1、BRITISH STANDARD BS ISO 8262-1:2005 Milk products and milk-based foods Determination of fat content by the Weibull-Berntrop gravimetric method (Reference method) Part 1: Infant foods ICS 67.100.01 BS ISO 8262-1:2005 This British Standard was published under the authority of the Standards Policy and
2、Strategy Committee on 12 January 2006 BSI 12 January 2006 ISBN 0 580 47145 4 National foreword This British Standard reproduces verbatim ISO 8262-1:2005 and implements it as the UK national standard. It supersedes BS 7142-2:1989 which is withdrawn. The UK participation in its preparation was entrust
3、ed to Technical Committee AW/5, Milk and milk products, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related int
4、ernational and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BS
5、I Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for
6、its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to vi, pages 1 to 8, an inside back cover and a back cover. The BSI copyr
7、ight notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Reference numbers ISO 8262-1:2005(E) IDF 124-1:2005(E)INTERNATIONAL STANDARD ISO 8262-1 IDF 124-1 Second edition 2005-09-15 Milk products and milk-based food
8、s Determination of fat content by the Weibull-Berntrop gravimetric method (Reference method) Part 1: Infant foods Produits laitiers et produits base de lait Dtermination de la teneur en matire grasse par la mthode gravimtrique Weibull-Berntrop (Mthode de rfrence) Partie 1: Aliments pour enfants en b
9、as ge BS ISO 8262-1:2005ii BS ISO 8262-1:2005 iii Contents Page Foreword iv Introduction . vi 1 Scope . 1 2 Terms and definitions. 1 3 Principle . 1 4 Reagents and materials . 1 5 Apparatus 2 6 Sampling 3 7 Procedure 3 7.1 Preparation of test sample. 3 7.2 Test portion . 4 7.3 Blank test. 4 7.4 Prep
10、aration of extraction flask 4 7.5 Determination 4 8 Calculation and expression of results 6 9 Precision 6 9.1 Interlaboratory test . 6 9.2 Repeatability 6 10 Notes on procedure 7 10.1 Blank tests to check the solvent and filter papers 7 10.2 Blank test carried out simultaneously with the determinati
11、on 7 11 Test report . 7 Bibliography . 8 BS ISO 8262-1:2005 iv 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 com
12、mittees. 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, in liaison with ISO, also take part in the work. ISO collaborates closely with the
13、 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 task of technical committees is to prepare International Standards. Draft Internatio
14、nal 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. Attention is drawn to the possibility that some of the elements of this document may be t
15、he subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 8262-1IDF 124-1 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF). It is being publish
16、ed jointly by ISO and IDF. This edition of ISO 8262-1 IDF 124-1 cancels and replaces ISO 8262-1:1987, of which it constitutes a minor revision. ISO 8262 IDF 124 consists of the following parts, under the general title Milk products and milk-based foods Determination of fat content by the Weibull-Ber
17、ntrop gravimetric method (Reference method): Part 1: Infant foods Part 2: Edible ices and ice-mixes Part 3: Special cases v 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
18、the right to be represented on 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 Committees are circ
19、ulated 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 rights. IDF shall not
20、 be held responsible for identifying any or all such patent rights. ISO 8262-1 IDF 124-1 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 work was ca
21、rried out by the Joint ISO/IDF/AOAC Group of Experts on Fat determination (E 31), under the aegis of its chairman, Mr J. Eisses (NL). This edition of ISO 8262-1 IDF 124-1 cancels and replaces IDF 124A:1988, of which it constitutes a minor revision. ISO 8262 IDF 124 consists of the following parts, u
22、nder the general title Milk products and milk-based foods Determination of fat content by the Weibull-Berntrop gravimetric method (Reference method): Part 1: Infant foods Part 2: Edible ices and ice-mixes Part 3: Special cases BS ISO 8262-1:2005vi Introduction This International Standard has been pr
