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1、 Reference numbers ISO 1736:2008(E) IDF 9:2008(E) ISO and IDF 2008 INTERNATIONAL STANDARD ISO 1736 IDF 9 Fourth edition 2008-10-15 Dried milk and dried milk products Determination of fat content Gravimetric method (Reference method) Lait sec et produits base de lait sec Dtermination de la teneur en
2、matire grasse Mthode gravimtrique (Mthode de rfrence) ISO 1736:2008(E) IDF 9:2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are license
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5、In the unlikely event that a problem relating to it is found, please inform the ISO Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO and IDF 2008 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or
6、by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO or IDF at the respective address below. ISO copyright office International Dairy Federation Case postale 56 CH-1211 Geneva 20 Diamant Building Boulevard Auguste Reyers 80 B-103
7、0 Brussels Tel. + 41 22 749 01 11 Tel. + 32 2 733 98 88 Fax + 41 22 749 09 47 Fax + 32 2 733 04 13 E-mail copyrightiso.org E-mail infofil-idf.org Web www.iso.org Web www.fil-idf.org Published in Switzerland ii ISO and IDF 2008 All rights reserved ISO 1736:2008(E) IDF 9:2008(E) ISO and IDF 2008 All r
8、ights reserved iii Contents Page Foreword iv Foreword. v 1 Scope 1 2 Normative references1 3 Terms and definitions .1 4 Principle2 5 Reagents.2 6 Apparatus .2 7 Sampling.3 8 Preparation of test sample4 9 Procedure .4 9.1 Test portion4 9.2 Blank tests4 9.3 Preparation of fat-collecting vessel.5 9.4 D
9、etermination.5 10 Calculation and expression of results.7 10.1 Calculation7 10.2 Expression of results 8 11 Precision.8 11.1 Interlaboratory test8 11.2 Repeatability.8 11.3 Reproducibility.8 12 Test report8 Annex A (informative) Notes on procedures9 Annex B (informative) Alternative procedure using
10、fat-extraction tubes with siphon or wash-bottle fittings.11 Bibliography14 ISO 1736:2008(E) IDF 9:2008(E) iv ISO and IDF 2008 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of
11、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 organizations, governmental and non-governmental,
12、 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 ISO/IEC Directives, Part 2. The main t
13、ask 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 the member bodies casting a vote. Attent
14、ion 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 1736IDF 9 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and mil
15、k products, and the International Dairy Federation (IDF). It is being published jointly by ISO and IDF. This fourth edition of ISO 1736IDF 9 cancels and replaces the third edition (ISO 1736:2000), of which it constitutes a minor revision. ISO 1736:2008(E) IDF 9:2008(E) ISO and IDF 2008 All rights re
16、served v Foreword IDF (the International Dairy Federation) is a non-profit 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 m
17、embers of IDF have the right to be represented at the IDF 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
18、Committees are circulated to the National Committees for voting. 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 this document may be the subject of patent ri
19、ghts. IDF shall not be held responsible for identifying any or all such patent rights. ISO 1736IDF 9 was prepared by the International Dairy Federation (IDF) and Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It is being published jointly by IDF and ISO. All
20、 work was carried out by the Joint ISO-IDF Action Team Fat of the Standing Committee on Main components in milk under the aegis of its project leader, Mr G.J. Beutick (NL). This edition of ISO 1736IDF 9 cancels and replaces IDF 9:1987, of which it constitutes a minor revision. -,-,- -,-,- INTERNATIO
21、NAL STANDARD ISO 1736:2008(E) IDF 9:2008(E) ISO and IDF 2008 All rights reserved 1 Dried milk and dried milk products Determination of fat content Gravimetric method (Reference method) WARNING The use of this International Standard may involve hazardous materials, operations and equipment. This Inte
22、rnational 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 applicability of regulatory limitations prior to use. 1 Scope This Internatio
23、nal Standard specifies the reference method for the determination of the fat content of dried milk and dried milk products. The method is also applicable to dried milk with a fat content of 40 % mass fraction or more, dried whole, dried partially skimmed, and dried skimmed milk, dried whey, dried bu
24、ttermilk and dried butter serum. The method is not applicable when the powder contains hard lumps which do not dissolve in ammonia solution or free fatty acids in significant quantities. NOTE When the powder contains hard lumps which do not dissolve in ammonia solution or contains free fatty acids i
25、n significant quantities, noticeable by a distinct smell, the result of the determination will be too low. With such products, a method using the Weibull-Berntrop principle is suitable (see ISO 8262-3IDF 124-33). 2 Normative references The following referenced documents are indispensable for the app
