BS ISO BRITISH STANDARD 20128:2006 Milk products Enumeration of presumptive Lactobacillus acidophilus on a selective medium Colony-count technique at 37 oC ICS 07.100.30; 67.100.10 BSi NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW British Standards BSISO 20128:2006 National foreword This British Standard was published by BSI. It is the UK implementation of ISO 20128:2006. 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 necessary provisions of a contract. Users are responsible for its correct application. Compliancewith a British Standard cannot confer immunityfrom legal obligations. This British Standard was Amendmentsissuedsincepublication published underthe authority of the Standards Policy and Amd. No. Date Comments Strategy Committee on29June2007 BSI 2007 ISBN9780580508745 BSISO 20128:2006 ISO INTERNATIONAL STANDARD 20128 IDF 192 First edition 2006-05-15 MilkproductsEnumerationof presumptive Lactobacillus acidophilus on a selective medium Colony-count technique at 37 °C Produits laitiersDénombrement deLactobacillus acidophilus presomptifs surun milieu selectifTechnique de comptage des colonies a 37 °℃ Reference numbers ISO 20128:2006(E) IDF 192:2006(E) ISO @ISOandIDF2006 ii BSISO20128:2006 Contents Page Foreword.. iv Foreword. Introduction 1 Scope. 2 Normative references... Terms and definitions. 4 Principle. 5 Diluents, culture media and reagents.. 5.1 Basic materials... 5.2 Diluent... 5.3 Culture media. 6 Apparatusandglassware 7 Sampling.. 8 Procedure.... 8.1 Samplepreparationanddecimaldilutions 8.2 Inoculation and incubation... 8.3 Enumerationofcolonies. 9 Calculationand expressionof results.. 9.1 Calculation.... 9.2 Expressionof results 9.3 Example..... 10 Precision. 10.1 Interlaboratorytest 10.2 Repeatability 10.3 Reproducibility 11 Testreport AnnexA(informative)Interlaboratorytest 10 Bibliography ii BSIS020128:2006 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 InternationalElectrotechnicalCommission(lEC)onallmattersofelectrotechnicalstandardization International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 2 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 memberbodies casting a vote rights. IsO shall not be held responsible for identifying any or all such patent rights. ISO20128jIDF192waspreparedbyTechnical CommitteeISO/TC34,Foodproducts,SubcommitteeSC5 IDF. iv BSIS020128:2006 Foreword IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a National Committeeineverymembercountry.EveryNationalCommitteehastherighttoberepresentedontheIDF Standing Committees carrying out the technical work. IDF collaborates with ISO 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 5o % 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 rights. IDF shall not be held responsible for identifying any or all such patent rights. ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It is being published jointly by IDF and Iso. Standing Committee on Microbiological methods of analysis, under the aegis of its project leader, Mrs D. Ellekaer (DK).