23、epared within the framework of producing a series of reference methods, which are harmonized to the greatest possible extent, for the gravimetric determination of the fat content of milk, milk products and milk-based foods. These methods are based on the Rse-Gottlieb (RG) method, or the Weibull-Bern
24、trop (WB) method, or the Schmid-Bondzynski-Ratzlaff (SBR) principle. For this part of ISO 8262 IDF 124, dealing with milk-based and other types of infant food containing more than 5 % (mass fraction) (dry matter) of starch or dextrin, or vegetable, fruit, meat, etc., a method based on the WB princip
25、le has been chosen for the following reasons: a) the RG procedure is not suitable owing to the high level of the above ingredients, which causes incomplete extraction of the fat and thus gives too low values for the fat content; b) the SBR procedure is not suitable owing to the generally high conten
26、t of carbohydrates, which gives rise to ether-extractable compounds in the digestion with acid and thus gives too high values for the fat content; c) the WB procedure, although it also includes acid digestion, is not adversely affected by the ether- extractable compounds, since the acid digest is fi
27、ltered and washed, and the dried residue on the filter does not contain compounds that are extractable by light petroleum; d) the method described is already used for this purpose in many countries and is recommended by the Codex Committee on Methods of Analysis and Sampling. The original Weibull me
28、thod was designed for bread; a considerably modified method, as specified in this International Standard, was developed by Berntrop. This version has found wide application for the determination of fat in many types of food product. BS ISO 8262-1:20051 Milk products and milk-based foods Determinatio
29、n of fat content by the Weibull-Berntrop gravimetric method (Reference method) Part 1: Infant foods 1 Scope This part of ISO 8262 IDF 124 specifies the reference method for the determination of the fat content of infant foods to which the Rse-Gottlieb method is not applicable i.e. those milk-based a
30、nd other types of infant food that contain more than 5 % (mass fraction) (dry matter) of starch or dextrin, or vegetable, fruit, meat, etc. The method is also applicable if the product contains free fatty acids in significant quantities or if hard lumps that do not dissolve completely in ammonia are
31、 present in the product. NOTE Other milk-based infant foods can be examined by the method utilizing the Rse-Gottlieb principle given in ISO 8381. Malto-dextrins without higher molecular dextrins, which are often present in infant foods, do not disturb the RG extraction even when present in high perc
32、entages. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 fat content all the substances determined by the method specified in this part of ISO 8262 IDF 124 NOTE It is expressed as a mass fraction in percent. 3 Principle A test portion is dige
33、sted by boiling with dilute hydrochloric acid. The hot digest is filtered through a wetted filter paper to retain fatty substances, then the fat is extracted from the dried filter paper using n-hexane or light petroleum. The solvent is removed by distillation or evaporation and the substances extrac
34、ted are weighed. (This is usually known as the Weibull-Berntrop principle.) 4 Reagents and materials Use only reagents of recognized analytical grade that leave no appreciable residue when the determination is carried out by the method specified. Use distilled or deionized water, or water of at leas
35、t equivalent purity. 4.1 Dilute hydrochloric acid, containing approximately 20 % (mass fraction) of HCl, 20approximately 1,10 g/ml. Dilute 100 ml of concentrated hydrochloric acid ( 20= 1,18 g/ml) with 100 ml of water and mix. BS ISO 8262-1:20052 4.2 Extraction solvent, free from water: n-hexane or
36、light petroleum having any boiling range between 30 C and 60 C. To test the quality of the extraction solvent, distil 100 ml of it from an extraction flask (5.4) prepared as specified in 7.4. Use an empty extraction flask, prepared in the same way, to check the mass (see 10.1). The solvent shall lea
