/ `orid Health Organization °,

Regional Office for Europe AO ltCopenhagen

. . . ... i.1.. ..

ass catenn

ions, European Series No. 15

The World Health Organization is a specialized agency of the United Nations withprimary responsibility for international health matters and public health. Throughthis Organization, which was created in 1948, the health professions of more than150 countries exchange their knowledge and experience with the aim of makingpossible the attainment by all citizens of the world by the year 2000 of a level of healththat will permit them to lead a socially and economically productive life.

The WHO Regional Office for Europe is one of six Regional Offices throughoutthe world, each with its own programme geared to the particular health problems ofthe countries it serves. The European Region has 33 active Member States,' and isunique in that a large proportion of them are industrialized countries with highlyadvanced medical services. The European programme therefore differs from those ofother Regions in concentrating on the problems associated with industrial society. Inits strategy for attaining the goal of "health for all by the year 2000" the RegionalOffice is arranging its activities in three main areas: promotion of lifestyles conduciveto health; reduction of preventable conditions; and provision of care that is adequate,accessible and acceptable to all.

The Region is also characterized by the large number of languages spoken by itspeoples, and the resulting difficulties in disseminating information to all who mayneed it. The Regional Office publishes in four languages - English, French, Germanand Russian - and applications for rights of translation into other languages aremost welcome.

a Albania, Algeria, Austria, Belgium, Bulgaria, Czechoslovakia, Denmark, Finland, France, GermanDemocratic Republic, Federal Republic of Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg,Malta, Monaco, Morocco, Netherlands, Norway, Poland, Portugal, Romania, San Marino, Spain, Sweden,Switzerland, Turkey, USSR, United Kingdom and Yugoslavia.

Cover: The Wedding Feast by P. Bruegel the Elder.Reproduced by kind permission ofKunsthistorisches Museum, Vienna.

World Health OrganizationRegional Office for Europe

Copenhagen

Mass catering

R.H.G. CharlesSenior Medical Officer

Department ofHealth and Social SecurityLondon, United Kingdom

WHO Regional Publications, European Series No. 15

ISBN 92 890 1106 8

© World Health Organization 1983

Publications of the World Health Organization enjoy copyright protection in ac-cordance with the provisions of Protocol 2 of the Universal Copyright Convention.For rights of reproduction or translation, in part or in toto, of publications issued bythe WHO Regional Office for Europe application should be made to the RegionalOffice for Europe, Scherfigsvej 8, DK -2100 Copenhagen 0, Denmark. The RegionalOffice welcomes such applications.

The designations employed and the presentation of the material in this publica-tion do not imply the expression of any opinion whatsoever on the part of theSecretariat of the World Health Organization concerning the legal status of anycountry, territory, city or area or of its authorities, or concerning the delimitation ofits frontiers or boundaries.

The mention of specific companies or of certain manufacturers' products doesnot imply that they are endorsed or recommended by the World Health Organiz-ation in preference to others of a similar nature that are not mentioned. Errors andomissions excepted, the names of proprietary products are distinguished by initialcapital letters.

The views expressed in this publication are those of the author and do notnecessarily represent the decisions or the stated policy of the World Health Organ-ization or of the Department of Health and Social Security, London.

TYPESET IN INDIA

PRINTED IN ENGLAND

CONTENTS

Page

Foreword vii

Acknowledgements ix

Introduction 1

Bibliography 2

1. GENERAL PROBLEMS 3

Contamination 3

Premises 5

Supply of raw ingredients 7

Hygienic practices 8

Workforce 10

Nutrition I 1

Bibliography 13

2. GENERAL METHODS OF CONTROL 15

Planning and licensing 15

Management and inspection 16

General hygiene 17

Raw material 18

Laboratory tests 19

HACCP 21

Water 22

Personal hygiene 23

Epidemiology 24

Bibliography 25

3. RECENT TECHNOLOGY 27

Cook -freeze and cook -chill 27

Slow cookers 28

Microwave cooking 28

Convenience foods 29

Electronic thermometers 29

Anaerobic packing 31

Bibliography 31

v

4. TRAINING 33

Bibliography 35

5. INSTITUTIONAL AND WELFARE CATERING 37

Hospitals 37

Schools and old people's homes and clubs 38

Meals -on- wheels 40

Bibliography 41

6. CANTEENS IN FACTORIES AND OTHERCOMMERCIAL ESTABLISHMENTS 43

7. OPEN AIR CATERING 45

Disasters 45

Festivals 47

Bibliography 48

8. TOURIST HOTELS AND HOLIDAY CAMPS 49

Bibliography 51

9. TRAVEL CATERING 53

Aeroplanes 53

Ships 56

Other vehicles 59

Bibliography 60

10. OTHER CATERING FOR TRAVELLERS 61

11. BANQUETING 65

12. SUMMARY 69

vi

Foreword

With the increase in urbanization, industrialization and tourism, masscatering systems are becoming increasingly popular throughout the worldin both industrialized and developing countries. They provide a convenientand economical means of catering for large numbers of people. Traditionalforms of catering have been associated with many outbreaks of foodpoisoning and other foodborne disease in the past. Mass cateringoperations, by reason of their scale and complexity, have the potential toproduce even more disastrous consequences for health, if the strictestprinciples of hygiene are not maintained. Since mass catering may accountfor much of the dietary intake of large sections of the population,particularly of highly vulnerable groups such as children and the elderly,careful nutritional surveillance is necessary. Because of the healthimplications of mass catering, it is important that both the healthauthorities and other officials and commercial interests should be aware ofthe problems. Staff employed in catering should understand what they needto do and why, and it is the responsibility of the food safety authorities toprovide adequate training facilities. This book is therefore intended forhealth officials who have little knowledge of commercial catering, and forfood, trade and other officials and commercial interests that have littleknowledge of public health. It does not set out to be a technologicalmanual or a text book of food hygiene or the epidemiology of foodbornedisease. Its aim is to draw attention to the relationship between masscatering and public health and to show where further information can befound.

While many of the principles of hygiene, food safety and nutrition arecommon to all forms of catering, many systems of mass catering andsituations in which mass catering is employed present their own peculiarproblems. This book therefore starts by dealing with the general aspects ofpublic health in relation to catering, planning, monitoring and training, andthen goes on to deal in subsequent chapters with the specific problems ofparticular aspects of catering, such as travel catering, institutionalcatering, banqueting and so on. A selected bibliography of useful referencebooks and papers for those who require more information about the subjectappears at the end of most chapters.

vii

On behalf of WHO I wish to thank all those experts in many countrieswho have assisted Dr Charles in the preparation of this book, andparticularly those in Bulgaria, the Federal Republic of Germany andSweden who so kindly arranged and took part in visits by the author andhis collaborator, Mr Hughes.

"Der Mensch ist, was er isst"Feuerbach

Leo A. KaprioWHO Regional Director for Europe

viii

Acknowledgements

The author wishes to express his thanks for all the assistance he hasbeen given by friends and colleagues in government service and thecatering industry in many countries, especially Professor Shindolev,Professor Kaloyanova, Professor Efremov, Dr Stroeva and DrGheorgiev in Bulgaria, Dr Kobbe in the Federal Republic of Germany,Dr Florin and Dr Augustinsson in Sweden, Mrs Cynthia Sadler for theillustrations and Mrs Maureen Simpson for all her invaluable help.

He particularly wishes to express his gratitude to Mr H. L. Hughes,Environmental Health Officer, late of the Department of Health andSocial Security, who collaborated closely in this work. Not only didMr Hughes assist with his wide knowledge and experience, but alsovisited Sweden and the Federal Republic of Germany for the author.

ix

Introduction

It is becoming increasingly common for people to come together in largenumbers, usually outside their own homes, for medical care, socialactivities, education, employment, etc. and in the course of theseactivities to eat food that they have not prepared themselves. This isseen to the greatest extent in the industrialized countries. For example, ithas been estimated that in 1976 in the Federal Republic of Germany atleast 20 million people regularly had meals outside the home. Of allexpenditure on food in the United Kingdom one sixth is on foodprepared outside the home. With the increase of urbanization,industrialization, mass travel and tourism in the developing countries,similar trends in eating habits are beginning to appear there.

Such eating habits may be associated with many very differenthuman activities, in factories, schools and hospitals, on ships andaeroplanes, at arts and music festivals and tourist hotels, in cafeterias,and at take -away premises, wedding receptions and formal banquets. Allthese different activities have at least one thing in common: theyincreasingly demand the provision of food in a form that is ready to beeaten by a large number of people at the same time, or within a periodthat is relatively short in relation to the numbers to be fed.

This demand cannot be met economically by traditional forms ofcatering. In traditional catering, the meals are individually ordered forone customer, or at most a small group of customers, and are preparedat the time of ordering and served with very little delay. In contrast withthis, modern catering requirements make it necessary for large quantitiesof food to be prepared in advance of demand and served rapidly, indeedalmost simultaneously, to a large number of people. The food may alsohave to be served at more than one outlet, often at many outletsdistributed over a wide area. The advanced technology and theexpensive and specialized equipment usually needed for the satisfactoryproduction of food in bulk may make it more economical to prepare allthe food at a single central kitchen.

To use this equipment and trained staff efficiently and cost -effectivelyit may be advantageous to have a continuous operation throughout theworking day. The importation of new technology and intensive

1

centralized food production may create serious difficulties in countriesthat lack the appropriate technological and sanitary infrastructure. Inany country, centralized food production may lead to long delaysbetween cooking and eating. There may also be a considerable distancebetween the place where the food is cooked and the places where it is tobe served and eaten. Special precautions are needed during storage anddistribution to keep the food both safe and appetizing.

The term "mass catering" is conveniently applied to all thesetechniques of bulk preparation and cooking of food, which areperformed without prior consideration of each individual consumer. Theterm "time -shift catering" is used to describe systems that embody aninterval of more than two hours, and often several days or weeks,between cooking the food and serving and eating it. The differentsituations in which mass catering is employed have similar basicrequirements. They may also have their own specific problems, whichwill be considered in the appropriate chapters.

Bibliography

King, S. Eating behaviour and attitudes to food, nutrition and health.London, British Nutrition Foundation, 1981.

Economic Commission for Europe & Food and AgricultureOrganization of the United Nations. Proceedings, Symposium onTechnical and Economic Aspects of Catering, Budapest, 20 -23 April1982. Budapest, Hungarian Central Technical Library andDocumentation Centre (in press).

2

1

General problems

Contamination

In mass catering, as in all catering, the most important problem is thatof ensuring that the food does not injure the health of the consumer.Food becomes harmful because of the presence of undesirable chemicalor biological agents. Some harmful biological agents are disease -causingbacteria such as the food poisoning salmonellae or the dysenteryorganisms, parasites such as the tapeworms or Giardia spp., or virusessuch as those causing infective jaundice. Other biological agents aretoxins produced in food by bacteria such as Staphylococcus aureus andClostridium botulinum, or occurring naturally in the living animal orplant such as algal poison in shellfish or the toxins in some fungi.Chemical poisons may enter plants and grazing animals from theenvironment; they may be present naturally, as lead in some soil, or maybe caused by industrial pollution. Contamination of food or animalswith synthetic chemical substances may follow accidental environmentalpollution or their deliberate use as insecticides or growth -promotingantibiotics. If these are used without proper control, undesirable levelsof residues will be found in the food. Contamination can also occur iffood is stored where it comes into contact with poisonous substances, orif poisonous metals dissolve from the surface of food containers orequipment. There are frequent reports from all over the world ofoutbreaks of acute poisoning due to the storage of acid foods, such ascooked fruit, in copper containers or lead -glazed vessels, from whichsome of the metal has dissolved into the food.

A serious outbreak of liver disease occurred some years ago inEngland, following the consumption of bread made from flour that hadaccidentally become contaminated with fungicide carried in the samelorry. The deliberate adulteration of food with cheaper substances canbe a hazard to health if the adulterants are harmful. Sometimes, ashappened in Spain in 1981, even the perpetrators of the fraud may notbe aware that the adulterants contain highly poisonous substances.

Properly produced raw food ingredients should be free of undesirablelevels of chemical additives and contaminants. Harmful microorganismsare constantly present in the environment or in food animals themselves,

3

4

Nyu1s1.:aL°:?

w,."c"

17*

_-_---.

THIS KITCHEN 4)AS NOT DUET FOR MASS CA ÎERINCI

and it must be assumed that they will be present in all raw food. This istrue even when the food comes from the most modern and apparentlyhygienic farms or slaughterhouses. At this stage it is rare formicroorganisms to be present in sufficient numbers to cause illness. Thefew that will cause illness even in small doses, for example the typhoidbacillus or the hepatitis virus, are inactivated by cooking and often byother processes used in food preparation such as pickling and curing.There are some microorganisms, however, that will survive normalcooking, such as the spores of C. botulinum and C. perfringens, but thesedo not cause illness unless they can grow in the food. Food can becontaminated with harmful organisms after cooking, sometimes from aninfected food handler, but much more often directly or indirectly fromraw food. This is usually only a question of small numbers of organisms,and the food remains safe if it is held at temperatures at which thecontaminating organisms are unable to increase and reach an infectivedose or produce toxins in the food. To prevent the activity of dangerousmicroorganisms, food should be kept at a temperature above 60 °C orbelow 10 °C. If the food is to be kept cold for more than 6 hours itshould be below 5 °C. Fish should ideally be kept below 3 °C since thetype of C. botulinum found on fish, type E, will grow slowly attemperatures over about 3.5 °C. At these low temperatures and undernormal conditions, psychrophilic spoilage organisms grow faster thanC. botulinum and make the fish unpalatable before it becomesdangerous. If the fish is partially cooked or cured, however, thesespoilage organisms may be destroyed or unable to grow and will nottherefore give an indication that the food is unsafe to eat.

The scale of mass catering means that workers, food handlingpractices, equipment and premises must reach the highest standard ofhygiene that can reasonably be obtained.

Premises

Many catering premises are not purpose -built and, though satisfactoryfor small -scale catering, cannot be adequately adapted to the larger scaleand different techniques of mass catering. However prestigious or longestablished an hotel or restaurant may be, mass catering should not beundertaken there unless there is certainty that it can be donesatisfactorily. Mass catering cannot be performed safely merely byincreasing the size or quantity of the type of equipment traditionallyused in conventional kitchens for the preparation of individual dishes.Only properly designed equipment is satisfactory for bulk cooking. It isnot adequate to have domestic types of cooker on which large pans haveto be balanced across several burners or heating elements; instead,cookers with solid continuous tops should be provided. Rather thanlocally modified large saucepans and frying pans, there should be heavy -duty commercial steamers, pressure cookers and bratt pans. Forced -airconvection ovens are usually essential for the proper cooking of largepoultry carcasses and joints of meat. Equipment for the accurate

5

INDu5TRIRLPOLLUTION

GROWTHPROMOTER$

CONTAMINATEDF001JSTWFF$

F 9 Ea Iiff$ He,

hppi

V PESTICIDES

NICHT Soll_

INCORRECT STORHgE

INADEfeUATECOOK INCi

Z.CRa,S CONTgMINgT1oN

60'G.

I O. C

o°c.

THERE ARE MANY SOURCES OF CONTAMINATIONOUT THEY ALL HAVE THE SAME EFFECT

6

monitoring of the time and temperature of cooking helps to ensurethorough cooking while minimizing the loss of nutrients and theexpenditure of energy. All equipment must be designed to be cleanedthoroughly and frequently. There must be appropriate and sufficientstorage facilities for raw ingredients and for cooked food, refrigerated ifnecessary. When new premises are planned for a mass cateringoperation, the site should be carefully chosen. It should lend itself to thehygienic layout and construction of the premises and should have easyaccess for supplies and employees. Appropriate sanitary services shouldbe readily available.

Economic and cultural factors may influence the choice of site, forexample a remote area of great natural beauty that is attractive totourists, a traditional centre of mass recreation or entertainment, or anindustrial area where there are rail, road and power facilities and a largenumber of factory workers close at hand to provide an immediatemarket for the catering services. Industrial areas may, however, presentproblems of contamination from fumes and smoke, while remote ruralareas, particularly in some developing countries, may lack an adequatesanitary infrastructure for a large -scale food manufacturing operation.

Supply of raw ingredients

There should be an adequate supply of raw materials of satisfactoryquality; this can impose a serious strain on the local food supplies. Thepressure to increase food production may lead to the use of undesirableamounts of natural or synthetic fertilizers and manures, and ofpesticides and growth -promoting substances. These can all causeincreased chemical or microbial contamination of food. While raw foodcontaining infectious microorganisms can usually be made safe bythorough cooking, there is very little that can be done with food that iscontaminated with undesirable chemical substances or that containsresidues of such substances as pesticides or antibiotics. This can only beavoided by proper control and by the intelligent and informed use ofsuch substances. To achieve this the national government must establishan appropriate organization for the control of these substances and mustprovide proper advice and instruction for farmers and agriculturalworkers.

The manager of a mass catering establishment must be prepared toexercise some form of quality control over the raw materials that hebuys. If necessary he may have to lay down commercial specificationsfor his suppliers and develop some laboratory or other means ofchecking that these specifications are met. This becomes even moreimportant if he is buying -in partially prepared ingredients that have notbeen processed under his direct control. He may have to buy suchingredients routinely or he may buy them only as a temporary expedientto meet unexpected demand.

