Handbook of hygiene control in the food industry

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Handbook of hygiene control

in the food industry

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Handbook of hygiene control in the food

industry

Edited by

H. L. M. Lelieveld, M. A. Mostert and J. Holah

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Published by Woodhead Publishing Limited Abington Hall, Abington

Cambridge CB1 6AH England

www.woodheadpublishing.com

Published in North America by CRC Press LLC 6000 Broken Sound Parkway, NW

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First published 2005, Woodhead Publishing Limited and CRC Press LLC

ß 2005, Woodhead Publishing Limited, except Chapter 21 which is ß 2005 Institute of Food Science and Technology

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Contributor contact details . . . xvii

Preface . . . xxiii

1 Introduction . . . 1

S. Notermans and S. C. Powell, Lancashire Postgraduate School of Medicine and Health, UK, and E. Hoornstra, TNO Nutrition and Food Research, The Netherlands 1.1 Introduction: the evolution of food hygiene . . . 1

1.2 Definitions of hygiene . . . 11

1.3 Sources of food contamination . . . 13

1.4 Hygiene control measures in food processing . . . 17

1.5 Future trends . . . 21

1.6 References . . . 24

Part I Risks 2 The range of microbial risks in food processing . . . 31

M. H. Zwietering and E. D. van Asselt, Wageningen University, The Netherlands 2.1 Introduction: the risk of microbial foodborne disease . . . 31

2.2 The control of food safety . . . 37

2.3 Using food safety objectives to manage microbial risks . . . 38

2.4 Conclusions . . . 44

A. Friis and B. B. B. Jensen, Technical University of Denmark 11.1 Introduction: the hygienic performance of closed equipment 191 11.2 The importance of flow parameters in hygienic performance 192 11.3 Computational fluid dynamics models for optimising hygiene 197 11.4 Applications of computational fluid dynamics in improved hygienic design . . . 200

12 Improving the hygienic design of heating equipment . . . 212

A. P. M. Hasting, Tony Hasting Consulting, UK 12.1 Introduction . . . 212

12.2 Heat exchanger design . . . 213

12.3 Developments in heat exchanger design . . . 215

13 Improving the hygienic design of equipment in handling dry materials . . . 220

K. Mager, Quest International, The Netherlands 13.1 Introduction: principles of hygienic design . . . 220

13.2 Dry particulate materials and hygienic processing . . . 220

13.3 Cleaning regimes . . . 221

13.4 Design principles . . . 222

13.5 Types of equipment in dry material handling areas . . . 226

13.6 Conclusions: improving hygiene in powder processing . . . 227

14 Improving the hygienic design of packaging equipment . . . 228

C. J. de Koning, CFS b.v., The Netherlands 14.1 Introduction . . . 228

14.2 Requirements for hygienic design . . . 229

14.3 Application of ISO 14159 . . . 229

14.4 Other standards and guidelines . . . 237

14.5 Conclusion . . . 238 viii Contents

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15 Improving the hygienic design of electrical equipment . . . 239

L. Uiterlinden, GTI Process Solutions BV, The Netherlands, H. M. J. van Eijk, Unilever R&D Vlaardingen, The Netherlands and A. Griffin, Unilever ± Port Sunlight, UK 15.1 Introduction . . . 239

15.2 Hygienic zoning . . . 240

15.3 Hygienic electrical design principles . . . 242

15.4 Installation requirements for medium hygiene areas . . . 244

15.5 Installation requirements for high-hygiene areas . . . 250

15.6 General requirements for construction materials . . . 257

15.9 Appendix: abbreviations . . . 262

16 Improving the hygienic design of valves . . . 263

F. T. Schonrock, 3-A Sanitary Standards Inc., USA 16.1 Introduction . . . 263

16.2 Valve types . . . 263

16.3 Hygienic aspects of valve design . . . 268

16.4 Current guidelines, standards, and references . . . 272

17 Improving the hygienic design of pipes . . . 273

H. Hoogland, Unilever R&D Vlaardingen, The Netherlands 17.1 Introduction . . . 273

17.2 Piping design: good practice . . . 273

17.3 Materials of construction . . . 274

17.4 Product recovery . . . 275

17.5 Microbial growth in piping systems . . . 276

17.6 Plant design . . . 277

18 Improving the hygienic design of pumps . . . 279

R. Stahlkopf, Tuchenhagen GmbH, Germany 18.1 Introduction: types of pump used in food processing . . . 279

18.2 Components used in pumps . . . 279

18.3 Cleanability, surface finish and other requirements . . . 284

18.4 Materials and motor design . . . 285

18.5 Summary . . . 285

19 Improving hygienic control by sensors . . . 287

M. BuÈcking, Fraunhofer IME, Germany and J. E. Haugen, Matforsk AS, Norway 19.1 Introduction . . . 287

19.2 Sensor types . . . 289 Contents ix

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19.3 Common industrial applications and future trends . . . 298

Part III Improving hygiene management and methods 20 Risk assessment in hygiene management . . . 309

I. H. Huisman, Nutricia, The Netherlands and E. Espada Aventin, Unilever R&D Vlaardingen, The Netherlands 20.1 Introduction . . . 309

20.2 Quality management and risk assessment . . . 312

20.3 Examples of risk assessments . . . 316

21 Good manufacturing practice (GMP) in the food industry . . . 324

J. R. Blanchfield, Consultant, UK 21.1 Introduction . . . 324

21.2 Effective manufacturing operations and food control . . . 327

21.3 Personnel and training . . . 329

21.4 Documentation . . . 330

21.5 Premises, equipment, product and process design . . . 330

21.6 Manufacturing and operating procedures . . . 331

21.7 Ingredients and packaging materials . . . 332

21.8 Managing production operations: intermediate and finished products . . . 335

21.9 Storage and movement of product . . . 336

21.10 Special requirements for certain foods . . . 337

21.11 Rejection of product and complaints handling . . . 340

21.12 Product recall and other emergency procedures . . . 342

21.13 `Own label' and other contract manufacture . . . 344

21.14 Good control laboratory practice (GLP) . . . 344

21.16 References . . . 347

22 The use of standard operating procedures (SOPs) . . . 348

R. H. Schmidt, University of Florida, USA and P. D. Pierce, Jr, US Army Veterinary Corps 22.1 Introduction: defining standard operating procedures (SOPs) 348 22.2 The key components of SOPs and SOP programs . . . 349

22.3 SOP requirements under regulatory HACCP programs . . . 355

22.4 Common problems in implementing SOPs effectively . . . 358

22.5 Sources of further information . . . 360

22.6 References . . . 361 x Contents

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23 Managing risks from allergenic residues . . . 363