37、ve no residue greater than 1,0 mg. Replace or distil the solvent if it does not meet this requirement. 4.3 Filter papers, of diameter 150 mm, pleated, medium grade, preferably defatted. To test the quality of the filter paper, carry out a blank test as specified in 7.3, using a solvent satisfying th
38、e requirement of 4.2. Use an empty extraction flask (5.4), prepared as specified in 7.4, to check the mass (see 10.1). The paper shall leave no residue greater than 2,5 mg. Replace unsatisfactory filter papers. 4.4 Blue litmus paper. 4.5 Diatomaceous earth (optional; see 7.5.3). 4.6 Pure lactose (op
39、tional; see 7.5.3). 4.7 Cotton wool, defatted by extraction with the solvent (4.2) for 1,5 h and dried. 5 Apparatus WARNING Since the determination involves the use of volatile flammable solvents, electrical apparatus employed may be required to comply with legislation relating to the hazards in usi
40、ng such solvents. Usual laboratory equipment and, in particular, the following. 5.1 Analytical balance. 5.2 Blender, for homogenizing the laboratory sample, if necessary. For example, use a food chopper or a high-speed blender with a blender jar, of capacity 1 litre, fitted with a lid. 5.3 Extractio
41、n apparatus, continuous or semi-continuous. For example, use a Soxhlet type, consisting of an extraction flask (flat-bottomed, short-necked) of capacity 150 ml, an extractor with a siphoning volume of 40 ml to 60 ml, and an efficient reflux condenser fitted with a drying tube or plug of cotton wool.
42、 5.4 Extraction flasks, of capacity 150 ml, flat-bottomed and short-necked. 5.5 Extraction thimbles, made of defatted filter paper, glass, alumina or PTFE 1) , contributing no appreciable residue in the blank test, or made of cellulose, single thickness, of internal diameter 22 mm and external lengt
43、h 80 mm, for use with the extraction apparatus (5.3). 5.6 Water baths, capable of being maintained at the following temperatures: 40 C to 60 C (see 7.1.1); 30 C to 40 C (see 7.1.2). 1) Polytetrafluoroethylene. BS ISO 8262-1:20053 5.7 Heating apparatus, for the extraction apparatus. For example, use
44、a water bath, sand bath or a thermostatically controlled hotplate. 5.8 Boiling aids, fat-free, such as glass beads or pieces of non-friable, non-porous porcelain or silicon carbide. 5.9 Conical flask, of capacity 250 ml, fitted with a reflux condenser, preferably of the Liebig type. 5.10 Heating app
45、aratus, for heating a conical flask fitted with a condenser. For example, use a wire gauze and gas burner, an electric hotplate or a sand bath. 5.11 Filter funnel, suitable for use with the pleated filter paper (4.3). 5.12 Beakers with spouts, of capacities 100 ml and 250 ml. 5.13 Distillation appar
46、atus, to enable the solvent to be gently distilled from the flasks at a temperature not exceeding 100 C. 5.14 Drying oven, electrically heated, with ventilation port(s) fully open, capable of being maintained at a temperature of 102 C 2 C throughout the working space. The oven shall be fitted with a
47、 suitable thermometer. 5.15 Measuring cylinders, of capacities 50 ml, 100 ml and 250 ml. 5.16 Tongs, made of metal, suitable for holding flasks or beakers. 5.17 Tweezers, flat-tipped, for holding filter papers and thimbles. 6 Sampling A representative sample should have been sent to the laboratory.
48、It should not have been damaged or changed during transport or storage. Sampling is not part of the method specified in this part of ISO 8262 IDF 124. A recommended sampling method is given in ISO 707 IDF 50. All liquid, viscous or pasty laboratory samples shall be kept at a temperature of 2 C to 4
49、C from the time of sampling to the time of commencing the procedure. In the case of a sealed can or bottle, store it unopened at a temperature below 20 C. 7 Procedure 7.1 Preparation of test sample 7.1.1 Liquid products Shake and invert the container. Open the container, pour the product slowly into a second container (provided with an airtight lid) and mix by repeated transfer, taking care to incorporate in the sam
