BS ISO 5544-2008 Caseins - Determination of fixed ash (Reference method)《酪蛋白 固定灰分的测定(参考方法)》.pdf

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1、BRITISH STANDARDBS ISO 5544:2008Caseins Determination of “fixed ash” (Reference method)ICS 67.100.99g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58

2、BS ISO 5544:2008This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 February 2008 BSI 2008ISBN 978 0 580 60643 4National forewordThis British Standard is the UK implementation of ISO 5544:2008. It supersedes BS 6248-2:1982 which is withdrawn.

3、The UK participation in its preparation was entrusted to Technical Committee AW/5, Chemical analysis of milk and milk products.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions o

4、f a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments/corrigenda issued since publicationDate CommentsReference numbersISO 5544:2008(E)IDF 89:2008(E)INTERNATIONAL STANDARD ISO5544IDF89Second edition

5、2008-01-15Caseins Determination of “fixed ash” (Reference method) Casines Dtermination des cendres fixes (Mthode de rfrence)BS ISO 5544:2008ii iiiForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of

6、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,

7、 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

8、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

9、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 5544IDF 89 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and mi

10、lk products, and the International Dairy Federation (IDF). It is being published jointly by ISO and IDF. This second edition of ISO 5544IDF 89 cancels and replaces the first edition (ISO 5544:1978), of which it constitutes a minor revision. BS ISO 5544:2008iv Foreword IDF (the International Dairy Fe

11、deration) 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 members of IDF have the right to be represented at

12、 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 circulated to the National Committ

13、ees 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 be held responsible for ident

14、ifying any or all such patent rights. ISO 5544IDF 89 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 carried out by the former Joint ISO-ID

15、F-AOAC Group of Experts (E11-E701) which is now part of the Joint ISO-IDF Action Team on Physical properties and rheological tests of the Standing Committee on Minor components and characterization of physical properties. This edition of ISO 5544IDF 89 cancels and replaces IDF 89:1979, of which it c

16、onstitutes a minor revision. BS ISO 5544:20081Caseins Determination of “fixed ash” (Reference method) 1 Scope This International Standard specifies a reference method for the determination of the “fixed ash” of caseins, as a percentage by mass, obtained by acid precipitation or lactic fermentation,

17、of ammonium caseinates, of their mixtures with rennet casein and with caseinates, and of caseins of unknown type. NOTE For the determination of ash of rennet caseins and caseinates (except ammonium caseinates), see ISO 5545IDF 902. 2 Normative references The following referenced documents are indisp

18、ensable 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 648, Laboratory glassware Single volume pipettes ISO 3310-1, Test sieves Technical require

19、ments and testing Part 1: Test sieves of metal wire cloth ISO 5550IDF 78, Caseins and caseinates Determination of moisture content (Reference method) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 “fixed ash” of caseins substances determined

20、 by the procedure specified in this International Standard NOTE “Fixed ash“ of caseins is expressed as a percentage by mass. 4 Principle The test portion is incinerated at (825 25) C in the presence of magnesium acetate to bind all phosphorus of organic origin. The residue is then weighed and the ma

21、ss of ash originating from magnesium acetate subtracted. 5 Reagents Use only reagents of recognized analytical grade, and only distilled or demineralized water or water of equivalent purity. BS ISO 5544:20082 5.1 Magnesium acetate tetrahydrate, Mg(CH3CO2)24H2O, 120 g/l solution. 6 Apparatus Usual la

22、boratory apparatus, and in particular the following. 6.1 Analytical balance, capable of weighing to the nearest 0,000 1 g. 6.2 One-mark pipette, of capacity 5 ml, complying with the requirements of ISO 648, class A. 6.3 Silica or platinum dishes, of diameter about 70 mm and depth 25 mm to 50 mm. 6.4

23、 Drying oven, capable of being controlled at (102 2) C. 6.5 Electrical furnace, with air circulation, capable of being controlled at (825 25) C. 6.6 Water bath, capable of being maintained at boiling point. 6.7 Desiccator, containing an effective desiccant. 6.8 Grinding device, for grinding the labo

24、ratory sample, if necessary (see 8.1.4), without development of undue heat and without loss or absorption of moisture. A hammer-mill shall not be used. 6.9 Test sieve, wire cloth, of diameter 200 mm, of nominal size of aperture 500 m, with receiver, complying with ISO 3310-1. 7 Sampling A representa

25、tive 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 recommended sampling method is given in ISO 707|IDF 50 1. 8 Procedure 8.1 Preparation of the tes

