1、 Reference numbers ISO 8967:2005(E) IDF 134:2005(E) ISO and IDF 2005INTERNATIONAL 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 en poudre Dtermination de la masse volumique ISO 8967:2005(E) IDF 134:2
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7、opyrightiso.org E-mail infofil-idf.org Web www.iso.org Web www.fil-idf.org Published in Switzerland ii ISO and IDF 2005 All rights reservedISO 8967:2005(E) IDF 134:2005(E) ISO and IDF 2005 All rights reserved iii Foreword ISO (the International Organization for Standardization) is a worldwide federa
8、tion 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 committ
9、ee. 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 accordance
10、 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 requires ap
11、proval 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 8967 IDF 134 was prepared by Technic
12、al 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 8967 IDF 134 cancels and replaces ISO 8967:1992, of which it constitutes a minor revision. ISO 8967:2005(E
13、) IDF 134:2005(E) iv ISO and IDF 2005 All rights reservedForeword 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
14、 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 IDF National Committees for voting. Publication as an
15、 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 subject of patent rights. IDF shall not be held responsible for identifying any or all such patent rights.
16、 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 by IDF and ISO. All work was carried out by the Joint ISO/IDF/AOAC Group of Experts on Physical proper
17、ties 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. ISO 8967:2005(E) IDF 134:2005(E) ISO and IDF 2005 All rights reserved v Introduction Different steps during production can influence the vol
18、ume 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 concentrate. Also, homogenization of the concentrate and
19、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 the fines to the wet zone in the spray drier (
20、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 bulk density were tested. In one method the cy
21、linder 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 achieve reasonably constant volume. From this work
22、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. INTERNATIONAL STANDARD ISO 8967:2005(E) IDF 134:2005(E) ISO and IDF 2005 All rights reserved 1 Dried milk and dried mil
23、k products Determination 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
24、applicable to dried whey, 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, t
25、he following terms and definitions 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
26、 powder after 100 tappings 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 Intern
27、ational Standard NOTE 1 For 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 d
28、ried milk products are traditionally 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 Organiz
29、ation, and the World Health Organization. ISO 8967:2005(E) IDF 134:2005(E) 2 ISO and IDF 2005 All rights reserved3 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 calculat
30、ed. 4 Apparatus Usual laboratory equipment and, in particular, the following. 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
31、.3 Bulk density apparatus (see Figure 1), having the components specified in 4.3.1 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, capabl
32、e of recording from 0 to 625 taps, fitted with an automatic stop, capable of being 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
33、: total height, 100 mm; length of tube, 30 mm; diameter of tube, 20 mm; upper 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
34、the method specified in this International Standard. A recommended sampling method 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 tempera
35、ture (20 C to 25 C). Thoroughly mix the sample (avoid the breakage of particles) 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, airti
36、ght container of adequate capacity and mix as described above. In the case of instant dried milk, the mixing shall be very gentle to avoid reducing the particle size of the sample. ISO 8967:2005(E) IDF 134:2005(E) ISO and IDF 2005 All rights reserved 3 Key 1 measuring cylinder 2 rubber sleeve 3 hold
37、er for measuring cylinder 4 shaft 5 sleeve 6 anvil 7 cam Dimensions in millimetres Figure 1 Bulk density apparatus ISO 8967:2005(E) IDF 134:2005(E) 4 ISO and IDF 2005 All rights reserved7 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
38、 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 using the spatula (4.4). If necessary, use the brush (4.7) to transfer all traces of powder to the measuring cylinder.
39、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 apparatus (4.3) and tap 100 times. Level off the surface with the spatula and record the volume in millilitres (V
40、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 Expression of results Calculate the result, expressed in grams per millilitre, according to the appropriate formul
41、a 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 transfer, after 100 tappings and after 625 tappings, respectively; m is the mass of the test portion, in grams; V 0, V
42、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. ISO 8967:2005(E) IDF 134:2005(E) ISO and IDF 2005 All rights reserved 5 9 Precision 9.1 Interlaboratory test The values for repeatabil
43、ity 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 identical test material in the same laboratory by the same oper
44、ator 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 both results if the difference exceeds 0,025 g/ml and carry o
45、ut 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 equipment, will in not more than 5 % of cases be greater than 0,
46、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 used, with reference to this International Standard, i.e. ISO 89
47、67 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 repeatability has been checked, the final quoted result obtained.
48、 ISO 8967:2005(E) IDF 134:2005(E) 6 ISO and IDF 2005 All rights reservedBibliography 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 3 ISO 57
49、25:1986, 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 Research Group, Analytical methods for dry milk products, 4th edn., Niro Atomizer, Copenhagen, 1978 ISO 8967:2005(E) IDF 134:2005(E) ICS 67.100.10 Price based on 6 pages ISO and
