1、March 2009DEUTSCHE NORM English price group 12No part of this standard 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 67.230!$VV“1515199www.di
2、n.deDDIN EN ISO 8381Milk-based infant foods Determination of fat content Gravimetric method (Reference method) (ISO 8381:2008)English version of DIN EN ISO 8381:2009-03Suglingsnahrung auf Milchbasis Bestimmung des Fettgehaltes Gravimetrisches Verfahren (Referenzverfahren) (ISO 8381:2008)Englische Fa
3、ssung DIN EN ISO 8381:2009-03SupersedesDIN EN ISO 8381:2000-04www.beuth.deDocument comprises 22 pagesDIN EN ISO 8381:2009-03 2 National foreword This standard has been prepared by Technical Committee ISO/TC 34 “Food products” (Secretariat: AFNOR, France), Subcommittee SC 5 “Milk and milk products” (
4、Secretariat: NEN, Netherlands) in collaboration with Technical Committee CEN/TC 302 “Milk and milk products Methods of sampling and analysis” (Secretariat: NEN, Netherlands). The responsible German body involved in its preparation was the Normenausschuss Lebensmittel und landwirtschaftliche Produkte
5、 (Food and Agricultural Products Standards Committee), Technical Committee Milch und Milchprodukte Probenahme- und Untersuchungsverfahren. Based on the results of parallel voting, ISO 8381:2008 has been adopted as a European Standard. For reasons of environmental and worker protection, the German em
6、ployers liability insurance associations and inspectorates forbid the open evaporation of diethyl ether, which this standard allows as an alternative method. One way of reducing risks is to substitute diethyl ether with an equivalent amount of tert-butyl methyl ether (t-BME). This deviation from the
7、 specified procedure is to be stated in the test report. The DIN Standards corresponding to the International Standards referred to in this document are as follows: ISO 707 DIN EN ISO 707 ISO 835 DIN EN ISO 835 ISO 1042 DIN EN ISO 1042 ISO 4788 DIN EN ISO 4788 Amendments This standard differs from D
8、IN EN ISO 8381:2000-04 as follows: a) Clause 1 “Scope” has been rendered more precise. b) Clause 2 “Normative references” and clause 7 “Sampling” have been revised. c) The standard has been revised in form and substance and brought in line with the current rules of presentation. d) The bibliography
9、has been updated. Previous editions DIN EN ISO 8381: 2000-04 DIN EN ISO 8381:2009-03 3 National Annex NA (informative) Bibliography DIN EN ISO 707, Milk and milk products Guidance on sampling DIN EN ISO 835, Laboratory glassware Graduated pipettes DIN EN ISO 1042, Laboratory glassware One-mark volum
10、etric flasks DIN EN ISO 4788, Laboratory glassware Graduated measuring cylinders DIN EN ISO 8381:2009-03 4 This page is intentionally blank EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 8381October 2008ICS 67.230 Supersedes EN ISO 8381:2000 English VersionMilk-based infant foods - Determinat
11、ion of fat content -Gravimetric method (Reference method) (ISO 8381:2008)Aliments base de lait pour enfants en bas ge -Dtermination de la teneur en matire grasse - Mthodegravimtrique (Mthode de rfrence) (ISO 8381:2008)Suglingsnahrung auf Milchbasis - Bestimmung desFettgehaltes - Gravimetrisches Verf
12、ahren(Referenzverfahren) (ISO 8381:2008)This European Standard was approved by CEN on 14 October 2008.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up
13、-to-date lists and bibliographical references concerning such nationalstandards 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 translationunde
14、r the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hun
15、gary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: r
16、ue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 8381:2008: EContents Page Foreword. 3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Principle5 5 Reagents.5 6 Apparatus .5
17、7 Sampling.6 8 Preparation of test sample7 8.1 Liquid products7 8.2 Viscous or pasty products7 8.3 Dried products .7 9 Procedure .7 9.1 Test portion 7 9.2 Blank tests8 9.3 Preparation of fat-collecting vessel.8 9.4 Determination.8 10 Calculation and expression of results.11 10.1 Calculation11 10.2 E
18、xpression of results 11 11 Precision.11 11.1 Interlaboratory test 11 11.2 Repeatability.11 11.3 Reproducibility.12 12 Test report 12 Annex A (informative) Notes on procedures 13 Annex B (informative) Alternative procedure using fat-extraction tubes with siphon or wash-bottle fittings .15 Bibliograph
