Guidelines for Food Safety

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Guidance NoteNo.3

Guidelinesfor theInterpretation of

Results of Microbiological

Analysis of SomeReady-To-Eat

Foods Sampledat Point of Sale


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Guidelines for the Interpretation of Resultsof Microbiological Analysis

of Some Ready-To-Eat FoodsSampled at Point of Sale

Published by:Food Safety Authority of Ireland

Abbey CourtLower Abbey Street

Dublin 1

Tel:+353 1 8171 300 Fax:+353 1 8171 301Email: [email protected] Website:www.fsai.ie

2001

Applications for reproduction should be made to the FSAI Information Unit

ISBN 0-9539183-5-1


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Other Food Safety Guidance Notes available from

the Food Safety Authority of Ireland:Guidance Note No 1 Inspection of a Food Business (2000)

ISBN 0-9539183-2-7

Guidance Note No 2 Classification of Food (2001)ISBN 0-9539183-3-5


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INTRODUCTION 1

BACKGROUND 2

MICROBIOLOGICAL CRITERIA 2

GUIDELINES FOR MICROBIOLOGICAL ENFORCEMENT 3

READY-TO-EAT FOODS 4

INTERPRETATION OF GUIDELINES 4

REVISED GUIDELINES 4

MICROBIOLOGICAL QUALITY LEVELS 5

INDICATOR ORGANISMS 6

PATHOGENS 7

TABLE 1:GUIDELINES FOR THE MICROBIOLOGICAL QUALITY 8OF SOME READY-TO-EAT FOODS AT POINT OF SALE

TABLE 2: AEROBIC COLONY COUNT CATEGORIES FOR 9DIFFERENT TYPES OF READY-TO-EAT FOODS

REFERENCES 11

ACKNOWLEDGEMENTS 12

Contents


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Background The Microbiology Sub-committee of the Food Safety Authority of Ireland has undertaken areview of the microbiology guidelines for some ready-to-eat foods sampled at point of saleas they appear in the 1995 report of the former Food Safety Advisory Committee 1.

The 1995 guidelines were adapted from guidelines published by the UK Public HealthLaboratory Service (PHLS) in 1992 2. The revision and expansion of the PHLS guidelines in19963 and subsequent revision in 2000 4, have necessitated the current review by theMicrobiology Sub-committee.The following guidelines draw heavily on those of the PHLS.

This document does not purport to have any legal standing.The microbiological criteria

listed in Table 1 are not statutory standards.Revisions to these guidelines will continue tobe made as experience is gained of their value in practice and as additional informationbecomes available.

In addition to these guidelines for ready-to-eat foods sampled at point of sale, there is asupporting document that contains relevant material 5.The supporting document broadlydescribes the approach to establishing microbiological criteria and food sampling plans forall foods sampled at any point in the food chain. It also includes a summary of themicrobiological criteria (standards and guidelines) as listed in current EU legislation.

Microbiological CriteriaMicrobiological criteria are essentially of three types: guidelines, standards andspecifications.These terms were originally defined by Codex Alimentarius 6 and have sincebeen redefined both by Codex and other international organisations.They can be describedas follows:

A microbiological guideline is a criterion which relates to the microbiological

condition of the food sample that is applied at any stage of food processing andretailing.It aids in identifying situations requiring attention for food safety or qualityreasons.Guidelines arise from many sources - the food industry,enforcementagencies and,national and international committees,and are especially applied toindicator organisms. While guidelines may be written in law they are not legallyenforceable,but serve to provide assistance to enforcement agencies in interpretingwhether producers are complying with the general policy in relation to standards.

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Guidelines can both complement legally enforceable standards and provide abenchmark in the situations where standards are not considered necessary. Apersistent and widespread breach of the guidelines could be an indication of poor manufacturing or handling practice.Guidelines also provide a benchmark againstwhich unacceptable microbial contamination of food can be identified. Guidelinelevels for microbiological hazards are proposed as a mechanism to identifythe maximum level of contamination that is reasonably acceptable and toprovide a trigger for remedial action when these levels are exceeded.An adverse health effect is not an inevitable consequence of consumption of foodscontaining microorganisms above the guideline levels. However, the presence of microorganisms above the guideline levels does indicate that human exposure toparticular micro-organisms may occur at undesirable and preventable levels.

A microbiological standard is a microbiological criterion contained in a law wherecompliance is mandatory. The food industry must ensure full compliance with thesestandards which are monitored by enforcement agencies.

A microbiological specification is a microbiological criterion applied to rawmaterials, ingredients or the end-product which is used in a purchase agreement.

Specifications are set by purchasers and are usually more stringent thanmicrobiological standards in order to provide an extra margin of safety.

