Microbiological Risk Assessment of Raw Milk Cheese Risk Assessment Microbiology Section December 2009 MICROBIOLOGICAL RISK ASSESSMENT OF RAW MILK CHEESES ii TABLE OF CONTENTS ACKNOWLEDGEMENTS ................................................................................................. VII ABBREVIATIONS ............................................................................................................. VIII 1. EXECUTIVE SUMMARY .................................................................................................. 1 2. BACKGROUND ................................................................................................................... 8 3. PURPOSE AND SCOPE ..................................................................................................... 9 3.1 PURPOSE...................................................................................................................... 9 3.2 SCOPE .......................................................................................................................... 9 3.3 DEFINITION OF RAW MILK CHEESE ............................................................................... 9 3.4 APPROACH ................................................................................................................ 10 3.5 OTHER RAW MILK CHEESE ASSESSMENTS .................................................................. 16 4. INTRODUCTION .............................................................................................................. 18 4.1 CLASSIFICATION OF CHEESES .................................................................................... 18 4.2 PRINCIPAL CATEGORIES OF CHEESE ........................................................................... 19 5. RAW MILK CHEESES ..................................................................................................... 22 6. CONSUMPTION OF CHEESE ........................................................................................ 23 6.1 PRODUCTION OF RAW MILK CHEESE .......................................................................... 23 6.2 CONSUMPTION OF RAW MILK CHEESE ........................................................................ 25 6.3 SUMMARY ................................................................................................................. 27 7. FOODBORNE ILLNESS ASSOCIATED WITH RAW MILK CHEESES ................. 28 7.1 FOODBORNE ILLNESS ................................................................................................. 28 7.2 SUMMARY ................................................................................................................. 31 8. OCCURRENCE OF PATHOGENS IN RAW MILK CHEESES ................................. 32 8.1 RAW MILK CHEESE – COW ORIGIN ............................................................................. 33 8.2 RAW MILK CHEESE – GOAT ORIGIN ............................................................................ 34 8.3 RAW MILK CHEESE – SHEEP ORIGIN ........................................................................... 34 8.4 EU RAPID ALERT SYSTEM ........................................................................................ 34 8.5 SUMMARY ................................................................................................................. 35 9. MANUFACTURE AND SAFETY OF RAW MILK CHEESE ..................................... 36 9.1 CHEESEMAKING FACTORS AFFECTING SAFETY .......................................................... 38 9.2 CONTAMINATION OF RAW MILK CHEESE POST-MANUFACTURE .................................. 52 9.3 CHALLENGE STUDIES ON EFFECTS OF RIPENING/MATURATION ON PATHOGENIC MICROORGANISMS ......................................................................................................... 53 10. ASSESSING THE SAFETY OF SELECTED RAW MILK CHEESES .............. 56 10.1 SUMMARY OF RAW MILK EXTRA HARD CHEESE RISK ASSESSMENT ............................ 56 10.2 SUMMARY OF RAW MILK SWISS-TYPE CHEESE RISK ASSESSMENT .............................. 58 10.3 SUMMARY OF RAW MILK CHEDDAR CHEESE RISK ASSESSMENT ................................. 60 10.4 SUMMARY OF RAW MILK BLUE CHEESE RISK ASSESSMENT ........................................ 62 10.5 SUMMARY OF RAW MILK FETA CHEESE RISK ASSESSMENT ........................................ 64 10.6 SUMMARY OF RAW MILK CAMEMBERT CHEESE RISK ASSESSMENT ............................ 66 11. DISCUSSION ............................................................................................................. 69 MICROBIOLOGICAL RISK ASSESSMENT OF RAW MILK CHEESES iii 12. DATA GAPS AND RESEARCH NEEDS ................................................................ 