Evaluation of Physical and Chemical Techniques for Decontaminating Food and Food Contact Surfaces By Abdulhakeem Abdullah Alzahrani A Thesis Presented to The University of Guelph In partial fulfillment of requirements for the degree of Master of Science in Food Science Guelph, Ontario, Canada ©Abdulhakeem Alzahrani, July, 2014 a ABSTRACT Evaluation of Physical and Chemical Techniques for Decontaminating Food and Food Contact Surfaces Abdulhakeem Abdullah Alzahrani Advisory Committee: University of Guelph, 2014 Dr. Keith Warriner Dr. Tatiana Koutchma Dr. Lisa Duizer A range of novel surface decontamination methods for treating food and food contact surfaces have been evaluated. A unit based “cold steam” that was generated by heating water under high pressure and temperature was shown to support reduction >4 log cfu of E. coli and Listeria on a range of surfaces (stainless steel, cutting boards and agar plates). However, bacterial inactivation was more associated with thermal effects as opposed to generation of free radicals. Hydroxyl radical generators supported reduction of bacteria on surfaces including lettuce. However, it was unclear if the antimicrobial effect was due to drying effects or via radical formation. Coatings based on titanium dioxide and cocamidoropyl betaine could inactivate vegetative cell inoculated on food contact surfaces although Bacillus endospores were resistant. The most effective treatment evaluated was acidic electrolyzed water that could decontaminate a range of food and contact surfaces without detrimental effects. b Acknowledgments First and foremost, I want to thank God, whose many blessings have made me who I am today. I would also like to thank my advisor Dr. Keith Warriner for encouraging me to pursue graduate studies and for the unbelievable amount of help and assistance he has provided me throughout every stage of my research and writing. I never would have finished this without Dr. Warriner’s patience and invaluable guidance. I extend my thanks to my committee members Dr. Tatiana Koutchma and Dr. Hamid Salsali for their advices and supports. Also, I would like to thank King Saud University for giving me a scholarship to pursue graduate studies. Thank you also to my friends Sandi and Jess who have helped edit my work in order to help me more clearly express myself and improve my English writing and speaking. My Canadian support system has been extremely important in ensuring my success. To my lab mates- Mohammad Melebari, Fan Wu, Thais Bernard, Azadeh Namvar, Daniela Persoglio, and Di Wang, thank you for your help and kindness. Additionally, I am grateful for the friends I have met in Canada who have always encouraged me unconditionally to pursue my studies (Muath, Yazeed, Aldoghaim, Alzahrani, Alsalihi, Amir, Waleed Almotiry, Bazid, Asem, Majed, Alassaf, Sami, Alquifily, Al-Qasem, Alhawas, Alghamidi, Thafeed, Al-Qahtani, etc). Of course, without family, none of this would have been possible. The extended family I have in Bozena Pasiuk helped me settle and become comfortable in Canada. Thank you to my dad Abdullah Alzharani (Allah's mercy on him) who had always encouraged me to obtain a great education. I would also like to thank my mom princess Mastoora Alzahrani who takes care of me and encourages me. I would also like to thank my brothers (Saad, Ahmad, Abdulrahman, and Mohammed) and my beautiful sisters (Jamila, Khadija, and Aisha). Finally, without my beautiful loving wife Alanoud and her continuous support, this journey would have never been possible. iii TABLE OF CONTENTS Abstract…………………………………………………………………………………… ii Acknowledgment…………………………………………………………………………. iii List of Tables……………………………………………………………………………… vii List of Figures…………………………………………………………………………….. ix Chapter I 1.1. General Introduction ………………………………………………………………... 1 1.2. Literature Review……………………………………………………………………. 2 1.3. Foodborne Illness……………………………………………………………………. 2 1.4. The Risk Associated With Contaminated Surfaces………………………………….. 4 1.5. Food Surface & Food Contact Surface Contamination Sources…………………….. 5 1.6. Cross-Contamination………………………………………………………………… 5 1.7. Approaches to Prevent Contamination on Food Surface and Food Contact Surfaces…………………………………………………………………………….... 6 1.7.1. Thermal Surface Decontamination Methods…………………………………. 7 1.7.1.1. Hot Water, Steam, and Hot Air………………………………………... 7 1.7.1.2. Thermal Radiation……………………………………………………... 9 1.7.2. Non-Thermal Surface Decontamination Methods………………………….. 9 1.7.2.1. Physical Methods………………………………………………………. 10 1.7.2.2. Chemical Methods……………………………………………………… 14 1.7.2.3. Biological Methods…………………………………………………….. 16 1.8. Optimal Method of Surfaces Decontamination……………………………………… 16 1.9. Indoor BICCSAN Apparatus……………………………………………………….. 