19、y 18 2EN ISO 8381:2008 (E) DIN EN ISO 8381:2009-03 3 Foreword This document (EN ISO 8381:2008) has been prepared by Technical Committee ISO/TC 34 “Agricultural food products“ in collaboration with Technical Committee CEN/TC 302 “Milk and milk products - Methods of sampling and analysis” the secretar
20、iat of which is held by NEN. This 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 April 2009, and conflicting national standards shall be withdrawn at the latest by April 2009. Attention is drawn to th
21、e 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. This document supersedes EN ISO 8381:2000. According to the CEN/CENELEC Internal Regulations, the national sta
22、ndards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
23、Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 8381:2008 has been approved by CEN as a EN ISO 8381:2008 without any modification. EN ISO 8381:2008 (E) DIN EN ISO 8381:2009-03 WARNING The use of this International Standard
24、may involve hazardous materials, operations and equipment. This International Standard does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this International Standard to establish safety and health practices and determine the applicabi
25、lity of regulatory limitations prior to use. 1 Scope This International Standard specifies the reference method for the determination of the fat content of milk-based infant foods. The method is applicable to liquid, concentrated and dried milk-based infant foods with no, or not more than a mass fra
26、ction of 5 % (dry matter) of such added matter as starch, dextrin, vegetables, fruit, and meat. NOTE 1 Malto-dextrins without higher molecular mass dextrins, which are often present in infant foods, do not disturb the Rse-Gottlieb extraction even when present in high concentrations. The method is no
27、t applicable to products which do not dissolve completely in ammonia owing to the presence of starch or dextrin at mass fractions of more than a few percent, or to the presence of hard lumps. The method is also not applicable to products which contain free fatty acids in significant quantities. The
28、results obtained for these products are too low. NOTE 2 For such products, a method utilizing the Weibull-Berntrop principle is suitable (see ISO 8262-1IDF 124-13). 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references,
29、 only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 835, Laboratory glassware Graduated pipettes ISO 1042, Laboratory glassware One-mark volumetric flasks ISO 3889IDF 219, Milk and milk products Specification
30、of Mojonnier-type fat extraction flasks ISO 4788, Laboratory glassware Graduated measuring cylinders 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 fat content of milk mass fraction of substances determined by the procedure specified in this
31、 International Standard NOTE The fat content is expressed as a percentage mass fraction. 4EN ISO 8381:2008 (E) DIN EN ISO 8381:2009-03 4 Principle An ammoniacal ethanolic solution of a test portion is extracted with diethyl ether and light petroleum. The solvents are removed by distillation or evapo
32、ration. The mass of the substances extracted is determined. NOTE This is usually known as the Rse-Gottlieb principle. 5 Reagents Use only reagents of recognized analytical grade, unless otherwise specified, and only distilled or demineralized water or water of equivalent purity. The reagents shall l
33、eave no appreciable residue when the determination is carried out by the method specified (see 9.2.2). 5.1 Ammonia solution, containing a mass fraction of NH3of approximately 25 % (20= 910 g/l). NOTE If ammonia solution of this concentration is not available, a more concentrated solution of known co
34、ncentration may be used (see 9.4.2). 5.2 Ethanol (C2H5OH), or ethanol denatured by methanol, containing a volume fraction of ethanol of at least 94 %. (See Clause A.5.) 5.3 Congo red solution Dissolve 1 g of Congo red (C32H22N6Na2O6S2) in water in a 100 ml one-mark volumetric flask (6.14). Make up t
35、o the mark with water. NOTE The use of this solution, which allows the interface between the solvent and aqueous layers to be seen more clearly, is optional (see 9.4.4). Other aqueous indicator solutions can be used provided that they do not affect the result of the determination. 5.4 Diethyl ether
