SIST EN ISO 21187:2006
(Main)Milk - Quantitative determination of bacteriological quality - Guidance for establishing and verifying a conversion relationship between routine method results and anchor method results (ISO 21187:2004)
Milk - Quantitative determination of bacteriological quality - Guidance for establishing and verifying a conversion relationship between routine method results and anchor method results (ISO 21187:2004)
This International Standard gives guidelines for the establishment of a conversion relationship between the results of a routine method and an anchor method, and its verification for the quantitative determination of the bacteriological quality of milk.
Milch - Quantitative Bestimmung der bakteriologischen Qualität - Leitfaden für die Erarbeitung einer Übertragungsbeziehung zwischen den Messwerten von Routine- und Bezugsverfahren sowie deren Verifizierung (ISO 21187:2004)
Diese Internationale Norm gibt Anleitungen für die Erarbeitung einer Übertragungsbeziehung zwischen den Ergebnissen eines Routine- und eines Kontrollverfahrens sowie für deren Verifizierung für die quantitative Bestimmung der bakteriologischen Qualität von Milch.
Lait - Mesure quantitative de la qualité bactériologique - Lignes directrices pour établir et vérifier une relation de conversion entre les résultats de la méthode de routine et les résultats de la méthode d'ancrage (ISO 21187:2004)
L'ISO 21187|FIL 196:2004 donne des lignes directrices pour l'établissement d'une relation de conversion entre les résultats d'une méthode de routine et une méthode d'ancrage et sa vérification en vue de la mesure de la qualité bactériologique du lait.
Mleko – Kvantitativno določanje bakteriološke kakovosti – Navodila za ugotavljanje in preverjanje konverzijske povezave med rezultati rutinske metode in rezultati uveljavljene metode (ISO 21187:2004)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 21187:2006
01-marec-2006
0OHNR±.YDQWLWDWLYQRGRORþDQMHEDNWHULRORãNHNDNRYRVWL±1DYRGLOD]D
XJRWDYOMDQMHLQSUHYHUMDQMHNRQYHU]LMVNHSRYH]DYHPHGUH]XOWDWLUXWLQVNHPHWRGHLQ
UH]XOWDWLXYHOMDYOMHQHPHWRGH ,62
Milk - Quantitative determination of bacteriological quality - Guidance for establishing and
verifying a conversion relationship between routine method results and anchor method
results (ISO 21187:2004)
Milch - Quantitative Bestimmung der bakteriologischen Qualität - Leitfaden für die
Erarbeitung einer Übertragungsbeziehung zwischen den Messwerten von Routine- und
Bezugsverfahren sowie deren Verifizierung (ISO 21187:2004)
Lait - Mesure quantitative de la qualité bactériologique - Lignes directrices pour établir et
vérifier une relation de conversion entre les résultats de la méthode de routine et les
résultats de la méthode d'ancrage (ISO 21187:2004)
Ta slovenski standard je istoveten z: EN ISO 21187:2005
ICS:
07.100.30 Mikrobiologija živil Food microbiology
67.100.10 0OHNRLQSUHGHODQLPOHþQL Milk and processed milk
SURL]YRGL products
SIST EN ISO 21187:2006 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 21187:2006
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SIST EN ISO 21187:2006
EUROPEAN STANDARD
EN ISO 21187
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2005
ICS 67.100.01; 07.100.30
English Version
Milk - Quantitative determination of bacteriological quality -
Guidance for establishing and verifying a conversion relationship
between routine method results and anchor method results (ISO
21187:2004)
Lait - Mesure quantitative de la qualité bactériologique - Milch - Quantitative Bestimmung der bakteriologischen
Lignes directrices pour établir et vérifier une relation de Qualität - Leitfaden für die Erarbeitung einer
conversion entre les résultats de la méthode de routine et Übertragungsbeziehung zwischen den Messwerten von
les résultats de la méthode d'ancrage (ISO 21187:2004) Routine- und Bezugsverfahren sowie deren Verifizierung
(ISO 21187:2004)
This European Standard was approved by CEN on 30 September 2005.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21187:2005: E
worldwide for CEN national Members.
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SIST EN ISO 21187:2006
EN ISO 21187:2005 (E)
Foreword
The text of ISO 21187:2004 has been prepared by Technical Committee ISO/TC 34 "Agricultural
food productss” of the International Organization for Standardization (ISO) and has been taken
over as EN ISO 21187:2005 by Technical Committee CEN/TC 302 "Milk and milk products -
Methods of sampling and analysis", the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by April 2006, and conflicting national
standards shall be withdrawn at the latest by April 2006.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Endorsement notice
The text of ISO 21187:2004 has been approved by CEN as EN ISO 21187:2005 without any
modifications.
