guidelines for the interpretation of microbiological analysis of rte foods

Guidance Note

No. 3

Guidelines for theInterpretation of

Results ofMicrobiological

Analysis of SomeReady-To-Eat

Foods Sampled at Point of Sale

fsai-guidance note 3 v3-15029 29/6/01 4:08 PM Page 3 Derek ALPHA:Desktop Folder:FSAI:FSAI-Guidance Note 3-15029:

Guidelines for the Interpretation of Results

of Microbiological Analysis

of Some Ready-To-Eat Foods

Sampled 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


Other Food Safety Guidance Notes available fromthe 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


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 8

OF SOME READY-TO-EAT FOODS AT POINT OF SALE

TABLE 2: AEROBIC COLONY COUNT CATEGORIES FOR 9

DIFFERENT TYPES OF READY-TO-EAT FOODS

REFERENCES 11

ACKNOWLEDGEMENTS 12

Contents


The Food Safety Authority of Ireland Act, 1998, facilitated the establishment of the Food

Safety Authority of Ireland (FSAI) to perform the functions assigned to it by this Act. The

principal function of the Authority shall be to take all reasonable steps to ensure that:

(a) food produced in the State (whether or not distributed or marketed in the State),

and

(b) food distributed or marketed in the State,

meets the highest standards of food safety and hygiene reasonably attainable and it shall, in

particular, take all reasonable steps to ensure that such food complies:

1) with any relevant food legislation in respect of food safety and hygiene standards, or

2) in the absence of any such legislation, with the provisions of generally recognised

standards or codes of good practice aimed at ensuring the achievement of high

standards of food hygiene and food safety.

The FSAI believes that Guidance Notes have a major role to play in helping both the

regulators and the food industry achieve a higher degree of compliance with Regulations

and with good practice generally. A good, well prepared, Guidance Note must, if it is to

achieve these objectives, provide regulators and industry alike with clear guidance towards

the application of the relevant legislation. While a Guidance Note is not, of course, a

substitute for the Regulations, the FSAI believes that adherence to it should make

compliance easier by providing the basis for a high degree of consistency in application of

those Regulations.

We hope this series of Guidance Notes will meet the aims we have set out here and that

they will contribute to the development of the high standards we aim to achieve in the food

inspection services.

Introduction

1


BackgroundThe Microbiology Sub-committee of the Food Safety Authority of Ireland has undertaken a

review of the microbiology guidelines for some ready-to-eat foods sampled at point of sale

as they appear in the 1995 report of the former Food Safety Advisory Committee1.

The 1995 guidelines were adapted from guidelines published by the UK Public Health

Laboratory Service (PHLS) in 19922. The revision and expansion of the PHLS guidelines in

19963 and subsequent revision in 20004, have necessitated the current review by the

Microbiology 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 to

be made as experience is gained of their value in practice and as additional information

becomes available.

In addition to these guidelines for ready-to-eat foods sampled at point of sale, there is a

supporting document that contains relevant material5. The supporting document broadly

describes the approach to establishing microbiological criteria and food sampling plans for

all foods sampled at any point in the food chain. It also includes a summary of the

microbiological criteria (standards and guidelines) as listed in current EU legislation.

Microbiological CriteriaMicrobiological criteria are essentially of three types: guidelines, standards and

specifications.These terms were originally defined by Codex Alimentarius6 and have since

been redefined both by Codex and other international organisations. They can be described

as 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 and

retailing. It aids in identifying situations requiring attention for food safety or quality

reasons. Guidelines arise from many sources - the food industry, enforcement

agencies and, national and international committees, and are especially applied to

indicator organisms. While guidelines may be written in law they are not legally

enforceable, but serve to provide assistance to enforcement agencies in interpreting

whether producers are complying with the general policy in relation to standards.

2


Guidelines can both complement legally enforceable standards and provide a

benchmark in the situations where standards are not considered necessary. A

persistent and widespread breach of the guidelines could be an indication of

poor manufacturing or handling practice. Guidelines also provide a benchmark against

which unacceptable microbial contamination of food can be identified. Guideline

levels for microbiological hazards are proposed as a mechanism to identify

the maximum level of contamination that is reasonably acceptable and to

provide a trigger for remedial action when these levels are exceeded.

An adverse health effect is not an inevitable consequence of consumption of foods

containing microorganisms above the guideline levels. However, the presence of

microorganisms above the guideline levels does indicate that human exposure to

particular micro-organisms may occur at undesirable and preventable levels.