17 1.10. Hydroxyl Radicals…………………………………………………………………… 20 1.10.1. Production of Hydroxyl Radicals…………………………………………… 20 1.10.2. Hydroxyl Radicals Generators……………………………………………… 21 1.10.2.1. Overview of Hydroxyl Radicals Generators……………………….. 23 1.10.2.2. Using Hydroxyl Generators to Create Hydroxyl Radicals…………. 23 1.10.2.3. Current Research and Hydroxyl Generators……………………….. 25 1.10.2.4. Effectiveness of Hydroxyl Generator……………………………… 27 1.11. Titanium Dioxide……………………………………………………………………. 29 1.11.1. Photocatalytic mechanism of Titanium Dioxide…………………………… 30 1.11.2. Advantages and Disadvantages of Titanium dioxide………………………. 31 1.11.3. Mechanisms of Microbial Inactivation Resulting From Titanium Dioxide... 32 1.11.4. Effectiveness of Titanium dioxide…………………………………………. 34 1.12. Cocoamidopropyl Betaine Protection……………………………………………….. 35 1.13. Electrolyzed Water………………………………………………………………….. 36 iv 1.13.1. Generation of Electrolyzed Water………………………………………… 37 1.13.2. Advantages and Disadvantages of Electrolyzed Water…………………….. 39 1.13.3. Mechanisms of Microbial Inactivation Resulting From Electrolyzed Water 40 1.13.4. Effectiveness of Electrolyzed Water……………………………………….. 41 1.14. Research Hypothesis and Objectives ……………………………………………….. 43 Chapter II 2. MATERALS AND METHODS………………………………………………………. 44 2.1. Bacteria and cultivation conditions………………………………………………….. 44 2.1.1. Escherichia coli P36 cultivation and enumeration………………………….. 44 2.1.2. Salmonella cultivation and enumeration …………………………………… 44 2.1.3. Listeria innocua cultivation and enumeration………………………………. 45 2.1.4. Bacillus subtilis PS346 spores preparation…………………………………. 45 2.2. Sample Preparation and Survival Recovery…………………………………………. 46 2.2.1. Inactivation of model bacteria on agar plates ………………………………. 46 2.2.2. Inactivation of model bacteria inoculated onto filter paper………………… 46 2.2.3. Inactivation of model bacteria inoculated onto stainless steel surfaces…….. 47 2.2.4. Inactivation of model bacteria inoculated onto cutting board surfaces……... 48 2.2.5. Inactivation of model bacteria inoculated onto beef surface………………... 49 2.2.6. Inactivation of Model Bacteria Inoculated onto Lettuce Leaves surface…… 49 2.3. Surface decontamination treatments………………………………………………… 50 2.3.1. Control Samples……………………………………………………………... 50 2.3.2. Indoor Biccsan Apparatus (IBA) Treatments……………………………….. 50 2.3.3. Odorox Mobile Disinfection Unit (OMDU) and Boss Hydroxyl Odor Producer (BHOP) Treatments……………………………………………….. 51 2.3.4. Titanium Dioxide Coating Treatments…………………………………….. 52 2.3.5. Cocamidopropyl Betaine Coating Treatments…………………………….. 53 2.3.6. Electrolyzed Water Treatments……………………………………………. 54 2.4. Experimental Design and Statistics………………………………………………….. 54 Chapter III 3. THE RESULTS…………………………………………………………………………. 55 3.1. The Results of Indoor Biccsan Apparatus (IBA)……………………………………... 55 3.2. The Results of Odorox Mobile Disinfection Unit (OMDU) and Boss Hydroxyl Odor Producer (BHOP)……………………………………………………………………. 80 3.3. The Results of Titanium Dioxide, Cocamidopropyl Betaine Protection, and Kangen Electrolyzed Water ………………………………………………………………….. 91 Chapter IV 4.1. Discussion of Indoor Biccsan Apparatus (IBA)…………….………………………… 104 v 4.2. Discussions of OMDU and BHOP………………………….………………………… 109 4.3. Efficacy of titanium dioxide coatings………………………………………………… 114 4.4. Efficacy of Cocamidopropyl Betaine coatings………………………………………... 116 4.5. Efficacy of Kangen Electrolyzes Water………………………………………………. 118 Chapter V 5.1. Conclusion……………….……………………………………………………………. 121 5.2. Future Work…………………………………………………………………………... 123 References………………………………………………………………………………… 124 vi List of Tables Table (3-1) The effect of cold steam containing 8 % H2O2 on contaminated filter papers with E.Coli p36……………………………………..……… 56 Table (3-2) Effect of cold steam containing multiple percentages of H2O2 on inactivation of model microbes on multiple surfaces………………… 60 Table (3-3) Effect of cold steam on inactivation of E. coli P36 and B. subtilis on multiple surfaces…………………………………………………….…... 63 Table (3-4) The effect of cold steam, and then vacuum system on contaminated stainless steel………………………………………..…. 65 Table (3-5) The effect of cold steam and vacuum system (V1, V2) on contaminated surfaces…………………………………………………. 68 Table (3-6) The effect of 20 second treatment of cold steam-vacuuming (V2) using IBA containment accessory type C on contaminated surfaces…………………………………………………………………… 77 Table (3-7) Inactivation of Escherichia coli inoculated onto different surfaces and exposed to free radicals generated by Mobile Disinfection Unit within a closed reactor…………………………………………………... 81 Table (3-8) Inactivation of Escherichia coli and Listeria innocua inoculated onto different food surfaces and treated with free radicals generated by Mobile Disinfection Unit (operating at 250 cubic feet per min)