BS ISO 5550-2006 Caseins and caseinates - Determination of moisture content (Reference method)《酪蛋白和酪蛋白酸盐 水含量的测定(参照法)》.pdf

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1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58moisture content (Reference method)ICS 67.100.99Caseins and caseinates Determination of BRITISH STA

2、NDARDBS ISO 5550:2006BS ISO 5550:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2006 BSI 2006ISBN 0 580 49632 5Amendments issued since publicationAmd. No. Date Commentscontract. Users are responsible for its correct applicati

3、on.Compliance with a British Standard cannot confer immunity from legal obligations.National forewordThis British Standard was published by BSI. It is the UK implementation of ISO 5550:2006. It supersedes BS 6248-8:1982 which is withdrawn.The UK participation in its preparation was entrusted to Tech

4、nical Committee AW/5, Chemical analysis of milk and milk products. A list of organizations represented on AW/5 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a Reference numbersISO 5550:2006(E)IDF 78:2006(E)INTERNATIONAL STAND

5、ARD ISO5550IDF78Second edition2006-10-01Caseins and caseinates Determination of moisture content (Reference method) Casines et casinates Dtermination de la teneur en humidit (Mthode de rfrence) BS ISO 5550:2006ii iiiContents Page Foreword iv Foreword. v 1 Scope . 1 2 Terms and definitions. 1 3 Princ

6、iple. 1 4 Apparatus 1 5 Sampling 2 6 Preparation of test sample. 2 7 Procedure 2 7.1 Preparation of the dish. 2 7.2 Test portion . 2 7.3 Determination 2 8 Calculation and expression of results 3 8.1 Calculation. 3 8.2 Expression of results . 3 9 Precision 3 9.1 Interlaboratory tests . 3 9.2 Repeatab

7、ility 3 9.3 Reproducibility 4 10 Test report . 4 Annex A (informative) Interlaboratory tests 5 Annex B (informative) Influence of the size of the casein grains on precision figures 7 Bibliography . 8 BS ISO 5550:2006iv Foreword ISO (the International Organization for Standardization) is a worldwide

8、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 on that c

9、ommittee. 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 drafted in acco

10、rdance 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 Standard requi

11、res 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 5550IDF 78 was prepared by Tec

12、hnical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO and IDF. This edition of ISO 5550IDF 78 cancels and replaces ISO 5550:1978, which has been technically revised. BS ISO 5550:2006vFo

13、reword 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 the right to be represented on the IDF Standing Committees carrying out the technical work. IDF collaborates with ISO in the d

14、evelopment 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 Committees for voting. Publication as an International Standard requires approval by at least 50 % of t

15、he 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 identifying any or all such patent rights. ISO 5550IDF 78 was prepared by the International Dairy Fed

16、eration (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 Joint ISO-IDF Action Team Water, of the Standing Committee on Main components in milk, under the aegis of its proje

17、ct leader, Mrs M. Nicolas (FR). This edition of ISO 5550IDF 78 cancels and replaces IDF 78C:1991, which has been technically revised. BS ISO 5550:2006blank1Caseins and caseinates Determination of moisture content (Reference method) 1 Scope This International Standard specifies the reference method f

18、or the determination of the moisture content of all types of caseins and caseinates. 2 Terms and definitions For the purpose of this document, the following terms and definitions apply. 2.1 moisture content loss of mass determined by the procedure described in this International Standard NOTE The mo

19、isture content is expressed as a mass fraction in percent. 3 Principle A test portion is dried at 102 C 2 C then weighed to determine its loss of mass. 4 Apparatus Usual laboratory equipment and, in particular, the following. 4.1 Analytical balance, capable of weighing to the nearest 1 mg, with a re

20、adability of 0,1 mg. 4.2 Drying oven, well ventilated, capable of being maintained at a temperature of 102 C 2 C throughout the working space. 4.3 Flat bottomed dish, made of a material that is non-corrodible under the conditions of the test (e.g. a glass dish with ground-glass cover, or aluminium o

21、r stainless-steel dish), of diameter at least 65 mm (preferably 75 mm) and depth of at least 25 mm, equipped with a tight-fitting lid which can be readily removed. 4.4 Desiccator, containing an effective desiccant (e.g. freshly dried silica gel), with hygrometric indicator. 4.5 Grinding device, for