Guidelines for Microbiological Enforcement The purpose of these guidelines is to provide authorised officers with assistance indetermining the microbiological quality of various ready-to-eat foods sampled at point of sale. Traditionally, in enforcement situations, microbiological examination has played animportant role in evaluating the microbiological safety of food. Food inspection services

generally rely on the examination of single food samples rather than statistically basedsampling plans. The results from single sample examination may provide evidence that foodhygiene regulations have been contravened or provide the basis for additional inspectionand/or food sampling. They may also give valuable baseline data (usually where samples formpart of a specific survey) which can be used for trend analysis. Where there is routinesampling, the choice of food to be sampled will vary according to the local need, and theoccurrence of cases and outbreaks of foodborne illness in the area or nationally.

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Ready-to-Eat FoodsAll composite foods purchased by or supplied to a consumer for their consumption andwhich do not require significant further processing other than re-heating or completion of a cooking process are included in the ready-to-eat category. If not consumed immediately,these foods usually require refrigeration to ensure shelf-life. There is considerable variationin the composition of ready-to-eat foods. They range from those containing someingredients that are uncooked, such as sandwiches, to those that are cooked immediatelyprior to being provided to the consumer. A list of the more common ready-to-eat foodsand their categories are outlined in Table 2. Excluded categories include low water activityfoods and other ambient temperature stable foods such as jams,canned food,cured food

and food preserved by pH reduction (including pickled foods).

Interpretation of Guidelines The figures given in Table 1 are guidelines and not statutory microbiological standards. These guidelines have no legal standing. They are intended for use by food examiners andauthorised officers. They may be used to monitor the microbiological quality of a food. Themicrobiological criteria used in the guidelines can be of prime importance in deciding if afood is unfit or in reinforcing other observations,such as breaches in operational hygiene,

and providing reasons to suspect a food may not meet sound public health and hygienestandards. It should be noted that the specification of a criterion for a particular organismdoes not imply that all foods should be examined for that organism as a matter of routine.

Authorised officers should be aware that a number of EU directives contain microbiologicalcriteria for a variety of foodstuffs.Some of these criteria may apply to ready-to-eat foodssampled at point of sale. For convenience, these directives and their criteria aresummarised in the supporting document.To ensure correct application of these criteria,thecurrent legislation must be read. In addition, it should be noted that the European

Commissions Scientific Committee on Veterinary Measures Relating to Public Health hasrecently evaluated the legal standards and has expressed an opinion on possible changes 7.

Revised Guidelines The following changes have been included in the revised guidelines:1. The term aerobic plate count has been renamed aerobic colony count and is based

on incubation at 30 oC for 482h.

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2. Five categories of ready-to-eat foods have been identified (Table 2). To avoidconfusion with the 21 EU categories 8(designated by the numbers 1-21) from theguidelines on Article 14 of Directive 89/397/EEC,the five ready-to-eat categories inthis document are designated by the upper case letters A to E. The first fourcategories are based on a range of aerobic colony counts expected according tothe type of product and the processing it has received. The fifth category refers tocertain fermented foods for which guidelines for aerobic colony counts may not beapplicable. Only foods for which sufficient microbiological data exist are listed in

Table 2. When a food which is not listed is submitted for analysis, the food shouldbe assessed as to which of the five categories it best fits into - based on the type of product, the processing it has received and the potential for microbial growthduring storage.

3. Four quality levels remain,but the term fairly satisfactory has been renamedacceptable. Hence,the four categories are satisfactory,acceptable,unsatisfactory,and unacceptable/potentially hazardous (see below).

4. New or modified criteria have been included for Enterobacteriaceae, Escherichia coli,Listeria spp.,E. coli O157 and other verocytotoxigenic producing E. coli (VTEC),Vibrio cholerae,V. parahaemolyticus, Clostr idium perfringens,Bacillus cereus and other pathogenicBacillus spp.(see sections on indicator organisms and pathogens).

Microbiological Quality Levels The classification of satisfactory means that the test results indicate good

microbiological quality.

The classification of acceptable is suggested to take account of the limitations inmicrobiological sampling,handling, testing and wide confidence limits in enumeration.Due to these factors,some samples will fall between what is considered satisfactory

and unsatisfactory.

Samples in the unsatisfactory category indicate that the acceptability threshold hasbeen exceeded. Further sampling may be necessary and the authorised officer maywish to carry out a detailed inspection of premises,food production and handlingprocesses to determine whether hygiene practices for food production or handlingare inadequate. The judgement of the authorised officer and the observation of trends will indicate the level of response. In general, the ready-to-eat guidelines aresimilar to or less stringent than the microbiological standards in the relevant EU

Directives 5. If an authorised officer suspects that the product may be in breach of

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the legal criteria,they are advised to consult the relevant directive and inform therelevant authorised officer under the directive in force. There are examples wherethe ready-to-eat guidelines are more stringent than the criteria in the EU Directives.As these examples only relate to the unsatisfactory category and not to theunacceptable/potentially hazardous category,the issue of possible withdrawal underthe ready-to-eat guidelines should not arise (see definition of theunacceptable/potentially hazardous category).

