Milk - Bacterial count - Protocol for the evaluation of alternative methods (ISO 16297:2020)

This document specifies a protocol for the evaluation of instrumental alternative methods for total bacterial count in raw milk from animals of different species.

Milch - Bestimmung der Gesamtkeimzahl - Protokoll für die Bewertung alternativer Verfahren (ISO 16297:2020)

Dieses Dokument legt ein Protokoll für die Bewertung alternativer instrumenteller Verfahren zur Bestimmung der Gesamtkeimzahl in Rohmilch von verschiedenen Tierarten fest.
ANMERKUNG   Das Dokument ist eine Ergänzung zu ISO 16140 2 und ISO 8196 | IDF 128 (alle Teile).

Lait - Dénombrement bactériologique - Protocole pour l'évaluation de méthodes alternatives (ISO 16297:2020)

Le présent document spécifie un protocole pour l'évaluation de méthodes instrumentales alternatives pour le dénombrement bactérien total dans le lait cru provenant d'animaux de différentes espèces.
NOTE Le document est complémentaire à l'ISO 16140-2 et à l'ISO 8196 | FIL 128 (toutes les parties).

Mleko - Število bakterij - Protokol za vrednotenje alternativnih metod (ISO 16297:2020)

Ta dokument določa protokol za vrednotenje bistvenih alternativnih metod za štetje bakterij v surovem mleku različnih vrst živali.

General Information

Status
Published
Public Enquiry End Date
04-Jul-2019
Publication Date
10-Feb-2020
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
30-Jan-2020
Due Date
05-Apr-2020
Completion Date
11-Feb-2020

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SLOVENSKI STANDARD
SIST EN ISO 16297:2020
01-marec-2020
Nadomešča:
SIST EN ISO 16297:2014
Mleko - Število bakterij - Protokol za vrednotenje alternativnih metod (ISO
16297:2020)
Milk - Bacterial count - Protocol for the evaluation of alternative methods (ISO
16297:2020)
Milch - Bestimmung der Gesamtkeimzahl - Protokoll für die Bewertung alternativer
Verfahren (ISO 16297:2020)
Lait - Dénombrement bactériologique - Protocole pour l'évaluation de méthodes
alternatives (ISO 16297:2020)
Ta slovenski standard je istoveten z: EN ISO 16297:2020
ICS:
67.100.10 Mleko in predelani mlečni Milk and processed milk
proizvodi products
SIST EN ISO 16297:2020 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 16297:2020
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SIST EN ISO 16297:2020
EN ISO 16297
EUROPEAN STANDARD
NORME EUROPÉENNE
January 2020
EUROPÄISCHE NORM
ICS 67.100.10 Supersedes EN ISO 16297:2014
English Version
Milk - Bacterial count - Protocol for the evaluation of
alternative methods (ISO 16297:2020)

Lait - Dénombrement bactériologique - Protocole pour Milch - Bestimmung der Gesamtkeimzahl - Protokoll

l'évaluation de méthodes alternatives (ISO für die Bewertung alternativer Verfahren (ISO

16297:2020) 16297:2020)
This European Standard was approved by CEN on 3 January 2020.

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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16297:2020 E

worldwide for CEN national Members.
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SIST EN ISO 16297:2020
EN ISO 16297:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 16297:2020
EN ISO 16297:2020 (E)
European foreword

This document (EN ISO 16297:2020) has been prepared by Technical Committee ISO/TC 34 "Food

products" in collaboration with 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 July 2020, and conflicting national standards shall be

withdrawn at the latest by July 2020.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 16297:2014.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 16297:2020 has been approved by CEN as EN ISO 16297:2020 without any modification.

