ISO INTERNATIONAL STANDARD 14461-1 IDF 169-1 First edition 2005-05-01 Milk and milk products Quality control in microbiological laboratories : Part 1: Analyst performance assessment for colony counts Lait et produits laitiers - Controle de qualite en laboratoires microbiologiques- Partie 1: Evaluation de la performance des analystes effectuant les comptages de colonies Reference numbers ISO 14461-1:2005(E) IDF 169-1:2005(E) @ ISO and IDF 2005 Copyright International Organization for Standardization Not for Resal ISO 14461-1:2005(E) IDF169-1:2005(E) PDFdisclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. Neither the ISo Central Secretariat nor the IDF accepts any liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by Iso member bodies and IDF national committees. In the unlikely event that a problem relating to it is found, please inform the ISO Central Secretariat at the address given below. @ ISO and IDF 2005 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, address below. ISO copyright office International DairyFederation Case postale 56. CH-1211 Geneva 20 Diamant Building ·Boulevard Auguste Reyers 80.B-1030 Brussels Tel. + 41 22 749 01 11 Tel. + 32 2 733 98 88 Fax + 41 22 749 09 47 Fax + 32 2 733 04 13 E-mail [email protected] E-mail [email protected] Web www.iso.org Web www.fil-idf.org Published in Switzerland yheatinaganzainfandardizatio @iSO'and IDF 2005 -All rights reserved Not for Resale ISO14461-1:2005(E) IDF169-1:2005(E) Contents Page Foreword. Introduction 1 Scope. 2 Normative references . 3 Termsanddefinitions, 4 Principle (see Figure 1)... 5 Diluent, culture media and reagents 3 6 Apparatus and glassware 7 Sampling 8 Preparation of test sample.. 8.1 Milk 8.2 Dried milk, 9 Procedure. 9.1 General... 9.2 Number of decimal dilution steps 9.3 Preparation of first decimal dilution .. 9.4 Preparationoffurtherdecimaldilutions. 9.5 Melting the medium 9.6 Preparation of binary dilutions and inoculation of the medium 9.7 Incubation.. 9.8 Randomization and counting of colonies.. 10 Statisticalevaluation 10 10.1 Adequacyof thedataset... .10 10.2 Evaluation of the complete data set (see Figure 2) ... .10 Annex A (informative) Weighted mean and homogeneity testing of colony counts.. 27 Annex B (Informative) BASIC programme for calculating the likelihood ratio index G2 Bibliography ... ii Copyright Interna Ise from IHS Not for Resale ISO 14461-1:2005(E) IDF 169-1:2005(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 International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the IsO/lEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adoptedbythetechnicalcommitteesarecirculatedtothememberbodiesforvoting.Publicationasan 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