7

Hygienic practices

In many countries the supply of suitably skilled workers is insufficient,leading to the use of a high proportion of unskilled workers who needcareful training and skilled supervision. Many mass catering systems userelatively advanced technology and require standards of hygiene thatmay be unfamiliar to the traditional food workers in some countries.The manager must at all times ensure that all workers understand andmaintain the general principles of food hygiene, cleanliness, adequatecooking, avoidance of contamination, and proper conditions for thestorage of raw and prepared food.

These problems apply to any industrial food manufacturingoperation, but large -scale catering operations are particularly hazardousbecause of the nature of the food produced and the way it must bestored and handled for rapid service. Most of the food prepared by masscatering establishments readily permits the growth of microorganisms ifheld in the temperature range that those organisms require. Between1970 and 1979 in England and Wales, of 1044 carefully analysedoutbreaks of food poisoning 67 % were caused by food produced on alarge scale; in more than 60 % of the outbreaks the food was preparedat least half a day before consumption and underwent inadequatetemperature control.

Mass catering establishments provide not only food that is generallyperishable but also food that is eaten at the same time by a largenumber of people. The consumers have little or no choice in, or controlover, the preparation or serving of this food.

The consumers may often be physically very vulnerable, for examplechildren, the elderly or hospital patients. Other consumer groups may beeconomically sensitive, such as workers in an essential industry. A largeoutbreak of food poisoning in a factory canteen can temporarily, butcompletely, shut down a factory that may be vital to the economy of theregion or even the country. In addition to the immediate loss ofproduction, the delay in delivery dates may cause loss of contracts or ofwhole markets, which it may take a long time to regain. Travellers andholiday- makers are another economically important group: an outbreakof food poisoning on an aeroplane or in a tourist hotel can easily givethat airline or tourist area a bad reputation. This may seriously damageits use by tourists and other travellers who are very important as asource of foreign currency for many countries. Furthermore, it may benecessary to pay large sums in compensation to holiday- makers whohave had their holidays ruined, or to businessmen who have lostcontracts because of illness.

Convenience in the supply of raw material or in preparation andhandling makes certain types of food popular for use in mass catering.These foods may, however, present particular hazards. Frozen meatsand poultry are convenient to store and supply in large quantities butthey can be difficult to thaw satisfactorily and to cook properly. Theintensive rearing of food animals may be necessary to produce sufficient

8

quantities of meat of a consistent size and quality for large -scale foodpreparation. It does, however, seem to increase the risk that the foodanimals, particularly poultry, will carry food poisoning microorganisms.Boned rolled joints of meat are convenient for cooking and carving intoidentical portions, but the operation of removing the bone and rollingthe meat will transfer microbes from the surface to the centre of thejoint, where they are better protected from the heat of cooking.

Cooked meat and poultry are sliced more easily when they arepartially cooled. If this delays complete cooling, pathogenic organismsmay grow and survive to cause food poisoning, especially if the food isnot then adequately reheated before serving. Indeed, when food isintended to be reheated, it may not be completely cooked in the firstplace, so as to avoid over -cooking when reheated. To prevent thegrowth of surviving microorganisms, it is essential to cool the foodquickly and to store it at a safe temperature. Very large joints of meatare extremely difficult to cook or cool satisfactorily.

When hot meals are prepared for immediate consumption by heatingcanned food or commercially produced ready -to -serve frozen foods, it isunusual for health problems to arise. On the other hand cold foods,especially elaborate cold buffets, require the greatest care if safety is tobe ensured.

Some aspects of mass catering demand that very large quantities offood are served in a very short time, such as for a banquet or in thelunch break at factory canteens. To give an even workload, and as far aspossible to avoid antisocial hours of work, it is common to spread thepreparation of such food over the whole of the working day or overseveral days by employing time -shift systems. Time -shift cateringtechniques are bound to increase greatly the delay between cooking andeating. This makes it essential to cool the food rapidly and to store itsafely at chill temperatures (0 -3 °C) or deep frozen ( -18 °C or below)and to reheat it rapidly and thoroughly before consumption. For this tobe done safely, properly designed and equipped "cook- chill" or "cook -freeze" systems must be used (see Chapter 3). This requires that theappropriate technology is made available and correctly employed byworkers who are well trained and who fully understand what they aredoing and the hazards involved. If it is not possible to provide suitablytrained workers who can use, monitor and maintain technologicallyadvanced catering equipment properly, then it is safer not to dabble inhighly sophisticated catering systems. Instead, simpler systems should bedevised which do not require such technology and which are within thecapabilities of the available workforce.

Since chilling and freezing have different effects on the quality ofdifferent foods, it is often convenient to use a mixture of frozen, chilledand fresh foods, even for just one meal. The catering system will thenhave to be designed or adapted to cope with the range of techniquesrequired. This may make the work more interesting for the kitchen staff,but it also requires them to have a thorough understanding of thetechniques involved.

9

Other recently developed items of cooking equipment, such as slowcookers and microwave ovens, can present problems if not properlyused. The vacuum packing and inert gas packing of prepared foods willreduce the growth of spoilage organisms but may not affect the growthof pathogens. These methods are all discussed more fully in Chapter 3.

Not only do the kitchen staff need to be properly trained, but so alsodo the staff who finally serve the food. The food may be reheated,dished up, portioned, served and consumed at a point very remote inboth space and time from the point of production. The manager of thecentral kitchen may not be able to exercise any form of direct controlover the staff at remote serving areas. It is therefore necessary that thefood be prepared and distributed in such a way that it can be servedwith the minimum of interference by the servers, thus reducing to aminimum the amount of training and supervision that they need and theharm that they can do by mishandling the food. Alternatively, thegovernment health authority, or the commercial or public institutionresponsible for the site or premises where the food is to be served, musttake suitable steps to ensure that the serving staff are properly trained,equipped and supervised.

The temperature control of food is just as important duringdistribution as during storage. Refrigerated vehicles or containers maybe necessary if it is to be carried any distance. The experience in Swedenis that during a journey of not more than 11 hours, the temperature ofchilled food in unrefrigerated containers does not rise by more than 2 °C.Sweden is a country with a generally cool climate; the temperature riseof unrefrigerated food will be much greater in hot countries. In anycountry, if food is not to be eaten within an hour or two of reaching adistant serving point, facilities for refrigerated storage must be providedat that point. All refrigerated vehicles, stores, cabinets, etc. should befitted with direct -reading thermometers, and preferably also withrecording thermometers. These usually measure only the air temperaturein the container or chamber, so supervisory staff and other workersresponsible for storing or receiving chilled or frozen food should beequipped with hand thermometers to check the temperature of the fooditself. Direct -reading electronic thermometers are by far the mostsuitable for this purpose. Even these must be properly maintained andregularly checked. Staff need to be trained in their use and encouragedto use them on all occasions.

Workforce

Workers in the food industry tend to come from the lowersocioeconomic levels. Because of limited education they may havecommunication problems, read poorly or not at all, and find it difficultto grasp the more advanced technological concepts. Formal training isoften not available in the traditional food industry, and even whentraining is given these people often do not find it easy to take advantageof it, which means that they are unlikely to rise above menial

10

occupations. This reduces job satisfaction and these workers tend tochange their employment frequently, throwing an even greater load onthe training facilities. Even without a rapid turnover in employees it ishard to explain the relationship between cleanliness and health to newworkers from an inadequate socioeconomic and educational back-ground.

These problems may be even greater in developing countries, whereunderstanding of and expectations for health, general sanitation andfood hygiene and safety are likely to be low even in the better educatedsections of the population. In an investigation carried out in an easternMediterranean country faecal organisms, including a wide selection ofintestinal pathogens, were found on the hands of over half the peopleexamined, most of whom were from the professional classes. Similarinvestigations in north -western Europe have not given such results andhave demonstrated that faecal organisms can be removed from the skinby thorough washing with soap and warm water. The disturbing findingsin the eastern Mediterranean country suggest that toilet practices andhygiene are unsatisfactory throughout the population, possibly forcultural or religious reasons that are common to all classes.

Nutrition

Mass catering provides a means of ensuring a minimum nutritionalintake for several sections of the population, especially children,although this depends on how much of the meal provided is actuallyeaten. In Finland it was found that only about one quarter of thenutritionally important foods provided in school meals were actuallyconsumed whereas it had previously been thought that these meals wereproviding one third of the childrens' total nutritional requirements. Arecent study in a Swedish general hospital showed that 7 % of patientsdid not eat the meat served at lunch and 1 % did not eat the meat servedat dinner, while 15 % did not eat the vegetables served at either meal.Failure to eat all the food provided is obviously more important incountries where nutrition is barely adequate. The introduction of masscatering may cause serious problems to a population with little or noprevious experience of mass -produced food, since it may createsignificant alterations in traditional dietary habits.

Epidemiological and nutritional studies may show that it is desirableto make changes in traditional diets, such as by reducing the fat content.Even with modern technology, however, it may be difficult to reproducethe flavour and texture that makes fried food so popular. It must also beremembered that dietary requirements may vary with climate as well aswith age, occupation and so on. Some methods of cooking and storing,including traditional methods, may affect the nutritional content offood; there may for instance be significant losses of vitamin C.Whenever new catering systems are introduced, samples of food shouldbe tested for their nutrient content, particularly those likely to be

11

EVEN (3ASIC HVÇIENE LAU- MAKE ALL 'THE DIFFERENCE

12

affected by the processes, and other sources of the nutrient should beadded to the diet if necessary.

While much of the economic advantage of mass catering is to befound in the repeated large -scale buying of a limited range of foods, andin bulk cooking, some flexibility is necessary to allow the provision of asmall number of individual meals for those who require special diets formedical or other reasons. This is especially important when catering forgroups that cannot easily obtain meals elsewhere, such as children inboarding schools and hospital patients. There is one overriding rule inmass catering: if you cannot ensure the safety of the system that youhave chosen, and monitor all its aspects, either do not do it at all orchoose a system that is within your capabilities. Time -shift catering, inparticular, requires sophisticated technology, intensive monitoring andconsiderable capital outlay. If these are not all available then simplersystems, with little delay between food preparation and service, will besafer and more satisfactory, though much more labour intensive.

Bibliography

Longree, K. Quantity food sanitation. New York, Wiley Interscience,1980.

Hobbs, B. C. & Gilbert, R. J. Food poisoning and food hygiene, 4th ed.London, Edward Arnold, 1978.

Treneva, M. & Demireva, M. [Mass catering, outlook, management andefficiency]. Sofia, Tehnika State Publishing House, 1981.

Bachman, M. R. Technology appropriate to food preservation indeveloping countries. In: Thorne, S., ed. Developments in foodpreservation. Barking, Applied Science Publishers, 1981, Vol. 1, pp.1 -37.

Blaxter, K. & Fowden, L. Food, nutrition and climate. Barking, AppliedScience Publishers, 1982.

Management of group feeding programmes. Rome, FAO, 1982 (Food andNutrition Paper, No. 23).

13

WASTE4Z SRFELy

5TO2EDFoy.(715PCIFlL

lr=

DISPOSROIETouELS

VESETR'.ESINK

tJR51f-NANDDRSIN

WRSN-NANDER 5114

LJRSTE Ou `GLAST CHI LIER

RAW MEATRND PouLTRyPREPARRTION GNIIL

STORE

SuvPUES IN

VE4ETROlbi LAILLED' .DRY STOREW,,--(

42V4-,

FR02EN / \FooD

MOTOR 0E113

CONDENSER COILS

:110,,ä, t,+

PRSTRY PREPARATION

CDNTAtn1ER STORE

ü - 1JgSH -HAND

DAS W

TOILETI.JNSN'HAND 60.S1,1

Cav'R FoCDOUT

GNANGINC.

Roots

» - ..a+a_ - .- iih3! OM r .V:itiiliih\M1<C:.ii"SCS ^IlGti3l1CYN

ONE POS5113LE LAYOUT FOR MASS GATERINC, PREMISES

2

General methods

of control

Planning and licensingIt is an advantage if some form of licensing can be applied to premisesengaged in mass catering to ensure at least a basic standard ofequipment, construction and layout. It is usually not possible toestablish more than very general rules about the legal standards thatmust be achieved before a licence is granted. The detailed requirementsfor buildings, equipment, etc. will have to vary widely according tothe type of food expected to be produced, the size and nature of thepopulation to be served, the local building materials available, therestrictions imposed by the site, and the availability of power, sanitaryfacilities and raw materials. The licensing inspector must consider firstand foremost the implications for the health of the consumer, theworker and people living near the intended premises.

Where licences for the setting up of mass catering premises are issuedby a central government department, all such licences should also beapproved by the ministry responsible for health. It may be useful forcentral government health departments to send special teams of expertsto assist in setting up mass catering projects and to reinforce the localhealth authorities in dealing with special problems, such as majoroutbreaks of food poisoning. Central assistance may also be needed atspecial times, such as at the start of the tourist season when all masscatering premises in tourist areas may need to be inspected.

When considering the introduction of highly sophisticated technologyto a new or existing mass catering industry, attention should be paid tocost - benefit and practicability. An assessment should be made of thelocal availability of suitably skilled labour. Is it worth the cost oftraining local people from scratch? Are spare parts easily obtained orwill they have to be bought from abroad, using up foreign exchange andcausing delays? Will the benefits of the system outweigh the cost ofproviding sufficient power, water and waste disposal facilities? Often asimpler scheme may be quite adequate to provide all the meals that areneeded and will give more local employment, especially to peoplelacking advanced technical skills.

15

Countries or organizations without previous experience of masscatering would be well advised to seek the advice of experts in this field,when drawing up or approving plans for the design, construction andequipment of individual premises. Help can be obtained through theWorld Health Organization (WHO), through governments of countrieswith experience of mass catering, or from commercial enterprisesmanufacturing or selling mass catering equipment. Whenever possible,inexperienced managers and inspectors should visit mass cateringestablishments of the type they wish to install, in order to familiarizethemselves with the technology involved and with its problems andspecial requirements.

When choosing sites for mass catering premises care should be takenthat they are well away from pens and lairages for live animals, rubbishtips, etc. which can encourage vermin and may be sources of pathogenicmicroorganisms. The premises should be protected from flooding andfrom seepage of possibly contaminated water in low -lying marshy sites.If mass catering premises are to be set up in industrial areas, thoughtshould be given to protecting them from industrial pollution.

Management and inspectionAny form of mass catering should use modern managerial techniquessuch as systems analysis, the evaluation of procedures and the auditingof results. This should be done as much for hygiene and safety reasonsas for the sake of production and profits. It is essential at all stages thatmanagers understand the health aspects of the processes for which theyare responsible.

There should be a free exchange of information between thoseresponsible for production and those responsible for safety. Ideally, eachestablishment should have a hygiene and quality control officer withstatus equal to that of the production manager. The official healthcontrol agency then has the responsibility only of ensuring that theestablishment's own quality control is satisfactory, and of giving adviceif necessary. The day -to -day running of the establishment can be left toits own quality control and production managers. This may not bepossible when mass catering systems are first introduced to somedeveloping countries where there is no experience of managing suchsystems. In such cases the official agency must exercise more continuousand detailed health control. Health agencies nonetheless should notbecome involved in supply and production problems unrelated to health,though other government agencies may need to do so. Health controlneeds to rest ultimately with an agency that has no responsibility fortrade or economic matters. Such control should be exerted as far aspossible by advice and education, but there must also be legal powers toensure safety if premises or procedures are so unsatisfactory that there isa danger to health. Legislation may need to be stricter and moredetailed when mass catering is being introduced to a population that hasno previous experience of such techniques.

16

It may provide an incentive to good hygiene if a certificate ofsatisfactory hygiene is provided for establishments that have passedregular inspection. This certificate could be displayed for customers tosee.

It may also be of value to have a legal requirement that managersmust be able to produce evidence of a basic knowledge of hygiene andfood technology, such as by having attended an approved course orhaving passed a recognized examination. Both official inspectors andcommercial managers should be kept informed of new food technologyand newly recognized hazards. This may need an exchange ofinformation and experience among countries as well as among differentcommercial enterprises. This may conflict with commercial and possiblywith national interests and it is therefore best effected throughinternational meetings, expert advisers, publications and other activitiesof non -commercial and non -political international bodies such as WHO,the Food and Agriculture Organization of the United Nations (FAO),and the Codex Alimentarius Commission.

General hygiene

Some foods should be handled only where adequate technology exists toensure that they can be processed safely. The mass production ofelaborate made -up meat dishes requires careful temperature control incooking, cooling, storage and distribution, and should not be attemptedif the facilities for all this are not available. Provided limitations of thisnature are properly appreciated, sensible organization, intelligentmanagement and adequate process control and monitoring canaccomplish a great deal, even in the absence of highly sophisticatedequipment. The aim should be to achieve a steady flow of work, makingfull use of the equipment available, but without overloading or creatinghold -ups at any point.

