1、June 2010 Translation by DIN-Sprachendienst.English price group 14No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 6
2、7.100.99; 67.200.10!$i“1700425www.din.deDDIN EN ISO 17678Milk and milk products Determination of milk fat purity by gas chromatographic analysis oftriglycerides (Reference method) (ISO 17678:2010)English translation of DIN EN ISO 17678:2010-06Milch und Milcherzeugnisse Bestimmung der Reinheit des Mi
3、lchfetts durch gaschromatographische Triglyceridanalyse(Referenzverfahren) (ISO 17678:2010)Englische bersetzung von DIN EN ISO 17678:2010-06Lait et produits laitiers Dtermination de la puret des matires grasses laitires par analyse chromatographiqueen phase gazeuse des triglycrides (Mthode de rfrenc
4、e) (ISO 17678:2010)Traduction anglaise de DIN EN ISO 17678:2010-06SupersedesDIN 10336:1994-09www.beuth.deIn case of doubt, the German-language original shall be considered authoritative.Document comprises 29 pages06.10 DIN EN ISO 17678:2010-06 2 A comma is used as the decimal marker. National forewo
5、rd This standard has been prepared by Technical Committee ISO/TC 34 “Food products” (Secretariat: AFNOR, France), Subcommittee SC 5 “Milk and milk products” (Secretariat: NEN, Netherlands) in collaboration with Technical Committee CEN/TC 302 “Milk and milk products Methods of sampling and analysis”
6、(Secretariat: NEN, Netherlands). The responsible German body involved in its preparation was the Normenausschuss Lebensmittel und landwirtschaftliche Produkte (Food and Agricultural Products Standards Committee) NA 057-05-13 AA Milch und Milchprodukte Probenahme- und Untersuchungsverfahren. Based on
7、 the results of parallel voting, ISO 17678:2010 has been adopted as a European Standard. The DIN Standards corresponding to the International Standards referred to in this document are as follows: ISO 707 DIN EN ISO 707 ISO 1211 DIN EN ISO 1211 ISO 2450 DIN EN ISO 2450 ISO 3696 DIN ISO 3696 ISO 5725
8、-1 DIN ISO 5725-1 ISO 5725-2 DIN ISO 5725-2 ISO 7328 DIN EN ISO 7328 Amendments This standard differs from DIN EN 10336:1994-09 as follows: a) Clause 2 “Normative references”, clause 7 “Sampling”, clause 12 “Test report” and the informative Annexes A to D have been added. b) The preparation of the p
9、acked column is now dealt with in the informative Annex A (formerly clause 8 “Procedure”). c) The quantification of the foreign fat content is described in the informative Annex B. The informative Annex C deals with the uncertainty of measurement. d) The informative Annex D specifies the results of
10、international interlaboratory tests. e) The standard has been revised in form and substance and brought in line with the current rules of presentation. f) Bibliography has been amended. Previous editions DIN 10336-2: 1979-07 DIN 10336: 1994-09 , Working CommitteeDIN EN ISO 17678:2010-06 3 National A
11、nnex NA (informative) Bibliography DIN EN ISO 1211, Milk Determination of fat content Gravimetric method (Reference method) DIN EN ISO 2450, Cream Determination of fat content Gravimetric method (Reference method) DIN ISO 3696, Water for analytical laboratory use Specification and test methods DIN I
12、SO 5725-1, Accuracy (trueness and precision) of measurement methods and results Part 1: General principles and definitions method for the determination of repeatability and reproducibility of a standard measurement method DIN EN ISO 7328, Milk-based edible ices and ice mixes Determination of fat con
13、tent Gravimetric method (Reference method) DIN ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic DIN EN ISO 707, Milk and milk products Guidance on sampling DIN EN ISO 17678:2010-06 4 This page is intentionally blank EUROPEAN STANDARD NORME EUROPENNE EURO
14、PISCHE 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 triglycerides (Reference method) (ISO 17678:2010) Lait et produits laitiers - Dtermination de la puret des matires grasses lait
15、ires par analyse chromatographique en phase gazeuse des triglycrides (Mthode de rfrence) (ISO 17678:2010) Milch und Milcherzeugnisse - Bestimmung der Reinheit des Milchfetts durch gaschromatographische Triglyceridanalyse (Referenzverfahren) (ISO 17678:2010) This European Standard was approved by CEN
16、 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 of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standard
17、s 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 version in any other language made by translation under the responsibility of a CEN member into its own language and notified to t
18、he 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 Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Ma
19、lta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2010 CEN All rights of exp
20、loitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 17678:2010: EContents EN ISO 17678:2010 (E) DIN EN ISO 17678:2010-06 2 Page Foreword3 1 Scope 4 2 Normative references 5 3 Terms and definitions .5 4 Principle5 5 Reagents.5 6 Apparatus .6 7 Sampling.
