1、BS ENISO 17678:2010ICS 67.100.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDMilk and milk products Determination ofmilk fat purity bygas chromatographicanalysis oftriglycerides(Reference method)This British Standard was published under theauthority of the St
2、andardsPolicy and StrategyCommittee on 31 August2010. BSI 2010ISBN 978 0 580 56557 1Amendments/corrigenda issued since publicationDate CommentsBS EN ISO 17678:2010National forewordThis British Standard is the UK implementation of EN ISO 17678:2010.The UK participation in its preparation was entruste
3、d to TechnicalCommittee AW/5, Chemical analysis of milk and milk products.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct app
4、lication.Compliance with a British Standard cannot confer immunityfrom legal obligations.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 17678 February 2010 ICS 67.100.99; 67.200.10 English Version Milk and milk products - Determination of milk fat purity by gas chromatographic analysis of
5、triglycerides (Reference method) (ISO 17678:2010) Lait et produits laitiers - Dtermination de la puret des matires grasses laitires par analyse chromatographique en phase gazeuse des triglycrides (Mthode de rfrence) (ISO 17678:2010) Milch und Milcherzeugnisse - Bestimmung der Reinheit des Milchfetts
6、 durch gaschromatographische Triglyceridanalyse (Referenzverfahren) (ISO 17678:2010) This European Standard was approved by CEN on 13 February 2010. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status o
7、f a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A ver
8、sion in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Re
9、public, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN
10、DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 17678:2010: EBS EN ISO17678:2010EN ISO 17678:2010 (E) 3 Foreword This doc
11、ument (EN ISO 17678:2010) has been prepared by Technical Committee ISO/TC 34 “Food products“ in collaboration with Technical Committee CEN/TC 302 “Milk and milk products - Methods of sampling and analysis”, the secretariat of which is held by NEN. This European Standard shall be given the status of
12、a national standard, either by publication of an identical text or by endorsement, at the latest by August 2010, and conflicting national standards shall be withdrawn at the latest by August 2010. Attention is drawn to the possibility that some of the elements of this document may be the subject of
13、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 following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
14、 Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The
15、text of ISO 17678:2010 has been approved by CEN as an EN ISO 17678:2010 without any modification. ISO 17678:2010(E) IDF 202:2010(E) ISO and IDF 2010 All rights reserved iiiContents Page Foreword iv 1 Scope1 2 Normative references2 3 Terms and definitions .2 4 Principle .2 5 Reagents 2 6 Apparatus.3
16、7 Sampling 4 8 Procedure.4 8.1 Preparation of test samples .4 8.2 Preparation of fat sample solution 5 8.3 Chromatographic triglyceride determination .5 9 Integration, evaluation and control of the analytical performance 8 10 Calculation and expression of results 9 10.1 Triglyceride composition9 10.
17、2 S-values 10 10.3 Detection of foreign fat .10 11 Precision 11 11.1 Interlaboratory test11 11.2 Repeatability 11 11.3 Reproducibility 12 12 Test report12 Annex A (normative) Preparation of the packed column .13 Annex B (informative) Quantification of the foreign fat content17 Annex C (informative)
18、Uncertainty of measurement .19 Annex D (informative) Interlaboratory test.20 Bibliography22 BS EN ISO 17678:2010ISO 17678:2010(E) IDF 202:2010(E) iv ISO and IDF 2010 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards b
19、odies (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 been established has the right to be represented on that committee. International organizati
20、ons, governmental and non-governmental, 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
21、 ISO/IEC 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 t
22、he 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 17678IDF 202 was prepared by Technical Committee ISO/TC 34, Food
23、 products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO and IDF. BS EN ISO 17678:2010ISO 17678:2010(E) IDF 202:2010(E) ISO and IDF 2010 All rights reserved vForeword IDF (the International Dairy Federation) is a non-pro
24、fit organization representing the 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 on the IDF Standing Comm
25、ittees carrying out the technical 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 a
26、re circulated to the National Committees for endorsement prior to publication as an International Standard. Publication as an International Standard requires approval by at least 50 % of the IDF National Committees casting a vote. Attention is drawn to the possibility that some of the elements of th
27、is document may be the subject of patent rights. IDF shall not be held responsible for identifying any or all such patent rights. ISO 17678IDF 202 was prepared by the International Dairy Federation (IDF) and Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It
28、is being published jointly by IDF and ISO. All work was carried out by the Joint ISO-IDF Project Group on Foreign fats of the Standing Committee on Analytical methods for composition under the aegis of its project leader, Dr J. Molkentin (DE). BS EN ISO 17678:2010BS EN ISO 17678:2010INTERNATIONAL ST
29、ANDARD ISO 17678:2010(E)IDF 202:2010(E) ISO and IDF 2010 All rights reserved 1Milk and milk products Determination of milk fat purity by gas chromatographic analysis of triglycerides (Reference method) 1 Scope This International Standard specifies a reference method for the determination of milk fat