R. W. R. Crevel, Unilever Colworth, UK 23.1 Introduction . . . 363

23.2 Food allergy and product safety . . . 364

23.3 Management of food allergy risks . . . 366

23.4 Role of allergen detection and other considerations . . . 369

24 Managing contamination risks from food packaging materials 378 L. Raaska, VTT Biotechnology, Finland 24.1 Introduction . . . 378

24.2 Potential microbiological problems with packaging . . . 380

24.3 Improving hygienic production and management . . . 386

25 Improving hygiene in food transportation . . . 396

E. U. Thoden van Velzen and L. J. S. Lukasse, Wageningen University and Research Centre, The Netherlands 25.1 Introduction . . . 396

25.2 Legislation . . . 396

25.3 Implementation of the current legislation . . . 397

25.4 Examples . . . 398

25.5 Temperature management . . . 399

25.6 Avoiding cross-contamination . . . 403

25.8 Acknowledgements . . . 405

25.9 References and notes . . . 405

26 Improving the control of insects in food processing . . . 407

E. Shaaya, The Volcani Center, Israel, R. Maller, Pepsi Co., USA M. Kostyukovsky, The Volcani Center, Israel and L. Maller, United States Department of Agriculture 26.1 Introduction . . . 407

26.2 The grain bulk as an ecosystem . . . 408

26.3 Moisture migration in the grain bulk . . . 411

26.4 Dry- and wet-grain heating . . . 412

26.5 Insects in stored products . . . 414

26.6 Measures of control . . . 417

26.8 Acknowledgement . . . 424

26.9 Bibliography . . . 424 Contents xi

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27 Improving cleaning-in-place (CIP) . . . 425

K. Lorenzen, Tuchenhagen GmbH, Germany 27.1 Introduction: limitations in current CIP systems . . . 425

27.2 Cleaning and disinfection parameters . . . 426

27.3 Factors determining the effectiveness of a CIP system . . . 429

27.4 Improving CIP systems . . . 438

27.6 References and further reading . . . 444

28 Improving cleaning-out-of-place (COP) . . . 445

L. Keener, International Product Safety Consultants, USA 28.1 Introduction . . . 445

28.2 Best practices in developing an effective COP process . . . 446

28.3 Defining the process . . . 447

28.4 Elaboration of process parameters . . . 448

28.5 Validation . . . 463

28.6 Records and process documentation . . . 464

28.7 Summary . . . 465

29 Improving the cleaning of heat exchangers . . . 468

P. J. Fryer and G. K. Christian, University of Birmingham, UK 29.1 Introduction . . . 468

29.2 Processing effects on fouling and cleaning . . . 472

29.3 Investigations into cleaning process parameters . . . 479

29.4 Ways of improving cleaning . . . 486

30 Improving the cleaning of tanks . . . 497

S. Salo, VTT Biotechnology, Finland, A. Friis, Technical University of Denmark and G. Wirtanen, VTT Biotechnology, Finland 30.1 Introduction to cleaning tanks . . . 497

30.2 Factors affecting cleaning efficacy . . . 498

30.3 Hygienic design test methods . . . 501

30.4 Detecting the cleanliness of tanks . . . 502

30.5 Using computational fluid dynamics (CFD) to assess cleanability of closed process lines . . . 503

31 Ozone decontamination in hygiene management . . . 507

L. Fielding and R. Bailey, University of Wales Institute Cardiff, UK 31.1 Introduction . . . 507 xii Contents

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31.2 Historical uses of ozone . . . 509

31.3 The effect of ozone on microorganisms . . . 510

31.4 Undesirable effects of ozone . . . 510

31.5 Practical applications of ozone . . . 511

31.6 Future potential . . . 513

31.7 Conclusion . . . 513

32 Enzymatic cleaning in food processing . . . 516

A. Grasshoff, Federal Dairy Research Centre, Germany 32.1 Introduction . . . 516

32.2 Enzyme-based cleaning procedures . . . 518

32.3 Laboratory trials of enzyme-based cleaning . . . 522

32.4 Field trials . . . 531

32.5 Risks . . . 534

33 Contamination routes and analysis in food processing environments . . . 539

J. LundeÂn, J. BjoÈrkroth and H. Korkeala, University of Helsinki, Finland 33.1 Introduction to contamination analysis in the food industry . . 539

33.2 Different types of contamination analyses . . . 540

33.3 Listeria monocytogenes contamination in food processing environments . . . 543

33.4 Psychrotrophic lactic acid bacterium contamination in meat processing environments . . . 547

33.5 Applying knowledge from contamination analysis to improve hygienic food manufacturing . . . 550

34 Testing surface cleanability in food processing . . . 556

J. Verran, Manchester Metropolitan University, UK 34.1 Introduction . . . 556

34.2 Microorganisms . . . 557

34.3 Hygienic surfaces . . . 560

34.4 Organic soil . . . 564

34.8 References . . . 568 Contents xiii

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35 Improving the monitoring of fouling, cleaning and disinfection in

closed process plant . . . 572

A. P. M. Hasting, Tony Hasting Consulting, UK 35.1 Introduction . . . 572

35.2 Background . . . 573

35.3 Current approaches to monitoring . . . 574

35.4 Laboratory/pilot-scale studies . . . 581

35.5 Industry requirements and potential benefits . . . 584

36 Improving surface sampling and detection of contamination . . . 588

C. Griffith, University of Wales Institute Cardiff, UK 36.1 Introduction . . . 588

36.2 Microbiological surface sampling . . . 596

36.3 Non-microbiological surface sampling . . . 603

36.4 Monitoring/sampling protocols and strategies . . . 608

37 Improving air sampling . . . 619

H. Miettinen, VTT Biotechnology, Finland 37.1 Introduction . . . 619

37.2 Microbial viability in the air . . . 620

37.3 Why, how and what to sample . . . 621

37.4 Bioaerosols and bioaerosol samplers . . . 622

37.5 Air sampling methods . . . 624

37.6 Bioaerosol assay methods . . . 632

37.7 Interpretation of bioaerosol results . . . 635

37.9 References and further reading . . . 637

38 Testing the effectiveness of disinfectants and sanitisers . . . 641

J.-Y. Maillard, Cardiff University, UK 38.1 Introduction . . . 641

38.2 Types of biocidal products . . . 642

38.3 Criteria for testing biocidal action . . . 651

38.4 Tests for disinfectants and sanitisers . . . 656

38.5 Test limitations and scope for improvement . . . 661

38.8 References . . . 665 xiv Contents

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39 Traceability of cleaning agents and disinfectants . . . 672