21、7 8 Procedure .7 8.1 Preparation of test samples7 8.2 Preparation of fat sample solution.8 8.3 Chromatographic triglyceride determination .8 9 Integration, evaluation and control of the analytical performance . 11 10 Calculation and expression of results 12 10.1 Triglyceride composition . 12 10.2 S-
22、values 13 10.3 Detection of foreign fat 13 11 Precision 14 11.1 Interlaboratory test . 14 11.2 Repeatability 14 11.3 Reproducibility 15 12 Test report . 15 Annex A (normative) Preparation of the packed column. 16 Annex B (informative) Quantification of the foreign fat content . 20 Annex C (informati
23、ve) Uncertainty of measurement 22 Annex D (informative) Interlaboratory test 23 Bibliography. 25 Forew rd oThis European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by August 2010, and conflicting national sta
24、ndards 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 patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC I
25、nternal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Lu
26、xembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 17678:2010 has been approved by CEN as an EN ISO 17678:2010 without any modification. EN ISO 17678:2010 (E) DIN EN ISO 17678:2010
27、-06 3 This document (EN ISO 17678:2010) has been prepared by Technical Committee ISO/TC 34 “Food products” and analysis”, the secretariat of which is held by NEN. in collaboration with Technical Committee CEN/TC 302 “Milk and milk products Methods of sampling 1 Scope This International Standard spec
28、ifies a reference method for the determination of milk fat 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 me
29、thod applies to bulk milk, or products made thereof, irrespective 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. Howev
30、er, under the circumstances listed hereafter, a false positive 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 vegetabl
31、e oils such as rapeseed oil; d) obtained from colostrum; e) 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
32、 using detergents (e.g. the Bureau of Dairy Industries method). 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 ch
33、eese, whose ripening process can also affect the fat composition 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 ani
34、mal fats to be made. However, due to the large variation of 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)
35、. NOTE 2 In practice, quantitative results cannot be derived 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. EN ISO 17678:2010 (E) DIN EN ISO 17678:2010-06 4
36、2 Normative references 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 Determ
37、ination of fat 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 fa
38、t content Gravimetric 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 deter
39、mined using S-values, 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 (T
40、Gs), separated 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 pr
41、esence of foreign 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 rea
42、gents of recognized 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
43、milk fat standard 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. EN ISO 17678:2010 (E) DIN EN ISO 17678:2010-06 5 5.5 n-Hexane CH3
44、(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 laboratory equipment and, in parti
45、cular, 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 split injector is unsuitable
46、. 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, glass, of internal diameter 2 mm
47、 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,
48、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 (8.2) within no more than 2 days by using the settings given in 8.3.4.2. After that, ensure that the response fac
49、tors (8.3.3) are close to 1 and not higher than 1,250 0. Because of the variable overlap between C24 and cholesterol, a higher response factor may be accepted for C24. Columns with different dimensions and a different non-polar, highly temperature-resistant phase may be used as long as their performance is consistent with this International Standard. However, the column length is restricted by the indispensable limitation in resolution as shown in Figure 1. See also 8.3.4.2. 6.3 Extrelut column
