1、BRITISH STANDARD BS ISO 2920:2004 Whey cheese Determination of dry matter (Reference method) ICS 67.100.30 BS ISO 2920:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 October 2004 BSI 28 October 2004 ISBN 0 580 44692 1 National forewo
2、rd This British Standard reproduces verbatim ISO 2920:2004 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee AW/5, Milk and milk products, which has the responsibility to: A list of organizations represented on this committee
3、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 BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility o
4、f 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 its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid
5、 enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages Thi
6、s document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 4, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comme
7、nts Reference numbers ISO 2920:2004(E) IDF 58:2004(E) OSI DI dnaF 4002INTERNATIONAL STANDARD ISO 2920 IDF 58 Second edition 2004-10-15 Whey cheese Determination of dry matter (Reference method) Fromage de srum Dtermination de la matire sche (Mthode de rfrence) BSISO2920:2004IS:0292 O4002(E) ID:85 F4
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13、pyrightisoo.rg -Emailni off-lidif.org We bwww.is.o gro We bwww.fil-idf.o gr Plbuisdehi n Switlrez dnaii ISO dnaID 4002 FA ll rihgtsser edevrBSISO2920:2004IS:0292 O4002(E) ID:85 F4002(E) I SO dna ID 4002 F All irhgts seredevr iiiForeword ISO (the International Organization for Standardization) is a w
14、orldwide federation of national standards bodies (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
15、on that committee. International organizations, 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 drafte
16、d 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 International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Stand
17、ard 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 the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 2920 IDF 58 was prepa
18、red by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF), in collaboration with AOAC International. It is being published jointly by ISO and IDF and separately by AOAC International. This edition of ISO 2920 IDF 58 c
19、ancels and replaces ISO 2920:1974, of which it constitutes a minor revision. BSISO2920:2004IS:0292 O4002(E) ID:85 F4002(E) iv I SO dna ID 4002 F All irhgts seredevrForeword IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a National Committee in every membe
20、r country. Every National Committee has the right to be represented on the IDF Standing Committees carrying out the technical work. IDF collaborates with ISO and AOAC International in the development of standard methods of analysis and sampling for milk and milk products. Draft International Standar
21、ds adopted by the Action Teams and Standing Committees are circulated to the National Committees for voting. Publication as an International Standard requires approval by at least 50 % of the National Committees casting a vote. ISO 2920 IDF 58 was prepared by Technical Committee ISO/TC 34, Food prod
22、ucts, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF), in collaboration with AOAC International. It is being published jointly by ISO and IDF and separately by AOAC International. This edition of ISO 2920 IDF 58 cancels and replaces IDF 58:1970, of which it co
23、nstitutes a minor revision. BSISO2920:2004NITERNATNOIAL STANDARD IS:0292 O4002(E) ID:85 F4002(E)I SO dna ID 4002 F All irhgts seredevr 1Whey cheese Determination of dry matter (Reference method) 1 Scope This International Standard specifies a reference method for the determination of the dry matter
24、of whey cheese. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 dry matter of whey cheese residue obtained by application of the procedure specified in this International Standard and including the water of crystallization of lactose NOTE It
25、is expressed as a mass fraction in percent. 3 Principle A sample of whey cheese is desiccated in a ventilated oven set at a temperature of 88 C. 4 Apparatus and materials 4.1 Grinding mill or other appropriate device. 4.2 Analytical balance, capable of weighing to the nearest 0,000 5 g. 4.3 Desiccat