D. Rosner, Ecolab GmbH & Co., Germany 39.1 Introduction . . . 672

39.2 General issues in tracing of cleaning solutions and hygiene products . . . 673

39.3 Particular issues in tracing of hygiene products . . . 675

39.4 Conclusion . . . 683

40 Improving hygiene auditing . . . 684

P. Overbosch, Kraft Foods, Germany 40.1 Introduction . . . 684

40.2 Why have a hygiene improvement audit in the first place? . . 686

40.3 Auditing and the hierarchy of a controlled system . . . 686

40.4 Purposes of an auditing system . . . 688

40.5 Designing a system for improvement audits . . . 689

40.6 Performing the audit . . . 690

Index . . . 697 Contents xv

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(* = main contact)

Chapter 1

Professor S. Notermans Obrechtlaan 17

3723 KA Bilthoven The Netherlands

E-mail: S.Notermans@wxs.nl

Chapter 2

Professor M. H. Zwietering* and Dr E. D. van Asselt

Laboratory of Food Microbiology Wageningen University

PO Box 8129

6700 EV Wageningen The Netherlands

E-mail: Marcel.Zwietering@wur.nl

Chapter 3

Dr G. Wirtanen* and Ms S. Salo VTT Biotechnology

PO Box 1500 Espoo

FIN-02044 VTT Finland

E-mail: gun.wirtanen@vtt.fi satu.salo@vtt.fi

Chapter 4

Ir A. J. van Asselt and Dr M. C. te Giffel*

NIZO Food Research Kernhemseweg 2 PO Box 20 6710 BA Ede The Netherlands

E-mail: meike.te.giffel@nizo.nl arjan.van.asselt@nizo.nl

Contributor contact details

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Chapter 5

Dr D. Burfoot

Silsoe Research Institute Wrest Park

Silsoe

Bedford MK45 4HS UK

E-mail: dean.burfoot@bbsrc.ac.uk

Chapter 6

Professor Lynn J. Frewer and Dr Arnout R. H. Fischer*

Marketing and Consumer Behaviour Group

Wageningen University Hollandseweg 1 6706 KN Wageningen The Netherlands

E-mail: Lynn.frewer@wur.nl arnout.fischer@wur.nl

Chapters 7 and 10

Mr D. J. Graham

Graham Sanitary Design Consulting Limited

14318 Aitken Hill Court Chesterfield MO 63017 USA

E-mail: grahamdj@prodigy.net

Chapter 8

Dr John Holah

Campden & Chorleywood Food Research Association Chipping Campden GL55 6LD UK

E-mail: j.holah@campden.co.uk

Chapter 9

Dr Brigitte Carpentier

AFSSA (French Food Safety Agency) Laboratoire d'eÂtude et de recherches

sur la qualiteÂ des aliments et sur les proceÂdeÂs agro-alimentaires 23 avenue du GeÂneÂral de Gaulle F-94706 Maisons-Alfort cedex France

Tel: 33(0)149 77 26 46 Fax: 33(0)149 77 26 40 E-mail: b.carpentier@afssa.fr

Chapter 11

Professor A. Friis* and Dr B. B. B.

Jensen Biocentrum

Technical University of Denmark Building 221

Soltofts Plads 2800 Lyngby Denmark

E-mail: af@biocentrum.dtu.dk bbb@biocentrum.dtu.dk

Chapters 12 and 35

Dr A. P. M. Hasting Tony Hasting Consulting 37 Church Lane

Sharnbrook Bedford UK

E-mail: tony.hasting@virgin.net xviii Contributors

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Chapter 13

Ing. Karel Mager Quest International PO Box 2

NL-1400 CA Bussum The Netherlands

E-mail: karel.mager@questintl.com

Chapter 14

Ir C. J. de Koning

CFS b.v. (Convenience Food Systems) PO Box 1

5760 AA Bakel The Netherlands

E-mail: cees.de.koning@cfs.com

Chapter 15

Dr L. Uiterlinden*

GTI Process Solutions BV PO Box 845

NL-5201 AV 's- Hertogenbosch The Netherlands

E-mail: luiterlinden@gti-group.com Dr H. M. J. van Eijk

The Food Processing Group Unilever R&D Vlaardingen PO Box 114

NL-3130 AC Vlaardingen The Netherlands

Chapter 16

Mr F. T. Schonrock 11302 Alms House Court Fairfax Station

Virginia USA

E-mail: ftracy1@cox.net

Chapter 17

Dr H. Hoogland

Unilever R&D Vlaardingen PO Box 114

E-mail: hans.hoogland@unilever.com

Chapter 18

Dr R. Stahlkopf Tuchenhagen GmbH Am Industrie Park 2-10 D-21514 Buchen Germany E-mail:

stahlkopf.ralf@tuchenhagen.de

Chapter 19

Dr M. BuÈcking*

Environmental and Food Analysis Fraunhofer IME

Auf dem Aberg 1 57392 Schmallenberg Germany

E-mail:

mark.buecking@ime.fraunhofer.de Dr J. E. Haugen

Matforsk AS Osloveien 1 N-1430 As Norway E-mail: john-

erik.haugen@matforsk.no

Contributors xix

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Chapter 20

Dr I. H. Huisman*

Nutricia PO Box 1

2700 MA Zoetermeer The Netherlands

E-mail: i_huisman@hotmail.com Dr E. Espada AventõÂn

Unilever R&D Vlaardingen PO Box 114

Chapter 21

Professor J. Ralph Blanchfield MBE 17 Arabia Close

Chingford London E4 7DU UK

E-mail: jralphb@easynet.co.uk

Chapter 22

Professor R. H. Schmidt Department of Food Science University of Florida Gainsville

Florida 32611-0370 USA

E-mail: rschmidt@ifas.ufl.edu

Chapter 23

Dr ReneÂ Crevel

Safety & Environmental Assurance Centre

Unilever R&D Colworth Bedford MK44 1LQ UK

E-mail: rene.crevel@unilever.com

Chapter 24

Dr Laura Raaska VTT Biotechnology PO Box 1500 Espoo

E-mail: Laura.Raaska@vtt.fi

Chapter 25

Dr E.U. Thoden van Velzen* and Dr Ir. L.J.S. Lukasse

Agrotechnology and Food Innovations Wageningen University and ResearchBV

Centre Bornsesteeg 59 6708 PD Wageningen The Netherlands E-mail:

ulphard.thodenvanvelzen@wur.nl

Chapter 26

Professor E. Shaaya

Department of Food Science AROThe Volcani Center

Bet Dagan 50-250 Israel

E-mail: vtshaaya@agri.gov.il xx Contributors

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Chapter 27

Knuth Lorenzen

GEA Tuchenhagen Dairy Systems Am Industriepark 2-10GmbH

D-21514 Buchen Germany

Tel: 49(0) 4155 49 2427 Fax: 49(0) 4155 49 2764 E-mail:

lorenzen.knuth@tuchenhagen.de

Chapter 28

Mr L. Keener

International Product Safety Consultants, Inc.

