BS ISO BRITISH STANDARD 7251:2005 Microbiology of food and animal feeding stuffs Horizontal method for the detection and enumeration of presumptive Escherichia coli- Most probable number technique ICS 07.100.30 BSi NOCOPYINGWITHOUTBSIPERMISSIONEXCEPTASPERMITTEDBYCOPYRIGHTL British Standards BS ISO 7251:2005 National foreword This British Standard reproduces verbatim IS0 7251:2005 and implements it as the UK national standard. It supersedes BS 5763-8:1994 and BS ISO 11866-1:1997 which are withdrawn. The UK participation in its preparation was entrusted to Technical Committee AW/9, Microbiology, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled "International Standards Correspondence Index", or by using the “Search' facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not ofitself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 13 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication This British Standard was publishedunderthe authority Amd. No. Date Comments of the Standards Policy and Strategy Committee on 5May2005 @ BSI 5 May 2005 ISBN 0 580 43482 6 BS ISO 7251:2005 INTERNATIONAL ISO STANDARD 7251 Third edition 2005-02-01 Microbiology of food and animal feeding stuffs Horizontal method for the detection and enumeration of presumptive Escherichia coli Most probable number technique Microbiologie des aliments - Methode horizontale pour la recherche et le dénombrement d'Escherichia coli preésumés- Technique du nombre leplusprobable Reference number ISO 7251:2005(E) ISO BS ISO 7251:2005 = BS ISO 7251:2005 Contents Page Foreword Introduction 1 Scope. 2 Normative references. 3 Terms and definitions. 2 4 Principle.. 4.1 Detection method ... 4.2 Enumeration method 5 Diluent, culture media and reagent.. 6 Apparatus and glassware 7 Sampling.. 8 Preparation of test sample .6 9 Procedure.. 9.1 Detection method, 9.2 Enumeration method 10 Expression of results. 10.1 Detectionmethod.... 10.2 Enumerationmethod 11 Test report .8 AnnexA(normative)MPNtable 10 Bibliography 13 ii BS IS0 7251:2005 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 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 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 ISO 7251 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 9. Microbiology. This third edition cancels and replaces the second edition (ISO 7251:1993