22、grinding the laboratory sample (if necessary, see 6.4), without development of undue heat and without loss or absorption of moisture. A hammer-mill shall not be used. 4.6 Test sieve, wire cloth, of diameter 200 mm and nominal size of aperture 500 m, with receiver. BS ISO 5550:20062 5 Sampling A repr

23、esentative 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 707IDF 50. Store the sample in such a way that

24、 deterioration and change in composition are prevented. 6 Preparation of test sample 6.1 Thoroughly mix the test sample by repeatedly shaking and inverting the container (if necessary, after having transferred all test sample to an airtight container of sufficient capacity to allow this operation to

25、 be carried out). 6.2 Transfer about 50 g of thoroughly mixed test sample to the test sieve (4.6). 6.3 If the 50 g of test sample directly passes or almost completely passes through the sieve, for the determination use the sample as prepared in 6.1. 6.4 Otherwise, grind the 50 g of test sample using

26、 the grinding device (4.5) until it passes through the sieve. Immediately transfer all 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 moisture content of th

27、e product. 6.5 After the test sample has been prepared, proceed with the procedure (Clause 7) as soon as possible. 7 Procedure 7.1 Preparation of the dish 7.1.1 Heat the uncovered dish and its lid (4.3) in the drying oven (4.2) set at 102 C for at least 1 h. 7.1.2 Place the lid on the dish and trans

28、fer the covered dish to the desiccator (4.4). Allow the covered dish to cool to the temperature of the balance room. Then weigh it to the nearest 1 mg, recording the mass to 0,1 mg. 7.2 Test portion 7.2.1 Caseins Transfer approximately 5 g of prepared test sample (6.5) to the dish. Cover the dish wi

29、th the lid and weigh the whole to the nearest 1 mg, recording the mass to 0,1 mg. 7.2.2 Caseinates Transfer approximately 2 g of prepared test sample (6.5) to the dish. Cover the dish with the lid and weigh the whole to the nearest 1 mg, recording the mass to 0,1 mg. 7.3 Determination 7.3.1 Uncover

30、the dish (7.2.1 or 7.2.2) and place it with its lid in the drying oven (4.2) set at 102 C for 3 h. BS ISO 5550:200637.3.2 Replace the lid on the dish and transfer the covered dish to the desiccator (4.4). Allow the covered dish to cool to the temperature of the balance room. Then weigh it to the nea

31、rest 1 mg, recording the mass to 0,1 mg. 7.3.3 Uncover the dish and heat it again with its lid in the drying oven (4.2) set at 102 C for 1 h. Then repeat step 7.3.2. 7.3.4 Repeat the heating and weighing procedure (7.3.1 to 7.3.3) until the mass of the dish with its lid decreases by 1 mg or less, or

32、 increases between two successive weighings. Take for the calculation the lowest mass recorded. NOTE The total drying time will normally not exceed 6 h. 8 Calculation and expression of results 8.1 Calculation Calculate the moisture content of the sample, w, using the following equation: 1210()100 %(

33、)mmwmm=where w is the moisture content of the test sample, expressed as a mass fraction in percent; m0is the mass of the dish and the lid (7.1.2), in grams; m1is the mass of the dish, the lid and the test portion before drying (7.2.1 or 7.2.2), in grams; m2is the mass of the dish, the lid and the te

34、st portion after drying (7.3.4), in grams. 8.2 Expression of results Report the results to two decimal places. 9 Precision 9.1 Interlaboratory tests Details of two interlaboratory tests on the precision of the method are summarized in Annex A, and have been published for caseinates4. The values deri

35、ved from these tests may not be applicable to concentration ranges and matrices other than those given. Repeatability and reproducibility values depend on the size of the grains of casein (see Annex B). 9.2 Repeatability The absolute difference between two independent single test results, obtained u

36、sing 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 than: for caseins 0,34 %; for caseinates 0,32 %. BS ISO 5550:20064 9.3 Reproducibility The absolute diff