36、(C2H5OC2H5), free from peroxides (see Clause A.3), containing no more than 2 mg/kg of antioxidants, and complying with the requirements for the blank test (see 9.2.2, Clauses A.1 and A.4). WARNING The use of diethyl ether can lead to hazardous situations. Observe current safety precautions for handl
37、ing, use, and disposal. 5.5 Light petroleum, with any boiling range between 30 C and 60 C or, as equivalent, pentane (CH3CH23CH3) with a boiling point of 36 C and complying with the requirements for the blank test (see 9.2.2, Clauses A.1 and A.4). The use of pentane is recommended because of its hig
38、her purity and consistent quality. 5.6 Mixed solvent Shortly before use, mix equal volumes of diethyl ether (5.4) and light petroleum (5.5). 6 Apparatus WARNING Since the determination involves the use of volatile flammable solvents, all electrical apparatus employed shall comply with legislation re
39、lating to the hazards in using such solvents. Usual laboratory equipment and, in particular, the following. 6.1 Analytical balance, capable of weighing to the nearest 1 mg, with a readability of 0,1 mg. 5EN ISO 8381:2008 (E) DIN EN ISO 8381:2009-03 6.2 Centrifuge, capable of holding the fat-extracti
40、on flasks or tubes (6.6) and capable of spinning at a rotational frequency of 500 min1to 600 min1to produce a radial acceleration of 80g to 90g at the outer end of the flasks or tubes. The use of the centrifuge is optional but recommended (see 9.4.7). 6.3 Distillation or evaporation apparatus, for d
41、istilling the solvents and ethanol from the boiling or conical flasks, or evaporating from beakers and dishes (see 9.4.14) at a temperature not exceeding 100 C. 6.4 Drying oven, electrically heated, with ventilation port(s) fully open, capable of being maintained at a temperature of 102 C 2 C throug
42、hout its working space. The oven shall be fitted with a suitable thermometer. 6.5 Water baths, capable of being maintained at temperatures of between 30 C and 40 C, 40 C and 60 C, and 60 C and 70 C. 6.6 Mojonnier-type fat-extraction flasks, as specified in ISO 3889IDF 219. NOTE It is also possible t
43、o use fat-extraction tubes, with siphon or wash-bottle fittings, but then the procedure is different. The alternative procedure is given in Annex B. The fat-extraction flasks shall be provided with good quality cork bungs or stoppers of other material (e.g. silicone rubber or polytetrafluoroethylene
44、) unaffected by the reagents used. Cork bungs shall be extracted with the diethyl ether (5.4), kept in water at a temperature of 60 C or more for at least 15 min, and shall then be allowed to cool in the water so that they are saturated when used. 6.7 Rack, for holding the fat-extraction flasks (or
45、tubes) (6.6). 6.8 Wash bottle, suitable for use with the mixed solvent (5.6). A plastics wash bottle shall not be used. 6.9 Fat-collecting vessels, such as boiling flasks (flat-bottomed), of capacities 125 ml to 250 ml, conical flasks, of capacity 250 ml, or metal dishes. If metal dishes are used, t
46、hey shall be of stainless steel, flat-bottomed with a diameter of 80 mm to 100 mm and a height of approximately 50 mm. 6.10 Boiling aids, fat-free, of non-porous porcelain or silicon carbide (optional when metal dishes are used). 6.11 Measuring cylinders, of capacities 5 ml and 25 ml, complying with
47、 the requirements of ISO 4788, class A, or any other apparatus suitable for the product concerned. 6.12 Pipettes, graduated, of capacity 10 ml, complying with the requirements of ISO 835, class A. 6.13 Tongs, made of metal, for holding flasks, beakers or dishes. 6.14 Volumetric flask, one-mark, of c
48、apacity 100 ml, complying with the requirements of ISO 1042, class A. 7 Sampling A representative sample should have been sent to the laboratory. It should not have been damaged or changed during transport or storage. Sampling is not part of the method specified in this International Standard. A rec
49、ommended sampling method is given in ISO 707IDF 501. Store all liquid, viscous or pasty laboratory samples at a temperature of between 2 C and 6 C from the time of sampling to the time of commencing the procedure. Store laboratory samples in sealed cans or bottles unopened at a temperature below 20 C until the time of commencing the procedure. 6EN ISO 8381:2008 (E) DIN EN ISO 8381:2009-03 8 Preparation of test sample 8.1 Liquid products Shake and invert the sample container. Open the container to p
