistachios than on corresponding sinkers and on floater pistachios with ≥25% hull adhering to the shell surface than on corresponding floaters with <25% adhering hull. Maximum Salmonella populations (2 to 7 log CFU/g) were ∼2-log higher on floaters than on corresponding sinkers. The growth of E. coliO157:H7 and Salmonella on hulled pistachios was similar, but a longer lag time (approximately 11 h) and significantly lower maximum populations (4 versus 5 to 6 log CFU/g; P < 0.05) were predicted for L. monocytogenes. Significant growth of pathogens on hulled pistachios is possible when delays between hulling and drying are longer than 3 h, and pathogen growth is enhanced in the presence of adhering hull material.

HIGHLIGHTS

  • Foodborne pathogens multiplied on undried inshell pistachios.

  • Pathogen growth was greater when hull material was present.

  • Drying delays of >3 h led to significant increases in pathogen populations.

  • Managing drying delays will reduce the risk for growth of foodborne pathogens.

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Posted in E.coli, E.coli O157, E.coli O157:H7, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Safety, Food Technology, Food Testing, Pathogen, pathogenic, Salmonella, Uncategorized

Research – Atmospheric Cold Plasma and Peracetic Acid–Based Hurdle Intervention To Reduce Salmonella on Raw Poultry Meat

Posted on May 4, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

In Canada, Salmonella-related foodborne illness accounts for more than 88,000 cases annually. Poultry products represent one of the major vectors for the zoonotic transmission of Salmonella. The majority of the current disinfection strategies that are applied in the poultry industry involve the use of diverse chemical antimicrobial agents; however, knowledge about the efficacy of novel antimicrobial technologies such as atmospheric cold plasma (ACP) and the potential of hurdle interventions is very limited. The objective of this study was to evaluate the synergetic effect of ACP and peracetic acid (PAA) as a hurdle antimicrobial intervention to reduce Salmonella enterica Typhimurium on raw poultry meat. Raw poultry meat samples were inoculated with Salmonella Typhimurium followed by the application of different treatments consisting of ACP and PAA (100 and 200 ppm) alone as well as in combination. Different hurdle interventions using PAA and ACP treatments resulted in significant (P ≤ 0.05) reductions in Salmonella Typhimurium, ranging from 2.3 to 5.3 log CFU/cm2, in comparison to PAA treatments alone with 100 or 200 ppm or ACP treatment alone, resulting in the reduction of Salmonella populations by 0.6, 1.3, and 2.3 CFU/cm2, respectively. Treatments involving application of PAA followed immediately by ACP and ACP followed by PAA resulted in the highest (P ≤ 0.05) reduction in Salmonella by 4.7 and 5.3 log CFU/cm2, respectively. Transmission electron microscopy images indicated that combined treatments resulted in destruction of Salmonella cells with visible cellular deformation and loss of cellular integrity. Color and moisture content of poultry meat samples were affected; thus, for large-scale application, further research needs to be done for optimizing this hurdle intervention. In conclusion, this study demonstrates the synergistic effect of ACP and PAA and its potential application for the safety of poultry products.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Technology, microbial contamination, Microbiology, Salmonella, Technology, Uncategorized

Research – Efficacy of Acetic Acid or Chitosan for Reducing the Prevalence of Salmonella- and Escherichia coli O157:H7–Contaminated Leafy Green Plants in Field Systems

Posted on May 3, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Outbreaks associated with fresh-cut leafy greens continue to occur despite efforts to implement horticultural practices that minimize introduction of enteric pathogens to the crop. The experimental trials in this study were designed to examine the efficacy of an acetic acid (AA)- and chitosan-based spray treatment, applied 1 day prior to harvest, for reducing the prevalence of Escherichia coli O157:H7 (O157) and Salmonella in field-grown leafy greens contaminated at levels detectable only through enrichment culture. Responses to the treatment solution were variable and depended on the type of leafy green (leafy lettuce, spinach, or cabbage), cultivar, pathogen, and AA concentration (0.3 to 0.7%). No significant differences in E. coli O157 prevalence were found for untreated and treated cabbage heads and spinach plants (P > 0.05). In contrast, treatment significantly affected Salmonella on ‘Bravo F1’ green cabbage and ‘7-Green’ spinach (P < 0.05), with odds ratios of 2.2 and 3.3 for finding the pathogen on untreated versus treated greens, respectively. Salmonella was also 7.1 times more likely to be found on an untreated lettuce plant than on a lettuce plant sprayed with a 0.7% AA treatment solution (95% confidence interval [CI], 4.1 to 12.2; P < 0.0001). In studies addressing the efficacy of chitosan (0.1 or 0.3%), this chemical failed to reduce the prevalence of either pathogen on lettuce (P > 0.05). Similarly, spraying with 0.3% AA did not affect the prevalence of Salmonella on lettuce plants (P > 0.05); however, treatment solutions with 0.4% AA reduced the likelihood of detecting Salmonella in treated versus untreated plants by 6.6 times (95% CI, 2.1 to 20.9; P = 0.0007). After the lettuce was harvested and hand washed, consumers failed to distinguish either visually or organoleptically between untreated lettuce and lettuce sprayed with an acetic acid solution (P > 0.05). These results indicate that acetic acid could be used to reduce the microbiological risk of preharvest leafy greens.