All equipment and utensils must be easy to clean, without anydamaged areas, crevices, cracks or small apertures that cannot beproperly cleaned. Otherwise food, debris and dirt will accumulate andmicroorganisms, including pathogens, will grow if they are introducedfrom raw food, from the environment or on workers' hands or clothing.It is equally important that walls, floors, ceilings and other structuresare clean, free from cracks and in good repair. Drains should be keptclean and clear of rubbish, and covered with grills to keep out vermin.For the same reason windows and doors should be screened.

When a large bulk of food is cooked, cooled or stored, it isimportant to be able to measure the temperature at its centre; it shouldnot be assumed that this is the same as the temperature of the air in theoven or in the chiller or refrigerator.

Raw and cooked food should be stored and handled completelyseparately to prevent any direct or indirect transfer of microorganismsfrom the raw to the cooked food. Wooden working surfaces, chopping

17

blocks, knife handles, etc. can never be cleaned satisfactorily and shouldbe replaced by steel or synthetic materials.

When food is cooked rapidly and served immediately after cooking,it is often possible to get away with a less than adequate standard ofhygiene because there is no time for pathogens to grow in the food.Sooner or later, however, this is likely to lead to disaster, especially if onoccasions there are delays before the food is eaten. Therefore, badhygiene should never be allowed to persist in any catering establishment,and only the highest standards can be permitted when time -shift cateringis being performed.

Staff should be employed at work consistent with their level oftraining; they should understand what they need to do and why. Ifemployees do not understand the reasons for their instructions they willnot be motivated to follow them strictly, and hygiene is likely to suffer.At all times it is essential that managers set a good example byobserving the same hygienic rules as the employees, especiallyconcerning washing hands, wearing protective clothing, and refrainingfrom eating and smoking in areas where food is handled. This applieswith equal force to official inspectors, and to distinguished visitors tofood premises.

The use of temporary employees should be avoided as far aspossible. They certainly should not be used in highly vulnerable areas ofwork such as the handling and chilling of cooked food. It is common toemploy such casual, frequently unskilled, and lowly paid workers forwashing the equipment and utensils. If they must be used for thispurpose, intensive supervision is necessary. Washing up must be donethoroughly and correctly to ensure that all items are free fromcontamination. A properly controlled disinfecting rinse with chemicaldisinfectant or hot (at least 80 °C) water is always essential at the finalstage of cleaning, and care should be taken that subsequentcontamination is avoided. Automatic mechanical dish and equipmentwashers are often more reliable than manual washing up, but have highcapital and running costs. The running costs can be somewhat reducedby installing heat recovery systems.

Raw material

It is important to ensure that there are sufficient supplies of goodquality raw material. There should be adequate space to store it undergood conditions, properly protected from pests and the environment. Asfar as possible, raw materials should be supplied frequently andregularly, and excessive quantities should not be stored. There shouldnonetheless be sufficient reserves to meet any unexpected increase indemand, rather than having to make ad hoc purchases from local small -scale producers of materials of uncertain quality. Commercial specifi-cations must be devised as part of the contracts with suppliers. Toincrease the value of these specifications in ensuring and controlling thequality of raw material, it is desirable to have long -term contracts with

18

reliable suppliers who have been shown to have adequate and consistentquality control.

Laboratory tests

Each mass catering establishment should have access to facilities for thechemical and microbiological analysis of raw materials, finished productsand in- process samples. Care must be taken that pathogenic microorgan-isms isolated in the laboratory of a food establishment are notinadvertently carried back to the food -handling areas. If the establish-ment does not have its own laboratory, use can often be made of areliable commercial or government laboratory. However much testing isdone by the establishment's own quality and hygiene control staff(autocontrol), the official health control agency will wish to check thisfrom time to time by sending samples to an official laboratory. Thebacteriological methods used in clinical bacteriology are not necessarilythe same as those required for the examination of food. Theconventional medical or veterinary microbiologist may need furthertraining in food microbiology. A number of WHO- approved courses areavailable, at the Institut Pasteur in Lille, at the University of Surrey, atZeist in the Netherlands, and through the FAO /WHO CollaboratingCentre for Training and Research in Food Hygiene and Zoonoses,Berlin (West).

Even if a mass catering establishment does not possess its ownlaboratory, quality control productionbe able to perform a few simple chemical and microbiological screeningtests for general hygiene, compositional quality, and the presence ofcommon contaminants.

When considering any test it is necessary to look at its weaknesses aswell as its advantages. All tests have their inherent errors and lack ofsensitivity, microbiological more so than chemical tests. The agent thatthe test is intended to detect may not be distributed evenly through theconsignment being sampled; again, this is more likely to occur withmicrobial than chemical contamination. It is often not economicallyfeasible to take and test sufficient samples to get a result sufficientlyrepresentative of the entire batch. Indeed, particularly with some formsof microbial contamination, one could test and find satisfactory all butone item out of a batch of several million and still not be absolutelycertain that the last item was not contaminated. Testing therefore cannottake the place of proper supervision of the hygiene of all aspects ofpreparation, storage and distribution. Laboratory testing is a useful aidin providing further checks on that process control, but on its own itcan never ensure safety.

Laboratory resources and trained staff are expensive and in shortsupply in all countries especially, of course, in the developing countries.Laboratory tests should therefore be used only when they will beeffective and where no other less expensive method of control can beused.

19

Ingredients should be of reasonable microbiological quality, but theyneed not necessarily be free from pathogens if they are to be cooked ortreated in such a way as to kill microorganisms or render them non -infective. Simple bacteriological tests, such as total mesophilic colonycounts and coliform counts, may be of value in giving a generalindication of the cleanliness and freshness of raw ingredients. Often,however, these counts do not correlate well with the presence orabsence of pathogens and it is not wise to use them as absoluteindicators of the microbiological safety of raw foods. Furthermore,much if not all of the food is likely to have been processed andconsumed before the results of the test are known. Such tests can beused to provide a retrospective assessment of the level and consistencyof the quality of the raw material provided by different producers, thusassisting the catering manager to check that his quality and hygienestandards have been met by the supplier. As he gains experience this willenable him to buy only from suppliers who can maintain adequatestandards. Chemical testing can be done rather more quickly; again, it isprobably not practicable to test all consignments. It is far moreimportant that some form of assurance be obtained that the rawmaterials have not been exposed to undesirable contaminants, or thatpesticides or growth promoters have not been used in excessivequantities or used within a certain period before slaughter or harvesting.Producers or official agencies may be able to provide certificates to thiseffect, or official certificates may be given after appropriate testing. Theresults of even these official tests may be affected by sampling errors orlaboratory variations. If official tests are not performed the cateringmanager may well wish to do occasional spot checks for additives andcontaminants that are a local problem, in order to verify the reliabilityof his suppliers.

Routine microbiological testing of the end -product is probably nevercost -effective. Nonetheless, samples may be taken for testing fromcritical points in the production process. Simple tests such as totalcounts and coliform counts are generally most useful for this purpose.They are inexpensive and can be repeated frequently, and the results areavailable relatively quickly. The catering manager will probably need toestablish his own normal limits based on intensive testing. This testingshould be carried out when any mass catering establishment first goesinto operation, and different numerical limits may be needed fordifferent types of food. If there is any significant change in equipment ortechniques of production or in types of food, then these tests will needto be repeated. Once the norms are established, any deviation from themshould be used as an indication that something has gone wrong andshould lead to intensive investigation as to the cause. It may notnecessarily indicate that the food is unsafe, but it must lead to furtherchecking. In addition to testing the food at appropriate points along theproduction line, it may also be necessary to swab working surfaces andequipment to detect any build -up of organisms. The efficacy of cleaningand disinfecting procedures should also be checked in this way. It needs

20

to be remembered that normal values for food are significant only forthe point in the production line where they have been established. It isextremely unwise to assume that a normal value derived from tests onfood sampled immediately after cooking and just before chill or frozenstorage, will be equally applicable to the food at the end of the storageperiod, during distribution or after reheating.

Convenient and repeated microbiological testing can be done withdip slides. These are plastic slides covered with a choice of general orselective growth media. They can be dipped into fluid or pressed againstsolids. They were originally devised for testing urine, but it has beenshown that they can be applied to the sampling of a wide range ofliquids or solid surfaces. After inoculation the slide is replaced in itssterile container and incubated for a specified time. Visible colonies arethen counted. These slides are made by a commercial mediummanufacturer and, though relatively expensive, can be used by peoplewith little training in microbiology. The catering staff can easily beshown how to use them to establish normal limits for different parts ofthe kitchen or serving areas. They can then identify points where abuild -up of organisms may occur, recognize when such a build -up isoccurring, and assess the relative effectiveness of different cleaning anddisinfecting regimes. This test is also extremely useful in demonstratingto staff that microbiological problems exist, how they occur and howthey can be avoided.

When an establishment or process first goes into operation, it may beof value to look for pathogens relevant to the raw material or to theprocedure. For example, it may be useful to look for the survival ofsalmonellae in cooked food of animal origin, or for Staphylococcusaureus or Clostridium perfringens in food that is extensively manipulated,in order to assist in determining that the procedures used will producesafe food. This needs to be done as a pilot investigation before theestablishment goes into full commercial operation. Under normalcommercial conditions the food will have been distributed and eatenbefore the results are obtained.

Chemical testing of the end -product for undesirable additives andcontaminants is probably unnecessary if there is adequate control of theraw materials or assurance that the raw materials are free from chemicalcontamination, and if there is no reason to suspect that undesirableadditives or contaminants have entered the food during processing. It isimportant to be sure that not only the main raw materials but alsospices, salts, and processing adjuvants are all of a chemical puritysatisfactory for human consumption. The level of purity normallyrequired for some industrial chemicals, sodium chloride for example,may not be adequate for their use in foods.

HACCPA procedure that is being extensively adopted in the United States ofAmerica involves the concept of a "hazard analysis critical control

21

point" (HACCP). A food or group of foods is identified as hazardouson the basis of the technical details of the process or subsequenthandling, or evidence of illness or spoilage. A detailed and systematicinvestigation of the entire procedure of production, distribution and useof the food is then carried out. The results of this investigation areanalysed to identify how and where these hazards arise, at which pointscontrols should be established, and what control and monitoringprocedures should be applied at these points. These pro-cedures may consist of the microbiological testing of samples of the foodtaken at each critical point, or other tests that may be more appropriate,such as time and temperature monitoring or pH measurement. None ofthis is particularly new, but what is important is the greatly increasedemphasis on systematic analysis of the hazard and on identifying thecritical points, and the concentration of resources on the mostappropriate means of control at those points. At some critical points, ofcourse, complete control by objective test may not be possible. Then, thedetection and prevention of cross contamination may rely more on thesupervision and proper training of workers than on a microbiologicaltest.

Use of this method seems likely to be considerably more cost -effective than intensive end -product testing, which it will largely orentirely replace. Essential concomitants of the HACCP procedure arethe retention of all process records and results of monitoring, a meansof identifying all batches of the food, and a system for preventing theuse or distribution of hazardous food. While this procedure wasdeveloped to deal with microbial contamination, a similar approach canbe devised for chemical contamination.

Water

It is imperative that the mains water supply be of the highest standardfor drinking water recommended by the World Health Organization.°All water entering the premises for use in food preparation, includingthe washing of utensils and equipment, must be of this standard, that isthat no coliforms should be detectable in 100 ml. If supplies of water oflower quality enter the premises, for fire -fighting or cooling for example,care must be taken that there is no connection with the drinking watersupply. Non -drinking water must not even be used for washing thefloors in food handling areas. If there is any leak from the non -drinkingwater system that might contaminate food such food must be rejected,or at least washed to remove any chemical contamination and given abactericidal cook. The official agency responsible for health must beconsulted before attempting to salvage any such food. If the quality ofthe water is likely to deteriorate after entering the premises, by storagein a tank for example, samples taken at a number of outlets should be

a International standards for drinking water, 3rd ed. Geneva, WHO, 1971.

22

regularly tested. Coliform tests should be performed at least monthly.The water should at all times meet the criteria of the WHO drinkingwater guidelines, and if it is to come into contact with food that will notreceive a thorough cook before consumption, no coliforms should bedetectable in any 100 -ml sample. A weekly total colony count shouldalso be performed after three days' incubation at 22 °C. From the resultsof repeated tests, a normal value for the total colony count should befound for each catering establishment; any deviation from this should beintensively investigated to discover the cause and its significance forhealth. As a general rule, the limits should be below 100 colonies in1 ml. This testing may be done by the official health agency or by theestablishment's own quality control laboratory, but it is the responsi-bility of the official agency to satisfy itself of the reliability of theestablishment's own control, by checking results and sending samples toan official laboratory as necessary. Before the catering establishmentgoes into operation, sufficient samples of water should have beenanalysed to show that the water in the mains supply and the distributionsystem is consistently of a satisfactory quality. If there are any doubtsabout the water reaching the premises or distributed in the premises, itshould be treated appropriately. Microbial contamination is the mostlikely hazard, and if there is any fear of this the water should bechlorinated or otherwise disinfected on the premises. If chlorine gas orhypochlorite is used, sufficient should be added to give a residual freechlorine concentration of at least 0.2 mg /litre in water entering thedistribution system. This should be measured at least twice a day.Disinfection of the water does not remove the need for regularmicrobiological testing.

Personal hygiene

The routine clinical and microbiological examination of food handlers isnot recommended as a means of preventing the contamination of foodwith the organisms that cause food poisoning and other foodbornediseases. It is very expensive in medical and laboratory resources andcan never guarantee that all carriers of intestinal diseases are excludedfrom food handling. Anyway, carriers among food handlers areresponsible for only a very small proportion of outbreaks of foodbornedisease; disease is usually due to contamination from the raw foodingredients or from the environment by way of dust, polluted water,pests, etc. Risks from carriers can be eliminated if proper hygiene isalways observed, especially by thorough washing of the hands aftervisiting the toilet, and if at all times the food is handled and processedin such a way that no pathogenic organisms or their toxins can survivein an active harmful form in the finished food. Whilst routine medicaland laboratory examination of food handlers is not recommended, it isimportant that anyone with an obvious infection of the skin, nose, earor throat, or any gastrointestinal upset, should not be allowed to workwhere he could contaminate food, without the consent of the medical

23

authorities. It is a good idea for the manager or supervisor to inspectthe workers daily for signs of infection of exposed areas of skin. Thisalso affords the opportunity to remind them to report any gastro-intestinal symptoms in themselves or their immediate families. Workerswith diarrhoea should never be allowed to handle open food, even if nopathogens can be isolated from their stools; many organisms, especiallyenteroviruses, cannot be detected on routine culture.

Even if they have already washed their hands in the toilet orchanging room, all people (workers, managers, inspectors, etc.) shouldwash their hands thoroughly with soap and warm water immediately onentering the food handling area. Workers handling raw food shouldwash their hands before touching cooked food or entering an area wherecooked food is handled.

The hand -washing basins must be quite separate from the sinksused for washing food or equipment and utensils. There should be agood supply of suitable soap and warm water, or hot and cold water.Preferably the taps should be of the type that do not have to be touchedby the hand. If towels are used for drying the hands, they should be thekind that are used only once.

Kitchen staff should not be allowed to bring any food into the foodhandling areas, or to smoke, eat or drink there, since this may spreadcontamination from their mouths and noses to the food that is beingprocessed. They should have all their meals in the main canteen or in astaff dining -room quite separate from the kitchen.

Epidemiology

While the actual organisms associated with foodborne disease may differsomewhat from country to country, the basic principles of food hygieneremain the same. It is not necessary for a great deal of time and moneyto be spent on obsessively detailed research into prime causes whenenough is already known (as it usually is) about the immediate cause toenable preventive measures to be taken to reduce the risk of illnesssignificantly, even if not to eradicate it totally. There is no need forevery country that wishes to develop a mass catering industry to huntfor every organism that might be present in the national food supply,and then to perform even more prolonged research to establish if theseorganisms are in fact pathogens. The experience of countries with long -

established food industries and programmes for monitoring the effect offood on the public health indicates clearly that it is best to assume thatall raw food contains pathogenic organisms. It is equally clear that thesecan be killdd, removed or reduced to concentrations that are harmless byappropriate treatment of the food. This includes cooking or washing,with or without a mild disinfectant, then preventing recontamination asfar as possible, especially from raw food, and keeping the food attemperatures that will not permit the growth of pathogens. Thesemeasures are valid for all foods in all countries.

A great deal of information is already available about the effect of

24

processing, storage and reheating on the nutritional qualities of food.With unusual foods or new technology, however, it may be necessary, atthe start of a mass catering operation, to test the foods for theirnutritional value, particularly to see if there are any significant changesin the vitamin content. This is extremely important when mass cateringis intended to make a major contribution to the dietary intake of all orpart of the population.

It is vital to have a feedback of clinical and epidemiologicalinformation about the immediate and long -term effects of mass cateringon the health of the population. In the short term there must be amechanism for reporting episodes of acute illness, in particular foodpoisoning, which might be related to the catering system. These reportsmust be collated and assessed so as to establish rapidly if and how thecatering system is at fault. The early reporting and investigation ofsuspicious incidents is essential. Medical practitioners should beencouraged to make and report provisional diagnoses of food poisoningor foodborne disease, based on clinical, dietary and epidemiologicalevidence, without waiting for laboratory confirmation. The sooner aninvestigation can start the more likely it is to discover the cause as wellas prevent further outbreaks. To aid investigation, mass cateringestablishments should keep samples of all food produced. These shouldbe stored under refrigeration, preferably frozen, and retained for at leastthree days beyond the date by which that batch of food couldreasonably be expected to have been consumed.

