1、BSI Standards PublicationBS EN ISO 16297:2014Milk Bacterial count Protocol for the evaluationof alternative methods (ISO16297:2013)BS EN ISO 16297:2014National forewordThis British Standard is the UK implementation of EN ISO 16297:2014. It is identical to ISO 16297:2013. It supersedes BS ISO 16297:2
2、013 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee AW/5, Chemical analysis of milk and milk products.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the
3、 necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2014. Published by BSI Standards Limited 2014ISBN 978 0 580 84187 3ICS 67.100.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Stand
4、ard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2014.Amendments/corrigenda issued since publicationDate Text affected31 July 2014 This corrigendum renumbers BS ISO 16297:2013 as BS EN ISO 16297:2014BRITISH STANDARDEUROPEAN STANDARD NORME EUROPENNE EURO
5、PISCHE NORM EN ISO 16297 May 2014 ICS 67.100.10 English Version Milk - Bacterial count - Protocol for the evaluation of alternative methods (ISO 16297:2013) Lait - Dnombrement bactrien - Protocole pour lvaluation des mthodes alternatives (ISO 16297:2013) Milch - Bestimmung der Gesamtkeimzahl - Proto
6、koll fr die Bewertung alternativer Verfahren (ISO 16297:2013) This European Standard was approved by CEN on 1 May 2014. 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
7、 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 lan
8、guage 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, Denma
9、rk, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE
10、FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 16297:2014 E3 Foreword The
11、text of ISO 16297:2013 has been prepared by Technical Committee ISO/TC 34 “Food products” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 16297:2014 by Technical Committee CEN/TC 302 “Milk and milk products - Methods of sampling and analysis” the secreta
12、riat 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 November 2014, and conflicting national standards shall be withdrawn at the latest by November 2014. Attention is draw
13、n to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the followin
14、g countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norw
15、ay, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 16297:2013 has been approved by CEN as EN ISO 16297:2014 without any modification. BS EN ISO 16297:2014 EN ISO 16297:2014 (E)BS EN ISO 16297:2014ISO 16297:
16、2013(E)IDF 161:2013(E) ISO and IDF 2013 All rights reserved iiiContents PageForeword ivIntroduction vi1 Scope . 12 Normative references 13 Terms and definitions . 14 Transformation of results . 15 Attributes of the alternative method . 25.1 Description of the method to be evaluated 25.2 Measuring ra
17、nge 25.3 Carry-over . 35.4 Stability 55.5 Precision . 56 The alternative method as an estimate of the reference method 66.1 Evaluation of factors affecting the estimation . 66.2 Measurement protocol . 76.3 Calculations 76.4 Attributes of the alternative method expressed in units of the reference met
18、hod .107 Rating of the elaborated attributes 10Annex A (informative) Expression of precision parameters 11Bibliography .13BS EN ISO 16297:2014ISO 16297:2013(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies).
19、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-g
20、overnmental, 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.
21、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 vo
22、te.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 16297|IDF 161 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5,
23、Milk and milk products and the International Dairy Federation (IDF). It is being published jointly by ISO and IDF.IDF 161:2013(E)iv ISO and IDF 2013 All rights reservedBS EN ISO 16297:2014ISO 16297:2013(E)ForewordIDF (the International Dairy Federation) is a non-profit organization representing the
24、dairy sector worldwide. IDF membership comprises National Committees in every member country as well as regional dairy associations having signed a formal agreement on cooperation with IDF. All members of IDF have the right to be represented at the IDF Standing Committees carrying out the technical
25、work. IDF collaborates with ISO in the development of standard methods of analysis and sampling for milk and milk products.The main task of Standing Committees is to prepare International Standards. Draft International Standards adopted by the Standing Committees are circulated to the National Commi
26、ttees for endorsement prior to publication as an International Standard. Publication as an International Standard requires approval by at least 50 % of IDF National Committees casting a vote.Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
27、 rights. IDF shall not be held responsible for identifying any or all such patent rights.ISO 16297|IDF 161 was prepared by the International Dairy Federation (IDF) and Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It is being published jointly by IDF and IS
28、O.All work was carried out by Joint ISO-IDF Project Group (S07) of the Standing Committee on Statistics and automation under the aegis of its project leader, Mrs. I. Andersson (SE).This first edition of ISO 16297|IDF 161 cancels and replaces IDF 161A:1995, which has been technically revised.IDF 161:
29、2013(E) ISO and IDF 2013 All rights reserved vBS EN ISO 16297:2014ISO 16297:2013(E)IntroductionAny 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 co-ordinates of a multidimensional