4021 W. Bertona Street Seattle

WA 98199-1934 USA

E-mail: lkeener@aol.com

Chapter 29

Professor P. J. Fryer* and Dr G. K.

Christian

Centre for Formulation Engineering Department of Chemical Engineering University of Birmingham

Birmingham B15 2TT UK

E-mail: p.j.fryer@bham.ac.uk

Chapter 30

Dr S. Salo

VTT Biotechnology PO Box 1500

Espoo

E-mail: satu.salo@vtt.fi

Chapter 31

Dr L. Fielding* and Mr R. Bailey School of Applied Sciences

University of Wales Institute Cardiff Llandaff Campus

Western Avenue Cardiff CF5 2YB UK

E-mail: lfielding@uwic.ac.uk

Chapter 32

Dr Ing A. Grasshoff

Federal Dairy Research Centre PO Box 60 69

D-24121 Kiel Germany

E-mail: grasshoff@bafm.de

Chapter 33

Dr J. LundeÂn*, Professor J. BjoÈrkroth and Professor H. Korkeala

Department of Food and Environmental Hygiene Faculty of Veterinary Medicine University of Helsinki

Finland

E-mail: janne.lunden@helsinki.fi Contributors xxi

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Chapter 34

Professor Joanna Verran

Department of Biological Sciences Manchester Metropolitan University Chester Street

Manchester M1 5GD UK

E-mail: j.verran@mmu.ac.uk

Chapter 36

Professor C. Griffith School of Applied Sciences

University of Wales Institute Cardiff Llandaff Campus

Western Avenue Cardiff CF5 2YB UK

E-mail: cgriffith@uwic.ac.uk

Chapter 37

Dr H. Miettinen VTT Biotechnology Espoo

PO Box 1500 FIN-02044 VTT Finland

E-mail: hanna.miettinen@vtt.fi

Chapter 38

Dr Jean-Yves Maillard Welsh School of Pharmacy Cardiff University

Redwood Building King Edward VII Avenue Cardiff CF10 3XF UK

E-mail: MaillardJ@Cardiff.ac.uk

Chapter 39

Dietmar Rosner

Training & Service Manager Food & Beverage Division Ecolab GmbH & Co. OHG Reisholzer Werftstrasse 38±42 40589 Duesseldorf

Germany

E-mail: dietmar.rosner@ecolab.com

Chapter 40

Dr P. Overbosch Kraft Foods R&D Bayerwaldstrasse 8 D-81737 Munich Germany

E-mail: poverbosch@krafteurope.com xxii Contributors

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Following the publication of Hygiene in Food Processing, the editors have focussed in this book on how current best practice in hygiene may be further improved. The food related illnesses reported daily in surveys of the European and American food safety authorities, for example, show that, in many instances, such improvements are highly desirable. We hope therefore that this book will not only reach those who are now responsible for product quality and safety in food companies, and for the design, building and installation of food plants, but particularly also to those who will assume such responsibility in the future.

Students in food science, food technology, food engineering, microbiology and food chemistry may benefit from using this handbook, since much of the information needed in practice in the food industry ± in its widest sense ± is, in most cases, not part of the courses they follow.

The book starts with an introduction discussing the history of hygiene. This chapter discusses the first origins of hygiene as a concept thousands of years ago. It demonstrates very clearly why hygiene is so important and why, even today, people die because of not complying with basic hygiene requirements. To be able to decide on measures to control product safety, it is essential to understand the risks associated with product safety. Part I therefore is devoted to the range of microbiological risks in food processing. Risk perception is one of the most important determinants of consumer behaviour in the hygienic handling and consumption of food. It is also important because factors influencing consumer behaviour may be very similar to those affecting the behaviour of employees in the food chain. Part I therefore includes a chapter discussing consumer risk perception since an understanding of such behaviour may help to devise effective measures to reduce risks or eliminate undue hazards.

Part II is devoted to improving the design of production facilities: buildings,

Preface

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equipment and equipment components. It covers areas not covered in previous books on the subject such as requirements for electrical installations and sensors.

Understanding risks in food production and hygienic design requirements, however, will not guarantee hygienic production. Inadequate management is often a factor in food safety incidents. Part III therefore discusses risk management and control, covering such areas as good manufacturing practice (GMP) and standard operating procedures (SOPs) in relation to processing, cleaning and sanitation. It also covers ways of monitoring the effectiveness of hygiene in food processing.

If you bought this book to address issues that you want to solve, we hope that you will find the answers or, at least, where to go next to find the answers. In case you come across issues that you feel are important but have not been addressed, we invite you to contact us so that we may take this into account in future editions of the book.

In Part I, chapter 2 provides a general introduction to what the following chapters cover. Parts II and III include brief introductions to the main themes that follow.

Huub Lelieveld Tineke Mostert John Holah xxiv Preface

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1.1 Introduction: the evolution of food hygiene

The art of healing is almost as old as people themselves. Instincts, needs and experiences taught humans the art of healing. Throughout history, medicine and hygiene have been counterparts in healing and preventing diseases. Both disciplines have mostly gone hand in hand with improving human health. This introductory chapter starts with the early aspects of hygiene and, where necessary, interfaces between healing and preventing diseases will be discussed.

After the recognition of germs as causative agent of diseases, the significance of hygiene developed rapidly and is now considered as the cornerstone of safe food production.

1.1.1 The origin of the hygiene concept Hygeia, the goddess of health

In Greek mythology, Asclepius, son of Apollo and referred to as the god of medicine or healing, was a healer who became a Greek demigod, and was a famous physician. He was the most important among the Greek gods and heroes who were associated with health and curing disease. Shrines and temples of healing, known as Asclepieia, were erected throughout Greece where the sick came to worship and sought cures for their ills. Among the children of Asclepius the best known are his daughters Hygeia and Panacea. Hygeia became the goddess of healing and she focused on the healing power of cleanliness. She introduced and promoted the idea of washing patients with soap and water. She had lots of hospital shrines and played an important role in the cult of Asclepius

1 Introduction

S. Notermans and S. C. Powell, Lancashire Postgraduate School of Medicine and Health, UK and E. Hoornstra, TNO Nutrition and Food Research, The Netherlands

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as a giver of health. At the beginning she was the goddess of corporal well- being. Later she was also connected to mental health; the aphorism `mens sana in corpore sano' applies to this, `a healthy mind in a healthy body'. Her sister was faced, like her father, with healing by medicines.