• A microbiological standard is a microbiological criterion contained in a law where

compliance is mandatory. The food industry must ensure full compliance with these

standards which are monitored by enforcement agencies.

• A microbiological specification is a microbiological criterion applied to raw

materials, ingredients or the end-product which is used in a purchase agreement.

Specifications are set by purchasers and are usually more stringent than

microbiological 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 in

determining the microbiological quality of various ready-to-eat foods sampled at point of

sale. Traditionally, in enforcement situations, microbiological examination has played an

important role in evaluating the microbiological safety of food. Food inspection services

generally rely on the examination of single food samples rather than statistically based

sampling plans. The results from single sample examination may provide evidence that food

hygiene regulations have been contravened or provide the basis for additional inspection

and/or food sampling. They may also give valuable baseline data (usually where samples form

part of a specific survey) which can be used for trend analysis. Where there is routine

sampling, the choice of food to be sampled will vary according to the local need, and the

occurrence of cases and outbreaks of foodborne illness in the area or nationally.

3


Ready-to-Eat FoodsAll composite foods purchased by or supplied to a consumer for their consumption and

which 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 variation

in the composition of ready-to-eat foods. They range from those containing some

ingredients that are uncooked, such as sandwiches, to those that are cooked immediately

prior to being provided to the consumer. A list of the more common ready-to-eat foods

and their categories are outlined in Table 2. Excluded categories include low water activity

foods and other ambient temperature stable foods such as jams, canned food, cured food

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

Interpretation of GuidelinesThe 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 and

authorised officers. They may be used to monitor the microbiological quality of a food. The

microbiological criteria used in the guidelines can be of prime importance in deciding if a

food 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 hygiene

standards. It should be noted that the specification of a criterion for a particular organism

does 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 microbiological

criteria for a variety of foodstuffs. Some of these criteria may apply to ready-to-eat foods

sampled at point of sale. For convenience, these directives and their criteria are

summarised in the supporting document.To ensure correct application of these criteria, the

current legislation must be read. In addition, it should be noted that the European

Commission’s Scientific Committee on Veterinary Measures Relating to Public Health has

recently evaluated the legal standards and has expressed an opinion on possible changes7.

Revised GuidelinesThe 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 30oC for 48±2h.

4


2. Five categories of ready-to-eat foods have been identified (Table 2). To avoid

confusion with the 21 EU categories8 (designated by the numbers 1-21) from the

guidelines on Article 14 of Directive 89/397/EEC, the five ready-to-eat categories in

this document are designated by the upper case letters A to E. The first four

categories are based on a range of “aerobic colony counts” expected according to

the type of product and the processing it has received. The fifth category refers to

certain fermented foods for which guidelines for aerobic colony counts may not be

applicable. 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 should

be 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 growth

during storage.

3. Four quality levels remain, but the term “fairly satisfactory” has been renamed

“acceptable”. 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, Clostridium perfringens, Bacillus cereus and other pathogenic

Bacillus 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 in

microbiological 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 has

been exceeded. Further sampling may be necessary and the authorised officer may

wish to carry out a detailed inspection of premises, food production and handling

processes to determine whether hygiene practices for food production or handling

are 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 are

similar to or less stringent than the microbiological standards in the relevant EU

Directives5. If an authorised officer suspects that the product may be in breach of

5


the legal criteria, they are advised to consult the relevant directive and inform the

relevant authorised officer under the directive in force. There are examples where

the 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 the

“unacceptable/potentially hazardous” category, the issue of possible withdrawal under

the ready-to-eat guidelines should not arise (see definition of the

unacceptable/potentially hazardous category).

• The numbers quoted under the heading “unacceptable/potentially hazardous”

represent a potential health hazard to those consuming such food. Samples falling in

the “unacceptable/potentially hazardous” category should prompt a rapid response

by the authorised officer and a detailed assessment should take place. Product

withdrawal 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. Coliforms

have been the traditional indicator group in this context. Coliforms are those

members of the Enterobacteriaceae that ferment lactose and include Enterobacter,

most Escherichia, Klebsiella and Citrobacter. Tests for coliform bacteria will only detect

organisms capable of fermenting lactose. If large numbers of non-lactose-fermenting

bacilli are present, reliance on tests for coliform bacteria may lead to falsely

reassuring 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 family

Enterobacteriaceae instead of coliforms may give a better indication of the likelihood

of the presence of pathogens, as well as providing more accurate information about

the handling and storage of the foodstuff. It should be noted that this test is not

applicable 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 column

have been deleted (Table 1). Additionally, Listeria spp. has been modified to include

