Use of Chlorine Dioxide Gas as an Antimicrobial Agent for Foods and Food Contact Surfaces

1. Use of Chlorine Dioxide Gas as an Antimicrobial Agent for Foods and Food Contact Surfaces Richard H. Linton, Professor of Food Safety Valentina Trinetta, Postdoctoral Research Associate Mark T. Morgan, Professor of Food Engineering October 25, 2010

2. Impact of Fresh Produce Safety “Of 110 recent outbreaks, 35% were associated with fresh fruits and vegetables” - CDC “Fresh fruit and vegetables are responsible for more illnesses, by far, than any other commodity we regulate” - FDA

3. Produce Associated Outbreaks (Data taken from Beuchat et al. 1996; CDC 2010; NACMCF 2009)

4. Aqueous Chemical Use for Produce (Cherry, J. Food Technology Vol. 53, No. 11)

5. Chlorine Dioxide? 2001 Clean-up postal office at Hamilton Township, NJ An EPA laboratory bus circles the Hart building to monitor the air for gas leaks

6. Greenish-yellow gas, smells like chlorine Highly soluble in water Higher oxidation capacity than chlorine (2.5 x) Oxidizes rather than chlorinates Works over broad pH range (2 – 10) Wide spectrum of antimicrobial capabilities Low dosage required Aqueous and gaseous forms can be used A Promising Antimicrobial Alternative Chlorine Dioxide (ClO2)

7. Aqueous ClO2 • History of uses of aqueous ClO2 • - 1811 First generated by Davy (acidification of KClO3) • - 1930’s Industrial scale preparation with sodium chlorite • - 1940’s Bleaching agent in pulp and paper industry • - 1967 Registered with EPA as disinfectant/sanitizer • - 1977 Used for water treatment plants in USA and Europe • - 1990’s 500-900 water utilities in USA • -1995 Approved by FDA for poultry processing water • -1998 Approved by FDA for washing produce (<3ppm)

8. Gaseous ClO2 • History of uses of gaseous ClO2 • - 1988 Registered by EPA as a sterilant • (for hard surfaces and implements) • - 1990’s Research on pathogen reduction in produce • - 2000 GRAS status for ClO2 releasing LDPE films • (Bernard Technologies, Inc., Chicago, IL) • - 2001 Approved by EPA for emergency use in anthrax decontamination • - 2002 Approved by EPA for storage of potatoes

9. 2 % Chlorine Gas Generation of ClO2 Gas Sodium Chlorite ClO2 Monitor %RH Controller Cl2 + 2 NaClO2 → 2 ClO2 + 2 NaCl

10. Other Methods to Generate ClO2 Gas (Courtesy of ICA TriNova, LLC, Atlanta, GA) 4 HA + 5 NaClO24 ClO2 + NaCl + 4 Na+ + 2 H2O

11. Can we commercially sterilize aseptic holding tanks? Can we kill pathogens on food contact surfaces? Produce surfaces? What are the optimum conditions? What impact is there on quality (microbial, chemical, physical) and chemical safety? How can we build systems that the industry can use? How do we gain approval from FDA, EPA? Our Journey…

12. ClO2 on Epoxy Aseptic Tank Surfaces for Inactivation of Spoilage Organisms

13. ClO2 on Epoxy Aseptic Tank Surfaces for Inactivation of Spoilage Organisms

14. Cl2/N2 gasGenerator Chamber Monitor Humidifier Batch ClO2 Gas Treatment System Cl2 + 2 NaClO22 ClO2 + 2 NaCl

15. ClO2 Gas Treatment (Batch) on Strawberries Treated with 3 mg/l ClO2 for 30 min and stored for 6 weeks at 4oC Untreated and stored for 6 weeks at 4oC

16. Inactivation of E. coli O157:H7 by ClO2 Gas on Peppers • Treatments for 30 min at 20oC under 90-95%RH • Significant differences (P<0.05) (Han et al., 2001)

17. ClO2 Gas Treatment (Batch) on Strawberries 0.2- 4 mg/l ClO2 gas treatments (batch system) for 30 min at 22oC and 90-95% relative humidity. Initial inoculation levels ~ 8.0 log cfu

18. Work Summary: ClO2 Gas Treatment (Batch System)

19. 1 9 7 8 3 4 5 2 6 1. Chlorine gas 2. ClO2 gas generator 3. Chamber 4. Alternative door 5. Sample in and out 5. Operating gloves 7. ClO2 gas monitor 8. Gas mixer 9. ClO2 gas and humidity monitor Continuous ClO2 Gas Treatment System

20. Experimental Protocol • Microbiological Studies: • D-values for several ClO2 concentrations • Z-values across ClO2 concentrations • Quality studies: • Visual color test • Instrumental (Hunter) color test • Microbial Shelf-life studies • Total aerobic plate counts • Psychrotrophic plate counts • Yeast/Mold counts • Surfaces • Sprouts, berries, leafy greens, melons, tomatoes