Hygeia was celebrated in many places in the Greek and Roman world. She was sung about and represented by many artists from the 4th centuryBCuntil the end of the Roman period. Statues of Hygeia were made by well-known masters such as Skopias, Tomotheos and Bryaxis. The name of Hygeia has survived in the word hygiene and its components. Her sacred snake together with the rod of Asclepius is the sign for medicine.

Hippocrates (460±377 BC)

Hippocrates, the most famous doctor in ancient Greece, was called the Father of Medicine. Hippocrates based medicine on objective observation and deductive reasoning. His medical school and sanatorium on the island of Kos developed principles and methods in curing that have been used ever since. Hippocrates and his followers elaborated an entirely rational system that was based on the classification of the symptoms of different diseases. He taught that medicine should build the patient's strength through diet and hygiene, resorting to more drastic treatment only when necessary. All historians agree that he taught validly concerning epidemics, fever, epilepsy, fractures, the difference between malig- nant and benign tumours, health in general and, most of all, the importance of hygiene, the healing power of food and the need for high ethical values in the practice of medicine. He laid utmost stress on hygiene and diet, but used herbal remedies and surgery when necessary.

An overview of the work of Hippocrates is presented in the book Magni Hippocratis Coi Opera Omnia (Hollier, 1623). It contains everything that had been ascribed to Hippocrates up to the 17th century.

Other hygiene measures

Over many millennia, humankind has learned how to select edible plant and animal species, and how to produce, harvest and prepare them for food purposes. This was mostly done on the basis of trial and error and from long experience. Many of the lessons learned, especially those relating to adverse effects on human health are reflected in various religious taboos, which include a ban on eating specific items, such as pork, in the Jewish and Muslim religions (Tannahill, 1973). Other taboos showed a more general appreciation of food hygiene. In India, for example, religious laws prohibited the consumption of certain `unclean' foods, such as meat cut with a sword, or sniffed by a dog or cat, and meat obtained from carnivorous animals (Tannahill, 1973). Most of these food safety requirements were established thousands of years ago when religious laws were likely to have been the only ones in existence. The introduction of control measures in civil law was of a much later date.

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The re-emergence of hygiene

In the Middle Ages folk-medicine developed rapidly. Medicinal plants, animal parts and minerals were used to get rid of disease symptoms. Later, surgery was used as a cure. At the beginning of the 1800s the excesses of doctors and the cottage industry of drugs led to general loathing and ridicule of the medical profession by the public in the USA and Europe. For at least a century strychnine was the best remedy the profession had for palsy and paralysis. It was used to kill rats, cats and dogs. But when given as medicine, it was tonic, a nerving, a remedy for palsied people. It was standard medical practice to with- hold water from the ill, and thousands of patients literally died of dehydration.

Alcohol was a foundation of the many bitters that were sold to the people as tonics, as it was the chief ingredient in many of the patent nostrums sold.

Remedies were sold against alcoholism that were chiefly alcohol. In addition to drugging their patients to death, physicians have frequently bled them to death.

Bleeding was employed in wounds and head injuries that resulted in uncon- sciousness. Not only were pregnant mothers bled, but physicians also drew blood from blue babies. In these days patients were bled, blistered, purged, vomited, narcotised, mercurialised or alcoholised into chronic invalidism or into the grave. The death rate was high and the sick person who recovered without sequelae was so rare as to be negligible. In that time hygiene was very poor as well. Physicians not only frowned upon but opposed bathing. Surgeons performed operations without washing their hands, and operating rooms of hospitals were veritable pig-sties. Physicians would go from the post-mortem room directly to the delivery room and assist in the birth of a child without washing their hands. Child-bed fever was a very common disease and the death rate from it was very high.

This is the time when the revolt, `hygiene', re-emerged. Out of the contradictions, confusions, chaos and delusions called the science of medicine grew a need for new thoughts, and a crusade for health reform developed.

The `Natural Hygiene' concept

One of the first pioneers was Isaac Jennings (see the book Awakening our self- healing body by Arthur Michael Baker (1994)). In 1822, after having practised medicine for 20 years and being thoroughly discouraged with the results, Jennings begins to administer placebos of bread pills, starch powders and coloured water tonics to patients, while instructing them in healthy living.

Jennings and physiologist/minister Sylvester Graham started to educate citizens with failures and contradictions of current medical practice and theory. Graham developed a significant following of Grahamites in response to his eloquent lectures and writings. To the temperance movement he offered a vegetarian diet as a cure for alcoholism. He also advocated sexual restraint and hygiene measures such as bathing.

The truths proclaimed by Jennings and Graham found immediate and widespread acceptance. After becoming fully convinced of the correctness of his

`Do-Nothing Cure' and the `No-Medicine Plan', Jennings announced his Introduction 3

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discovery to the world, but he was misunderstood. The work of Jennings in the USA was continued by many others. People were taught to bathe, to eat more fruit and vegetables, to ventilate their homes, to get exercise and sunshine.

Hygiene became so popular, that traditional medicine finally had to adopt parts of the `Natural Hygiene' concept. Later, when it became clear that `germs' were the cause of many diseases, the new `hygiene' was incorporated with the drug usage of medicine and the word hygiene got the meaning it has today.

Hygienic developments in Europe

In the middle of the 19th century two people laid the foundation of modern hygiene: the Hungarian physician Semmelweis and the British surgeon Lister.

Both introduced hygienic methods that are still essential in modern society.

IgnaÂc FuÈloÈp Semmelweis (1818±1865) was a Hungarian physician who demonstrated that puerperal fever¹ (also known as `childbed fever') was contagious and that its incidence could be drastically reduced by enforcing appropriate hand-washing behaviour by medical care-givers. Semmelweis made this discovery in 1847 while working in the Maternity Department of the Vienna Lying-in Hospital. He realised that the number of cases of puerperal fever was much larger in clinic 1 where students did both post-mortem examinations with human cadavers in the autopsy rooms and midwifery in the maternity rooms. In clinic 1 the average death rate amounted to 9.92%. In clinic 2 where students were involved in midwifery and not allowed to do autopsies, the average death rate was much less at around 3.38%. After testing a few hypotheses, Semmelweis found that the number of cases was drastically reduced if the doctors washed their hands carefully before dealing with a pregnant woman (see Table 1.1). Risk was especially high if they had been in contact with corpses before they treated the women. The germ theory of disease had not been developed at the time. Thus, Semmelweis concluded that some unknown

`cadaveric material' caused childbed fever. Since the cadaverous matter could not been removed from the doctors' hands merely by washing them with soap and water Semmelweis started experiments with different chemicals. Finally he prescribed the additional use of chlorinated lime. Due to this the death rate caused by puerperal fever deceased to zero (see Table 1.1).

