BS ISO 8967-2006 Dried milk and dried milk products - Determination of bulk density《奶粉及奶粉制品 散装密度的测定》.pdf

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1、BRITISH STANDARD BS ISO 8967:2005 Dried milk and dried milk products Determination of bulk densityICS 67.100.10 BS ISO 8967:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 23 January 2006 BSI 23 January 2006 ISBN 0 580 47512 3 National f

2、oreword This British Standard reproduces verbatim ISO 8967:2005 and implements it as the UK national standard. It supersedes BS 1743-5:1992 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee AW/5, Chemical analysis of milk and milk products, which has th

3、e responsibility to: 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 BSI Catalogue under the section entitled “Interna

4、tional 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 its correct application. Compliance with a Brit

5、ish Standard does not of itself confer immunity from legal obligations. 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 international and Eu

6、ropean developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 6, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when t

7、he document was last issued. Amendments issued since publication Amd. No. Date Comments Reference numbers ISO 8967:2005(E) IDF 134:2005(E)INTERNATIONAL STANDARD ISO 8967 IDF 134 Second edition 2005-12-15 Dried milk and dried milk products Determination of bulk density Lait sec et produits laitiers e

8、n poudre Dtermination de la masse volumique BS ISO 8967:2005ii iii 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

9、 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, in liaison with ISO, also take part in the work. ISO collaborates closely with

10、 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 task of technical committees is to prepare International Standards. Draft Intern

11、ational 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

12、be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 8967 IDF 134 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 publis

13、hed jointly by ISO and IDF. This edition of ISO 8967 IDF 134 cancels and replaces ISO 8967:1992, of which it constitutes a minor revision. BS ISO 8967:2005iv Foreword IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a National Committee in every member coun

14、try. 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 development of standard methods of analysis and sampling for milk and milk products. Draft International Standards adopted by the Action Team

15、s and Standing Committees are circulated to the IDF National Committees for voting. Publication as an International Standard requires approval by at least 50 % of the National Committees casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subje

16、ct of patent rights. IDF shall not be held responsible for identifying any or all such patent rights. ISO 8967 IDF 134 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 b

17、y IDF and ISO. All work was carried out by the Joint ISO/IDF/AOAC Group of Experts on Physical properties of dried milk products (E701), under the aegis of its chairman, Mr J. de Vilder (BE). This edition of ISO 8967 IDF 134 cancels and replaces IDF 134A:1995. BS ISO 8967:2005v Introduction Differen

18、t steps during production can influence the volume taken up by a certain mass of milk powder. The most important parameters affecting the volume of milk powder and hence its bulk density (see the definitions in Clause 2) are the dry matter content, the viscosity and the temperature of the concentrat

19、e. Also, homogenization of the concentrate and the spray-drying conditions, such as the inlet and outlet temperatures of the air and the peripheral velocity of the atomizer wheel or the pressure during nozzle atomization, are important steps. Special spray-drying conditions, such as recirculation of

20、 the fines to the wet zone in the spray drier (straight-through atomization), two-stage drying or rewetting for the production of instant milk powder, also have an influence on the volume. In an interlaboratory study involving seven laboratories and nine samples, two methods for the determination of

21、 bulk density were tested. In one method the cylinder was dropped manually and in the other a mechanical apparatus was used for the tapping. The aim of this work was not only to establish the repeatability and reproducibility of the methods but also to determine the number of tappings needed to achi

22、eve reasonably constant volume. From this work it was clear that the mechanical operation gives far better results than the manual operation. For the mechanical test, the same apparatus as that specified in ISO 787-11 was used. BS ISO 8967:2005blank1 Dried milk and dried milk products Determination

23、of bulk density 1 Scope This International Standard specifies a method for the determination of the bulk density of dried whole milk, dried partly skimmed milk and dried skimmed milk as defined in FAO/WHO Standard A-5 1) , whether non- instant or instant. The method is also applicable to dried whey,

24、 dried buttermilk and dried milk-based infant food, as well as to any of the dried products indicated above in which milk fat has been replaced by another fat, or which has been roller-dried instead of spray-dried. 2 Terms and definitions For the purposes of this document, the following terms and de

25、finitions apply. 2.1 poured bulk density quotient of the mass and volume of a powder after transferring it to a specific cylinder NOTE For dried milk and dried milk products, it is expressed in grams per millilitre. 2.2 loose bulk density quotient of the mass and volume of a powder after 100 tapping

26、s under the conditions specified in this International Standard NOTE For dried milk and dried milk products, it is expressed in grams per millilitre. 2.3 bulk density quotient of the mass and volume of a powder after 625 tappings under the conditions specified in this International Standard NOTE 1 F

27、or dried milk and dried milk products, it is expressed in grams per millilitre. NOTE 2 In the Systme international dunits the concepts of density as defined above are expressed in kilograms per cubic metre. In commercial practice, however, these densities of dried milk and dried milk products are tr

28、aditionally expressed in grams per millilitre. 1) FAO/WHO Standard A-5 for whole milk powder, partly skimmed milk powder and skimmed milk powder, elaborated under the Code of principles concerning milk and milk products, 8th edition (1984), Rome: Food and Agriculture Organization, and the World Heal

29、th Organization. BS ISO 8967:20052 3 Principle A test portion of the dried product in a measuring cylinder is tapped. After a specified number of taps, the volume of the product is recorded and its bulk density is calculated. 4 Apparatus Usual laboratory equipment and, in particular, the following.