2
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SIST EN ISO 21187:2006
INTERNATIONAL ISO
STANDARD 21187
IDF
196
First edition
2004-12-01
Milk — Quantitative determination of
bacteriological quality — Guidance for
establishing and verifying a conversion
relationship between routine method
results and anchor method results
Lait — Mesure quantitative de la qualité bactériologique — Lignes
directrices pour établir et vérifier une relation de conversion entre
les résultats de la méthode de routine et les résultats de la méthode
d'ancrage
Reference numbers
ISO 21187:2004(E)
IDF 196:2004(E)
©
ISO and IDF 2004
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SIST EN ISO 21187:2006
ISO 21187:2004(E)
IDF 196:2004(E)
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Published in Switzerland
ii © ISO and IDF 2004 – All rights reserved
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SIST EN ISO 21187:2006
ISO 21187:2004(E)
IDF 196:2004(E)
Contents Page
Foreword. iv
Introduction . vi
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 1
4 Principles . 2
4.1 Prerequisites . 2
4.2 Organizational set-up . 2
5 Establishing a conversion relationship. 3
5.1 Consideration of influencing factors and their consequences. 3
5.2 Test samples . 4
5.3 Pretreatment of test samples. 5
5.4 Analysis. 6
5.5 Calculation. 7
5.6 Expression of results. 7
6 Verification of a conversion relationship . 8
6.1 Frequency of verification . 8
6.2 Test samples . 8
6.3 Pretreatment of test samples. 8
6.4 Analysis. 8
6.5 Calculation and verification of a conversion relationship. 8
7 Test report. 9
Annex A (informative) Number of samples for linear regression. 10
Bibliography . 13
© ISO and IDF 2004 – All rights reserved iii
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SIST EN ISO 21187:2006
ISO 21187:2004(E)
IDF 196:2004(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has
been established has the right to be represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 21187IDF 196 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5,
Milk and milk products, and the International Dairy Federation (IDF), in collaboration with AOAC International.
It is being published jointly by ISO and IDF and separately by AOAC International.
iv © ISO and IDF 2004 – All rights reserved
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SIST EN ISO 21187:2006
ISO 21187:2004(E)
IDF 196:2004(E)
Foreword
IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a National
Committee in every member country. Every National Committee has the right to be represented on the IDF
Standing Committees carrying out the technical work. IDF collaborates with ISO and AOAC International in
the development of standard methods of analysis and sampling for milk and milk products.
Draft International Standards adopted by the Action Teams and Standing Committees are circulated to the
National Committees for voting. Publication as an International Standard requires approval by at least 50 % of
the National Committees casting a vote.
ISO 21187IDF 196 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5,
Milk and milk products, and the International Dairy Federation (IDF), in collaboration with AOAC International.
It is being published jointly by ISO and IDF and separately by AOAC International.
All work was carried out by the Joint ISO/IDF/AOAC Action Team, Routine analysis in quantitative
microbiology, of the Standing Committee on Quality assurance, statistics of analytical data and sampling,
under the aegis of its project leader, Mr H.J.C.M. van den Bijgaart (NL).
© ISO and IDF 2004 – All rights reserved v
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SIST EN ISO 21187:2006
ISO 21187:2004(E)
IDF 196:2004(E)
Introduction
Conversion in quantitative microbiology means expressing the result of a quantitative determination of the
bacteriological status of a test sample as obtained with a routine method in units of another method, generally
a reference or anchor method. Through this, quantitative results obtained with routine methods can be
compared to values or limits that are stated in reference or anchor method units. For establishing and applying
a conversion relationship, a number of prerequisites should be met. These are referred to in this International
Standard, but are generally described elsewhere.
Although a considerable part of the applied principles for conversion coincides with those applied for the
calibration of indirect or routine methods against a reference method, or by means of (certified) reference
materials, it is stressed that the background and aims for applying conversion are different from those for
calibration. Calibration involves the determination of the adjustment needed for each level of an analyte to
closely approximate the true value of its concentration or number. However in quantitative microbiology, a true
value in its strict sense cannot be established and is only defined by the method description applied. When
applying routine methods in the quantitative determination of bacteriological quality, one is often dealing with
different methodological principles and therefore also other units. Conversion is used to transfer results
obtained with different methods to a common scale.