When mass catering systems are used to provide a significantproportion of the total diet of large sections of the population for a longtime (schoolchildren, the armed services, or some factory workers, forexample) studies should be made of their long -term nutritional effects.

The collection of statistics of mortality and morbidity associated withfood should not just result in the accumulation of meaningless figures;they should be in a form that can be used to monitor, and wherenecessary suggest improvements to, the catering services. Statistics mayindicate areas where amendment of the food control legislation isneeded. There must be full cooperation and exchange of informationamong all official agencies and ministries concerned with food, health,agriculture, trade and industry. The publication of such statistics enablesuseful and instructive comparisons to be made between countries andbetween different parts of the same country.

International statistics may also be useful, such as those collectedand published by the FAO /WHO collaborating centre in Berlin (West),in the newsletter of the WHO surveillance programme for control offoodborne infections and intoxications in Europe.

Bibliography

Bulgaria, Ministry of Public Health. [Sanitary regulations for masscatering establishments No. 0 -14/2 April 1971]. D'r aven Vestnik

(State Gazette) No. 50 (1971).

25

Bulgaria, Ministry of Internal Trade and Service Industries.[Regulations for the organization of mass catering establishments,Order No. 2216/11 November 1972]. Bulletin of the Ministry of

Internal Trade and Service Industries, No. 3 (1973).A self inspection programme for food service operators in sanitation and

safe food handling. Washington, DC, USA National RestaurantAssociation, 1973.

Boberg, B. J. & David, B. D. HACCP models for quality control ofentree production in food service systems. Journal of food protection,40: 632 -638 (1974).

Food hygiene in catering establishments. Legislation and model regu-lations. Geneva, World Health Organization, 1977 (WHO OffsetPublication, No. 34).

Betriebsverpflegung. [Industrial catering]. Frankfurt, DeutscheGesellschaft für Ernährung, 1978.

Food control laboratories: report on a Conference. Copenhagen, WHORegional Office for Europe, 1978 (document ICP /FSP 003).

Food service equipment standards. Michigan, USA National SanitationFoundation, 1978.

Lawson, F. R. Principles of catering design, 2nd ed. London,Architectural Press, 1979.

Charles, R. H. G. Microbiological standards for foodstuffs. Healthtrends, 11: 1 -4 (1979).

Health examinations of food- handling personnel: report on a WorkingGroup. Copenhagen, WHO Regional Office for Europe, 1980(document ICP /FSP 007).

Frentz, J. C. Grand livre des métiers de bouche. [Manual for the cateringtrade]. Paris, ERTILECERF, 1980.

Johnson, R., ed. Food safety services. Copenhagen, WHO RegionalOffice for Europe, 1981 (Public Health in Europe, No. 14).

Davenport, J. K. Food hygiene in the catering and retail trade. London,H. K. Lewis, 1982.

Codex Alimentarius. Revised general principles of food hygiene. Rome,Food and Agriculture Organization of the United Nations (in press).

Codex Alimentarius. Code of' hygienic practice for the preparation ofpre-cooked meals. Rome, Food and Agriculture Organization of theUnited Nations (in preparation by the Codex Alimentarius FoodHygiene Committee).

26

3

Recent technology

Cook -freeze and cook -chill

Cook -freeze and cook -chill systems can now be safely employed usingmodern equipment, especially for rapid cooling which is probably themost hazardous part of the operation. Both systems have a high capitalcost. The energy costs for cook -chill are lower than those for cook -freeze, but the system is less flexible, having a very limited storage timeand a much smaller margin of safety: fluctuations in storage temperaturehave a far more serious effect on both quality and safety in cook -chillthan in cook -freeze systems. If the kitchen is properly designed andequipped and the equipment is working correctly, however, both systemsare largely independent of ambient temperature. The limited storagetime allowed by chill temperatures makes it important that batches areused in order of production. It is therefore necessary to have methods ofindentifying each batch and all items in each batch. These methods mustbe easily understood by all the food handlers.

Rapid chilling or freezing of large quantities of food requires theproper equipment: blast chillers, blast freezers or cryogenic equipmentdesigned to meet the specific need for temperature reduction. It is notsatisfactory to attempt to cool large quantities of cooked food in arelatively cool corner of the kitchen, in a larder or in a domesticrefrigerator. In such circumstances, cooling is far too slow, so the foodstays for a dangerously long time in the temperature range between 10 °Cand 60 °C, where harmful microorganisms grow rapidly. Placing hotfood in an unventilated refrigerator or cool larder causes condensationwhich encourages the growth of slime- forming spoilage organisms, andreduces the efficiency of a refrigerating system by freezing on the coolingcoils.

A great deal of heat is produced by the motors and condensing coilsnecessary to the operation of the powerful rapid -cooling equipment andlow temperature stores needed for cook -chill and cook - freeze systems.These motors and condensers often attract dust and are difficult toclean. Equipment therefore needs to be placed in carefully designed andconstructed premises, so that the motors are outside the food rooms orare at least in ventilated areas that are well separated from the food

27

handling areas. This equipment must be properly maintained andrepaired, and a continuous supply of power must be assured. Rulesshould be set down as to what should be done if the power or theequipment fails. The staff should know exactly what to do and just whatincrease in temperature can be permitted before the food must bethrown away as unsafe to eat.

Chill storerooms and frozen storerooms are not designed to cool hotfood; they are for keeping already chilled or frozen food at the correcttemperature. If hot food is put into them, not only may they fail to coolit rapidly, but also the hot food may raise the temperature of other foodin the store to a dangerous level. All these storerooms must be fittedwith devices for measuring and preferably also recording the airtemperature. In addition to this the centre temperature of the food mustbe checked frequently, expecially in chill stores where the temperaturesafety margin is very narrow. Reheating must also be fast, so that thefood passes quickly through the hazardous temperature range. This willusually require the use of forced air ovens, or infrared or microwave re-heaters. Since chilling the food does not significantly reduce the numberof microorganisms, repeated short periods at temperatures suitable formicrobial growth will have a cumulative effect on microbial numbers.

Slow cookersSlow cooking ovens and electric pans are becoming widely used. Theybegin to cook at a temperature usually between 80 °C and 100 °C for ashort while and then hold the food at about 60 °C while it continues tocook slowly. They are relatively economical in energy and the food losesless weight or volume from dehydration than in conventional cooking.During the slow cooking phase, however, even the best of these ovensoperate very close to the limits of safety. In some of them thetemperature during the slow cooking phase does actually drop withinthe range at which microbial growth can occur. Before such ovens areput into use in commercial catering premises they should be thoroughlytested, both microbiologically and by continuous measurement of centretemperatures under actual conditions of normal use. When in use, themanufacturers' instructions should be followed, centre temperaturesshould be checked frequently, and the ovens should be kept in a goodstate of repair. They should not be overloaded and food should not beleft in them when the slow cooking phase is completed. Certain foods,such as many raw beans, contain natural toxins which are destroyed byboiling. Slow cookers do not reach a high enough temperature todestroy these toxins, so if these beans are to be cooked in a slow cookerthey should be boiled for about 10 minutes first.

Microwave cookingMicrowave cookers can be used for the initial cooking of food or forreheating but they have some drawbacks. They heat food from the

28

centre outwards, and may not give a bactericidal cook to the surfacewhere most pathogens are likely to be found. Heating may be unevenand cold spots may occur. Radiation may leak from misused, badlydesigned or badly maintained microwave cabinets and could cause severedamage to the eyes of workers. The usual causes of leakage are worn orill- fitting door seals or failure of the locking device that prevents thedoor being opened while the microwave source is switched on.

Convenience foodsCommercially produced frozen or chilled cooked foods (conveniencefoods), though not intended solely for use in mass catering, are oftenused for this purpose. They may be bought to meet a sudden increase indemand, or kept as an emergency store, especially in a cook -chill unit. Ahighly specialized food item that it is not possible or convenient toprepare in the mass catering establishment may sometimes be obtainedin this way.

The production of these foods is usually fully industrialized withgood control over workers, raw ingredients, processes, etc. Some veryspecial local foods may, however, be produced by small firms usingtraditional methods. The manager of a mass catering establishment shouldmake sure that the hygiene of such firms is satisfactory and that themethods of production are compatible with the techniques necessary forchilling or freezing food and its satisfactory storage and reheating.

Even if the production is satisfactory, it is equally important thattemperature control of perishable foods is strictly maintained. Thesefoods may pass through several hands (distributors, wholesalers,suppliers) before consumption, even during the short shelf -life of chilledfoods. Furthermore, the cost of the food may encourage middle men tokeep the food too long or to sell it even though it has not been kept at acontrolled temperature. The catering manager must ensure that he buysonly from responsible suppliers or preferably direct from manufacturerswhom he knows to have satisfactory premises and quality control. Thelong shelf -life of frozen foods and the wide gap between normal storagetemperatures and dangerous temperatures give considerable flexibilityin handling and allow wide distribution. If contamination and thegrowth of microorganisms has occurred before freezing, however, thewide distribution and long life of these foods can put a large number ofpeople at risk over a long period.

Electronic thermometersElectronic direct reading thermometers with a range of all temperatureslikely to be met in mass catering are essential pieces of equipment for atleast all the supervisory staff at the central cook -chill or cook -freezekitchens, and at the reheating and serving points. These thermometersshould have probes for inserting into solid or liquid food to measure thecentre temperature and suitable sensors for measuring the surface

29

CHID, oR FREEZES-roRAcX

DISTR1WTiON

TEMPERATURE MON ITORINC, AND CONTROLARE VITAL AT EVERY 5TAÇE

30

temperature. Ovens should be fitted with built -in leads and probes formeasuring the centre temperature of food during cooking. This isparticularly important if the oven has an automatically controlled timeand temperature cycle.

The temperature of perishable raw food, such as meat and fish,should be measured when it is delivered to the kitchen, to help to checkthat it is being transported at the right temperature. The same probesshould not be used for both raw and cooked foods unless they can bethoroughly cleaned and disinfected in between. Staff using thethermometers should know the appropriate temperatures for each foodat each stage of the operation and should understand the reasons formaintaining the correct temperatures. Thermometers and sensors shouldbe regularly checked for accuracy and recalibrated if necessary. Thethermometers and the time and temperature recording devices onheating, cooking, cooling and storage equipment should similarly beregularly checked.

Anaerobic packingA method of vacuum packing cooked food before chilling was devised atthe Nacka hospital in Sweden. It allows chilled food to be kept for up toone month before it becomes unpalatable, as opposed to the four- tofive -day life of normal chilled food. Inert gas packing has a similareffect. It has been shown, however, that unless the temperature is keptstrictly below 6 °C, growth of Clostridium botulinum can occur, thoughspoilage organisms do not grow and the food tastes and smells normal.

BibliographyArrêté du 26 juin 1974 du Ministre de l'Agriculture et du Secrétaire

d'Etat aux Transports réglementant les conditions d'hygiène relativesà la préparation, la conservation, la distribution et la vente des platscuisinés à l'avance. [Order of 26 June 1974 of the Minister ofAgriculture and the Secretary of State for Transport regulating theconditions of hygiene for the preparation, preservation, distribution,and sale of pre- cooked dishes]. Journal officiel de la Républiquefrançaise, No. 116, pp. 7397 -7399 (1974).

Codex Alimentarius. Recommended international code of practice for theprocessing and handling of quick frozen foods. Appendix 1: method forchecking product temperature. Rome, Food and AgricultureOrganization of the United Nations, 1978 (addendum 1 -1978-CAC /RCP 8- 1976).

Glew, G., ed. Advances in catering technology. Barking, Applied SciencePublishers, 1980.

England, Department of Health and Social Security. Guidelines on pre-cooked chilled food. London, H. M. Stationery Office, 1980.

Siebente Durchführungsbestimmung zum Lebensmittelgesetz- Lebensmittelund ernahrungshygienische Absicherung von Grossveranstaltungen.

31

[Seventh Regulation for the implementation of the Food Law. Foodsafety and hygienic food -handling in mass catering]. Gesetzblatt derDeutschen Demokratischen Republik, Part I, No. 4, pp. 49 -55 (1981).

England, Department of Health and Social Security. Pre- cooked frozenfood. London, H. M. Stationery Office, (in press).

32

4

Training

The importance of the correct training has already been mentioned. It isessential that it starts at the top. The health authorities must ensure thatmanagers and employers fully understand the need for hygiene and howit must be achieved, in addition to the imperatives of production andprofitability or economy. They must realize that hygiene plays a part inachieving these objectives as well.

The training of employees is first and foremost the responsibility ofmanagement, though the authorities have an important role in initiating,assisting and supervising this activity. In establishing an educationprogramme for workers in the catering industry, the followingprocedures need to be gone through.

1. There should be a critical assessment of the hygiene problems inthe food premises.

2. The whole process and its problems should be considered andthere should be an analysis of the areas where hygiene problems arelikely to occur.

3. The seriousness of each hygiene problem should be assessed andappropriate methods elaborated to combat it. The health authorities canoften be of assistance here.

Initially a modular teaching scheme can be devised incorporatingpoints of common interest for all members of the workforce. This mayneed to include the basic aspects of hygiene, the concept of the germtheory of disease, the way in which germs breed, how they can bedestroyed, etc. Ideally, the bulk of such basic education should have beenattained by the food handlers during their schooldays as part of thegeneral school curriculum. In addition to the points of common interest,detailed training should be given to those working in each different areaor department of the food establishment, to show how they can applythe principles of hygiene to their specific job, for example how theyshould strip and maintain their own machines, what are appropriatecleaning methods, and what is the level of risk of contamination fromand to the ingredients of the product they are handling. Managers andsupervisors need further training in hygiene and may benefit fromspecial training in techniques for teaching hygiene.

33

All teaching programmes should include a means of evaluating theprogramme and incorporating feedback from the students. Teachingmethods need to suit the intellectual and educational abilities of thestudents. Appropriate teaching aids can be produced locally by theindustry or by enforcement agencies. Central government bodies mayalso provide such material, especially books, leaflets and posters. At alllevels of teaching, suitable microbiological techniques can be extremelyvaluable in indicating both the effects of hygiene and the effects of alack of it. Techniques could include swabbing hands before and afterwashing them, swabbing working surfaces before and after cleaning,showing how pathogens can be present on raw material and, whereappropriate, demonstrating how similar pathogens can be obtained frompeople suffering from food poisoning. The workers need to know thecommon sources of harmful microorganisms, such as raw meat andpoultry.

It is important that all teaching should be flexible and should havelocal relevance. The object of teaching is not only to tell people what todo, but to tell them why they need to do it, so that they themselves willbe continually motivated to maintain the proper hygiene standards. Ateaching programme should win the interest of the students; it shouldnot challenge their understanding.

The principles of food hygiene that need to be taught are verysimple: to prevent contamination and to relate time and temperature.The practical application of these principles is not excessively difficult; itis achieving the motivation to apply them that sometimes seems almostimpossible.

Managers must ensure that not only do workers have good initialcourses in hygiene but also that they have refresher courses as often asnecessary. In addition to this, it is the responsibility of all levels ofmanagement, right down to shop floor supervisors and even seniorworkers, continually to ensure by precept and example that hygienestandards are maintained.

In his relationship with the food industry and the food trade, theofficial inspector should always combine inspection with ad hoc adviceand education. This will, of course, be largely directed towards themanagers who will pass it on to the shop floor workers.

The inspectors may need additional training to appreciate thehazards of mass catering techniques and appropriate methods of control,especially where new technology is being introduced. Inspectors shouldalso set an example of strict hygienic behaviour when visiting foodestablishments, wearing correct clean protective clothing, washing theirhands, etc., and should insist that the same standards are observed byemployers or other officials accompanying them.

Food hygiene laboratories should maintain good liaison withinspectors, and ensure that the significance of laboratory findings is fullyunderstood and that inspectors are aware of any developments in testprocedures. Laboratory staff should always be ready to go into foodpremises with the inspectors to see the conditions for themselves, learn

34

about the processes and problems, and further explain and discuss theirlaboratory findings with the catering managers.

Central and local government health officials should ensure thatdesigners, builders, architects and engineers of food handling machineryand of food buildings have a proper knowledge of the problems andhazards associated with food.

Advice on particular aspects of hygiene and technical training orcomplete training courses can often be obtained from manufacturers offood handling, cooking, cooling and storing equipment, from producersof disinfecting and cleaning materials, and from the parent companies offranchise operations.