Semmelweis lectured publicly about his results in 1850. However, the reception by the medical community was cold, if not hostile. His observations went against the current scientific opinion of that time, which blamed diseases on an imbalance of the basic `humours' in the body. It was also argued that even if his findings were correct, washing one's hands each time before treating a pregnant woman, as Semmelweis advised, would be too much work. Nor were doctors eager to admit that they had caused so many deaths. Semmelweis spent 14 years developing his ideas and lobbying for their acceptance, culminating in a book he wrote in 1861 (Semmelweis, 1861). The book received poor reviews,

1. A serious form of septicaemia contracted by a woman during childbirth or abortion (usually attributable to unsanitary conditions); formerly widespread but now uncommon.

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and he responded with polemic. His failure to convince his fellow doctors was not helped by his poor ability to communicate. In 1865, he suffered a nervous breakdown and was committed to an insane asylum where he soon died from blood poisoning. Only after Dr Semmelweis's death was the germ theory of disease developed. He is now recognised as a pioneer of antiseptic policy and prevention of nosocomial disease.

Joseph Lister (Lord Lister, 1827±1912) introduced antiseptic surgery. By the middle of the 19th century, post-operative sepsis infection accounted for the death of almost half of patients undergoing major surgery. A common report by surgeons was: operation successful but patient died. For many years he had explored the inflammation of wounds, at the Glasgow Infirmary. These observations led him to consider that infection was not due to bad air alone, and that `wound sepsis' was a form of decomposition. When, in 1865, Louis Pasteur suggested that decay in wounds was caused by living organisms in the air, which on entering matter caused it to ferment, Lister made the connection with wound sepsis. As a meticulous researcher and surgeon, Lister recognised the relationship between Pasteur's research and his own. He considered that microbes in the air were likely to be causing the putrefaction and must be destroyed before they entered the wound. In 1864 Lister had heard that `carbolic acid' was being used to treat sewage in Carlisle (UK), and that fields treated with the effluent became free of parasites causing disease in cattle. Even before the work of Pasteur on fermentation and putrefaction, Lister had been convinced of the importance of scrupulous cleanliness and the usefulness of deodorants in the operating room. In 1865 he began spraying a carbolic acid solution during surgery to kill germs. In the end, Lister gives Semmelweis his due by saying

`Without Semmelweis, my achievements would be nothing'. Through Pasteur's researches, he realised that the formation of pus was due to bacteria, so he Table 1.1 The effect of hand-washing and hand-washing with chlorinated lime on maternal death caused by puerperal fever

Year/period Maternal death rate in (%)

Medical students Midwife students

(clinic 1) (clinic 2)

1841±1846 9.92 3.38

May 1847 12.42

Introduction of hand-washing

June 1847 2.38

July 1847 1.20

August 1847 1.89

Introduction of chlorinated lime hand-washing

October 1847 1.27 1.33

March 1848 0 0

August 1848 0 0

Introduction 5

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proceeded to develop his antiseptic surgical methods. The immediate success of the new treatment led to its general adoption, with results of such beneficence as to make it rank as one of the great discoveries of the age. Lister also began to clean wounds and dress them using a solution of carbolic acid. He was able to announce at a British Medical Association meeting, in 1867, that his wards at the Glasgow Royal Infirmary had remained clear of sepsis for nine months.

German surgeons were also beginning to practise antiseptic surgery, which involved keeping wounds free from microorganisms by the use of sterilised instruments and materials.

The 1870s were some of the happiest years of Lister's life, largely because of the German experiments with antisepsis during the Franco-German War. His clinics were crowded with visitors and eager students. Lister made a triumphal tour of the leading surgical centres in Germany in 1875. Here he met Robert Koch who demonstrated in 1878 the usefulness of steam for sterilising surgical instruments and dressings.

1.1.2 Foodborne diseases and hygiene since 1850 Foodborne diseases

Public health concern with foodborne diseases emerged around the 1880s. This was after microorganisms had been found to be infectious agents. Koch and his assistants devised the techniques for culturing bacteria outside the body, and formulated the rules for showing whether or not a bacterium is the cause of a disease (Koch, 1883). Before that time two types of illness with foodstuffs were recognised: one associated with ageing, and the other with foods normally not causing illness and apparently incapable of adulteration such as meat and fish.

The last type had long been associated with decomposition; in the early 19th century it was thought to be due to chemical poisons, later to ptomaines,²or putrefactive alkaloids (Dewberry, 1959). Uncooked fruit and vegetables were also associated with upset stomachs, but here illness was generally attributed to unripeness or acidity (Hardy, 1999).

It was not until the late 1880s that the generic term `food poisoning' emerged:

before this, and still occasionally for decades thereafter, episodes were usually described by the precise item of food involved: `cheese poisoning', `meat poisoning', `pork-pie poisoning', etc. Despite Robert Koch's identification of specific organisms causing foodborne diseases, such as anthrax, in 1876 (Koch, 1876) the above terms for food poisoning remain in use and examples have been described by, among others, Durham (1898) and Peckham (1923±24) who reported on respectively outbreaks of meat poisoning and pork-pie poisoning.

2. Food poisoning, erroneously believed to be the result of ptomaine ingestion. The word ptomaine was invented by the Italian chemist Selmi for the basic substances produced in putrefaction. They belong to several classes of chemical compounds and are any of various amines (such as putrescine or cadaverine) formed by the action of putrefactive bacteria.

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The 1880s were also the decade when bacterial food poisoning displaced ptomaine poisoning. In the late 1870s, German researchers had begun to draw attention to connections between septic and pyaemic³diseases in animals used for food and meat poisoning outbreaks. In the early 1880s they started to investigate meat poisoning outbreaks bacteriologically (described by Ostertag, 1902).

Hard historical information about the incidence rate of foodborne infections in the 19th century is lacking. One of the reasons is that food poisoning was not notifiable. (In the UK food poisoning became notifiable in 1939.) There are, however, two indicators for the behaviour of food infections in cities: typhoid and epidemic diarrhoea. Typhoid emerged in the UK as a major urban hazard in the 1830s and was largely water-borne. The role of human carriers and of contaminated foodstuffs is likely to have been significant. Death rates from typhoid fell rapidly between 1870 and 1885, as urban water supplies were improved, but then stabilised until early in the 20th century (Greenwood, 1935).