26、or, provided with an efficient drying agent (e.g. silica gel with hygrometric indicator). 4.4 Drying oven, well ventilated and thermostatically controlled, capable of being maintained at 88 C 2 C. 4.5 Dishes, of stainless steel, nickel or aluminium, with height about 20 mm and diameter 60 mm to 80 m
27、m. 4.6 Quartz sand or sea sand, which passes through a sieve with 10 openings per centimetre but not through a sieve with 40 openings per centimetre. For example, use woven wire cloth test sieves with nominal size of aperture of 500 m and 180 m respectively (for details, see ISO 565). If necessary,
28、the sand shall be washed with hot concentrated hydrochloric acid and water, then dried and ignited. BSISO2920:2004IS:0292 O4002(E) ID:85 F4002(E) 2 I SO dna ID 4002 F All irhgts seredevr4.7 Glass stirrers, flat ended. 5 Sampling A representative sample should have been sent to the laboratory. It sho
29、uld not have been damaged or changed during transport or storage. Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 707. 6 Preparation of test sample Grind the representative sample of the cheese by means of the grinding mill (
30、4.1). If the soft consistency of the cheese makes the use of a grinding mill impossible, mix the sample thoroughly by means of another appropriate device (e.g. a glass stirrer or spatula). Avoid losses by evaporation. Keep the prepared sample in a suitable airtight container until analysis. Start th
31、e analysis within 1 h. 7 Procedure 7.1 Number of determinations Carry out two determinations of the same test sample. 7.2 Determination 7.2.1 Weigh about 20 g of sand (4.6) in a dish (4.5) together with a glass stirrer (4.7). With hard and semi-hard whey cheeses, which can be adequately ground by me
32、ans of the grinding mill, the use of sand may be omitted. 7.2.2 Moisten the sand with water and dry the dish to constant mass in the oven (4.4) set at 88 C. 7.2.3 Allow the dish to cool in the desiccator (4.3) and weigh to the nearest 0,000 5 g. 7.2.4 Quickly weigh, to the nearest 0,000 5 g, about 3
33、 g of the test sample in the dish. 7.2.5 Thoroughly mix the test portion with the sand by means of the stirrer. 7.2.6 Dry the dish and contents in the oven (4.4) set at 88 C for 4 h. 7.2.7 Allow to cool in the desiccator (4.3) and weigh to the nearest 0,000 5 g. 7.2.8 Dry in the oven (4.4) again for
34、 1 h. Cool in the desiccator and weigh to the nearest 0,000 5 g. 7.2.9 Repeat the operations of drying and cooling until the difference in mass between two successive weighings is not more than 0,001 g BSISO2920:2004IS:0292 O4002(E) ID:85 F4002(E) I SO dna ID 4002 F All irhgts seredevr 38 Calculatio
35、n and expression of results 8.1 Calculation The mass fraction of dry matter, w, expressed in percent, is given by the formula: 20 10 100 % mm w mm = where m 0is the mass, in grams, of the dish containing the sand and stirrer (7.2.3); m 1is the mass, in grams, of the dish and contents before drying (
36、7.2.4); m 2is the mass, in grams, of the dish and contents after drying (7.2.9). 8.2 Expression of results Take as the result the arithmetic mean of the two determinations, if the requirement of repeatability (see Clause 9) is satisfied. 9 Repeatability The absolute difference between two independen
37、t single test results, obtained using the same method on identical test material in the same laboratory by the same operator using the same equipment within a short interval of time, will in not more than 5 % of cases be greater 0,2 % of dry matter per 100 g of the product. 10 Test report The test r
38、eport shall specify: a) all information necessary for the complete identification of the sample; b) the sampling method used, if known; c) the test method used, with reference to this International Standard; d) all operating details not specified in this International Standard, or regarded as option
39、al, together with details of any incidents which may have influenced the test results; e) the test results obtained, clearly mentioning the method of expression used. BSISO2920:2004IS:0292 O4002(E) ID:85 F4002(E) 4 I SO dna ID 4002 F All irhgts seredevrBibliography 1 ISO 565, Test sieves Metal wire
40、cloth, perforated metal plate and electroformed sheet Nominal sizes of openings 2 ISO 707, Milk and milk products Guidance on sampling 1)1) Equivalent to IDF 50. BSISO2920:2004blankBS ISO 2920:2004 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent nati
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