In some countries it is a legal requirement that all people enteringthe food trade should undergo an official food hygiene course. In othercountries, official courses da not exist but one or more workers in anyfood establishment are expected to have evidence of having undertakensome approved course in food hygiene. This has certain advantages, butthere is the disadvantage that the worker may go through the ritual oftaking the compulsory course but may then not apply the knowledge hehas obtained, looking on the course as a meaningless legal requirement.This is particularly likely to happen if what he has learned on the courseis not continually reinforced by all levels of management. Othercountries feel that, since the responsibility for producing or selling safefood lies first and foremost with the manufacturer, employer or shop -owner, it is up to him to arrange such hygiene education as isappropriate for his workers. It is then necessary for the manufacturer,employer or shop -owner to be satisfied that such hygiene education issufficient to achieve the hygienic practices appropriate to his establish-ment. In all countries, industry has a duty to produce safe and whole-some food, so management needs to be motivated and to understandproperly the need to teach workers how best to achieve the necessarystandards of hygiene. In considering the desirability of compulsory orvoluntary hygiene education, it is necessary to take into account thenational attitudes and policies regarding food legislation.

In the long term it is necessary to change the attitudes of society.Social pressure is always much more effective than legislation, thoughlegislative action can both direct and reinforce social pressures.Conversely, where a government does not make any laws on a mattersuch as food hygiene, the food industry and the public will tend to feelthat it cannot be a really important matter.

BibliographyDavies, R. & Jacob, M. Training guideline for safe food handling in

hotels, restaurants and similar establishments. Geneva, World HealthOrganization, (in preparation).

35

5

Institutional andwelfare catering

Hospitals

Hospitals have to provide food both for staff and for patients. For thebulk of staff and patients' meals there is a peak demand time, yetflexibility is also necessary to provide food for staff working irregularhours. Care must be taken to ensure an adequate and balancednutritional intake for seriously ill or convalescent patients, and for thoseon special diets.

Patients are extremely vulnerable to foodborne disease and onceintroduced by food the disease may be spread from person to person. In1981, there was an outbreak of salmonellosis in a Swedish hospitalprobably caused by incorrectly stored sandwiches. Initially 102 patientsand 17 staff were affected. There were then 14 secondary cases, probablyspread from person to person. Though patients may not be initiallyinfected in a food poisoning outbreak among staff, they may acquire itsecondarily, or be indirectly affected because staff are too ill to lookafter them.

Food may be served to the patients by nursing or similar staff overwhom the kitchen manager has no direct control. There may beproblems in providing meals for hospital staff who work unsocial hourswhen the kitchens are usually closed. Rather than allow night nursingand medical staff to use the kitchen and have access to cold stores, etc.,it may seem desirable to leave some warm or cold food out on serverycounters. Since this food is likely to be left under very inadequatetemperature control and if no cook is available to prepare or reheat thefood, facilities should instead be provided for it to be stored safely, in aspecial refrigerator for instance, separate from the main cold store, andfor the night staff to have access to a reheating oven.

Because of the high capital and running costs of modern hospitalsand methods of treatment, there is often an attempt to make economiesby reducing the cost of catering. This can be achieved to some extent bythe bulk buying of food and the mass preparation of meals at a centralkitchen, serving several hospitals. Further savings may be obtained bythe use of time -shift techniques so that most of the food handlers work

37

normal hours and do not require extra pay for antisocial hours. It istempting to try to make yet more savings by selecting cateringequipment for cheapness rather than satisfactory performance, bypurchasing lower quality foods, and by keeping raw or cooked foodsthat have exceeded their safe storage life or have been reheated forserving and then not eaten.

Attempting to save on catering in this way is unwise in conventionalcatering practice; it may be very dangerous when associated with centralfood preparation and time -shift catering. Quite apart from thehumanitarian aspects, the cost of dealing with an outbreak of foodbornedisease and of prolonging patients' stay in hospital may be greater thanthe savings achieved in the kitchen.

If mass catering techniques are introduced to a hospital, the cateringmanager must ensure that whoever are responsible for reheating andserving the food, be they nurses, maids or kitchen staff, understand fullythe hygienic requirements of the system.

In 1979, there was an outbreak of food poisoning at a hospital in thenorth of England. Twenty -nine patients suffered from staphylococcalfood poisoning. Some were extremely ill, though none died. A mincedmeat dish had been kept warm for over six hours before consumption.The cook was found to be a nasal carrier of the same phage -typedorganism as that isolated from samples of vomit and faeces. The cookhad no signs or symptoms of staphylococcal infection of the skin orupper respiratory tract. Despite the staphylococcal contamination of thefood, no food poisoning would have occurred if the food had not beenstored for so long at a temperature that permitted growth of theorganism and production of enterotoxin.

Patients may react in an unusually severe way to infection with afood poisoning organism. In 1975, an outbreak of Clostridiumperfringens food poisoning occurred in a long -stay hospital in southernEngland. This was caused by inadequate refrigeration of a chopped hamdish served to severely disabled patients of whom 379 were affected andone died. A feature of the outbreak was the degree of general malaiseand severe vomiting in the sufferers, thought to be associated withincreased absorption of the toxins from the gut of usually chronicallyconstipated patients. The man who died was normally severelyconstipated. He died from inhalation of vomit, though vomiting is veryrare in C. perfringens food poisoning; at the post -mortem, his intestinewas found to be very inflamed.

Schools and old people's homes and clubs

In schools, and homes and clubs for old people, there tends to be a peakdemand in the middle of the day, and possibly again in the evening. Foreconomy and efficiency food may need to be produced in centralkitchens and transported a considerable distance to the point of serviceand consumption. Chilled or frozen foods are reheated at the point ofserving or food can be transported hot, though this is usually only

38

practicable for short journeys. Either way, the food must be kept at asafe temperature, while food to be eaten cold needs to be kept cold foraesthetic as well as hygienic reasons. Some food may be reheated andserved by staff such as nurses and teachers, who are not under thecontrol of catering management, while even catering staff in peripheralserveries are not under the direct supervision of the manager of the foodproduction unit. To limit transport costs, several days' food may bedelivered to an institution at one time. A common means of transportinghot foods is in insulated containers. Sometimes the food is under-cooked at the site of preparation in the expectation that it will continueto cook while it is transported hot in the insulated container. Thetemperatures maintained may not, however, be sufficient to preventbacterial growth. Cook -freeze or cook -chill systems would seem to beideal for central production of food and service in institutions, but thisrequires sufficient technology and scientific understanding for themaintenance of safe temperatures. This becomes particularly importantif food is to be stored at a peripheral institution for several days beforereheating and serving.

C. perfringens food poisoning is particularly liable to be associatedwith food produced at a central kitchen and distributed for con-sumption. The organism in its spored form is unlikely to be killed bynormal cooking, and because of its ubiquity is likely to contaminate thefood further when it is handled after cooking. In order to cause foodpoisoning, however, the spores need suitable conditions and time toconvert to the vegetative form and to grow to sufficient numbers tocause illness, i.e. several hours in moist food at temperatures between15 °C and 60 °C.

In 1971, a large outbreak of C. perfringens food poisoning took placein some schools in Finland. A meal of meat balls and gravy wasprepared in a central kitchen and delivered cold to 32 schools where itwas warmed up for lunch the same day. Food poisoning occurred in twoschools, with 800 cases in one and 30 in the other. It was concludedthat it was due to slow cooling and insufficient reheating of the food.Since then, thermometers have been provided at all such schools inFinland and all food is reheated to 90 °C. There have been no furthersimilar outbreaks.

In England in 1976, 146 out of 582 children in two schools developeddiarrhoea 10 -12 hours after a meal of roast beef. C. perfringens wasisolated, and it was found that the cooked beef had been keptunrefrigerated for at least three hours before consumption. Outbreaks ofsalmonellosis have also occurred in schools, usually after inadequatecooking that allowed some of the organisms to survive or whencontamination occurred after cooking, usually directly or indirectly fromraw food. Even then it is usually necessary for time and temperature tobe suitable for the few surviving or contaminating organisms to multiplyto an infecting dose.

Because in schools and old people's institutions the meals providedmay make up a substantial part of the diet, it is important that the

39

amount and type of food actually eaten is monitored as an assessmentof the true dietary intake. If foods are rejected then they contributenothing to the diet. More acceptable foods should be substituted even ifthis means some compromise between nutritional quality and ac-ceptability.

Meals -on- wheels

Ready -prepared meals that are delivered, usually once a day, directly tothe elderly or the disabled in their own homes are known as meals -on-wheels. In the past they have been delivered hot and are intended toarrive at lunchtime to be eaten immediately. The use of larger but moredistant central kitchens and a more economic use of fewer deliveryvehicles has meant that it is more difficult to ensure that the food stayshot enough to be safe throughout the delivery round. In England in1976, four old people became ill with C. perfringens food poisoning about12 hours after eating a diced veal and ham dish which was delivered toabout 160 old people in their own homes. In this case, 40 kg of veal and10 kg of ham were diced and boiled for two hours. The cooked foodwas then transferred to food containers. It probably cooled somewhatwhile being transferred and it is probable that the temperature of thefood in the containers was below 60 °C. The four who became ill were atthe end of the delivery round.

Another problem with old people is that they often do not eat all thefood when it is delivered, keep some to warm up again and eat inthe evening. Even if they have a refrigerator it can be difficult topersuade them to put the food into it, when they are going to have toreheat it in a few hours. It has been suggested therefore that meals couldbe delivered chilled to old people and kept until wanted in an insulatedcontainer or a refrigerator. This would mean ensuring that each oldperson had not only a refrigerator but also some suitable device forrapid reheating of the food. Apart from the economic problems,however, it would be almost impossible to be sure that everything wasused properly.

A partial answer to the meals -on- wheels problem is to transport thefood chilled or frozen and already divided into portions. An appropriatenumber of portions could be reheated on arrival at each house, using areheating device in the delivery vehicle: a microwave oven is usually themost convenient. One could then at least be sure that the food was in asgood a microbiological state as possible at the time of delivery, thusincreasing the margin of safety in case of subsequent mishandling by theclient, such as by keeping it warm for some hours on a central heatingradiator.

An attempt should be made here, by limited but continuous surveyfor instance, to assess just how much food is eaten, what kind of food iseaten, and how it is handled by the consumer. This may demonstrate aneed to withdraw certain foods or to provide supplementary sources, sayof vitamin C in which the elderly easily become deficient.

40

Bibliography

Tuomi, S. et al. Temperature and microbial flora of refrigerated groundbeef gravy subjected to holding and heating as might occur in a schoolfood service operation. Journal of milk & food technology, 37 (9): 457-462 (1974).

41

6

Canteens in factoriesand other commercial

establishments

Subsidized meals are often provided to ensure that even the lowest paidworkers get one good meal a day. Where factories are some distancefrom the workers' homes and no suitable public eating places areavailable near by, provision of a canteen saves a prolonged interruptionof the working day while the workers find somewhere to eat. A canteenprovides a meeting place for all the workforce and helps to promote aspirit of unity. On the other hand, if there is an outbreak of foodpoisoning in such a canteen, it may severely disrupt the functioning ofthe factory or other business.

Canteens have peak periods with an intensive demand for rapidservice and little or no demand for service during the rest of the day.This makes it virtually essential that food be prepared in advance unlessthe canteen has a relatively large staff and only a very limited choice ofdishes is provided. Even then, it is usually necessary to provide at leastone choice for workers who want a low calorie meal.

The peak demand for food is usually at lunchtime, and this canmake it necessary for at least some of the food to be cooked on theprevious afternoon. Storage at a proper temperature is essential. Somevariation of the menu each day is often considered necessary, with achoice of dishes, and any uneaten dishes may be retained to provide afurther choice the next day. Again, temperature control is essential andno food that has once been warmed up for serving should be re- chilledand stored.

Since the total numbers to be fed remain much the same from day today, the requirements for food and kitchen staff can be estimated well inadvance. It is not usually necessary to take on extra kitchen or servingstaff to meet an unexpected major increase in demand. If the canteen issubsidized, there may be pressure to save money but this should not beallowed to compromise safety.

Especially in factories, it may be necessary to provide food foremployees working at night. These may be only a relatively small

43

number of workers and it may not be economical to keep catering staffon duty for them. As in hospitals there is therefore a tendency to closethe kitchen and, for reasons of security, not to give these workers accessto the main cold stores, etc. Often they are given food that has beenkept warm in some serving area, or they may have access to a reheatingdevice but have little or no training in its use. For such night -shiftworkers a small self- service chill store should be available. Either all thenight workers should be taught how to use the reheating oven, or oneresponsible worker should be taught and, as part of his work, shouldhave the duty of reheating the food for the whole night- shift.

Poor temperature control in canteens may affect many workers. In1976, in the kitchen of a factory canteen in England, two 5 -kg joints ofbeef were stewed with 15 kg of vegetables for seven hours. The food wasthen left on the hot stove for three hours and kept in a refrigeratorovernight. Because of the bulk, cooling would have been very slow, evenin the refrigerator. Six food handlers in the kitchen developed severeabdominal pain and diarrhoea 6 -15 hours after eating some of thecold stew. Large numbers of Clostridium perfringens were isolated fromthe stools of four of the patients and more than 100 000 per gram werefound in the beef. It had been intended to serve the stew to a largenumber of workers in the factory, but in view of the illness of the foodhandlers this fortunately was not done. It is unlikely that the stewwould have been more than warmed up before serving, and if it hadbeen served, probably most of the workers would have been ill and awayfrom work for at least a day, with serious loss of productivity. In thesame year an insurance company in another country was not so luckywhen 35 -45 -kg joints of meat were boiled in gravy. They then stood inthe kitchen for an hour before being placed in the cooling room where,because of their size, they would have cooled only slowly. Two dayslater, the meat was re- warmed and served; 500 employees became illwith C. perfringens food poisoning and the work of the company wasseverely affected for some days.

Unless the canteens are providing more than half the workers' totalfood intake, detailed nutritional control is probably not necessary, butthe menu should be such that all workers are likely to choose areasonably well balanced meal. Where some or all of the workforceperforms heavy manual labour, an adequate source of calories should beprovided, though even in such an industry there is still a need to providethe choice of low calorie meals for the less physically active staff, suchas clerks and managers. Some industries may employ relatively largenumbers of youngsters, such as apprentices, who will need a dietappropriate for growth as well as energy replacement; it will also haveto be acceptable to the adolescent palate.

44

7

Open air catering

Open air festivals are becoming increasingly popular as a means ofexhibiting many forms of art, music, dancing, etc. The emphasis isusually on the informality of the proceedings to match the naturalevolvement of the folk arts and cultures that are represented. Suchfestivals attract audiences and performers from increasingly far away,often from all over the world. The provision of food on a large scale isneeded for all these festivals, be they youth festivals, folk festivals, orfestivals of popular commercial music for the young (pop festivals).

Very similar catering techniques are required to feed large numbersof people who have suffered a natural or man -made disaster, whennormal supplies of food and domestic cooking facilities are destroyed orunavailable. Some authorities might consider that pop festivals fall intothis category rather than the previous one.

DisastersIt may be necessary to provide food for refugees who have left a disasterarea or to take catering services to survivors still in the disaster area. Inthe former situation some choice of site can often be made where akitchen can be set up with access to at least some facilities, such as firmdry ground, shelter, clean well or spring water, even power supplies. Inmany ways this situation is similar to that of any open air catering,though refugees may be severely malnourished and dispirited, especiallyif they have travelled any distance. When actually in a disaster area,there will probably be complete loss of virtually all facilities. There willbe a varying degree of disruption of social organization and an absenceof traditional figures of authority. This social disruption and loss ofmorale may not, however, be as severe as among refugees who are awayfrom their normal place of residence.

The refugee camp is likely to be reasonably accessible for supplies offood. This is not likely to be so easy in a disaster area. Food providedin a refugee camp or sent into a disaster area may come from districtsvery different from the home districts of the victims and may have beenprocessed by people of a different culture, even in the same country.

45

This particularly applies to disasters in remote areas of countries wheretravel facilities are limited. The disaster victims may find the foodunfamiliar, and may not even know how to prepare it for consumption;for example a rice -eating people may not know what to do with wheator have the implements to prepare it. Also, food needs to be not onlynutritionally satisfactory, but also aesthetically, religiously and culturallyacceptable. Even correctly prepared food may not be equally nutritiousto all ethnic groups within a country. The ability of adults to digestcows' milk appears to be restricted to those races with a history,however long ago, of a nomadic, pastoral way of life. Other races lackto a varying degree the enzymes necessary to digest the lactose in milk,which not only is not absorbed but may interfere with the absorption ofother foods.

Some of the problems in refugee camps and disaster areas can besolved by the bulk preparation of all food. This ensures the mostefficient use of food, equipment and such skilled cooks as are available.If the food is unfamiliar locally, its correct preparation can be moreeasily supervised. If all food is stored centrally it can be more easilyprotected from weather and vermin, and shared out equally. This appliesboth to relief supplies and to the food salvaged from the disaster area.Damaged food can be checked and often it will be safe if it is usedquickly and handled properly. Perishable foods can be sorted out andused first. The total available food supply can be assessed and mealsmade as varied and well balanced as supplies will permit. Importantdeficiencies can be identified and priority given to these items in reliefsupplies.

There must be a skilled and experienced manager who has fullauthority over his kitchen and food stores, though he will probably needto consult medical and food and environmental hygiene authorities ondetails of dietary requirements for babies or the ill and injured, orwhen choosing a site, improvising equipment, selecting water supplies,disposing of waste, etc. A great deal of intelligent improvisation may beneeded to provide things such as large cooking pots, fuel and ovens.Mobile field cooking units are available commercially, self containedwith their own food supply, but the manager should not rely on havinga sufficient supply of these or any at all.