With the discovery of the human carrier and of foodstuffs as a vehicle of infection, and with greater (hygienic) care of patients, death rates fell rapidly and disappeared around 1920. Epidemic diarrhoea contributed even more to food poisoning. The term encompasses infant diarrhoea, the condition responsible for some 30% of infant mortality before 1901. Huck's local studies (Huck, 1994) showed that rising infant mortality was closely associated with the growth of industrial towns in the early 19th century. Other contemporary studies found that infant death was only the visible tip of the iceberg of extensive familial episodes of diarrhoea (Woods et al., 1988) which emphasised a very high degree of multiple infections in households. It was Ballard (1887, cited by Hardy, 1999) who linked the infections with contaminated foodstuffs. When the first bacteriological analyses of epidemic diarrhoea came to performed, the leading contenders for causation came from bacteria belonging to the family of Salmonellae (Niven, 1909±1910). In 1888 the German GaÈrtner (1888) dis- covered and described the Salmonella bacterium, which he named Bacillus enteritidis. He demonstrated the presence of the organism in a slaughtered cow that had caused gastroenteritis in the people who had eaten its meat. The discovery of other such organisms quickly followed in the pioneering bacteriological laboratories of the 1890s and actually the identification of specific agents of disease became a competitive game. Despite new isolation and identification techniques, the bacteriology of food poisoning and infection appeared to be an immensely complicated subject, partly because of the number of different organisms apparently involved in the process, and partly because of the vexed questions of their nature and natural habit. For example, questions about whether Salmonella was a natural inhabitant of the intestinal tract of human and animals, was Salmonella present in the flesh of the animal or was it present only in diseased animals needed to be solved.

3. The invasion of bloodstream by pyogenic (pus-forming) organisms.

Introduction 7

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Identification of agents involved in foodborne diseases and the aetiological research of foodborne diseases began at the end of the 19th century when the work of Van Ermengem served to clarify the aetiology of botulism in humans (Van Ermengem, 1897). Later milestones in this category included the recognition of Clostridium perfringens as a foodborne pathogen in 1943 (McClane, 1979) and Bacillus cereus in the 1950s (Kramer and Gilbert, 1989). Human infections with Listeria monocytogenes were well known by the 1940s and foodborne transmission was suspected (Rocourt and Cossart, 1997), but it was not until the occurrence of an outbreak in Canada in 1981 that proper evidence was obtained. In this case, illness followed the consumption of contaminated coleslaw (Farber and Peterkin, 2000). Since then, numerous foodborne outbreaks have been reported in different countries, and prevention of listeriosis has become a major challenge for the food industry. Around 1980±1985 Salmonella Enteritidis re-emerged via the internal contamination of chicken eggs. At the same time a new emerging pathogenic started to emerge:

Escherichia coli O157: H7 (Willshaw et al., 2001). This organism causes haemorrhagic colitis. Some victims, particularly the very young, may develop haemolytic uremic syndrome (HUS) which is characterised by renal failure and haemolytic anaemia. From 0 to 15% of haemorrhagic colitis victims may develop HUS. The disease can lead to permanent loss of kidney function.

Although there were enormous developments in foodborne disease research at the beginning of the 20th century the reporting of incidents remained low.

Unless one or more deaths were involved, or an outbreak was on a considerable local scale, incidents of gastroenteritis rarely came to the knowledge of the authorities. Savage and Bruce White (1925) complained after a case in which an elderly woman died as a result of eating canned salmon. Investigations were not carried out. Difficulties in reporting and adequate investigations were acknowledged obstacles to a fuller understanding of the nature of and factors in bacterial food poisoning. Before the Second World War, most food poisoning incidents undoubtedly remained hidden. To improve the situation in 1939 the UK established the `Emergency Public Health Laboratory Services' ± a network of 19 provincial and 10 metropolitan laboratories, whose services were to be available free of charge to medical officers of health if required for the investigation and control of infectious diseases.

The Second World War is generally seen as a seminal event in history of food poisoning. During and after the war, there was a rapid extension of mass catering, both in terms of feeding large numbers of people in canteens and restaurants, and in mass production of prepared foodstuffs. This resulted in many new problems. Egg-borne Salmonella infections received widespread publicity when incidents were traced to the use of bulk imports of American powdered eggs (Hardy, 1999). Trade in both human and animal foodstuffs became internationalised and opened many European countries to a large number of exotic Salmonella types from all over the world.

After the introduction of compulsory notification, foodborne diseases acquired a statistical profile. After an uncertain start notifications began to 8 Handbook of hygiene control in the food industry

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rise steadily. For example in the UK the notifications increased in a 10 year period (1941±1951) from an initial couple of hundred to over 3000 a year.

As indicated by Hardy (1999) in her historical overview of food poisoning in Britain, the history of foodborne disease is one of social and scientific change, but is not simply of an increasing preference for foodstuffs prepared outside the home rather than within it. Rather, it is the story of how social and scientific change has gradually exposed unchanging economies of time and hygiene that most people have always made in their everyday lives. However, information about foodborne diseases is still not complete. A current problem is that although most countries have mandatory systems for notifying foodborne diseases, the information provided is generally poor and there is a dramatic underreporting. This came to light after modern analyses were used, including sentinel and population studies. It became clear that in developed countries on average 10 000±20 000 persons per 1 000 000 population suffer yearly from a foodborne disease (de Wit et al., 2001; Fitzgerald et al., 2004). In addition in about 37.5% of the cases investigated in sentinel studies a causative organism was identified (see Table 1.2).

Hygiene

Following the discovery, around 1880, that food can be an important source of disease-causing organisms, investigations started to concentrate on the reservoirs and routes of transmission of pathogens. The research of Buchanan (cited by Oddy and Millar, 1985) revealed an association between infant diarrhoea, refuse tips and flies. Further elucidation of reservoirs and routes of transmission stimulated the British public health authorities to include this emerging field in preventive medicine. As an example, the health authorities began extensive anti-fly campaigns, both through public education and by Table 1.2 Microorganisms detected in patients with symptoms of acute enteritis and controls (de Wit et al., 2001)

Patients (N = 857) Controls (N = 574)

No. % No. %

Salmonella spp. 33 3.9 1 0.2

Campylobacter spp. 89 10.4 3 0.5

Yersinia spp. 6 0.7 6 1.1

Shigella spp. 1 0.1 0 0.0

VTEC 4 0.5 3 0.6

Rotavirus 45 5.3 8 1.4

Adenovirus 19 2.2 2 0.4

Astrovirus 13 1.5 2 0.4

Norwalk-like viruses 43 5.0 6 1.1

Sapporo-like viruses 5 2.1 1 0.2

Parasites 64 7.4 26 4.5

Total 322 37.6 58 10.1

Introduction 9

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tackling the breeding grounds of the flies themselves. At much the same time, attention began to focus on the presence of pathogenic bacteria in the intestines of animals, as a source of food contamination, and foods of animal origin, as routes of transmission to humans.

