Scientific Evaluation of Pasteurisation for Pathogen Reduction in Milk and Milk Products Dr Harley Juffs and Associate Professor Hilton Deeth May 2007 Scientific Evaluation of Milk Pasteurisation ii © Food Standards Australia New Zealand 2007 ISBN 978-0-642-34555-4 First published May 2007 This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from Food Standards Australia New Zealand (FSANZ). Requests and inquiries concerning reproduction and rights should be addressed to the Information Officer, FSANZ, PO Box 7186, Canberra BC, ACT 2610. An electronic version of this work is available on the Food Standards Australia New Zealand (FSANZ) website at http://www.foodstandards.gov.au. This electronic version may be downloaded, displayed, printed and reproduced in unaltered form only for your personal, non- commercial use or use within your organisation. Food Standards Australia New Zealand FSANZ Australia FSANZ New Zealand PO Box 7186 PO Box 10599, The Terrace Canberra BC ACT 2610 Wellington Australia New Zealand Tel +61 2 6271 2241 Tel + 64 4 473 9942 Fax +61 2 6271 2278 Fax +64 4 473 9855 Email [email protected] Mail [email protected] Scientific Evaluation of Milk Pasteurisation iii Disclaimer This report, ‘Scientific Evaluation of Pasteurisation for Pathogen Reduction in Milk and Milk Products’, was prepared for Food Standards Australia New Zealand, Canberra, at their request. The report is based on refereed scientific papers and reviews from the published literature, industry reports and information provided to the consultant by a representative sample of the commercial milk processors and dairy product manufacturers throughout Australia. The authors have assumed that: • the scientific papers we have used as sources of information accurately represent the findings of the research carried out under the conditions described in the papers; • the scientific reviews and industry reports we have used as sources of information accurately reflect the state of knowledge at the date of their publication; and • data provided by milk processors and dairy product manufacturers on pasteurisation conditions and related matters accurately reflect their commercial practices and technical knowledge. The report has been prepared with due care and attention to accuracy. The authors accept no liability if, for any reason, the information contained in the report is inaccurate, incomplete or out of date. Any errors in the reporting or analysis of facts are unintended. The authors will not be responsible for the consequences of any actions taken or decisions made on the basis of any of the information, conclusions or recommendations contained in this document. Scientific Evaluation of Milk Pasteurisation iv Acknowledgements The assistance and cooperation of the following people, organisations and companies with conduct of the evaluation is gratefully acknowledged: • Janet Werkmeister, Manager, Information Research Centre, Dairy Australia, Melbourne, for her assistance with the review of the scientific literature on milk pasteurisation and heat resistance of pathogenic microorganisms; • Mel Kippen, Library Technician and Helen Macpherson, Information Consultant, InfoResearch, Corporate Capability, Queensland Department of Primary Industries and Fisheries, Brisbane, for their assistance with the review of the scientific literature on milk pasteurisation and heat resistance of pathogenic microorganisms; • Safe Food Queensland, New South Wales Food Authority, Dairy Safe Food Victoria, Tasmanian Dairy Industry Authority, Dairy Authority of South Australia and Western Australia Department of Health, for their assistance with the distribution of a questionnaire to all commercial milk processors and dairy product manufacturers who pasteurise raw milk within their areas of jurisdiction; • New South Wales Food Authority, Tasmanian Dairy Industry Authority, Dairy Authority of South Australia and Western Australia Department of Health, for their additional assistance with the collection of the questionnaire and with follow-up of slow responders; and • Milk processors and dairy product manufacturers, for the provision of information on their milk pasteurisation conditions and related matters. Permission of Dairy Food Safety Victoria to use data from their report ‘Current practices and standards employed by the Victorian dairy industry for the operation of heat treatment equipment used for pasteurisation’ is gratefully acknowledged. The assistance of Mr Chris Hempenstall, Dairy Food Safety Victoria, with the provision of additional information about, and unpublished data from, the study outlined in this report is also gratefully acknowledged. The assistance of Mr Russell Stafford, State Foodborne Disease Epidemiologist, Queensland Health Scientific Services, with the provision of data on the epidemiological data on disease outbreaks linked to consumption of pasteurised milk in Australia and elsewhere from the OzFoodNet data base and other sources is also gratefully acknowledged. Prepared for Food Standards Australia New Zealand by: Dr Harley Juffs and Associate Professor Hilton Deeth Scientific Evaluation of Milk Pasteurisation v Table of Contents Executive Summary .................................................................................................................. 1 1. Introduction ................................................................................................................... 9 2. Pasteurisation of Milk by Traditional Thermal Processes...................................... 11 2.1 Review of the history of milk pasteurisation and thermisation .................. 11 2.2 Review of the issues impacting on the determination and interpretation of heat resistance data for pathogenic micro-organisms in milk at temperatures commonly employed in pasteurisation .................................. 19 2.3 Review of the scientific literature and available data on the effect of pasteurisation and thermisation on levels of pathogenic microorganisms in milk ................................................................................................................... 28 2.3.1 Bacillus spp. ..................................................................................................... 30 2.3.2 Brucella spp. including Brucella abortus and Brucella melitensis............... 36 2.3.3 Campylobacter jejuni and Campylobacter coli ............................................... 40 2.3.4 Coxiella burnetii............................................................................................... 43 2.3.5 Enterobacter sakazakii..................................................................................... 47 2.3.6 Pathogenic Escherichia coli, primarily E. coli O157:H7.............................. 49 2.3.7 Listeria monocytogenes.................................................................................... 53 2.3.8 Mycobacterium spp.: Mycobacterium tuberculosis, Mycobacterium bovis and Mycobacterium avium subsp. paratuberculosis ................................... 57 2.3.9 Salmonella spp. ................................................................................................ 69 2.3.10 Staphylococcus aureus..................................................................................... 73 2.3.11 Pathogenic Streptococcus spp. ........................................................................ 76 2.3.12 Yersinia enterocolitica...................................................................................... 79 2.4. Summary and discussion of published data on thermal death times of relevance to milk pasteurisation and thermisation and of identified gaps in knowledge......................................................................................................... 83 2.5. Epidemiological data on disease outbreaks linked to consumption of pasteurised milk............................................................................................... 92 3. Current industry practices in Australia in terms of the time and temperature combinations used for the pasteurisation and thermisation of milk ...................... 93 4. General discussion and conclusions – pasteurisation and thermisation .............. 119 References …………………………………………………………………………………..127 ATTACHMENT 1: Extract from standard 1.6.2, processing requirements (Australia only) of the Australia New Zealand Food Standards Code................................... 136 ATTACHMENT 2: Outbreaks of enteric infection associated with the consumption of pasteurised and unpasteurised milk in Australia and overseas............................ 137 ATTACHMENT 3: Copy of proforma industry questionnaire and covering letters.... 141 Scientific Evaluation of Milk Pasteurisation 1 Executive Summary Introduction A study titled ‘Scientific Evaluation of Pasteurisation for Pathogen Reduction in Milk and Milk Products’ was commissioned by Food Standards Australia New Zealand in February 2005. The objectives of the study were: • Define the effect of pasteurisation on levels of pathogenic microorganisms in milk; and • Determine how current industry pasteurisation practices compare with regulatory requirements. The results of this study are documented in this report. Methodology for the evaluation Three separate but complementary activities were undertaken during the study: (a) A desk-top review of the available scientific literature and epidemiological