It is especially important to avoid foodborne disease. Even themildest form of food poisoning can be serious for people who aremalnourished, exhausted, or without proper shelter or adequate medicalfacilities. Nb more food should be prepared than can be eaten at onemeal, and this should be eaten within two hours. When food is in shortsupply, it is very tempting to keep uneaten cooked perishable food forthe next meal. The risk arising from this must be weighed against therisk of starvation. If the food must be kept, it should be stored in ascool a place as possible, protected against contamination, and cooked toa centre temperature of at least 80 °C before serving.

The kitchen manager will probably have to make do with whatassistance he can get from among the disaster victims. Medical screening

46

of food handlers is never a particularly effective exercise and will beimpossible under these conditions. The most that can usually be done isto exclude anyone with diarrhoea, vomiting or infectious lesions ofexposed areas of skin. This will certainly not guarantee the exclusion ofcarriers of gastrointestinal pathogens, though it will keep out mostheavy excreters of such organisms. The kitchen manager must makeevery effort to provide soap and warm clean water for the foodhandlers, and insist on their washing their hands whenever they enterthe food area and after micturition and defaecation. Every effort shouldbe made to reduce the amount that the food Ls touched with the barehand. Many of the workers may not have worked in a kitchen before orhave much understanding of hygiene, so strict kitchen discipline will bevery important.

Where food supplies can be brought in regularly and frequently, itmight be safer and easier to cook the food at some fully equipped andwell staffed kitchen outside the area and bring it in chilled or frozen.When it is only necessary to reheat and serve the food in the disasterarea, much simpler facilities, a smaller staff and less fuel are requiredthan when the food is being completely prepared on site. The lesshandling the food has to receive under the poor conditions that arelikely to obtain in a disaster area or in a refugee camp, the less likely thefood is to become contaminated. It is not usually practicable totransport hot food into disaster areas unless distances are very short.

Festivals

Many aspects of open air festivals, especially the catering, haveimportant implications for health and should be planned in closeconsultation with the health authorities. Often, however, the organizersfeel that official involvement will destroy the sense of spontaneity andfreedom. Indeed, pop festivals frequently take a very understandablepride in their spirit of youthful rebellion and liberation from authorityand stifling officialdom. Nonetheless, some control of catering and otheraspects of hygiene is essential for the health and comfort of theparticipants as well as to prevent the introduction of a public healthnuisance or danger to the permanent residents of the district. Healthofficials must approach the organizers tactfully, pointing out that theydo not want to stop people having a good time and "doing their ownthing" as far as possible, and that they will keep any interference to theminimum that is essential to prevent harm to health.

It is important that festival promoters should use only reputable andexperienced caterers and should ensure that if the caterers sub -contract,then the sub -contractor should in turn be equally competent. It is oftennecessary to make a choice between large companies with considerableexperience in catering for large outdoor events, small specialistcompanies dealing in health foods, hot dogs, etc. and with varyingdegrees of experience, and voluntary organizations providing free orsubsidized food. In general, the main catering arrangements should be in

47

the hands of a large expert firm which should discuss all problemswidely and freely with the health authorities. This firm may sub -contractto the specialist firms. Voluntary organizations should not, and usuallycannot, be excluded, but they must be encouraged to liaise with thecommercial catering establishments and, in particular, with the healthauthorities. Care should be taken that the introduction of unusual, oftenforeign, foods and cooking techniques is not permitted to compromisethe requirements of hygiene.

Of course, there must be an adequate supply of drinking water forwashing, drinking, cooking and cleaning. Where washing facilities arelimited, disposable cups, plates and cutlery may be used. There must beadequate waste disposal services and there must be regular removal ofuneaten food and used disposable crockery, cutlery, etc. from servingand eating areas, whether in huts, tents, marquees or the open air.Since these festivals take place largely in the summer in the open air,control of vermin, particularly insects, is important, but care must betaken that insecticides and sprays do not contaminate food. Separatetoilet accommodation should be arranged for the sole use of foodhandling personnel and adequate hand -washing facilities are essential.Proper storage facilities for the food are very important and protectionfrom the sun and from mud must be arranged.

Temperature control and the prevention of contamination can oftenbe extremely difficult on an open stall in hot weather. It is thereforeparticularly important that only small quantities of food should bedisplayed for sale at any one time, so that food is not left on the stallfor long periods. The age of the customers may encourage excessiveemphasis on cheapness; the health authorities should ensure thateconomy does not lead to serious deterioration in hygiene. There may beunexpected lulls in the purchase of food associated with the times whenparticularly popular performers are appearing. Care should be takenthat these do not lead to an accumulation of prepared food and anexcessive delay before it is all eventually eaten, if it cannot be keptunder adequate temperature control.

Unlicensed and uncontrolled food sellers should not be allowed onthe festival site.

Bibliography

Food and nutrition procedures in times of disaster. Rome, Food andAgriculture Organization of the United Nations, 1967 (FAONutritional Studies, No. 21).

England, Department of the Environment. Advisory Committee on popfestivals, report and code of practice. London, H. M. Stationery Office,1973.

Protein Advisory Group. A guide to food and health relief operations fordisasters. New York, United Nations, 1977.

48

8

Tourist hotels and

holiday camps

In the holiday season many extra food handlers may be employed tocope with the increase in work. It is very difficult to ensure adequatetraining of these temporary workers (often students earning extra moneyfor their own holidays) who may stay for only a few weeks. Not onlythe permanent staff but the hotel or holiday camp kitchens may beinadequate to deal with peak loads. Space may be insufficient for theproper separation of foods in different stages of preparation: unwashedvegetables and raw meat from cooked foods, for instance. Inadequatecooking and chilling facilities may lead to delays before the food iscooked, or before it is cooled for storage afterwards, while there maynot be enough storage space to keep all perishable food underrefrigeration, either raw or cooked. The serving of food can becomplicated not only by peak loads but also, paradoxically, byextended serving times that create the need to keep food alreadyprepared and readily available for late- comers; this can lead to seriousfailures of temperature control.

A combination of these factors, especially cross -contaminationbetween raw and cooked meat and poor temperature control, causedtwo large outbreaks of salmonellosis in a holiday camp in easternEngland in 1979. More than 300 people became ill, many wereincapacitated for a week, and 12 had to be admitted to hospital.

The nutritional content of food does not usually create problems atthese tourist and holiday establishments, unless prolonged holidays arebeing provided, such as for children in summer camps.

The problems of mass catering for holidaymakers are oftenintensified in developing countries. Such countries often have theclimate, scenery and local rural customs that are highly attractive totourists from colder, industrialized and urbanized countries. Thesuccessful establishment of a mass tourist industry is an effective way ofearning foreign currency, attracts investment and provides employmentin undeveloped areas. This can lead to a very rapid development oftourist hotels and holiday camps in otherwise backward areas and maycreate a major load on local sanitary facilities. There is often a lack ofknowledge locally of the technology of mass catering, and there may

49

even be a shortage of semi -skilled workers. The hygiene habits of theworkforce may also be unsatisfactory and lead to a degree of illness inthe consumers which would be unacceptable in an industrializedcountry, though it is not necessarily considered unusual in a developingcountry. In an apparently modern hotel, tourists from industrializedcountries may well not take the precautions that they would normallytake when visiting a developing country. For example, they may drinkunboiled milk in the belief that it is pasteurized, and eat fruit and saladsunder the impression that these will only have been washed in cleanwater and then only touched by clean hands before being served. Theymay know not to drink ordinary tap water but may forget that ice fordrinks could also have been made from tap water. In their owncountries, it may be the custom to store all cold meat and poultry dishesunder refrigeration. Tourists may not appreciate that this is not thepractice in the country they are visiting.

Menus in tourist establishments may be extensive, with a display ofexotic fruits and local delicacies, which may create health problemsbecause of local methods of preparation, distribution, storage andcultivation, such as irrigation with wastewater. Ambient temperaturesare often high and there may be a high prevalence of endemicgastrointestinal disease. As on cruise liners, there is a great tendency tofavour prolonged displays of elaborate and decorative preparedperishable foods on open buffets, often under quite inadequatetemperature control. The problems caused by deficiencies in foodhygiene training in managers and staff of tourist establishments may beaggravated by a shortage of properly trained and reliable hygieneinspectors in these countries.

It is now well recognized by the public health authorities ofindustrialized countries that every year they will receive manycomplaints from tourists who have suffered in outbreaks of gastro-intestinal disease in developing countries. Swedish investigations indicatethat the risk of infection in relatively new tourist areas such as WestAfrica and the Middle East is ten times higher than that in thetraditional Mediterranean resorts. The risk is not negligible, however, onthe coasts and islands of the Mediterranean and, combined with the largenumber of tourists to these areas, it creates a significant public healthproblem for northern European countries. Attempts by public healthofficials in some Mediterranean countries to dismiss reports of illness intourists as due to too much wine or rich food, to heat or excitementactivating a latent infection with gastrointestinal pathogens, or to simplechanges in the natural intestinal flora, serve only to prevent properinvestigation and removal of the true cause. Many deficiencies can befound in these explanations, not least the finding, on their return to theirvarious home countries, of the same strains of pathogens in a number ofvictims of an outbreak in any one tourist resort. These strains are oftenrare in the home countries of the tourists but common in the holidayarea that they have all visited. A significant proportion of the cases oftyphoid and paratyphoid fever occurring in countries such as the

50

Federal Republic of Germany, Sweden and the United Kingdom arecaused by infection acquired in Mediterranean hotels and holidaycamps.

Bibliography

Salvato, J. A.., Jr. Guide to sanitation in tourist establishments. Geneva,World Health Organization, 1976.

51

STRPHYLOCQ-C-CAL RAPID gRoLITH OF ORÇANSVISLESION

ROOM -remoauuv-ruRe

ToxiN PRODUCTION

OPRN SToRNEON

r1FROPLANE

THE HPCZARDOU5 LIFE OF THE INFERNATIONAL 3E7 SET

52

9

Travel catering

Numerous outbreaks of foodborne disease have been associated with theconsumption of food served on board aeroplanes, ships and othervehicles.

Aeroplanes

The treatment and sanitary facilities on aeroplanes are very limited, andserious problems can occur if there is a major outbreak of foodpoisoning in an aeroplane that is a long way from an airport and fromadequate medical services.

In 1975, ham omelettes were prepared for an airline at a masscatering establishment in North America. The cook had a staphylococcallesion of the right hand. The prepared omelettes stood for aconsiderable time in the hot kitchen before they were chilled. They werethen taken on board a 747 jumbo jet making an intermediate stop on aflight from Tokyo to Paris. On the aeroplane, the omelettes were notstored under refrigeration, but were kept some time at room temperaturebefore being warmed, served and eaten. The two periods of standingwithout temperature control gave plenty of time for the staphylococcito grow and produce enterotoxin. Out of 343 passengers, 196 devel-oped food poisoning and one member of the crew of 20 was alsoaffected. When the aeroplane made an interim stop at Copenhagen, 143passengers and the crew member were so ill that they had to be taken tohospital. Fortunately nobody died of food poisoning, but the airline'scatering manager took the blame for the bad catering hygiene andcommitted suicide, although he had not been able directly to supervisethe food handling in the North American kitchen or on the aeroplane.

In 1976, six people developed typhoid after a flight to Australia.Water had been taken on board in an Asian country and this wasalmost certainly the source of infection. In the same year, passengers toAustralia on the same airline developed Vibrio parahaemolyticus foodpoisoning from prawn cocktails prepared in an Asian country; 36 ofthese passengers were admitted to hospital. Other airlines have also hadsimilar outbreaks of food poisoning from prawn dishes prepared in

53

Asian countries, and on one flight from Bangkok to London a crab dishmade over 200 people ill with V. parahaemolyticus food poisoning. In1977, there was a serious outbreak of salmonellosis among passengersflying on a West African airline to Europe.

Unfortunately, these are not isolated incidents. Aeroplanes canpresent considerable problems of space for storage, the control oftemperature, and facilities for reheating and serving. The training ofcabin staff includes education in food handling, but the cateringmanager and hygiene officers may not be permitted to make muchcontribution to this training. The cabin staff is often not responsible tothe catering manager and cannot be under his direct supervision when inthe air. Outbreaks of food poisoning are very frequently due tomishandling by the cabin staff of satisfactorily prepared food, thoughpoor hygiene during preparation very often also plays a part. All cabinstaff should be trained in basic food hygiene, and senior cabin staffshould have further training in food hygiene, especially in temperaturemeasurement and control. An identified senior member of the cabin staffshould have final responsibility for the supervision of all food handlingon the aeroplane and there should be proper temperature measurementand recording equipment, both hand -held and fixed, on food containersfor example. Complete control of all aspects of hygiene is essential atthe establishments on the ground where the initial preparation of flightmeals takes place.

Equally high standards of hygiene are necessary for food to beserved to passengers waiting for a flight (see Chapter 10). If suchpassengers become ill, the airline will usually get the blame, at leastinitially. If they become ill on the flight there are the same problems onboard as if an in -flight meal had been the cause. As a rule the airlinecatering manager has no control over airport catering services, which areusually provided by independent contractors ultimately responsible tothe airport authority. The airline catering manager should, however,keep a general watch on airport catering services and should encouragehis airline to put pressure on the airport authorities to see that hygienicstandards are maintained.

Airlines often feel obliged to provide expensive, exotic foods andnational delicacies. These may be difficult to prepare in a way that doesnot leave them extremely perishable and very liable to contamination.Because of the cost of many such delicacies there is a tendency to keepthem beyond their safe life. If they seem popular when served on anaeroplane, the cabin crew is often tempted to keep any that are uneatento serve later in the flight. The food may already have been standingwarm for some time during the course of the meal for which it wasintended, and there may be no suitable facilities for its cooling andfurther storage.

Limited reheating facilities may lead to plates of food being keptwarm after reheating until all the portions are ready to be served at thesame time. If no proper warm holding equipment is available,improvised measures may be used that do not keep the food at a high

54

enough temperature to prevent microbial growth: it has been reportedthat on one airline it was customary to keep food warm by wrapping theplates of portioned food in a blanket.

It can be difficult to maintain control of the standards of productionof food and drink collected at airports remote from the home base, andthis particularly applies to local delicacies. In some areas it may benecessary to fly out frozen food for collection, while in others locallyproduced fresh or chilled food may be satisfactory. It is important,however, to take the proper steps to ensure that local hygiene controlsand facilities are adequate in developing countries. There is a great needfor strict control of contractors. It may be necessary to lay downmicrobiological specifications and the airline may need to have access toa competent local laboratory for microbiological checks on theproduction standards of the contractors. Water is often collected atseveral points on a flight. It is ingested in some form by virtuallyeverybody for drinking, as ice in drinks, for brushing the teeth and soon, so that its microbiological quality is very important. The airline mayfind it necessary to supplement the local official microbiologicalmonitoring of water quality and may require further treatment, such asextra chlorination of water to be taken on board the plane and thatsupplied to local manufacturers of flight meals.

When a disease has a relatively long incubation period, such astyphoid, passengers may be widely scattered before they become ill, andthis makes recognizing the outbreak and tracing the source even moredifficult than usual. Full records of all food and water handling andmonitoring procedures must be kept if there is to be a chance ofidentifying the fault and preventing further outbreaks.

When illness actually occurs on a plane it may be difficult to discoverexactly which item of food, or even which of several meals on a longflight, has been the cause. All passengers tend to receive the same mealand many items may even be common to the different classes. Sincemeals are usually portioned onto plates at the time of preparation,one contaminated item, such as an undercooked cold roast joint ofmeat, may provide slices for many plates. These slices may contaminateother food on the plate, and the carving knife may contaminate otherfood it touches. Passengers may then become infected even though theyhave not eaten the undercooked item, especially if poor temperaturecontrol has permitted the multiplication of harmful microbes on thesecondarily contaminated food.

When aeroplanes are delayed, there must be facilities for maintainingthe refrigeration of food taken from the cold store in the expectation ofimmediate loading. If the food temperature cannot be otherwise assured,it should be returned to the cold store. Food should never be removedfrom the cold store earlier than is absolutely necessary, and if perishablefood has stood without refrigeration for more than two hours, theadvice of a responsible hygiene controller should be obtained before it isused for human consumption. This, of course, is especially important incountries with a high ambient temperature. A WHO working group on

55

aviation catering commented in 1976: "insufficient cooling and short-comings of hygiene were regarded as main causes of food poison-ing ... except for two cases [between 1967 and 1976] all airports wherecontaminated food has been taken aboard are situated in areas with hotclimates".a Such areas are, of course, often those where there is also alow standard of food and environmental hygiene and a relatively highprevalence of endemic gastrointestinal disease. A particular hazard isthat unpasteurized milk may be unwittingly taken on board, with theattendant risk of brucellosis, salmonellosis, Campylobacter infection andbovine tuberculosis. In many countries where milk is normally soldunpasteurized and is likely to be unsafe, it is the domestic practice toboil all milk before consumption. Foreign airline catering and cabin staffmay not be aware of the need for this precaution and local suppliersmay not appreciate their ignorance and may therefore fail to advise theairline staff of the need for boiling.