The numbers quoted under the heading unacceptable/potentially hazardousrepresent a potential health hazard to those consuming such food. Samples falling inthe unacceptable/potentially hazardous category should prompt a rapid responseby the authorised officer and a detailed assessment should take place. Productwithdrawal should be an option to be considered in this category only.

Indicator Organisms Enterobacteriaceae are included in the revised guidelines as they are useful indicators

of hygiene and post-processing contamination of heat processed foods.Coliformshave been the traditional indicator group in this context.Coliforms are thosemembers of the Enterobacteriaceae that ferment lactose and include Enterobacter ,most Escherichia, Klebsiella and Citrobacter . Tests for coliform bacteria will only detectorganisms capable of fermenting lactose. If large numbers of non-lactose-fermentingbacilli are present,reliance on tests for coliform bacteria may lead to falselyreassuring results. In addition,many food pathogens do not ferment lactose.Enterobacteriaceae is a broader term and includes Escherichia spp ., Citrobacter spp .,Enterobacter spp., Proteus spp., Salmonella enterica spp., Shigella spp., and Yersinia spp..

Thus,examining a sample for the presence of members of the familyEnterobacteriaceae instead of coliforms may give a better indication of the likelihood

of the presence of pathogens,as well as providing more accurate information aboutthe handling and storage of the foodstuff.It should be noted that this test is notapplicable to fresh fruit,vegetables and salad vegetables.

The criteria for Escherichia coli (total) and Listeria spp. (total) have been modified.Quantitative quality levels in the unacceptable/potentially hazardous columnhave been deleted (Table 1). Additionally, Listeria spp. has been modified to includeL.monocytogenes because of the changes to the quantitative criteria forL.monocytogenes (see below).

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Pathogens E. coli O157 and other VTEC have been included.

Vibrio cholerae has been included because the European Commission has madeseveral decisions in response to the isolation of this organism from various importedready-to-eat foods,mainly fishery products and,fruits and vegetables. Vibrio cholerae O1 and O139 are the two serogroups responsible for disease. V. parahaemolyticus inseafood has been retained,but the quantitative quality levels have been modified.

The quantitative quality levels for Listeria monocytogenes have been modified and the

classification of unsatisfactory is now not applicable in this case.The value of 102

cfu/g at point of sale/consumption represents a potential risk to health according toa number of recent opinions and published reports 6. It is recognised that someserotypes/phage types of L.monocytogenes may rarely be associated with humaninfection,however their presence reflects an inadequate level of hygiene.

The European Commission is currently drafting a decision on the control of L.monocytogenes in ready-to-eat foods. This decision will include zero tolerance forsome ready-to-eat foods and will take precedence over these guidelines.

The Clostr idium perfringens quantitative quality level for the satisfactory category isnow 10 5/g) inthe case of the diarrhoeal disease. In the case of the emetic disease,the minimumnumber of cells required in a food to produce the minimum intoxication dose is also>10 5/g. When present in foods, B.cereus is usually at concentrations of


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Table 1:Guidelines for the Microbiological Qualityof some Ready-To-Eat Foods at Point of Sale

Food Category(see Table 2) Criterion

Satisfactory Acceptable

Microbiological quality(cfu per gram unless otherwise stated) (a)

Unsatisfactory(b)

Unacceptable/potentiallyhazardous

(c)

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(a) For a detailed explanation of the categories of microbiological quality see page 6.(b) Further sampling may be necessary and the authorised officer may wish to initiate a detailed inspection by therelevant authorised officer of premises,food production and handling processes to determine whether hygienepractices for food production or handling are inadequate.

(c) Product withdrawal should be an option to be considered in this category only.(d) Guidelines for aerobic colony counts may not apply to certain fermented foods - e.g. salami, soft cheese and

unpasteurised yoghurt. These foods fall into Category E (see Table 2). Acceptability is based on appearance,smell, texture and the levels or absence of indicator organisms or pathogens.

(e) On occasion some strains may be pathogenic.(f) Enterobacteriaceae are indicators of hygiene and of post-processing contamination of heat processed foods.