vi © ISO and IDF 2004 – All rights reserved
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SIST EN ISO 21187:2006
ISO 21187:2004(E)
INTERNATIONAL STANDARD
IDF 196:2004(E)
Milk — Quantitative determination of bacteriological quality —
Guidance for establishing and verifying a conversion
relationship between routine method results and anchor
method results
1 Scope
This International Standard gives guidelines for the establishment of a conversion relationship between the
results of a routine method and an anchor method, and its verification for the quantitative determination of the
bacteriological quality of milk.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3534-1, Statistics — Vocabulary and symbols — Part 1: Probability and general statistical terms
ISO 8196-1IDF 128-1, Milk — Definition and evaluation of the overall accuracy of indirect methods of milk
analysis — Part 1: Analytical attributes of indirect methods
ISO 8196-2IDF 128-2, Milk — Definition and evaluation of the overall accuracy of indirect methods of milk
analysis — Part 2: Calibration and quality control in the dairy laboratory
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3534-1, ISO 8196-1IDF 128-1,
ISO 8196-2IDF 128-2 and the following apply.
3.1
routine method
alternative method
method of analysis allowing quantification of the bacteriological status of a test sample
NOTE 1 The method can be proprietary or non-commercial.
NOTE 2 The term “routine” or “alternative” in this International Standard refers to the entire method. It includes all
aspects (such as sample pretreatment, materials and instruments) required for the execution of the method.
NOTE 3 The term “routine method” is used in this International Standard.
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SIST EN ISO 21187:2006
ISO 21187:2004(E)
IDF 196:2004(E)
3.2
anchor method
reference method
method of analysis internationally recognized by experts or by agreement between parties, and used, for
instance, in legislation when expressing official limits for bacteriological quality
NOTE It is stressed that, in quantitative microbiology, any obtained value is only defined by the method description
applied. This applies to any routine method as well as, for instance, to the standard plate count for the enumeration of
microorganisms. For the purpose of conversion, the term anchor method is preferred over the term reference method and
therefore is used throughout this International Standard.
3.3
analyte
component or property which is measured by the method of analysis
NOTE The analyte may be the microorganism, stained particles (e.g. microscopic count), components of
microorganisms (e.g. lipopolysaccharides), the result of their ability to multiply (e.g. colony-forming units) or their metabolic
activity (e.g. change in conductivity/impedance).
3.4
organizing laboratory
laboratory, possibly appointed by the competent authorities, having the qualified staff and skills to organize, to
coordinate and to report on the outcome of the activities for the establishment or the maintenance of a
conversion relationship
4 Principles
4.1 Prerequisites
For establishing and verifying a conversion relationship between the results of a routine method and the
anchor method, the following prerequisites apply.
1)
a) The routine method should have been validated according to ISO 16140 . Procedures for sampling, test
sample preservation, sample transport, sample storage, sample pre-treatment, analysis and calculation of
results should be documented, strictly standardized and controlled in agreement with ISO/IEC 17025,
EA-4/10, or comparable standards.
b) The anchor method should have been validated, documented, strictly standardized and controlled in
agreement with ISO/IEC 17025, EA-4/10 or comparable standards.
c) The protocol for the establishment of the conversion relationship and its verification should be
documented. It should follow the guidelines of this International Standard. Approval by competent
authorities should be sought where the final aim is that results from a routine method are to be judged
against official limits stated in the anchor method units.
4.2 Organizational set-up
The establishment and verification of a conversion relationship is based on the examination of test samples
with both methods, covering the field of application and the spectrum of the samples as analysed using the
routine method.
A number of situations can be distinguished, as follows.
a) Both the routine method and the anchor method are fully carried out in the same laboratory.
1) Additional guidance on aspects relevant to milk and not covered by ISO 16140 can be found in IDF 161A.
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SIST EN ISO 21187:2006
ISO 21187:2004(E)
IDF 196:2004(E)
b) The routine method is carried out in a number of laboratories and the anchor method is carried out in one
laboratory (not necessarily a routine laboratory). In this situation, sub-samples must be prepared and
transported from the location where the routine method is to be carried out to the laboratory where the
anchor method is to be carried out, or the other way around.
c) Both the routine method and the anchor method are carried out in a number of laboratories. As in b), the
preparation and the transport of sub-samples must be properly considered.
Due to the instability and variability of the bacteriological status of milk samples, the most robust conversion
relationships will be obtained where the routine method and the anchor method are undertaken on the same
test samples, at the same place, at the same time; i.e. situation a).
In all cases, the organizational set-up should include all the necessary provisions to guarantee that the
obtained conversion relationship is representative of the circumstances under which the routine method is
carried out and the resulting conversion relationship is later applied.
The organizing laboratory should provide guidance to the collaborating laboratories. Furtherm
...
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