37、erence between two independent single test results, obtained using the same method on identical test material in different laboratories by different operators using different equipment, will in not more than 5 % of cases be greater than: for caseins 0,53 %; for caseinates 0,41 %. 10 Test report The

38、test report 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 o

39、ptional, together with details of any incidents which may have influenced the test result(s); e) the test result(s) obtained and, if the repeatability has been checked, the final quoted result obtained. BS ISO 5550:20065Annex A (informative) Interlaboratory testing A.1 Caseins An international colla

40、borative test involving ten laboratories from eight different countries was carried out on eight caseins: five rennet caseins and three acid ones. The French Agency for Food Safety and Security organized the trial. The results obtained were subjected to statistical analysis in accordance with ISO 57

41、25-1 and ISO 5725-2 to give the precision data shown in Table A.1. All values in Table A.1 are expressed as mass fraction in percent. Table A.1 Results of interlaboratory test on caseins Test samples (for sample identification, see foot of table) A B C D E F G H Mean No. of participants after elimin

42、ating outliers 10 9 10 10 10 10 10 10 Mean value, % 9,97 6,82 8,14 8,92 8,50 8,42 7,85 6,78 Repeatability standard deviation, sr, % 0,173 0,017 0,131 0,185 0,129 0,155 0,102 0,072 0,12 Coefficient of variation of repeatability, %1,737 0,247 1,613 2,073 1,512 1,847 1,297 1,055 1,42 Repeatability limi

43、t, r (= 2,8 sr), %0,490 0,048 0,372 0,523 0,364 0,440 0,288 0,202 0,34 Reproducibility standard deviation, sR, % 0,296 0,123 0,163 0,232 0,127 0,205 0,198 0,150 0,19 Coefficient of variation of reproducibility, %2,968 1,802 2,008 2,597 1,494 2,442 2,527 2,210 2,26 Reproducibility limit, R (= 2,8 sR)

44、, %0,837 0,348 0,463 0,655 0,360 0,582 0,562 0,424 0,53 Samples: A = rennet casein; B = acid casein; C = rennet casein; D = acid casein; E = rennet casein; F = acid casein; G = rennet casein; H = rennet casein. A.2 Caseinates An international collaborative test, organized by the Swiss Dairy Research

45、 Institute, was carried out on six double-blind samples of caseinates. The results obtained were subjected to statistical analysis in accordance with ISO 57251)to give the precision data shown in Table A.2. The test results for caseinates have been published 4. All values in Table A.2 are expressed

46、as mass fraction in percent. 1) ISO 5725:1986, Precision of test methods Determination of repeatability and reproducibility for a standard test method by interlaboratory tests (now withdrawn), was used to obtain the precision data. BS ISO 5550:20066 Table A.2 Results of interlaboratory test on casei

47、nates Test samples (for sample identification, see Table A.1) A B C D E F Mean No. of participants after eliminating outliers 12 12 12 12 13 12 Mean value, % 5,54 6,38 6,38 6,98 5,39 8,39 Repeatability standard deviation, sr, % 0,16 0,09 0,09 0,15 0,09 0,10 0,11 Coefficient of variation of repeatabi

48、lity, %2,84 1,48 1,46 2,07 1,63 1,17 1,81 Repeatability limit, r (= 2,8 sr), %0,44 0,26 0,26 0,41 0,25 0,27 0,32 Reproducibility standard deviation, sR, % 0,21 0,12 0,14 0,16 0,11 0,14 0,15 Coefficient of variation of reproducibility, %3,75 1,89 2,14 2,29 2,11 1,63 2,31 Reproducibility limit, R (= 2

49、,8 sR), %0,58 0,34 0,38 0,45 0,32 0,38 0,41 BS ISO 5550:20067Annex B (informative) Influence of the size of the casein grains on precision figures Table B.1 Influence of casein grain size on precision figures Samples (for sample identification, see foot of table) A B C D E F G H Initial mass, g 100,30 100,22 100,29 100,00 100,23 100,24 93,87 100,22 Mass retained by a 500 m sieve aperture, g (as mass fraction of initial mass, %) 0,38 (0,4) 0,88 (0,9) 1,09 (1,1) 0,32 (0,3) 0,82 (0,8) 0,24 (0,2) 0,93 (