Savage (1909) observed that faecal contamination of food must be very common. Milk, in particular, was suspected to be a vehicle of infection. Theodor Escherich, a German paediatrician, who devoted his efforts to improving childcare, particularly in relation to infant hygiene and nutrition, was the first to make a plea for heat-processing of milk to prevent infant diarrhoea (Escherich, 1890). After that time, the heating processes used for food began to improve. Real progress was made when Esty and Meyer (1922) developed the concept of process-performance criteria for heat treatment of low-acid, canned food- products to reduce the risk of botulism. Later, many other foods subjected to heat treatment were controlled in the same manner. An outstanding example is the work of Enright et al. (1956, 1957), who established performance criteria for the pasteurisation of raw milk that provided an appropriate level of protection against Coxiella burnetii, the causative agent of Q fever. Studies on the agent responsible for tuberculosis had been carried out earlier. These are early examples of the use of risk-assessment principles in deriving process criteria for control purposes.

The recognition of animal reservoirs of Salmonella served to reinforce the perceived complexity of the food poisoning problem. It was known that the key to preventing typhoid lay in blocking the routes by which the causative bacteria might pass from animals to humans and then among the human population.

From the public health viewpoint, it became clear that there were several elements in the food poisoning situation: firstly, there was the animal-health aspect, with veterinary, slaughterhouse and culinary factors to consider; then, there was the matter of personal hygiene, which involved toilet and hand- washing habits. The question of developing suitable legislation was also apparent and, finally, there was the bacteriological aspect, with the need for more extensive laboratory provision to help in unravelling evidence from the field. Based on the need to improve hygiene in slaughterhouses, the USA was one of the first countries to introduce a Meat Inspection Act in 1906. This brought the following reforms to the processing of cattle, sheep, horses, swine and goats destined for human consumption:

· all animals were required to pass an inspection by the US Drug Administration prior to slaughter;

· all carcasses were subject to a post-mortem inspection;

· standards of cleanliness were established for slaughterhouses and processing plants.

In the UK, it was recognised that legislation alone was not sufficient to protect consumers against foodborne diseases, and the health authorities became aware of the need for public education to achieve cleaner food supplies. Food handling practices were very poor. Some examples from the 1920s were described by Porter (1924±1925) and included the following:

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· Glass washing:

± it was common for glasses to be dipped only in dirty water before being re- used.

· Personal cleanliness among food handlers:

± food handlers regularly licked their fingers when dealing with wrapping paper;

± they blew into paper bags to open them;

± butchers often failed to wash their hands after eviscerating animals;

± the habit of fingering the nose and/or mouth, while serving food, was common.

When wrapped bread was introduced into the UK, the innovation proved unpopular among housewives. One reason was that the wrappers became dirty and people failed to realise that, without wrappers, the dirt would be on the bread (Hardy, 1999). Hand-washing facilities were mostly unavailable and, where present, were rarely used initially. Toilet paper, too, was accepted reluctantly and, when it became available, the quality was very poor (White- bread, 1926). Only when a new Food and Drug Act was introduced in the UK in 1938, was it necessary to use hygienic conditions and practices in handling, wrapping and delivering food, and adequate hand-washing facilities were required for food handlers.

A clear breakthrough in public health was the processing and disposal of domestic and sewage wastes, in conjunction with the purification of water supplies to ensure that any pathogens present were not passed to consumers via drinking water. Also, sanitary microbiologists were appointed to inspect food processing and eating establishments to ensure that proper food-handling procedures were followed. These made a significant contribution to the development of appropriate hygiene standards.

1.2 Definitions of hygiene

In ancient times, it was clear that diseases could be overcome, either by actively curing (Asclepius) or through the power of cleanliness (Hygeia). Curing diseases with the use of medicines was traditionally the role of the physician. Preventing diseases, on the other hand, became the domain of the hygienist. The first definitions of `hygiene' are derived from the work of the goddess Hygeia:

· `healing through cleanliness';

· `the science dealing with the preservation and promotion of health'.

In the course of time, medicines became the principal means of curing diseases.

However, because of the many failures during the 18th and 19th centuries, hygiene re-emerged as the key discipline. In the USA, the `Natural Hygiene' movement came into being. The main objective of this science-based movement was not to treat the effect, but to remove the cause of a disease (treating the Introduction 11

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effect without addressing the root cause was then the usual practice of medicine). Natural Hygiene addresses all aspects of living: the environment, food, work, home, economics, spirituality, psychology, politics, etc. and those other factors that positively influence health and well-being.

Following the recognition of germs as the principal causes of disease at the end of the 19th century, hygiene measures rapidly became established. By the beginning of the 20th century, it had become clear that preventive measures were the only way to produce safe food, and the discipline of food hygiene was born. Current definitions of `food hygiene' are presented in Table 1.3.

Based on these definitions, it can be concluded that the concept involves all necessary measures to produce safe and healthy food. Any means to prevent contamination, decontaminate food (such as pasteurisation) and measures to improve wholesomeness and fitness for consumption are considered to be part of the hygiene concept. Various factors are contributory, such as personal hygiene and hygienic design of facilities, equipment, etc., as well as activities relating to cleaning and disinfection of food premises and hygienic disposal of waste, which are referred to as `sanitation'.

1.2.1 Personal hygiene

Personal hygiene is of great importance for the maintenance of health in general.

Human beings are natural carriers of many microorganisms and sources include the hair, skin, mucous membranes, digestive tract, wounds, infections and clothing. Good personal hygiene is primarily directed towards preventing both disease and discomfort. Hand-washing, dental care, avoidance of spitting, daily showering, etc., as well as clean living, play an important part. Disposal of waste is also important. All these measures are preventive in character and are readily carried out.

Table 1.3 Definitions of food hygiene in current use.

· Conditions and practices that preserve the quality of food to prevent contamination and foodborne illnesses.

http://www.nlm.nih.gov/medlineplus/ency/article/002434.htm

· All measures necessary to ensure the safety and wholesomeness of foodstuffs.

EU's General Food Hygiene Directive (Anon., 1993).

· All conditions and measures necessary to ensure the safety and suitability of food at all stages of the food chain.

Codex Alimentarius Commission (CAC/RCP, 2003)

· The measures and conditions necessary to control hazards and ensure fitness for human consumption of a foodstuff, taking into account its intended use

Environmental Health Journal, 2000, 108/9; http://www.ehj-online.com/archive/2000/

september/sept10.html; Council Directive 93/43, 1993.