21. Experimental Protocol ClO2 treatments at 0.5, 1.0, 1.5, 3.0 and 5.0 mg/l for 0, 2, 4, 6, 8 and 10 min 100μl Air-dried (1 h) Spot inoculated Membrane transferring method TSA CT-SMAC E. coli O157: H7 MOX L. monocytogenes XLD S. enterica

22. D-and z-value determination

23. D-value and Z-value “Z”-value D “D”-value Z

25. Experimental Protocol ClO2 treatments at 0.5 and 5.0 mg/l for 0, 2 and 10 min PVC film Quality and shelf-life evaluation (after 0,4,8,12 and 16 days) Microbiological analysis (Mesophilic, Psycotrophic, Yeast & Molds counts) Analysis of appearance and color (Visual and by Hunter)

26. Color Evaluation

27. No Changes in Visual Color During Storage at 4oC Numerical values from 1 (light) -10 (dark red)

28. No Changes in Hunter Values (L) During Storage at 4oC 0 mg/l Day 0 .5 mg/l, 2 min. .5 mg/l, 10 min. 5.0 mg/l, 2 min. 5.0 mg/l, 10 min. Day 4 Day 8 Day 12 Day 16

29. 0 Days Storage of Treated/Untreated Strawberries Untreated 0.5 mg l-1/2min 0.5 mg l-1/10min 5 mg l-1/2min 5 mg l-1/10min

30. 16 days Storage of Treated/Untreated Strawberries Untreated 0.5 mg l-1/2min 0.5 mg l-1/10min 5 mg l-1/2min 5 mg l-1/10min

31. Day 0 of Treated/Untreated Cantaloupes Untreated 5 mg l-1/10min 5 mg l-1/2min

32. 9 Days Storage of Treated/Untreated Cantaloupes Untreated 5 mg l-1/2min 5 mg l-1/10min

33. Day 0 Treated/Untreated Tomatoes Untreated 0.5 mg l-1/10min

34. Day 21 for Tomatoes Untreated 0.2 mg l-1/30min

35. Day 0 Storage of Treated/Untreated Lettuce 0.5 mg l-1/2min 0.5 mg l-1/10min Untreated 5 mg l-1/10min 5 mg l-1/2min

36. 7 Days Storage of Treated/Untreated Lettuce 0.5 mg l-1/2min 0.5 mg l-1/10min Untreated 5 mg l-1/2min 5 mg l-1/10min

37. Day 0 for Treated Lettuce Leaves Untreated 0.2 mg l-1/30min

38. Microbial Shelf-life

39. Strawberries – Microbial Shelf-life Early = 0 days; Middle = 8 days; Late = 16 days Control = No treatment; Low = 0.5mg/l for 2 min.; High = 5 mg/l for 10 min.

40. Strawberries – Microbial Shelf-life Early = 0 days; Middle = 8 days; Late = 16 days Control = No treatment; Low = 0.5mg/l for 2 min.; High = 5 mg/l for 10 min.

41. Strawberries – Microbial Shelf-life Early = 0 days; Middle = 8 days; Late = 16 days Control = No treatment; Low = 0.5mg/l for 2 min.; High = 5 mg/l for 10 min.

42. Strawberries – Microbial Shelf-life Early = 0 days; Middle = 8 days; Late = 16 days Control = No treatment; Low = 0.5mg/l for 2 min.; High = 5 mg/l for 10 min.

43. Cantaloupes – Microbial Shelf-life Early = 0 days; Middle = 6 days; Late = 12 days Control = No treatment; Low = 5 mg/l for 2 min.; High = 5 mg/l for 10 min.

44. New Continuous System for Produce

45. New Continuous System for Produce

46. New Continuous System for Produce

47. Chemical By-Products

48. Residual Oxidative By-Products • Inorganic oxidative by-products: • ClO2, chlorite, and chlorate are of interest - measured using . amperometric titration methods (EPA approved for drinking water) • National Primary Drinking Water Regulations:Disinfectants and Disinfection Byproducts • <0.8 mg/l ClO2 maximum residual disinfectant level goal (MRDLG) • <1.0 mg/l chlorite maximum contaminant level goal (MCLG)

49. Potential Applications for Military Operations • Viable antimicrobial treatment option to improve safety and extends shelf-life of fruit and vegetables – during shipment and/or storage • Viable antimicrobial treatment option to sanitize and/or commercially sterilize food contact surfaces

50. Acknowledgements • FUNDING • USDA/CSREES • FDA • ClorDiSys Solutions, Inc. • Enerfab Inc. PEOPLE • Dr. Yingchan Han • Dr. Philip Nelson • Barakat Mahmoud • Arpan Bhagat • Jay Kim • Les Bourquin • Richa Vaid • All the undergraduate helpers!