L. monocytogenes because of the changes to the quantitative criteria for

L. monocytogenes (see below).

6


7

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

• Vibrio cholerae has been included because the European Commission has made

several decisions in response to the isolation of this organism from various imported

ready-to-eat foods, mainly fishery products and, fruits and vegetables. Vibrio cholerae

O1 and O139 are the two serogroups responsible for disease. V. parahaemolyticus in

seafood 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 to

a number of recent opinions and published reports6. It is recognised that some

serotypes/phage types of L. monocytogenes may rarely be associated with human

infection, 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 for

some ready-to-eat foods and will take precedence over these guidelines.

• The Clostridium perfringens quantitative quality level for the “satisfactory” category is

now <20 cfu/g to bring it in line with the levels for other gram positive pathogens.

• The microbiological criteria have been altered for the Bacillus cereus and other

pathogenic Bacillus spp. to take account of the minimum infective dose (of >105/g) in

the case of the diarrhoeal disease. In the case of the emetic disease, the minimum

number of cells required in a food to produce the minimum intoxication dose is also

>105/g. When present in foods, B. cereus is usually at concentrations of <103/g.

Bacillus species other than B. cereus, notably those of the B. subtilus-licheniformis group,

have also been implicated in outbreaks of food poisoning from meat and pastry

products and, meat or seafood rice dishes. This group is now included in the revised

guidelines. Initial isolation and enumeration procedures are similar to those for

B. cereus and biochemical tests are necessary for confirmation.


Table 1: Guidelines for the Microbiological Quality

of 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)

8

(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 the

relevant 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 paté and sliced meats.(i) If the Bacillus counts exceed 104 per gram, the organism should be identified.N/A Denotes not applicable.

Aerobic colony count (d)

30oC / 48h

A <103 103-<104 >104 N/A

B <104 104-<105 >105 N/A

C <105 105-<106 >106 N/A

D <106 106-<107 >107 N/AE N/A N/A N/A N/A

Indicator organisms(e)

A-E Enterobacteriaceae (f) <100 100-<104 >104 N/AA-E Escherichia coli (total) <20 20-<100 >100 N/AA-E Listeria spp. (total) <20 20-<100 >100 N/A

PathogensA-E Salmonella spp Not detected Detected

in 25g in 25gA-E Campylobacter spp. Not detected Detected

in 25g in 25gA-E E. coli O157 & other VTEC Not detected Detected

in 25g in 25gA-E Vibrio cholerae Not detected Detected

in 25g in 25gA-E Vibrio parahaemolyticus (g) <20 20-<100 100-<103 >103

A-E L. monocytogenes <20 (h) 20-<100 N/A >100A-E Staphylococcus aureus <20 20-<100 100-<104 >104

A-E Clostridium perfringens <20 20-<100 100-<104 >104

A-E Bacillus cereus & otherpathogenic Bacillus spp. (i) <103 103-<104 104-<105 >105


9

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) Dpork 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 Bpaté (meat, seafood or vegetable) Csamosa Bsatay Cspring rolls C


10

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 crudités Drice Cvegetables and vegetable meals (cooked) B


11

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

Guidelines for Foods. Report to the Minister for Health and the Minister for

Agriculture, Food and Forestry (Stationary Office, Dublin). Report No. 21,April 1995.

2 Public Health Laboratory Service (1992). Provisional microbiological guidelines

for 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 microbiological

quality 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 the

Interpretation 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 the

Codex 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 & Consumer

Protection 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 Authority

of Ireland.


12

AcknowledgementsThe Food Safety Authority of Ireland is most grateful for the advice and co-operation

of the Public Health Laboratory Service Environmental Surveillance Unit of the

Communicable Disease Surveillance Centre at Colindale, London, UK in the

preparation of these Guidelines. The FSAI is particularly grateful for the

categorisation of foods (Table 2) which is the result of the work of that Unit.


Notes


Food Safety Authority of Ireland

Abbey Court, Lower Abbey Street,

Dublin 1

Údarás Sábháilteachta Bia na hÉireann

Cúirt na Mainistreach, Sráid na Mainistreach Íocht.,

Baile Átha Cliath 1

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

E-mail: [email protected]: www.fsai.ieISBN 0-9539183-5-1


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