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SIST EN ISO 16297:2020
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SIST EN ISO 16297:2020
INTERNATIONAL ISO
STANDARD 16297
IDF 161
Second edition
2020-01
Milk — Bacterial count — Protocol for
the evaluation of alternative methods
Lait — Dénombrement bactériologique — Protocole pour
l'évaluation de méthodes alternatives
Reference numbers
ISO 16297:2020(E)
IDF 161:2020(E)
ISO and IDF 2020
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SIST EN ISO 16297:2020
ISO 16297:2020(E)
IDF 161:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO and IDF 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office International Dairy Federation
CP 401 • Ch. de Blandonnet 8 Silver Building • Bd Auguste Reyers 70/B
CH-1214 Vernier, Geneva B-1030 Brussels
Phone: +41 22 749 01 11 Phone: +32 2 325 67 40
Fax: +41 22 749 09 47 Fax: +32 2 325 67 41
Email: copyright@iso.org Email: info@fil-idf.org
Website: www.iso.org Website: www.fil-idf.org
Published in Switzerland
ii © ISO and IDF 2020 – All rights reserved
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SIST EN ISO 16297:2020
ISO 16297:2020(E)
IDF 161:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Transformation of results ........................................................................................................................................................................... 1

5 Attributes of the alternative method ............................................................................................................................................... 2

5.1 General ........................................................................................................................................................................................................... 2

5.2 Description of the method to be evaluated .................................................................................................................... 2

5.2.1 Description .................. .................................................... ...................................................................................................... 2

5.2.2 Checklist .................................................................................................................................................................................. 2

5.3 Measuring range .................................................................................................................................................................................... 2

5.3.1 Lower limit of quantification................................................................................................................................. 2

5.3.2 Upper limit of quantification ................................................................................................................................. 3

5.3.3 Linearity of the instrument signal .................................................................................................................... 3

5.4 Carry-over ................................................................................................................................................................................................... 4

5.5 Stability .......................................................................................................................................................................................................... 5

5.6 Precision ....................................................................................................................................................................................................... 6

5.6.1 General...................................................................................................................................................................................... 6

5.6.2 Repeatability ....................................................................................................................................................................... 6

5.6.3 Reproducibility .................................................................................................................................................................. 6

5.6.4 Evaluation of factors affecting the results .................................................................................................. 6

6 Alternative method as an estimate of the anchor method ........................................................................................ 6

6.1 General ........................................................................................................................................................................................................... 6

6.2 Evaluation of factors affecting the estimation ............................................................................................................. 7

6.3 Measurement protocol ..................................................................................................................................................................... 7

6.4 Calculations ................................................................................................................................................................................................ 7

6.4.1 General...................................................................................................................................................................................... 7

6.4.2 Visual check of a scatter diagram ...................................................................................................................... 7

6.4.3 Outliers ..................................................................................................................................................................................... 8

6.4.4 Accuracy of the estimate and accuracy profile ...................................................................................... 8

6.5 Attributes of the alternative method expressed in units of the anchor method .........................10

7 Rating of the elaborated attributes ................................................................................................................................................10

Bibliography .............................................................................................................................................................................................................................11

© ISO and IDF 2020 – All rights reserved iii
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SIST EN ISO 16297:2020
ISO 16297:2020(E)
IDF 161:2020(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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO’s adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5,

Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO

and IDF.

This second edition cancels and replaces the first edition (ISO 16297 | IDF 161:2013), which has been

technically revised with the following main changes:

— the number of samples and the calculation of the lower limit of quantification has been changed and

aligned with ISO 16140-2;
— an example of carry-over effect given in Figure 1 has been omitted;

— the requirements for the evaluation of the accuracy of the estimate and the accuracy profile have

been clarified and aligned with ISO 16140-2;
— Annex A (informative) has been omitted.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO and IDF 2020 – All rights reserved
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SIST EN ISO 16297:2020
ISO 16297:2020(E)
IDF 161:2020(E)

IDF (the International Dairy Federation) is a non-profit private sector organization representing the

interests of various stakeholders in dairying at the global level. IDF members are organized in National

Committees, which are national associations composed of representatives of dairy-related national

interest groups including dairy farmers, dairy processing industry, dairy suppliers, academics and

governments/food control authorities.