26、t sample 8.1.1 Thoroughly mix the laboratory sample by repeatedly shaking and inverting the container (if necessary, after having transferred all of the laboratory sample to an airtight container of sufficient capacity to allow this operation to be carried out). 8.1.2 Transfer about 50 g of the thor

27、oughly mixed laboratory sample to the test sieve (6.9). 8.1.3 If the 50 g portion directly passes or almost completely passes the sieve, use for the determination the sample as prepared in 8.1.1. 8.1.4 Otherwise, grind the 50 g portion, using the grinding device (6.8), until it passes the sieve. Imm

28、ediately transfer all of the sieved sample to an airtight container of sufficient capacity and mix thoroughly by repeatedly shaking and inverting. During these operations, take precautions to avoid any change in the water content of the product. 8.1.5 After the test sample has been prepared, the det

29、ermination (8.4) should proceed as soon as possible. Clean the device after grinding each sample. BS ISO 5544:200838.2 Preparation of the dishes Heat two dishes (6.3) in the electrical furnace (6.5), maintained at (825 25) C, for 30 min. Allow the dishes to cool in the desiccator (6.7) to the temper

30、ature of the balance room and weigh to the nearest 0,1 mg. 8.3 Test portion Weigh, to the nearest 0,1 mg, directly in or by difference approximately 3,000 0 g of the test sample (8.1) into one of the prepared dishes, designated dish A. 8.4 Determination Using the pipette (6.2), add 5 ml of the magne

31、sium acetate solution (5.1) to dish A so as to wet all of the test portion, and allow to stand for 20 min. Using the pipette (6.2), add 5 ml of the magnesium acetate solution (5.1) to the other prepared dish, designated dish B. Evaporate the contents of dish A and dish B to dryness on the water bath

32、 (6.6). Place dish A and dish B in the oven (6.4), maintained at 102 C, for 30 min. Heat dish A with its contents on a low flame until the test portion is completely charred, taking care that it does not burst into flame. Transfer dish A and dish B to the electrical furnace (6.5), maintained at 825

33、C, and heat for at least 1 h until all carbon has disappeared from dish A. Allow dish A and dish B to cool in the desiccator (6.7) to the temperature of the balance room and weigh to the nearest 0,1 mg. Repeat the operations of heating in the electrical furnace (6.5), cooling and weighing, until the

34、 mass remains constant to within 1 mg or begins to increase. Record the minimum mass. 9 Expression of results 9.1 Calculation 9.1.1 The “fixed ash” of the sample, including phosphorus, wfa, as a percentage by mass, is given by Equation (1): ()()mm mmwm=12 3 4fa0100 (1) where m0is the mass, in grams,

35、 of the test portion (8.3); m1is the mass, in grams, of dish A and residue (8.4); m2is the mass, in grams, of dish A (8.2); m3is the mass, in grams, of dish B and residue (8.4); m4is the mass, in grams, of dish B (8.2). Calculate the “fixed ash” to the nearest 0,01 % by mass and report the final res

36、ult to the nearest 0,1 % by mass. BS ISO 5544:20084 9.1.2 To calculate the “fixed ash” of the sample on the dry basis, as a percentage by mass, multiply the result obtained from Equation (1) by Factor (2) ww100100(2) where ww is the water content, as a percentage by mass, of the sample determined ac

37、cording to ISO 5550IDF 78. 9.2 Precision 9.2.1 Repeatability The absolute difference between two independent single 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

38、 than 5 % of cases be greater than 0,1 g of “fixed ash” per 100 g of product (numerically equivalent to 0,1 % by mass). 9.2.2 Reproducibility The absolute difference between two independent single test results, obtained using the same method on identical test material in different laboratories with

39、different operators using different equipment, will in not more than 5 % of cases be greater than 0,2 g of “fixed ash” per 100 g of product (numerically equivalent to 0,2 % by mass). 10 Test report The test report shall specify: a) all the information required for the complete identification of the

40、sample; b) the sampling method used, if known; c) the test method used, together with a reference to this International Standard; d) all operating details not specified in this International Standard, or regarded as optional, together with details of any incident that may have influenced the result(

41、s); e) the test result(s) obtained and, if the repeatability has been checked, the final quoted results obtained. BS ISO 5544:20085Bibliography 1 ISO 707|IDF 50, Milk and milk products Guidance on sampling 2 ISO 5545IDF 90, Rennet caseins and caseinates Determination of ash (Reference method) BS ISO

42、 5544:2008BS ISO 5544:2008BSI389 Chiswick High RoadLondonW4 4ALBSI British Standards InstitutionBSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter.Revisio

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