Ships

Ferries are rarely absent from their home ports for more than 12 hoursand usually for far less. As a rule they provide self- service andrestaurant facilities. Coastal pleasure boats and those on inlandwaterways are very similar to ferries in these respects. They should nothave difficulty in obtaining good quality provisions from well supervisedsuppliers, but space for food preparation on board may be limited.Long -term storage of large quantities of food is not needed, but eventemporary chilled storage and display space for raw and prepared foodmay be inadequate. It is often necessary to serve a large number ofmeals in a very short time. Some form of time -shift catering maytherefore be required for at least part of the food which, for example,may be cooked in bulk on shore and warmed up as needed on the boat.This sort of food seems particularly liable to temperature abuse on smallvessels.

In 1976, several outbreaks of Salmonella food poisoning affected overa thousand passengers on ferries between Sweden and Denmark whichhad unrefrigerated open buffets. Food handlers in the ships' galleys(kitchens) were found to be Salmonella carriers but it could not bedetermined if they were the sources or victims of the outbreaks. Therewas no time to clean the galleys properly between meals because of theheavy workload and rapid turnround of the ferries. In an outbreak on aferry from Denmark to Germany, 36 passengers developed Salmonellafood poisoning and several serotypes were isolated. The food waspossibly contaminated by food handlers with diarrhoea but the situationwas much aggravated by inadequate temperature control of the food.

In 1980, an English charitable organization arranged a boat trip onthe Thames. The next day, 51 out of 82 passengers and six out of the

a Aviation catering: report on a Working Group. Copenhagen, WHO Regional Office forEurope, 1977 (document ICP /FSP 004), p. 8.

56

crew of seven developed Salmonella food poisoning. Cooked turkeys,provided by a local butcher, had been carved on the working surfacewhere the raw birds had been trussed for the oven. The sliced meat waskept in the chill room on the butcher's premises, but there was norefrigerator on the boat. The meat was therefore kept at ambienttemperature for several hours on a warm summer evening before beingeaten. In the same summer, there were also some outbreaks ofSalmonella food poisoning associated with coastal cruises along thesouth coast of England. One outbreak, of more than 100 cases, appearedto be due to "cold" cooked chicken, which had been stored for fourdays at ambient temperature.

Ocean liners are also occasionally associated with outbreaks of foodpoisoning and other foodborne diseases, but their problems are ratherdifferent. Storage space for raw ingredients is usually satisfactory, butthere may be limited cooking and preparation space. Relatively unskilledlabour may be used for cooking and particularly for service. The samestaff must of necessity remain on the ship for a long time, so trainingand supervision are not difficult, but the managers may not have anadequate knowledge of hygiene and are often under pressure from theshipping lines to produce the wide range of exotic foods expected by thepassengers. Many liners pride themselves on their elaborate cold buffets,but food may be exposed on them for long periods without adequaterefrigeration and often in tropical seas. Unlike ferries and pleasureboats, which are never long away from their home port, it is virtuallyimpossible for deep water vessels to be supervised by national or localfood hygiene authorities other than intermittently when they return toport.

It can often be difficult to ensure the quality of food and water takenon board at ports where local hygiene control services are not yet wellestablished. Hygiene in the galley is very dependent on the ship's generalhygiene, particularly the waste disposal services and the water supply.These are usually outside the control of the catering manager, and areoften the responsibility of ships' officers who have had little training inhealth and hygiene.

Decks are often washed with seawater, which can be contaminatedwith sewage in harbour or close to shore. Even in the open sea it can becontaminated by the ship's own sewage outlet. Seawater, unless it isthoroughly disinfected, should not be used in the galley even for deckwashing, since it may splash on to food or working surfaces. Care mustbe taken at all times to avoid cross connections between drinking watertanks and pipelines and those used for non -potable water.

In 1977, there were numerous outbreaks of food poisoning on oneBritish ocean liner. During a seven -day cruise, a fifth of her passengerssuffered from diarrhoea. When the health authorities investigated theyfound that bags of ice cubes purchased in the West Indies were beingstored in a freezer used for raw fish. The bags were broken and thecubes were lying on the floor of the freezer. Microbiological examinationof the ice showed Escherichia coli too numerous to count, indicating a

57

DRINKINçwnTeR

UN REFRIC,E RHT ED

OUFFET

DIRTYuTENSILS

RYI(pIENT -fEMOERRiV%LEOF

n+EY7

5EA SEIJFÇE OUTLET

THE PRIDE OF THE FLEET

strong possibility of heavy contamination with faecal organisms. Thedeck of the galley was dirty and waste containers were uncovered andoverfilled. Flour and rice bags were standing on the deck. Supposedlyclean pots and pans were greasy and cutting boards were cracked.Frozen food was left to thaw at room temperature and chilled food waskept in refrigerators that at times reached 26 °C. The food handlers werenot clean and used unhygienic practices in the galley and serving areas.Food displayed on the buffet was unrefrigerated and left -over buffetfood was put out again.

An Eastern European cruise liner was responsible for outbreaks ofdisease, including dysentery, salmonellosis and typhoid fever, during orafter several cruises in the Mediterranean in 1978. Many of the affectedpassengers had boarded in London and epidemiological investigationswere started by the port health authorities there. These stronglysuggested that contaminated water supplies had been the cause, withsecondary contamination of food. When the liner returned to Londonon her next trip, the water supply was sampled and found to bebacteriologically satisfactory. It was, however, noted that all the ship'swater supplies had recently been heavily chlorinated. In addition to fourconfirmed cases of typhoid and three of Sonne dysentery, there wereover 100 cases of vomiting and diarrhoea among the passengers on onecruise, and 130 on another. Many of those who became ill had not eatenany food away from the ship and the epidemiological evidence leaves nodoubt that infection acquired on the ship was the cause of the outbreak.

Another cruise liner from the same country was the scene of anoutbreak of bacillary and amoebic dysentery in over half the 650Canadian passengers on a cruise to the West Indies in 1975.Epidemiological evidence indicated that the source of infection waswater taken aboard at a West Indian port. All those ill had beenexposed to the water in various ways, in natural drinking water, fruitdrinks, ice or in the swimming pool. Those who had not been illindicated a lesser degree of exposure to the water. The illness startedwithin three days of the water being taken on board. The masters ofboth ships originally denied the occurrence of any gastrointestinal illnessamong passengers on their ships to the London and Canadianauthorities respectively, thus delaying investigations and making it moredifficult to identify the cause and prevent it happening again.

Cruises do not normally last long enough to lead to problems ofnutrition, though it may be necessary to ensure that there are adequatesouces of vitamin C. The type of food provided and the calorie contentwill need to be appropriate to the climate.

Other vehicles

Food has been provided for many years on trains and is nowoccasionally provided on long- distance motor coaches, where there areconsiderable problems of space for cooking and storage. In somecountries official hygiene control can be difficult as the vehicle travels

59

from the area of one hygiene authority to another. Food often needs tobe served very rapidly, creating peak periods of service, so it isimportant that the food be suitable for these conditions. Previouslyportioned chilled or frozen food which merely needs to be reheatedseems especially suitable.

Bibliography

Lamoureux, V. B. Guide to ship sanitation. Geneva, World HealthOrganization, 1967.

Hobbs, B. C. et al. Food hygiene and travel at sea. Postgraduatemedical journal, 51: 817 -824 (1975).

Bailey, J. Guide to hygiene and sanitation in aviation. Geneva, WorldHealth Organization, 1977.

Bryan, F. L. et al. Time temperature observations of food andequipment in airline catering operations. Journal of food protection,41: 80 -92 (1978).

60

10

Other cateringfor travellers

Other forms of catering for travellers include static cafeterias associatedwith transport systems, in railway stations, airports and on trunk roads,fast food establishments, and take -away catering, including vendingmachines. Many of these facilities, particularly take -away establishmentsand vending machines, may also be used by local residents.

These types of catering have many problems in common. There is aneed for the continual rapid production of a wide range of foods. Thesemay be dished out from bulk by staff at the serving counter or taken bythe customers, already portioned on plates, from a locker or shelf, whichmay be heated or refrigerated according to the type of food. In someinstances the food is obtained by the customer inserting coins into thelocker (or automat) in order to be able to open the door. This use of anautomat in a cafeteria, however, does not alter the catering practices orthe problems involved in the cafeteria kitchen. It simply removes theneed for a cashier to take money for the food.

The load in these premises is fairly continuous though variable. Ittends to increase at conventional meal times and at other times inrelation to transport fluctuations, such as delays of trains at stations orthe arrival of coach parties at motorway cafeterias. The customers areoften in a hurry. The food must be of the sort that can be kept withoutdeterioration at a safe temperature, hot or cold, for a reasonable time atthe serving counter or food locker. The repetitive nature of the workand the production of unexciting dishes may make it difficult to recruitand retain good quality staff, with ensuing difficulties in maintaininggood hygiene. Fortunately there is usually a short time between cookingand consumption, though outside peak periods unpopular dishes maysuffer longer delays. Since many institutions of this sort, such as stationbuffets, are open to large numbers of the public, there is a tendency tostock a wide range of dishes. A time limit must be placed on the storageof any dish; certainly no food should be carried over to the next dayunless it has been kept all the time in a refrigerated compartment whereit is certain that a safe temperature has been maintained. The repeatedopening of refrigerated food locker doors by consumers to obtain thedishes is liable to lead to very wide fluctuations in temperature.

61

Automats at cafeterias are continually replenished from the kitchen,in the same way as ordinary lockers or serving counters, and they can besupervised by the kitchen staff and management. Some automats aresituated where they are completely separate from any kitchen orcafeteria and these may be considered as vending machines. Suchunattended vending machines are usually only for the sale of cold foods.Since these may be perishable, they must be properly refrigerated whilein the machine. They must also be properly refrigerated and protectedwhen being transported for the refilling of the machine. The operatormust understand the temperature and other hygiene requirements andmust check, on each visit, that the machine is functioning correctly.Operators often have no training in food handling but are simplymechanics who receive the food from some central preparation pointand insert it in the vending machines. They must be fully trained tounderstand that perishable food needs much more careful handling thanother items that go into vending machines, such as cigarettes orchocolate bars. The machine should be fitted with a temperaturerecording device, and this should be checked on each visit by theoperator. Ideally the machine should be fitted with a device thatprevents its delivering food if there is a failure of temperature control.

It is common to have vending machines that provide hot and colddrinks. The flavouring ingredients are usually dried powders or syrups inwhich bacterial growth is unlikely to occur. They nevertheless still needto be protected from contamination when the machine is being filled. Asatisfactory water supply is essential for drink vending machines. Ifwater is stored in the machine and is likely to become contaminated, itshould be heated to at least 80 °C before use. There are now vendingmachines that provide hot solid food. The food may be kept hot orheated up as required, usually from a stock of chilled or frozen food.Reheating often takes place in an automatic microwave oven. Thoughthese vending machines are preparing food to the customers' individualorders, the initial preparation of the food is usually done some time inadvance. Often the machine only reheats chilled or frozen precookedfood which has been prepared in a central kitchen. Under thesecircumstances, the same precautions are necessary as are required for allcook -chill or cook -freeze catering operations, especially temperaturecontrol.

Fast food outlets where the food is rapidly prepared as ordered(short -order cooking) do not come under the definition of mass catering.Many establishments such as hamburger premises, however, nowcontinually cook a limited range of food that is kept in a hot cabinet oran individual insulated container, until purchased for consumption on oroff the premises. The rapid turnover usually ensures safety, but nocooked foods should be kept under these conditions for more than twohours, and all unsold cooked food should be disposed of at the end ofthe working day. This type of cooking with a limited range of dishes canbe accomplished by staff with only a simple basic training, the staffactivities being broken down into simple standard tasks. The food is

62

often largely prepared by the supplier, raw ingredients being boughtalready chopped and mixed, and stored chilled or frozen before finalcooking at the time of service. Food of this sort may be produced underfranchise which often enables entire chains of outlets, though underdifferent individual owners, to buy their food from a single supplier.This provides strong purchasing power and the chain can insist onadequate specifications for control of the food ingredients. It can also beassociated, however, with narrow profit margins, and there is a tendencyto save money by indiscriminate bulk buying and by keeping foodlonger than desirable. Mould growth can be a particular problem infood kept too long at chill temperatures.

The popularity of well known franchise establishments, such ashamburger chains, may encourage developing countries to set them up,particularly in tourist areas. This can be a danger if the parent franchisecompany is not aware that the developing countries lack some or all ofthe sanitary and technological infrastructures necessary to allow theprocedures to be carried out safely.

Other types of take -away establishments prepare most of the food toorder, while certain items such as rice are prepared in bulk, portionsbeing warmed up or flash fried when required. If cooked rice is cooledits texture alters, while it tends to become dry or over -cooked if kept toohot. Unfortunately, storing warm cooked rice for several hours hascaused numerous outbreaks of Bacillus cereus food poisoning. If cookedrice or other foods cannot be kept above 60 °C or below 10 °C, onlysmall quantities should be prepared at any one time and after two hoursany remaining rice should be thrown away and a fresh batch cooked.

Mobile fast food outlets, such as vans selling hot sausages cooked asrequired, are well known. A recent development is for such mobileoutlets to carry chilled precooked food that has been prepared at acentral kitchen. The food is reheated, usually in a microwave oven, whenordered by the customer. Such mobile units may visit industrial estatesfor the lunch break, or may tour residential areas, especially in theevening. If ordered in advance, the food can be brought chilled to thehouseholder's front door at the time required and reheated only atthe last minute before delivery. Good control of the temperature of thechilled precooked food is, of course, essential for safety, but maintainingadequate refrigeration may be a problem because of the limited size andpower of the chill storage unit on the vehicle. This can be aggravated bythe entry of heat every time the chill store is opened to take somethingout. Unsold food should be thrown away at the end of the sale round,even though it has been kept in the vehicle's chill store.

63

11

Banqueting

Banqueting is the provision of a formal meal for a large number ofpeople on a social occasion. Highly exotic foods may be provided. Itrequires the simultaneous service of a large quantity of food, thoughusually of only a limited number of items. It also frequently occurs atwhat are considered, by the food handlers at least, to be unsocial hours.To obtain a large quantity of food to be served quickly, while spreadingthe production over the normal working day or over several workingdays, it is common to make use of precooking. The food is then eithercooled for storage and, immediately before serving, rewarmed to atemperature suitable for consumption or, if it is only a matter of severalhours, the food may be kept warm on a hotplate or in a waterbathuntil it is served. Frequently, the time interval is more than sufficient toallow the growth of pathogenic microorganisms that have not all beendestroyed by cooking or that have reached the food by other means,such as staphylococci from handlers and clostridia from the en-vironment. It is therefore extremely important that the food bemaintained at a temperature either too high or too low to permit thegrowth of pathogenic microorganisms. This can create problems, sincekeeping the food above, say, a safe temperature of 60 °C may cause it tobecome dry or overcooked, while some exotic dishes may not toleratecooling to a safe temperature for storage and cannot be reheatedadequately to a bactericidal temperature before serving. Dishes that mayhave to be kept for more than two hours before consumption should notbe considered.

The need to serve the food simultaneously to a large number ofpeople often leads to the employment of a large number of casual staff,for reheating, serving, washing up and performing numerous unskilledtasks in the kitchen. These staff may be of doubtful cleanliness and itcan be extremely difficult to ensure that they are properly trained inhygienic principles.

Banqueting may take place in permanent catering premises, such asrestaurants, where all the preparation of the food is undertaken. Thesewill have a nucleus of permanent staff, but may have to take on extrastaff for peak periods such as the Christmas season in many countries.

65

--i

' x.% °_.5gLMONELLg 1+/4DgR

66

ç

THE -TOYS OF THE FESTIVE SEASON

While not strictly banqueting, similar problems arise in the provision ofmeals to a large number of smaller groups at such times. If the meal is atraditional one associated with that festive period, all groups will bereceiving very similar foods and mass catering techniques will be used.Even in well established restaurants with experienced permanent staff,such mass catering techniques can lead to serious problems.

When a well known restaurant in the north of England served 800

Christmas meals in five days around Christmas 1978, over 150 peoplebecame ill with Salmonella hadar food poisoning. Investigations showedthat turkeys were first cooked, then sliced on the wooden choppingblocks where the uncooked birds had been prepared for the oven.S. hadar was isolated from cracks in these blocks. There was alsothe possibility that the cooked birds were contaminated from rawbirds stored in the same refrigerator. Temperature control generally waspoor.

In Sweden in 1976 a number of people developed diarrhoea 12 -14

hours after a meal in a well known hotel. A high coliform andEscherichia coli count was found in the salad they had eaten. The personwho was making the salad was found also to have been handlingunwashed raw mushrooms contaminated with artificial growing com-post. In the same year, there were two large outbreaks due to badtemperature control in restaurants in Finland. In one, there were 117

cases of food poisoning following the consumption of boiled beef tongueand, in the other, 270 cases of food poisoning following theconsumption In both outbreaks, slow cooling andinsufficient reheating were blamed.