30、 purity using gas chromatographic analysis of triglycerides. Both vegetable fats and animal fats such as beef tallow and lard can be detected. By using defined triglyceride equations, the integrity of milk fat is determined. Basically, the method applies to bulk milk, or products made thereof, irres
31、pective of feeding, breed or lactation conditions. In particular, the method is applicable to fat extracted from milk products purporting to contain pure milk fat with unchanged composition, such as butter, cream, milk, and milk powder. However, under the circumstances listed hereafter, a false posi
32、tive result can be obtained. Hence, the method is not applicable to milk fat: a) obtained from bovine milk other than cows milk; b) obtained from single cows; c) obtained from cows which received an exceptionally high feeding of pure vegetable oils such as rapeseed oil; d) obtained from colostrum; e
33、) subjected to technological treatment such as removal of cholesterol or fractionation; f) obtained from skim milk or buttermilk; g) extracted by using the Gerber, WeibullBerntrop or SchmidBondzynskiRatzlaff methods, or that has been isolated using detergents (e.g. the Bureau of Dairy Industries met
34、hod). With the extraction methods specified in g), substantial quantities of partial glycerides or phospholipids can pass into the fat phase. Consequently, the scope of this International Standard excludes certain products and particularly cheese, whose ripening process can also affect the fat compo
35、sition to such a degree that a false positive result is obtained. NOTE 1 In nature, butyric (n-butanoic) acid (C4) occurs exclusively in milk fat and enables quantitative estimations of low to moderate amounts of milk fat in vegetable and animal fats to be made. However, due to the large variation o
36、f C4, whose approximate content ranges from 3,1 % mass fraction to 3,8 % mass fraction, it is difficult to provide qualitative and quantitative information for foreign fat to pure milk fat ratios of up to 20 % mass fraction (see Reference 11). NOTE 2 In practice, quantitative results cannot be deriv
37、ed from the sterol content of vegetable fats, because they depend on production and processing conditions. Furthermore, the qualitative determination of foreign fat using sterols is ambiguous. BS EN ISO 17678:2010ISO 17678:2010(E) IDF 202:2010(E) 2 ISO and IDF 2010 All rights reserved2 Normative ref
38、erences The 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 1211IDF 1, Milk Determination of fat
39、content Gravimetric method (Reference method) ISO 2450IDF 16, Cream Determination of fat content Gravimetric method (Reference method) ISO 3696, Water for analytical laboratory use Specification and test methods ISO 7328IDF 116, Milk-based edible ices and ice mixes Determination of fat content Gravi
40、metric method (Reference method) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 milk fat purity absence of vegetable and animal fats determined by the procedure specified in this International Standard NOTE The purity is determined using S-v
41、alues, which are calculated from the content of triglycerides. Triglyceride mass fractions are expressed as percentages. 4 Principle Fat extracted from milk or milk products is analysed by gas chromatography (GC) using a packed or a short capillary column to determine triglycerides (TGs), separated
42、by total carbon numbers. By inserting the mass fraction, expressed as a percentage, of fat molecules of different sizes (C24 to C54, using even C numbers only) into suitable TG equations, S-values are calculated. If the S-values exceed the limits established with pure milk fat, the presence of forei
43、gn fat is detected. NOTE 1 The suitability and equivalence of both packed and capillary columns have been demonstrated previously (see References 8 to 10). NOTE 2 An S-value is the sum of weighted TG mass fractions. 5 Reagents During the analysis, unless otherwise stated, use only reagents of recogn
44、ized analytical grade. 5.1 Water complying with the requirements of ISO 3696, grade 2. 5.2 Carrier gas, nitrogen or, alternatively, helium or hydrogen, all with a purity of at least 99,995 % volume fraction. 5.3 Fat standards, purity at least 99 % mass fraction, for standardizing the milk fat standa
45、rd described in 8.3.3. 5.3.1 Triglyceride standards, saturated; suitable products are available commercially. 5.3.2 Cholesterol standard. 5.4 Methanol (CH3OH), with a water content of not more than 0,05 % mass fraction. BS EN ISO 17678:2010ISO 17678:2010(E) IDF 202:2010(E) ISO and IDF 2010 All right
46、s reserved 35.5 n-Hexane CH3(CH2)4CH3. 5.6 n-Heptane CH3(CH2)5CH3. 5.7 Other gases, hydrogen, purity at least 99,995 % volume fraction, free from organic impurities (CnHm 1 l/l); synthetic air, free from organic impurities (CnHm 1 l/l). 5.8 Anhydrous sodium sulfate (Na2SO4). 6 Apparatus Usual labora
47、tory equipment and, in particular, the following. 6.1 High-temperature gas chromatograph, suitable for use at temperatures of at least 400 C and equipped with a flame ionization detector (FID). For capillary GC, an on-column or a programmed temperature vaporization injector is indispensable while a
48、split injector is unsuitable. Septa used in the injector shall withstand high temperatures and exhibit a very low degree of “bleeding”. Always use graphite seals to connect the column as well as injector and/or detector inserts (where applicable). 6.2 Chromatography column. 6.2.1 Packed column, glas
49、s, of internal diameter 2 mm and length 500 mm, packed with a stationary phase of 3 % OV-1 on 125 m to 150 m (100 mesh to 120 mesh) Gas ChromQ 1). The preparation, silanization, packing and conditioning of the packed column is described in Annex A. Alternatively, a capillary column (6.2.2) may be used. 6.2.2 Capillary column, short, e.g. of length 5 m, with a non-polar stationary phase that can withstand temperatures up to 400 C or more 2). Condition the column by performing 20 analyses of a milk fat solution (
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