Brendan A. Niemira

Cold Plasma Reduction of Salmonella and Escherichia coli O157:H7 on Almonds Using Ambient Pressure Gases

Contamination of raw nuts, including almonds, is a food safety concern. Cold plasma is a novel antimicrobial intervention that can eliminate foodborne pathogens. The objective of this work was to evaluate the efficacy of rapid cold plasma treatments in eliminating Salmonella and Escherichia coli O157:H7 from dry almonds. Three isolates of Salmonella (S. Anatum F4317, S. Stanley H0558, and S. Enteritidis PT30) and 3 isolates of E. coli O157:H7 (C9490, ATCC 35150, and ATCC 43894) were separately grown and spot-inoculated (10 μL) onto whole almonds and allowed to dry for 10 min. Inoculated almonds were treated with a cold plasma jet, with treatment variables evaluated in a factorial design for each isolate: time, distance, and feed gas. Treatment time was 0 s (control), 10 s, or 20 s. Distance from the emitter was 2, 4, or 6 cm. Feed gas was dry air or nitrogen. After treatment, the almonds were sampled using swabs. Survivors were enumerated on tryptic soy agar (TSA) plates. Cold plasma significantly reduced both pathogens on almonds. The greatest reduction observed was 1.34 log cfu/mL reduction of E. coli O157:H7 C9490 after 20 s treatment at 6 cm spacing. The interaction of treatment time with distance from plasma emitter head was complex, and isolate-dependent. Longer duration of treatment did not always result in enhanced reductions. In general, nitrogen as a feed gas resulted in a reduced antimicrobial efficacy compared to dry air. These results indicate that short pulses of atmospheric pressure cold plasma can significantly reduce Salmonella and E. coli O157:H7 on almonds.

Microbial safety of fresh produce.

Section I: Microbial Contamination of Fresh Produce. Chapter 1. Enteric human pathogens associated with fresh produce: sources, transport and ecology (Robert E. Mandrell). Chapter 2. The origin and spread of human pathogens in fruit production systems (Susan Bach and Pescal Delaquis). Chapter 3. Internalization of Pathogens in Produce (Elliot T. Ryser, Jianjun Hao, and Zhinong Yan). Section II: Pre-harvest Strategies. Chapter 4. Produce safety in organic vs conventional crops (Francisco Diez-Gonzalez and Avik Mukherjee). Chapter 5. The Role of Good Agricultural Practices in Produce Safety (Robert B. Gravani). Chapter 6. Effective Managing through a Crisis (Will Daniels and Michael P. Doyle). Chapter 7. The Role of Water and Water testing in Produce Safety (Charles P. Gerba ). Chapter 8. Role of manure and compost in produce safety (Xiuping Jiang). Section III: Post-harvest Interventions. Chapter 9. Aqueous antimicrobial treatments to improve fresh and fresh-cut produce safety (Joy Herdt and Hao Feng). Chapter 10. Irradiation enhances quality and microbial safety of fresh and fresh-cut fruits and vegetables (Brendan A. Niemira and Xuetong Fan). Chapter 11. Biological control of human pathogens on produce (John Andrew Hudson, Craig Billington, and Lynn McIntyre). Chapter 12. Extension of Shelf-life and Control of Human Pathogens in Produce by Antimicrobial Edible Films and Coatings (Tara H. McHugh, Roberto J. Avena-Bustillos, and Wen-Xian Du). Chapter 13. Improving Microbial Safety of Fresh Produce Using Thermal Treatment (Xuetong Fan, Lihan Huang, Bassam Annous). Chapter 14. Enhanced Safety and Extended Shelf-life of Fresh Produce for the Military (Peter Setlow, Christopher J. Doona, Florence E. Feeherry, and Kenneth Kustin, Deborah Sisson, and Shubham Chandra). Section IV: Produce Safety during Processing and Handling. Chapter 15. Consumer and Food Service Handling of Fresh Produce (Christine M. Bruhn). Chapter 16. Plant Sanitation and Good Manufacturing Practices for Optimum Food Safety in Fresh-cut Produce (Edith Garrett). Chapter 17. Third party audit programs for the fresh produce industry (Kenneth S. Petersen). Chapter 18. Pathogen Detection in Produce using Applications of Immunomagnetic Beads and Biosensors (Shu-I Tu, Joseph Uknalis, Andrew Gehring, and Peter Irwin). Section V: Public, Legal, and Economic Perspectives. Chapter 19. Public Response to the 2006 Recall of Contaminated Spinach (William K. Hallman, Cara L. Cuite, Jocilyn E. Dellava, Mary L. Nucci, and Sarah C. Condry). Chapter 20. Produce in public: Spinach, safety and public policy (Douglas A. Powell, Casey J. Jacob and Benjamin Chapman). Chapter 21.Contaminated Fresh Produce and Product Liability: A Law-in-Action Perspective (Denis W. Stearns). Chapter 22. The Economics of Food Safety: The 2006 Foodborne Illness Outbreak Linked to Spinach (Linda Calvin, Helen H. Jensen and Jing Liang). Section VI: Research Challenges and Directions. Chapter 23. Research Needs and Future Directions (Brendan A. Niemira, Xuetong Fan, Christopher J. Doona, Florence E. Feeherry, Robert B. Gravani).