In addition to restaurant banqueting, outside catering is becomingincreasingly popular. This is the production of food, usually commer-cially, in one place, to be consumed on private or public premises by alarge number of guests. The food may be served at a formal sit -downmeal or as a buffet. Reheating equipment is frequently not available atthe point of consumption, particularly in private premises, so the foodhas to be transported already hot or must be kept cold. Often there areno proper facilities for refrigeration of the food displayed as a buffet,and at many such parties the food may be available on the buffet forlong periods. Equally, there is little or no control over the staff servingthe food, who may be unskilled staff taken on for the occasion by thehost or host organization. The host's family or the staff of the or-ganization may themselves assist in reheating and distributing the food.There is therefore little or no control over the premises where the food isdished up and served, even though the premises where the food isinitially prepared may be satisfactory. Sometimes even the initialpreparation of this food, although by a commercial undertaking, mayhave taken place on unsatisfactory premises. Many of these under-takings have started as small catering operations conducted from adomestic kitchen and have then expanded to a level where the space andsophistication of the kitchen is totally inadequate.

A few years ago a small outside catering business was run from a

67

domestic kitchen in the south west of England. This was successful andexpanded, and eventually was providing food for many public andprivate events in the district. The kitchen equipment unfortunately didnot expand likewise and on one occasion seven frozen chickens werecooked in one ordinary domestic oven. Not surprisingly they were notcooked thoroughly, and when they were sliced surviving salmonellaewere spread to other cooked meats. These were inadequately re-frigerated, allowing microbial growth. The cold meat and poultry wereserved at a wedding reception and a high proportion of the guestsdeveloped Salmonella food poisoning. Similar problems, sometimes evenworse, can arise in private non -commercial undertakings for charityevents, picnics, etc. An old folks' bank holiday coach outing was spoiledby staphylococcal food poisoning, caused by sandwiches prepared byvolunteers the evening before. These were stored unrefrigeratedovernight and were then kept in the hot boot of the coach for severalhours.

Even well established catering firms can make mistakes. In 1974, awell known caterer provided a Christmas meal to a famous publicschool in the south of England. Out of 60 boys, 30 developedsalmonellosis and it was found the turkeys had been cooked the previousday and left unrefrigerated overnight. In 1981, an outbreak of foodpoisoning occurred among journalists and others attending an EECsummit conference in the Netherlands. It is estimated that over 500people developed salmonellosis. The catering was done by a firm with agood reputation but with no experience of providing food on this scale,and the town hall, where the food was eaten, did not have adequatefood hygiene facilities. The problem appears to have been due tocontamination of a beef and potato salad and subsequent inadequaterefrigeration.

68

12

Summary

1. Mass catering is an efficient and economical way of providing foodfor large numbers of people.

2. In order to spread the workload for the kitchen staff time -shifttechniques are often employed.

3. Because of its scale, mass catering has the potential to cause illnessto a large number of people. The more sophisticated the techniquesinvolved, the more care needs to be taken

4. Mass catering techniques require a satisfactory food supply and anadequate sanitary infrastructure.

5. In all forms of catering, hygiene is important, but it is especially soin mass catering. The most important aspects are the prevention of crosscontamination of cooked food, and the control of the time andtemperature of both cooking and storage. It is particularly difficult tocook and cool large joints of meat adequately.

6. Staff should understand what they need to do and why. If employeesdo not understand the reasons for their instructions, they will not bemotivated to follow them strictly, and hygiene is likely to suffer. Specialcare must be taken over the education of workers with languageproblems.

7. Laboratory testing cannot take the place of proper supervision andhygiene. Laboratory tests should only be used when they will be effectiveand where no other less expensive method of control can be used.

8. It should be assumed that all raw food contains pathogenicorganisms, and that these can be killed, removed or reduced to harmlessconcentrations by appropriate treatment of the food.

9. Highly sophisticated techniques should not be attempted where the

69

facilities and technology are not available. Mass catering can, however,often be accomplished satisfactorily under such conditions by the use ofunsophisticated labour intensive systems.

10. In all mass catering systems, good management is essential. Thisincludes proper quality control, hygiene inspection and the training ofstaff.

11. Countries without previous experience of mass catering shouldconsult experts before embarking on a mass catering programme.

12. There must be a mechanism for reporting episodes of foodpoisoning. It should be established as fast as possible whether they aredue to the mass catering system, and if so where the system is at fault.

13. Whatever the trade and economic considerations, health aspects(safety and nutrition) must take priority. The final responsibility forhealth aspects must rest with a health authority that has noresponsibility for trade, tourism, employment, foreign policy, or anyother such interests.

14. There is one final rule that applies to all catering but particularly toany system of mass catering that is being considered: if you can't do itproperly, don't do it at all.

If, of all words of tongue and pen,The saddest are, "It might have been,"More sad are these we daily see:"It is, but hadn't ought to be!"

Bret Harte

70

WHO publications may be obtained, direct or throughALGERIA: Société Nationale d'Edition et de Diffusion, 3 bd Zirout

Youcef, ALGIERSARGENTINA: Carlos Hirsch SRL, Florida 165, Galerias GUemes,

Escritorio 453/465, BuurNos AIRESAUSTRALIA: Hunter Publications, 58A Gipps Street, COLLINGW00D,

VIC 3066 - Australian Government Publishing Service (Mail ordersales), P.O. Box 84, CANBERRA A.C.T. 2600; or over the counter (mmAustralian Government Publishing Service Bookshops ar: 70 AlingaStreet, CANBERRA CITY A.C.T. 2600; 294 Adelaide Street, BRISBANE,Queensland 4000; 347 Swanston Street, MELBOURNE, VIC 3000; 309Pitt Street, SYDNEY, N.S.W. 2000; Mt Newman House, 200 St.George's Terrace, PERTH, WA 6000; Industry House. 12 Pirie Street,ADELAIDE, SA 5000; 156 -162 Macquarie Street. HOBART, TAS 7000 -R. Hill & Son Ltd, 608 SL Kilda Road, MELBOURNE, VIC 3004;Lawson House, 10-12 Clark Street, CRow's NEST, NSW 2065

AUSTRIA: Gerold & Co., Graben 31, 1011 VIENNA IBANGLADESH: The WHO Programme Coordinator, G.P.O. Box 250,

DHAKA 5 - The Association of Voluntary Agencies, P.O. Box 5045,DHAKA 5

BELGIUM: Office international de Librairie, 30 avenue Marnix, 1050BRUSSELS - Subscriptions to World Health only: Jean de Lannoy, 202avenue du Roi, 1060 BRUSSELS

BRAZIL: Biblioteca Regional de Medicina OMS /OPS, Unidade deVedda de Publicagöes, Caixa Postal 20.381, Vila Clementino. 04023Sim PAULO, S.P.

BURMA: see India, WHO Regional OfficeCANADA: Canadian Public Health Association, 1335 Carling Avenue,

Suite 210, OTTAWA, Ont. KIZ 8N8. Subscription orders, accontpartiedby cheque made our to the Royal Bank of Canada, OTTAWA, AccountWorld Health Organization, nor also he sent to the World HealthOrganization, P.O. Box 1800, Postal Station B, OTTAWA, Ont. KIP5R5,

CHINA: China National Publications Import & Export Corporation,P.O. Box 88, BETTING (PEKING)

CYPRUS: "MAM ", P.O. Box 1722, NICOSIACZECHOSLOVAKIA: Ania, Ve Smeckach 30, 11127 PRAGUE IDENMARK: Munksgaard Export and Subscription Service, Narre

Segade 35, 1370 COPENHAGEN K (Tel: +45 1 12 85 70)ECUADOR: Libreria Cientifica S.A., P.O. Box 362, Luque 223,

GUAYAQUILEGYPT:Osiris Office for Books and Reviews, 50 Kane El Nil Street, CAIROFIJI: The WHO Programme Coordinator, P.O. Box 113, SUVAFINLAND: Akateeminen Kirjakauppa, Keskuskatu 2, 00101 HELSINKI

10FRANCE: Librairie Arnette, 2 rue Casimir -Delavigne, 75006 PARISGERMAN DEMOCRATIC REPUBLIC: Bachhaus Leipzig, Postfach

140, 701 LEIPZIGGERMANY, FEDERAL REPUBLIC OF: Govi- Verlag GmbH, Ginn -

heimcentrasse 20, Postfach 5360, 6236 EsceaonN - W. E. Saarbach.Postfach 101610, Follerstrasse 2, 5000 KOLN I - Alex. Horn, Spiegel -gasse 9, Postfach 3340, 6200 WIESRADE]

GHANA: Fides Enterprises, P.O. Box 1628, ACCRAGREECE: G. C. Eleftheroudakis S.A., Librairie internationale, rue

Nikis 4, ATHENS (T. 126)HAITI: Max Bouchereau, Librairie "A la Caravelle ", Boite postale I1 I-

B, PORT -AU -PRINCE

HONG KONG: Hong Kong Government Information Services, Bea-consfield House, 6th Floor, Queen's Road, Central, VICTORIA

HUNGARY: Kultura, P.O.B. 149, BUDAPEST 62 - Akadémiai Könyves-bolt, Véci urea 22, BUDAPEST V

ICELAND: Snaebjorn Jonsson & Co., P.O. Box 1131, Hafnarstraeti 9,REYKJAVIK

INDIA: WHO Regional Office for South -East Asia, World HealthHouse, Indraprastha Estate, Mahatma Gandhi Road, NEW DELHI110002 - Oxford Book & Stationery CO, Scindia House, NEW DeLot110001; 17 Park Street, CAIcuTrA 700016 (Sub-agent)

INDONESIA: P. T. Kalman Media Pusaka, Pusat Perdagangan Senen,Block I, 4th Floor, P.O. Box 3433/1kt, JAKARTA

IRAQ: Ministry of Information, National House for Publishing, Distri-buting and Advertising, BAGHDAD

IRELAND: TDC Publishers, 12 North Frederick Street, Duaun IISRAEL: Heiliger & Co., 3 Nathan Strauss Street, JERUSALEM 94227ITALY: Edizioni Minerva Medics, Corso Bramante 83 -85, 10126

TURIN; Via Lamarmora 3, 20100 MILANJAPAN: Maruzen Co. Ltd, P.O. Box 5050, TOKYO International,

100-31KUWAIT: The Kuwait Bookshops Co. Ltd, Thunayan AI- Ghanem Bldg,

P.O. Box 2942, KUWAITLAO PEOPLE'S DEMOCRATIC REPUBLIC: The WHO Programme

Coordinator, P.O. Box 343, VIENTIANELEBANON: The Levant Distributors Co. S.A.R.L., Box 1181, Makdassi

Street, Hanna Bldg, BEIRUT

booksellers, from:LUXEMBOURG: Librairie du Centre, 49 bd Royal, LUXEMBOURGMALAWI: Malawi Book Service, P.O. Box 30044, Chichiti, BLANTYRE 3MALAYSIA: The WHO Programme Coordinator, Room 1004, 10th

Floor, Wisma Lim Foo Yong (formerly Fitzpatrick's Building), JalanRaja Chulan, KUALA LUMPUR 05 -10; P.O. Box 2550, KUALA LUMPUR01-02 - Parry's Book Center, K. L. Hilton Hotel, Jln. Treacher, P.O.Box 960, Kuuc LUMPUR

MEXICO: Lihreria Internacional, S.A. de C.V., Av. Sonora 206, 06100 -MExlco, D.F.

MONGOLIA: are India, WHO Regional OfficeMOROCCO: Editions La Pone. 281 avenue Mohammed V, RABATMOZAMBIQUE: INLD, Caixa Postal 4030, MAPUTONEPAL: see India, WHO Regional OfficeNETHERLANDS: Medical Books Europe BV, Noorderwal 38, 7241 BL

LoceensNEW ZEALAND: Government Printing Office, Publications Section,

Malgrave Street, Private Bag, WELLINGTON 1; Walter Street, WEL-LINGroN; World Trade Building, Cubacade, Cuba Street, WELLINGTON.Government Bookshops as: Hannaford Burton Building, RutlandStreet, Private Bag, AUCKLAND; 159 Hereford Street, Private Bag,CHRISTCHURCH; Alexandra Street, P.O. Box 857, HAMILTON; T & GBuilding, Princes Street, P.O. Box 1104, DUNEDIN - R. Hill & Son,Ltd, Ideal House, Cnr Gillies Avenue & Eden St., Newmarket, AUCK-LAND I

NIGERIA: University Bookshop Nigeria Ltd, University of Ibadan,IBADAN

NORWAY: J. G. Tanum A/S, P.O. Box 1177 Sentrum, OSLO IPAKISTAN: Mirza Book Agency, 65 Shahrah -E- Quaid- E -Azam, P.O.

Box 729, LAHORE 3PAPUA NEW GUINEA: The WHO Programme Coordinator, P.O.

Box 646, KO.vEDOBUPHILIPPINES: World Health Organization, Regional Office for the

Western Pacific, P.O. Box 2932, MANILA -The Modern Book Com-pany Inc., P.O. Box 632, 922 Rizal Avenue, MANILA 2800

POLAND: Sktadnica Kniegarska, ul Mazowiecka 9, 00052 WARSAW(except periodical') - BKWZ Ruch, ul Wronia 23, 00840 WARSAW(periodicals only)

PORTUGAL: Livraria Rodrigues, 186 Rua do Ouro, LISBON 2REPUBLIC OF KOREA: The WHO Programme Coordinator, Central

P.O. Box 540, SEOULSIERRA LEONE: Njala University College Bookshop (University of

Sierra Leone), Private Mail Bag, FREETOWNSINGAPORE: The WHO Programme Coordinator, 144 Moulmein

Road, SINGAPORE 1130; Newton P.O. Box 31, SINGAPORE 9122 -Select Books (Pte) Ltd, 215 Tanglin Shopping Centre, 2 /F, 19 TanglinRoad, SINGAPORE 10

SOUTH AFRICA: Van Schaik's Bookstore (Pty) Ltd, P.O. Box 724, 268Church Street, PRETORIA 0001

SPAIN: Comercial Atheneum S.A., Consejo de Ciemo 130 -136, BARCE-LONA IS; General Moscardb 29, MADRID 20 - Libreria Diaz deSantos, Lagasca 95 y Maldonado 6. MADRID 6; Balmer 417 y 419,BARCELONA 22

SRI LANKA: see India, WHO Regional OfficeSWEDEN: For books: Aktiebolaget C.E. Fritzen Kung]. Hovbokhandel,

Regeringsgatan 12, 10327 STOCKHOLM. For periodicals: Wennergren-Williams AB, Box 30004, 104 25 STOCKHOLM

SWITZERLAND: Medizinischer Verlag Hans Huber, Länggass Strasse76, 3012 BERN 9

THAILAND: see India, WHO Regional OfficeTUNISIA: Société Tunisienne de Diffusion, 5 avenue de Carthage, TUNISTURKEY: Hases Kitapevi, 469 Istiklal Caddesi, Beyoglu, ISTANBULUNITED KINGDOM: H.M. Stationery Office: 49 High Holborn,

LONDON WCIV 6HB; 13a Castle Street, EDINBURGH EH2 3AR; 80Chichester Street, BELFAST BTI 41Y; Brazennose Street, MANCHESTERM60 8AS; 258 Broad Street, BIRMINGHAM BI 2HE; Southey House,Wine Street, BRISTOL BSI 2BQ. All mai! orders should be sent to:HMSO Publications Centre, 51 Nine Elms Lane, Lonoon SW8 5DR

UNITED STATES OF AMERICA: Single and bulk copies of indi-vidual publications (not subscriptions): WHO Publications CentreUSA, 49 Sheridan Avenue, ALBANY, N.Y. 12210. Subscriptions: Sub-scription orders, accompanied by check made our to the ChemicalBank, New York, Account World Health Organization, should be sentto the World Health Organization, P.O. Box 5284, Church Street Sta-tion, NEW YORK, N.Y. 10249. Correspondence concerning subscriptionsshould be addressed to the World Health Organization, Distributionand Sales, 1211 GENEVA 27, Switzerland. Publications are also avail-able from the United Nations Bookshop, NEW YORK, N.Y. 10017(retail only)

URUGUAY: Libreria Agropecuaria S. R. L., Casilla de Correo 1755,Alzaibar 1328, MONTEVIDEO

USSR: For readers in the USSR requiring Russian editions :: Komso-molskij prospekt 18, Medieinskaja Kniga, Moscow - For readersoutside the USSR requiring Russian editions :: Kuzneckij most 18,McOdunarodnaja Kniga, Moscow G -200

VENEZUELA: Libreria del Este, Aparlapo 60.337, CARACAS 106 - Li-breria Médira Paris, Apartado 60.681, CARACAS 106

YUGOSLAVIA: Jugoslovenska Knjiga, Terazije 27/11, 11000BELGRADE

ZAIRE: Librairie universitaire, avenue de la Paix Nu 167, B.P. 1682,KINSHASA I

Special terms for developing countries are obtainable on application to the WHO Programme Coordinators or WHORegional Offices listed above or to the World Health Organization, Distribution and Sales Service, 1211 Geneva 27, Swit-zerland. Orders from countries where sales agents have not yet been appointed may also be sent to the Geneva address,but must be paid for in pounds sterling, US dollars, or Swiss francs.Price: SW. fr.13 - Prices are subject to change without notice. C/1/83