30、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 le
31、sser extent any parameter that is measured. It is evident that any projection of an n-dimensional situation on to an 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 me
32、asurement is preferred.The term reference (or official or anchor) method in this International Standard 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 refere
33、nce method and to be based on the examination of suitable samples for its intended use.IDF 161:2013(E)vi ISO and IDF 2013 All rights reservedBS EN ISO 16297:2014INTERNATIONAL STANDARDISO 16297:2013(E)IDF 161:2013(E)Milk Bacterial count Protocol for the evaluation of alternative methods1 ScopeThis In
34、ternational Standard gives guidelines for the evaluation of instrumental alternative methods for total bacterial count in raw milk from animals of different species.NOTE The document is considered complementary to ISO 16140 and ISO 8196|IDF 128 (see Clause 2 and Reference 1).2 Normative referencesTh
35、e 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 5725-1, Accuracy (trueness and precision) of mea
36、surement methods and results Part 1: General principles and definitionsISO 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 methodISO 8196-1|IDF 128-1, Milk Definitio
37、n and evaluation of the overall accuracy of alternative methods of milk analysis Part 1: Analytical attributes of alternative methodsISO 8196-2|IDF 128-2, Milk Definition and evaluation of the overall accuracy of alternative methods of milk analysis Part 2: Calibration and quality control in the dai
38、ry laboratoryISO 16140-1, Microbiology of food and animal feed Method validation Part 1: VocabularyISO 16140-2, Microbiology of food and animal feed Method validation Part 2: Protocol for the validation of alternative (proprietary) methods against a reference methodISO 21187|IDF 196:2004, Milk Quant
39、itative determination of bacteriological quality Guidance for establishing and verifying a conversion relationship between routine method results and anchor method results3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 8196-1|IDF 128-1 and ISO 8196-2|
40、IDF 128-2 apply.For the definitions of precision, repeatability and reproducibility, see ISO 5725-1, ISO 5725-2, ISO 8196-1|IDF 128-1, and ISO 16140-1.4 Transformation of resultsA prerequisite for statistics most common in the evaluation of measuring methods is the approximation of a normal distribu
41、tion of the data. The exponential multiplication of microorganisms usually leads to a right-tailed distribution of quantitative microbiological parameters. Thus, in general, transformation of the raw data is necessary for approximation of normality. This is usually a common logarithmic transformatio
42、n or a square root transformation for low bacteria levels. The most appropriate transformation can be checked by comparing histograms. All statistics are then computed from the ISO and IDF 2013 All rights reserved 1BS EN ISO 16297:2014ISO 16297:2013(E)transformed data, unless specified otherwise, an
43、d only the final results are re-transformed to give a more expressive idea of the situation to the user (see also Annex A).5 Attributes of the alternative methodNOTE The parameters outlined in this clause do not need to be evaluated completely for every alternative method. For example, the measuring
44、 range (see 5.2) of the plate loop method is determined by the loop(s) used.5.1 Description of the method to be evaluated5.1.1 DescriptionThe description of the method under study shall be in line with the checklist in 5.1.2.Most of the information is found in the specification of the method given b
45、y the responsible supplier or any other source (author) of the technique specified.5.1.2 Checklista) Principle of the method.b) Parameter or unit.c) Technical design of the measurement procedure.d) Field of application:1) purpose: e.g. research, screening, milk grading;2) matrix: e.g. raw milk from
46、cows.e) Supplier(s) of instrument, reagents, standards.f) Specification of the method given by the producer or the author:1) prerequisites for sampling (often compared to the situation of fat analysis);2) possibilities for sample preservation reagent(s), storage condition(s);3) quantitative (units:
47、method under study or reference method) and qualitative (the kind of microorganisms covered) spectrum;4) precision (in units of the method under study or in reference method units);5) accuracy of the estimate (in reference method units);6) samples per hour;7) list of references.5.2 Measuring range5.
48、2.1 Lower limit of quantificationThe lower limit of quantification is defined as the average of milk without bacteria plus the n-fold of its standard deviation; generally, n = 10. See also ISO 16140-2.Analyse milk without bacteria or with a very low concentration of bacteria. Transform data by calcu
49、lating square root from each result. Calculate the mean, x , and the standard deviation, s, of the transformed results. Calculate the lower limit of quantification as xns+ .IDF 161:2013(E)2 ISO and IDF 2013 All rights reservedBS EN ISO 16297:2014ISO 16297:2013(E)5.2.2 Upper limit of quantificationThe upper limit of quantification is determined by the highest possible reading of the method or by methodological limitations, e.g. coincidence effects, inaccuracy in the upper measuring range, clogging of filters. Coincidence