They are not applicable to fresh fruit,vegetables and salad vegetables.(g) Relevant to seafood only.(h) Not detected in 25g for certain long shelf-life products under refrigeration, such as soft ripened cheese,

vacuum packed pat and sliced meats.(i) If the Bacillus counts exceed 10 4 per gram,the organism should be identified.N/A Denotes not applicable.

Aerobic colony count (d)30oC / 48h

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Table 2:Aerobic Colony Count Categories for Different Types of Ready-To-Eat Foods

Food Group Product Category(A-E)

Dairy cheese Eice-cream,milk shakes (non-dairy) Bice lollies,slush and sorbet Byogurt/frozen yogurt (natural) E

Dessert cakes, pastries, slices and desserts - with dairy cream Ccakes,pastries, slices and desserts - without dairy cream Bcheesecake Emousse/dessert Atarts,flans and pies Btrifle C

Meat beefburgers Aham - raw (e.g.Parma) Ekebabs Bmeat meals (shepherds/cottage pie/casseroles) Bmeat pies (steak and kidney,pastry) Ameat,sliced (beef,pork,poultry) Cmeat,sliced (cooked ham,tongue) D

pork pies Apoultry (unsliced) Bsalami and fermented meat products Esausage roll Asausages (smoked) Escotch egg A

Ready-to-Eat pasta/pizza BMeals meals (other) B

Sandwiches and with cheese EFilled Rolls with salad E

without salad D

Savoury bean curd Ebhaji (onion,spinach,vegetable) Acheese-based bakery products Bfermented foods Eflan/quiche Bhomous,tzatziki and other dips Dmayonnaise/dressings Bpat (meat,seafood or vegetable) Csamosa Bsatay Cspring rolls C


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Table 2:Aerobic Colony Count Categories for Different Types of Ready-To-Eat Foods

Food Group Product Category(A-E)

Seafood crustaceans (crab,lobster,prawns) Cherring and other raw pickled fish Amolluscs and other shellfish (cooked) Dother fish (cooked) Cseafood meals Csmoked fish Dtaramasalta D

Vegetable coleslaw Cfruit and vegetables (dried) Cfruit and vegetables (fresh) Eprepared mixed salads and crudits Drice Cvegetables and vegetable meals (cooked) B


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References1 Food Safety Advisory Committee (1995). Microbiological Standards Limits and

Guidelines for Foods.Report to the Minister for Health and the Minister forAgriculture,Food and Forestry (Stationary Office,Dublin).Report No.21,April 1995.

2 Public Health Laboratory Service (1992). Provisional microbiological guidelinesfor some ready-to-eat foods sampled at point of sale. Notes for PHLS examiners.PHLS Microbiological Digest 9:98-99.

3 Public Health Laboratory Service (1996). Microbiological guidelines for some

ready-to-eat foods sampled at the point of sale:an expert opinion from the PHLS.PHLS Microbiology Digest 13,(1),41-43.

4 Public Health Laboratory Service (2000). Guidelines for the microbiologicalquality of some ready-to-eat foods at the point of sale. Comm Dis Public Health 3,(3),163-167.http://www.phls.co.uk/publications/CDPHvol3/No3/cdph0300.pdf

5 Microbiology Sub-committee (2001). Material Relevant to Guidelines for theInterpretation of Results of Microbiological Analysis of Some Ready-To-Eat Foods

Sampled at Point of Sale. Food Safety Authority of Ireland.

6 Codex Alimentarius Commission (1981). Report of the 17th Session of theCodex Committee on Food Hygiene,Washington DC.17-21 November 1980.ALINORM 81/13 Appendix II. Codex Alimentarius Commission,FAO Rome.

7 Scientific Committee on Veterinary Measures relating to Public Health(1999). Opinion on L.monocytogenes .European Commission. Health & ConsumerProtection Directorate-General. Directorate B - Scientific Health Opinions.http://europa.eu.int/comm/food/fs/sc/scf/out63 _ en.pdf

8 Guidance Note No.2,Classification of Food (2001). Food Safety Authorityof Ireland.


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Acknowledgements The Food Safety Authority of Ireland is most grateful for the advice and co-operationof the Public Health Laboratory Service Environmental Surveillance Unit of theCommunicable Disease Surveillance Centre at Colindale,London,UK in thepreparation of these Guidelines. The FSAI is particularly grateful for thecategorisation of foods (Table 2) which is the result of the work of that Unit.


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Notes


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Notes


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Notes


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Food Safety Authority of IrelandAbbey Court, Lower Abbey Street,

Dublin 1

dars Sbhilteachta Bia na hireannCirt na Mainistreach,Srid na Mainistreach ocht.,Baile tha Cliath 1

Telephone: +353 1 817 1300Facsimile:+353 1 817 1301

E-mail: [email protected]:wwwfsaiie

Documents

Guidelines for Food Safety