26、lication 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 835, Laboratory glassware Graduated pipettes ISO 1042, Laboratory glassware One-mark volumetric flasks ISO 38
27、89IDF 219, Milk and milk products Specification 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 dried milk and dried milk prod
28、ucts mass fraction of substances determined by the procedure specified in this International Standard NOTE The fat content is expressed as a percentage mass fraction. ISO 1736:2008(E) IDF 9:2008(E) 2 ISO and IDF 2008 All rights reserved 4 Principle An ammoniacal ethanolic solution of a test portion
29、is extracted with diethyl ether and light petroleum. The solvents are removed by distillation or evaporation. 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 sp
30、ecified, and only distilled or demineralized water or water of equivalent purity. The reagents shall leave 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 NH3 of approximately 25 % (20 = 910 g/l). N
31、OTE If ammonia solution of this concentration is not available, a more concentrated solution of known concentration 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. Dis
32、solve 1 g of Congo red (C32H22N6Na2O6S2) in water in a 100 ml one-mark volumetric flask (6.14). Make up to 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 s
33、olutions can be used provided that they do not affect the result of the determination. 5.4 Diethyl ether (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). WARNIN
34、G The use of diethyl ether can lead to hazardous situations. Observe current safety precautions for handling, 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
35、for the blank test (see 9.2.2, Clauses A.1 and A.4). The use of pentane is recommended because of its higher 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
36、the use of volatile flammable solvents, all electrical apparatus employed shall comply with legislation relating 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
37、 0,1 mg. -,-,- ISO 1736:2008(E) IDF 9:2008(E) ISO and IDF 2008 All rights reserved 3 6.2 Centrifuge, capable of holding the fat-extraction flasks or tubes (6.6) and capable of spinning at a rotational frequency of 500 min1 to 600 min1 to produce a radial acceleration of 80g to 90g at the outer end o
38、f the flasks or tubes. The use of the centrifuge is optional but recommended (see 9.4.7). 6.3 Distillation or evaporation apparatus, for distilling 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
39、.4 Drying oven, electrically heated, with ventilation port(s) fully open, capable of being maintained at a temperature of 102 C 2 C throughout its working space. The oven shall be fitted with a suitable thermometer. 6.5 Water bath, capable of being maintained at a temperature of 65 C 5 C. 6.6 Mojonn
40、ier-type fat-extraction flasks, as specified in ISO 3889IDF 219. NOTE It is also possible to 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
41、 cork bungs or stoppers of another material (e.g. silicone rubber or polytetrafluoroethylene) 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 wate
42、r so that they are saturated when used. 6.7 Rack, for holding the fat-extraction flasks (or 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
43、 to 250 ml, conical flasks, of capacity 250 ml, or metal dishes. If metal dishes are used, they 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 me
44、tal dishes are used). 6.11 Measuring cylinders, of capacities 5 ml and 25 ml, complying with 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,
45、 made of metal, for holding flasks, beakers or dishes. 6.14 Volumetric flask, one-mark, of capacity 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
46、 storage. Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 707IDF 501. Store laboratory samples at a temperature between 2 C and 6 C from the time of sampling to the time of commencing the procedure. ISO 1736:2008(E) IDF 9:200
47、8(E) 4 ISO and IDF 2008 All rights reserved 8 Preparation of test sample Thoroughly mix the test sample by repeatedly rotating and inverting the sample container. If necessary, transfer all of the test sample to an airtight container of approximately twice the volume of the test sample to allow this
48、 operation to be carried out. 9 Procedure NOTE 1 If it is required to check whether the repeatability limit (11.2) is met, carry out two single determinations in accordance with 9.1 to 9.4. NOTE 2 An alternative procedure using fat-extraction tubes with siphon or wash-bottle fittings (see Note to 6.
49、6) is given in Annex B. 9.1 Test portion Mix the test sample (Clause 8) by gently stirring or rotating and inverting the container several times. Immediately weigh, to the nearest 1 mg, directly or by difference, in a fat-extraction flask (6.6), one of the following test portions: a) about 1,000 g of dried high-fat milk, of dried whole milk or of dried but