Effects of pre- or post-processing storage conditions on high-hydrostatic pressure inactivation of Vibrio parahaemolyticus and V. vulnificus in oysters.

The effects of storage conditions on subsequent high-hydrostatic pressure (HHP) inactivation of Vibrio parahaemolyticus and Vibrio vulnificus in oysters were investigated. Live oysters were inoculated with V. parahaemolyticus or V. vulnificus to ca. 7-8 log MPN/g by feeding and stored at varying conditions (i.e., 21 or 35 °C for 5h, 4 or 10 °C for 1 and 2 days and -18 °C for 2 weeks). Oyster meats were then treated at 225-300 MPa for 2 min at 4, 21 or 35 °C. HHP at 300 MPa for 2 min achieved a >5-log MPN/g reduction of V. parahaemolyticus, completely inactivating V. vulnificus (negative by enrichment) in oysters. Treatment temperatures of 4, 21 and 35 °C did not significantly affect pressure inactivation of V. parahaemolyticus or V. vulnificus (P>0.05). Cold storage at -18, 4 and 10 °C, prior to HHP, decreased V. parahaemolyticus or V. vulnificus populations by 1.5-3.0 log MPN/g, but did not increase their sensitivity to subsequent HHP treatments. The effects of cold storage after HHP on inactivation of V. parahaemolyticus in oysters were also determined. Oysters were inoculated with V. parahaemolyticus and stored at 21 °C for 5h or 4 °C for 1 day. Oyster meats were then treated at 250-300 MPa for 2 min at 21 or 35 °C and stored for 15 days in ice or in a freezer. V. parahaemolyticus populations in HHP-treated oysters gradually decreased during post-HHP ice or frozen storage. A validation study using whole-shell oysters was conducted to determine whether the presence of oyster shells influenced HHP inactivation of V. parahaemolyticus. No appreciable differences in inactivation between shucked oyster meat and whole-shell oysters were observed. HPP at 300 MPa for 2 min at 21 °C, followed by 5-day ice storage or 7-day frozen storage, and HPP at 250 MPa for 2 min at 21 °C, followed by 10-day ice or 7-day frozen storage, completely inactivated V. parahaemolyticus in whole-shell oysters (>7 log reductions). The combination of HHP at a relatively low pressure (e.g., 250 MPa) followed by short-term frozen storage (7 days) could potentially be applied by the shellfish industry as a post-harvest process to eliminate V. parahaemolyticus in oysters.

Advanced Technologies for Detection and Elimination of Pathogens

Publisher Summary This chapter discusses the latest research in developing rapid, sensitive, and accurate detection technologies and presents a summary of the latest research on advanced intervention technologies to inactivate pathogens on produce. The benchmarks and standards (the applicable Good Agricultural and Good Manufacturing Practices and guidance documents) of produce safety are the underpinning of the specific actions taken by growers, processors, shippers, and retailers. In the field, during harvest and processing, after packaging and shipping, and in the retail or foodservice environment, the steps taken to ensure the safety of fresh and fresh-cut fruits and vegetables fall into three general categories. These are protocols to exclude pathogens from the plants, produce, or packages, and protocols to contain or to eradicate pathogens. The study also explains the applicability of new technologies for the production and processing of organic fruits and vegetables. The regulations governing organic fruits and vegetables (National Organic Program) limit which technologies can be used during production and processing. These regulations establish science-based limits on what additives and processes can be used and applied, consistent with the tenets and philosophy of organic production. New technologies may not be specifically addressed by existing governing regulations. The most useful approach is to strike a balance of allowing scientific innovation to generate a host of new tools, and refining their implementation for the specific needs of important commodities or markets.

Evaluation of 405 nm Monochromatic Light for Inactivation of Tulane Virus on Blueberry Surfaces

The study aim was to evaluate the potential of 405‐nm light as a virus intervention for blueberries.

Evaluation of gaseous chlorine dioxide for the inactivation of Tulane virus on blueberries

To determine the effectiveness of gaseous chlorine dioxide (gClO2) against a human norovirus surrogate on produce, gClO2 was generated and applied to Tulane virus-coated blueberries in a 240u202fml-treatment chamber. gClO2 was produced by an acidifying sodium chlorite solution. Initial assessments indicated that blueberries treated with gClO2 generated from ≤1u202fmg acidified sodium chlorite in the small chamber appeared unaffected while gClO2 generated from ≥10u202fmg of acidified sodium chlorite solution altered the appearance and quality of the blueberries. Treatments of inoculated blueberries with gClO2 generated from 0.1u202fmg sodium chlorite reduced the virus populations by >1 log after exposure for 30 to 330u202fmin. For the 1u202fmg sodium chlorite treatments, the virus populations were reduced by >2.2 log after 15u202fmin exposure and to non-detectable levels (>3.3 logs reductions) after 180u202fmin exposure. Measured concentrations of gClO2 peaked in the treatment chamber at 0.9u202fμg/l after 10u202fmin for 0.1u202fmg treatments and 600u202fμg/l after around 20u202fmin for 1u202fmg treatment. Overall results indicate that gClO2 could be a feasible waterless intervention for blueberries and other produce.