EFFECT OF DIFFERENT MARINADE TREATMENTS ON SURVIVAL AND MORPHOLOGY OF PATHOGENS IN BEEF JERKY ________________________________________________________________________ A Thesis presented to the Faculty of the Graduate School at the University of Missouri ________________________________________________________________________ In Partial Fulfillment of the Requirements for the Degree Master of Science ________________________________________________________________________ by SANDEEP KHURANA Dr. Andrew D. Clarke, Thesis Supervisor DECEMBER 2009 The undersigned, appointed by the Dean of the Graduate School, have examined the thesis entitled EFFECT OF DIFFERENT MARINADE TREATMENTS ON SURVIVAL AND MORPHOLOGY OF PATHOGENS IN BEEF JERKY Presented by Sandeep Khurana A candidate for the degree of Master of Science And hereby certify that, in their opinion it is worthy of acceptance. _____________________________________________________________ Andrew D. Clarke, Ph.D., Department of Food Science _____________________________________________________________ Carol L. Lorenzen, Ph.D., Department of Animal Science _____________________________________________________________ Azlin Mustapha, Ph.D., Department of Food Science _____________________________________________________________ Ingolf Gruen, Ph.D., Department of Food Science _____________________________________________________________ Mark Ellersieck, Ph.D., Department of Statistics Dedicated to my Parents Sh. Krishan Gopal Khurana And Smt. Raj Kumari Khurana ACKNOWLEDGEMENTS It is with immense pleasure that I take this opportunity to express my deep sense of gratitude and indebtness to my esteemed guide and thesis supervisor, Dr. Andrew D. Clarke, for his able supervision, precious suggestions, taking care of me as a guardian in the absence of my parents and utmost interest in experimentation throughout the study. I express my deep regard and sincere thanks to Dr. Carol Lorenzen for her constructive criticism, Dr. Azlin Mustapha for allowing me to work in the Microbiology lab and answering all my questions with a lot of patience and Dr. Ingolf Gruen for helping me master the concepts of food chemistry. I owe special thanks to Dr. Mark Ellersieck for doing the statistical analysis of my research data and also making me understand the whole procedure. It was impossible for me to complete this work without the help and cheerful company of my friends, Harcharan, Jyotiwardhan, Rohan, Nitin, Simit, Jaydeep, Rajeev and Ganesh. I am also thankful to my lab mate Ayca and all the graduate students of the department for their help at some point of my study. My thanks are also due to the technical and non-teaching staff, especially Mr. Lakdas Fernando, Mr. Randy Tindall, Mr. Jim Browning, Ms. Melainia and Ms. Cheryl Jensen for the help provided by them whenever needed. ii I am very thankful to Ms. JoAnn Lewis for taking good care of me during my stay in the department and putting the hard work for carefully editing and perfecting my work. Last, but not least, I am grateful to the Almighty for giving me such loving parents and brother Maneesh, who with their inspiring affection and moral support helped me throughout to realize my ambition of academic pursuit. Finally, I am thankful to my room-mate and good friend Dr. Perminder Gulani for making my stay in Columbia a pleasant one. The funding given by the Research Council of University of Missouri for this research is duly acknowledged. iii TABLE OF CONTENTS ACKNOWLEDGEMENTS ......................................................................................... ii LIST OF FIGURES ..................................................................................................... viii LIST OF TABLES ....................................................................................................... x ABSTRACT ................................................................................................................. xii Chapter 1. INTRODUCTION 1.1. Background ..................................................................................................... 1 1.2. Objectives ....................................................................................................... 4 2. LITERATURE REVIEW 2.1. Beef Jerky ....................................................................................................... 5 2.1.1. Equipment ............................................................................................ 5 2.1.1.1. Electric Dehydrator ................................................................ 6 2.1.1.2. Smokers .................................................................................. 6 2.1.1.3. Oven Drying ........................................................................... 7 2.1.2. Making Jerky ....................................................................................... 7 2.1.2.1. Strip Jerky .............................................................................. 8 2.1.2.2. Ground Jerky .......................................................................... 8 2.1.3. Storage ................................................................................................. 9 2.2. Pathogens ........................................................................................................ 10 2.2.1. E. coli O157:H7 ................................................................................... 10 2.2.1.1. The Recognized Virulence Groups ........................................ 10 2.1.1.2. Enterohemorrhagic E. coli (EHEC) ....................................... 10 2.2.1.2.1. The Toxins ............................................................ 11 2.2.1.2.2. Human Disease Syndromes/Prevalence ................ 12 2.2.1.3. Prevention .............................................................................. 13 2.2.2. Salmonella ........................................................................................... 14 2.2.2.1. Distribution ............................................................................ 16 2.2.2.2. Growth and Destruction of Salmonellae ................................ 16 2.2.2.3. The Salmonella Food-Poisoning Syndrome .......................... 17 2.2.2.4. Incidence and Vehicle Foods ................................................. 19 iv 2.2.2.5. Prevention and Control of Salmonellosis .............................. 20 2.2.3. Staphylococcus .................................................................................... 21 2.2.3.1. Habitat and Distribution ........................................................ 22 2.2.3.2. Growth Requirements ........................................................... 23 2.2.3.3. Staphylococcal Enterotoxins ................................................. 24 2.2.3.3.1. Mode of Action .................................................... 24 2.2.3.4. The Gastroenteritis Syndrome .............................................. 25 2.2.3.5. Prevention ............................................................................. 25 2.2.4. Listeria ................................................................................................ 26 2.2.4.1. Growth ................................................................................... 26 2.2.4.2. Virulence Properties .............................................................. 27 2.2.4.2.1. Listeriolysin O ...................................................... 27 2.2.4.2.2. Intracellular Invasion ............................................ 28 2.2.4.2.3. Monocytosis - Producing Activity ........................ 29 2.2.4.3. Symptoms .............................................................................. 29 2.2.4.4. Regulatory Status of L. monocytogenes in Foods .................. 30 2.3. Electron Microscopy ....................................................................................... 31 2.3.1. Scanning Electron Microscopy ............................................................ 31 2.3.1.1. Electron Optical and Beam Control Systems ......................... 32 2.3.1.2. Specimen Preparation for Scanning Electron Microscopy ............................................................................ 32 2.3.2. Transmission Electron Microscopy ..................................................... 33 2.3.2.1. Basic Systems of Transmission Electron Microscope ............................................................................ 34 2.3.2.2. Specimen Preparation for Transmission Electron Microscopy ............................................................................ 34 2.3.3. Ultramicrotomy .................................................................................... 35 2.3.3.1. Thick Sectioning .................................................................... 36 2.3.3.2. Fine Trimming ....................................................................... 36 2.3.3.3. Types of Ultramicrotome Knives .......................................... 36 2.3.3.4. Grids ...................................................................................... 37 3. MATERIALS AND METHODS 3.1. Beef ................................................................................................................. 38 3.2. Bacterial Cultures ............................................................................................ 38 3.3. Chemicals and Reagents ................................................................................. 39 3.4. Growth Curve ................................................................................................