ISO and IDF collaborate closely on all matters of standardization relating to methods of analysis

and sampling for milk and milk products. Since 2001, ISO and IDF jointly publish their International

Standards using the logos and reference numbers of both organizations.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. IDF shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

This document was prepared by the IDF Standing Committee on Statistics and Automation and ISO

Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It is being

published jointly by IDF and ISO.

The work was carried out by the IDF/ISO Action Team (S18) of the Standing Committee on Statistics and

Automation under the aegis of its project leaders, Mrs V. Tzeneva (NL) and Mrs I. Andersson (SE).

© ISO and IDF 2020 – All rights reserved v
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SIST EN ISO 16297:2020
ISO 16297:2020(E)
IDF 161:2020(E)
Introduction

Any quantitative measurement in microbiology should consider that there is a requirement for the

microbiological state in a sample to be regarded as one point within the coordinates of a multidimensional

system, which is to be projected on to the one-dimensional scale of the method applied, i.e. plate count,

flow cytometry. Aspects such as flora (types and numbers of microorganisms and their distribution),

growth phase, sub-lethal damage, metabolic activity, and history, influence to a greater or lesser extent

any parameter that is measured. It is evident that any projection of an n-dimensional situation onto a

one-dimensional scale is bound to provide a picture of the real situation that is rather restricted. In this

respect, one has to bow to the inevitable, regardless of which method of measurement is preferred.

The term “anchor method” in this document means a method internationally recognized by experts,

used in legislation or by agreement between the parties. There are requirements for evaluation of

an alternative method to refer to the anchor method and to be based on the examination of suitable

samples for its intended use.
vi © ISO and IDF 2020 – All rights reserved
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SIST EN ISO 16297:2020
ISO 16297:2020(E)
INTERNATIONAL STANDARD
IDF 161:2020(E)
Milk — Bacterial count — Protocol for the evaluation of
alternative methods
1 Scope

This document specifies a protocol for the evaluation of instrumental alternative methods for total

bacterial count in raw milk from animals of different species.

NOTE The document is complementary to ISO 16140-2 and ISO 8196 | IDF 128 (all parts).

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 5725-1, Accuracy (trueness and precision) of measurement methods and results — Part 1: General

principles and definitions

ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method

for the determination of repeatability and reproducibility of a standard measurement method

ISO 8196 | IDF 128 (all parts), Milk — Definition and evaluation of the overall accuracy of alternative

methods of milk analysis

ISO 16140-1, Microbiology of the food chain — Method validation — Part 1: Vocabulary

ISO 21187 | IDF 196, Milk — Quantitative determination of bacteriological quality — Guidance for

establishing and verifying a conversion relationship between results of an alternative method and anchor

method results
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 5725-1, ISO 5725-2,

ISO 8196-1 | IDF 128-1, ISO 8196-2 | IDF 128-2, ISO 8196-3 | IDF 128-3 and ISO 16140-1 apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Transformation of results

A prerequisite for statistics most common in the evaluation of measuring methods is the approximation

of a normal distribution of the data. The exponential multiplication of microorganisms usually leads to a

right-tailed distribution with quantitative microbiological parameters. Thus, in general, transformation

of the raw data is necessary for approximation of normality. This is usually a common logarithmic

transformation. The most appropriate transformation can be checked by comparing histograms. All

statistics are then computed from the transformed data, unless specified otherwise, and only the final

results are re-transformed to give a more expressive idea of the situation to the user (see Reference [2]).

© ISO and IDF 2020 – All rights reserved 1
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SIST EN ISO 16297:2020
ISO 16297:2020(E)
IDF 161:2020(E)
5 Attributes of the alternative method
5.1 General

For each alternative method, only the relevant parameters outlined in this clause shall be

...

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