79 12.1 INCIDENCE AND PREVALENCE DATA FOR PATHOGENS IN RAW MILK .......................... 79 12.2 CHEESEMAKING PROCESS .......................................................................................... 79 12.3 PHYSICOCHEMICAL CHARACTERISTICS/PROPERTIES OF SPECIFIC CHEESES ................ 79 12.4 DATA ON SURVIVAL, INACTIVATION AND GROWTH OF PATHOGENIC MICROORGANISMS DURING THE CHEESEMAKING PROCESS ...................................................................... 79 12.5 CONSUMPTION DATA ................................................................................................. 81 12.6 EXTENT AND CAUSE OF SPORADIC HUMAN CASES OF RAW MILK CHEESES ASSOCIATED FOODBORNE ILLNESS ................................................................................................. 81 13. CONCLUSIONS ......................................................................................................... 82 APPENDICES ........................................................................................................................ 85 APPENDIX 1: QUALITATIVE FRAMEWORK FOR CATEGORISING HAZARDS .............................................................................................. 86 1 MATRIX ......................................................................................................................... 86 2 ASSUMPTIONS USED IN DETERMINING RISK ................................................................... 88 APPENDIX 2: PROBABILISTIC GROWTH MODELS ............................................ 90 1 ESCHERICHIA COLI GROWTH MODEL .............................................................................. 90 2 STAPHYLOCOCCUS AUREUS GROWTH MODEL .................................................................. 90 3 LISTERIA MONOCYTOGENES GROWTH MODEL .................................................................. 91 APPENDIX 3: CHEESE CLASSIFICATION SCHEMES .......................................... 93 1 TEXTURAL CLASSIFICATION SCHEMES ........................................................................... 93 2 COAGULATION BASED CLASSIFICATION SCHEMES ......................................................... 93 3 CLASSIFICATION SCHEMES BASED ON RIPENING INDICES ............................................... 94 4 CODEX CLASSIFICATION OF CHEESE .............................................................................. 94 5 PHYSICOCHEMICAL CHARACTERISTICS OF VARIOUS CHEESE VARIETIES ........................ 94 APPENDIX 4: FOODBORNE ILLNESS ASSOCIATED WITH CONSUMPTION OF RAW MILK CHEESES ................................................................ 100 APPENDIX 5: PREVALENCE/INCIDENCE OF MICROBIOLOGICAL HAZARDS IN RAW MILK CHEESES............................................. 105 1 PREVALENCE OF PATHOGENS IN RAW MILK CHEESE .................................................... 105 2 INCIDENCE OF PATHOGENS IN RAW MILK CHEESE ........................................................ 110 3 EUROPEAN UNION RAPID ALERT NOTIFICATIONS (2003 – 2006) ................................ 112 APPENDIX 6: CODEX STANDARDS FOR CHEESE ............................................. 114 APPENDIX 7: PREVALENCE OF MICROBIOLOGICAL HAZARDS IN RAW MILK ..................................................................................................... 115 1 RAW COW MILK ........................................................................................................... 115 2 RAW GOAT MILK ......................................................................................................... 122 3 RAW SHEEP MILK ......................................................................................................... 126 MICROBIOLOGICAL RISK ASSESSMENT OF RAW MILK CHEESES iv APPENDIX 8: RISK ASSESSMENT – EXTRA HARD RAW MILK CHEESES.. 128 1 INTRODUCTION ............................................................................................................ 128 2 HAZARD IDENTIFICATION AND HAZARD CHARACTERISATION ...................................... 129 3 EXPOSURE ASSESSMENT .............................................................................................. 129 4 RISK CHARACTERISATION ........................................................................................... 140 5 CONCLUSIONS ............................................................................................................. 142 APPENDIX 9: RISK ASSESSMENT – SWISS-TYPE RAW MILK CHEESES .... 144 1 INTRODUCTION ............................................................................................................ 144 2 HAZARD IDENTIFICATION AND HAZARD CHARACTERISATION ...................................... 145 3 EXPOSURE ASSESSMENT .............................................................................................. 145 4