ISO INTERNATIONAL STANDARD 18329 IDF 193 First edition 2004-10-15 Milk and milk products Determination of furosine content lon-pair reverse- phase high-performance liquid chromatography method Lait et produits laitiers Determination de la teneur en furosine Methode par chromatographie liquide a haute performance en phase inverse par paire d'ions Referencenumbers ISO 18329:2004(E) LSO IDF 193:2004(E) ii Contents Page Foreword. Foreword. 1 Scope. 2 Normative references 3 Terms and definitions. 4 Principle .. 5 Reagents 6 Apparatus 7 Sampling 8 Preparation of test portion.. 8.1 Milk 8.2 Cheese.. 8.3 Hydrolysis.... 8.4 Determination of protein content . 9 Procedure.... 9.1 Solid-phase extraction (SPE) of the filtered hydrolysate.. 9.2 10 Calculationandexpressionofresults 10.1 Calculation... 10.2 Expression of results.. 11 Precision... 11.1 Interlaboratory test 11.2 Repeatability... 11.3 Reproducibility 6 12 Test report. Annex A (informative) Examples of HPLC patterns ... Annex B (informative) Results of interlaboratory trials. 10 Bibliography ii 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. InternationalStandardsaredraftedinaccordancewiththerulesgivenintheISO/lECDirectives,Part2 adopted bythe technical committees are circulatedto the member bodiesfor 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 rights. IsO shall not be held responsible for identifying any or all such patent rights. ISO 18329|iDF 193 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5 Milk and milk products, and the International Dairy Federation (IDF), in collaboration with AOAC International. iv Foreword IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a National Committee in every member country. Every National Committee has the right to be represented on the IDF Standing Committees carrying out the technical work. IDF collaborates with ISO and AOAC International in thedevelopmentofstandardmethodsofanalysisandsamplingformilkandmilkproducts 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 50% of IDF National Committees casting a vote. International Standard ISO 18329JIDF 193 was prepared by Technical Committee ISO/TC 34, Food products. Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF), in collaboration with All work was carried out by the Joint ISO/IDF/AOAC Action Team, Characterization of heat treatment, of the project leader, Prof. P. Resmini (IT). blank Milk and milk products Determination of furosine content - lon-pair reverse-phase high-performance liguid chromatography method 1 Scope This International Standard specifies a method for the quantitative determination of furosine (c-furoylmethyl lysine) in milk and milk products. The method is particularly applicable to raw or heat-treated milk and to cheese. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated document (including any amendments) applies. ISO 8968-1|iDF 20-1, Milk -Determination of nitrogen content - Part 1- Kjeldahl method 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 furosine content mass fraction of substance determined by the procedure specifie