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Posted in E.coli, E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology Blog, Food Safety, Food Technology, Food Testing, Salmonella, Uncategorized

Research – Effects of Package Atmosphere and Storage Conditions on Minimizing Risk of Escherichia coli O157:H7 in Packaged Fresh Baby Spinach

Posted on April 27, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Packaged fresh spinach has been associated with outbreaks of illness caused by Escherichia coli O157:H7. The purpose of this study was to assess the behavior of E. coli O157:H7 in packaged baby spinach in response to storage conditions of temperature and package atmosphere and including effects of inoculation level, spinach leaf damage (cut leaves), internalized or leaf surface contamination, exposure to hypochlorite sanitizer, and package size. Behavior of E. coli O157:H7 inoculated at 2 and 4 log CFU/g on spinach packaged in polymer bags composed of a two-layer laminate (polypropylene and polyethylene) and stored under atmospheres of 20% O2–3% CO2 and 0% O2–15% CO2 (aerobic and anaerobic, respectively) was assessed at 5, 7, 12, and 15°C for up to 14 days. Growth kinetics were calculated using DMFit software. Temperature decreases progressively diminished growth or survival of the pathogen, and an aerobic package atmosphere resulted in longer lag times (4 to 6 days) and lower population levels (0.2 to 1.4 log CFU/g) compared with the anaerobic atmosphere at 15°C. Internalized contamination, leaf cuts, or exposure to 100 ppm of hypochlorite did not result in changes in pathogen behavior compared with controls; however, a growth minimization trend consisting of longer lag times and lower population levels was repeatedly observed in the aerobic compared with the anaerobic package atmospheres. In contrast, growth of indigenous mesophiles and Enterobacteriaceae was unaffected by package atmosphere. Spinach stored at 5 to 7°C in two sizes (5 and 16 oz) of polyethylene terephthalate clamshell packages with ambient air atmospheres was more likely to progress to lower-oxygen conditions in 16-oz compared with 5-oz packages after 7 days of storage (P < 0.05). Practices to maintain aerobic conditions within the package, as well as storage of the package at low temperature, are ways to limit growth of E. coli O157:H7 in packaged spinach.

HIGHLIGHTS

  • Cold aerobic conditions limited survival of E. coli O157:H7 in packaged spinach.

  • Low-oxygen atmosphere increased pathogen risk in temperature-abused packages.

  • Internalization, leaf cuts, and hypochlorite stress did not increase pathogen risk.

  • Large spinach packages trended toward lower-oxygen conditions more than small packages.

  • Maintaining cold aerobic conditions can limit pathogen risk in packaged spinach.

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Posted in E.coli, E.coli O157, E.coli O157:H7, Enterobacteriaceae, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Technology, microbial contamination, Microbiology, Uncategorized

Research – Comparison of Antimicrobial Treatments Applied via Conventional or Handheld Electrostatic Spray To Reduce Shiga Toxin–Producing Escherichia coli on Chilled Beef Outside Rounds

Posted on April 27, 2019 by | Leave a comment

Journal of Food Protection

The purpose of this study was to compare the efficacy of different antimicrobial interventions applied via either conventional spray (CS) or handheld electrostatic spray (ESS) to reduce Shiga toxin–producing Escherichia coli (STEC) on fresh beef surfaces. Hot-boned outside rounds (ORs) were inoculated within 1 h after harvest with a cocktail of eight isolates consisting of 8 O157 and non-O157 serogroups of STEC (STEC8). ORs were hung on sterile meat hooks at 4°C for 36 h to simulate a contaminated full carcass side in the chiller. ORs were then treated with lactic acid (LA; 4.5%, w/v), 3.0% lauric arginate ester (LAE), 0.8% cetylpyridinium chloride, 200 mg/L peracetic acid, 3 mg/L chlorine dioxide, 5 mg/L ClO2, or tap water by using CS or ESS. Temperatures of LA and peracetic acid were set at 55 and 42°C before spraying, whereas all other solutions were applied at room temperature (25°C). Pretreatment and posttreatment STEC8-inoculated beef tissue samples were aseptically collected to evaluate the efficacy of interventions by application method (CS or ESS). LA applied with CS achieved the greatest reduction in STEC8 numbers (3.3 log CFU/cm2) compared with all other treatments: 0.2 log CFU/cm2 (tap water) to 2.3 log CFU/cm2 (LAE). Only for LA did a significant difference arise in mean STEC8 reductions between CS and ESS applications (3.2 versus 1.7 log CFU/cm2, respectively). Among the treatments applied with ESS, LAE produced the greatest reduction of STEC8. Antimicrobial interventions applied via conventional wand or cabinet-applied technologies can reduce the O157 and non-O157 STEC on fresh beef carcass surfaces, reducing transmission to beef consumers.

HIGHLIGHTS

  • We found no advantage in the use of electrostatic spray to reduce STEC8 on cold beef.

  • Greatest reductions in STEC8 were achieved by lactic acid with conventional spray.

  • Lauric arginate ester was the second best antimicrobial agent at reducing STEC8.

  • Lactic acid reduced pH on the beef surface significantly.

  • There was no effect of antimicrobial solution on temperature increase on beef outside rounds.

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Posted in E.coli, E.coli O157, E.coli O157:H7, Food Microbiology, Food Microbiology Blog, Food Technology, microbial contamination, Microbiology, STEC, Uncategorized