30、4.1 Balance, accurate to the nearest 0,1 g. 4.2 Measuring cylinder, of 250 ml capacity, graduated from 0 ml to 250 ml, of scale length 245 mm 4 mm, of mass 190 g 15 g, and capable of being fixed onto the apparatus (4.3). 4.3 Bulk density apparatus (see Figure 1), having the components specified in 4

31、.3.1 to 4.3.3. 4.3.1 Screwing device, to fasten the measuring cylinder onto the apparatus, of 450 g 10 g mass. 4.3.2 Tapping device, capable of lifting up the screwing device (4.3.1). 4.3.3 Interval-counting device, capable of recording from 0 to 625 taps, fitted with an automatic stop, capable of b

32、eing regulated to stop after a previously defined number of taps. 4.4 Laboratory spatula. 4.5 Beaker, of 250 ml capacity. 4.6 Powder funnel, with short tube, in glass or antistatic material, having the following dimensions: total height, 100 mm; length of tube, 30 mm; diameter of tube, 20 mm; upper

33、diameter of funnel, 100 mm. 4.7 Laboratory brush. 5 Sampling A representative 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 me

34、thod is given in ISO 707 IDF 50. Place the laboratory sample in a clean, dry, airtight container. The intact unopened retail container may be used. 6 Preparation of test sample Keep the laboratory sample at ambient temperature (20 C to 25 C). Thoroughly mix the sample (avoid the breakage of particle

35、s) by repeatedly rotating and inverting the container. The container should be not more than two-thirds full. If the container is too full to allow thorough mixing, transfer all the laboratory sample to a clean, dry, airtight container of adequate capacity and mix as described above. In the case of

36、instant dried milk, the mixing shall be very gentle to avoid reducing the particle size of the sample. BS ISO 8967:20053 Key 1 measuring cylinder 2 rubber sleeve 3 holder for measuring cylinder 4 shaft 5 sleeve 6 anvil 7 cam Dimensions in millimetres Figure 1 Bulk density apparatus BS ISO 8967:20054

37、 7 Procedure 7.1 Test portion Weigh into a beaker (4.5) 100 g 0,1 g of powder. If 100 g of powder does not fit into the measuring cylinder (4.2), reduce the mass to 50 g 0,1 g. 7.2 Determination 7.2.1 Place the funnel (4.6) on the measuring cylinder (4.2) and transfer the powder to the cylinder usin

38、g the spatula (4.4). If necessary, use the brush (4.7) to transfer all traces of powder to the measuring cylinder. In order to make the reading easier, level off the surface with the spatula (4.4) and record the volume in millilitres (V 0 ). 7.2.2 Fix the measuring cylinder (4.2) in the bulk density

39、 apparatus (4.3) and tap 100 times. Level off the surface with the spatula and record the volume in millilitres (V 100 ). 7.2.3 Regulate the number of taps to 625 (including the 100 taps of 7.2.2). After tapping, level off the surface with the spatula and record the volume in millilitres (V 625 ). 8

40、 Expression of results Calculate the result, expressed in grams per millilitre, according to the appropriate formula given below. Poured bulk density 0= m/V 0 (1)Loose bulk density 100= m/V 100 (2)Bulk density 625= m/V 625 (3)where 0 , 100and 625are the densities, in grams per millilitre, after tran

41、sfer, after 100 tappings and after 625 tappings, respectively; m is the mass of the test portion, in grams; V 0, V 100and V 625are the volumes, in millilitres, after transfer, after 100 tappings and after 625 tappings, respectively. Express the results to the third decimal place. BS ISO 8967:20055 9

42、 Precision 9.1 Interlaboratory test The values for repeatability and reproductibility were derived from the results of an interlaboratory test carried out in accordance with ISO 5725:1986. 9.2 Repeatability The absolute difference between two single test results, obtained using the same method on id

43、entical 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 0,025 g/ml, where is the arithmetic mean of the two results. Take as the result if the repeatability is satisfactory. Reject

44、both results if the difference exceeds 0,025 g/ml and carry out two new single determinations. 9.3 Reproducibility The absolute difference between two single test results, obtained using the same method on identical test material in different laboratories with different operators using different equ

45、ipment, will in not more than 5 % of cases be greater than 0,04 g/ml where is the arithmetic mean of the two results. 10 Test report The 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 use

46、d, with reference to this International Standard, i.e. ISO 8967 IDF 134; d) all operating details not specified in this International Standard, or regarded as optional, together with details of any incidents which may have influenced the test result(s); e) the test result(s) obtained or, if the repe

47、atability has been checked, the final quoted result obtained. BS ISO 8967:20056 Bibliography 1 ISO 707 IDF 50, Milk and milk products Guidance on sampling 2 ISO 787-11:1981, General methods of test for pigments and extenders Part 11: Determination of tamped volume and apparent density after tamping

48、3 ISO 5725:1986, Precision of test methods Determination of repeatability and reproductibility for a standard test method by inter-laboratory tests (now withdrawn) 4 HARPER, J.M. An apparatus for measuring bulk density of dried milk. Food technology, 16, No. 9, 1962, p. 144 5 Niro Atomizer Dairy Res

49、earch Group, Analytical methods for dry milk products, 4th edn., Niro Atomizer, Copenhagen, 1978 BS ISO 8967:2005blankBS ISO 8967:2005 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI 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. Revisions B