1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58by uniaxial compression at constant displacement rateICS 67.100.30Cheese Determination of rheologic
2、al properties DRAFT FOR DEVELOPMENTDD ISO/TS 17996:2006DD ISO/TS 17996:2006This Draft for Development was published under the authority of the Standards Policy and Strategy Committee on 29 December 2006 BSI 2006ISBN 0 580 49828 Xan international Standard, to extend the life of the Technical Specific
3、ation or to withdraw it. Comments should be sent to the Secretary of the responsible BSI Technical Committee at British Standards House, 389 Chiswick High Road, London W4 4AL.The UK participation in its preparation was entrusted to Technical Committee AW/5, Chemical analysis of milk and milk product
4、s.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 contract. Users are responsible for its correct application.Amendments issued since publicationAmd. No. Date Commentsthat UK experi
5、ence can be reported to the international organization responsible for its conversion to an international standard. A review of this publication will be initiated not later than 3 years after its publication by the international organization so that a decision can be taken on its status. Notificatio
6、n of the start of the review period will be made in an announcement in the appropriate issue of Update Standards.According to the replies received by the end of the review period, the responsible BSI Committee will decide whether to support the conversion into National forewordThis Draft for Develop
7、ment was published by BSI. It is the UK implementation of ISO/TS 17996:2006. This publication is not to be regarded as a British Standard.It is being issued in the Draft for Development series of publications and is of a provisional nature. It should be applied on this provisional basis, so that inf
8、ormation and experience of its practical application can be obtained.Comments arising from the use of this Draft for Development are requested so Reference numbersISO/TS 17996:2006(E)IDF/RM 205:2006(E)TECHNICAL SPECIFICATION ISO/TS17996IDF/RM205First edition2006-09-01Cheese Determination of rheologi
9、cal properties by uniaxial compression at constant displacement rate Fromage Dtermination des proprits rhologiques par compression uniaxiale vitesse constante de translation DD ISO/TS 17996:2006ii iiiContents Page Foreword iv Foreword. v 1 Scope . 1 2 Terms and definitions. 1 3 Principle. 1 4 Appara
10、tus 1 5 Sampling 2 6 Procedure 2 6.1 Thermal equilibration of test samples 2 6.2 Test portion . 2 6.3 Test conditions . 3 7 Analysis of the compression curves 4 7.1 Data representation and calculation. 4 7.2 Parameters characterizing the compression curves 5 7.3 Expression of results . 8 8 Precision
11、 8 8.1 Interlaboratory test . 8 8.2 Repeatability 8 8.3 Reproducibility 9 9 Test report . 9 Annex A (normative) Figures 10 Annex B (normative) Non-standard sample conditions. 13 Annex C (informative) Examples of compression curves 15 Annex D (informative) Results of interlaboratory trial with one sa
12、mple 17 Bibliography . 18 DD ISO/TS 17996:2006iv 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 committees. Each
13、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 the International
14、 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 International Standards
15、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. In other circumstances, particularly when there is an urgent market requirement for such documents, a t
16、echnical committee may decide to publish other types of normative document: an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in an ISO working group and is accepted for publication if it is approved by more than 50 % of the members of the parent com
17、mittee casting a vote; an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting a vote. An ISO/PAS or ISO/TS is reviewed after three years in order to
18、decide whether it will be confirmed for a further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an International Standard or be withdraw
19、n. 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/TS 17996|IDF/RM 205 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee
20、 SC 5, Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO and IDF. DD ISO/TS 17996:2006vForeword IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a National Committee in every member country. Every Nat
21、ional 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. The main task of technical committees is to prepare International Stan
22、dards. 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 IDF National Committees casting a vote. In other circumstances, particularly w
23、hen there is an urgent market requirement for such documents, a Standing Committee may decide to publish an other type of normative document which is called by IDF: Reviewed method. Such a method represents an agreement between the members of a Standing Committee and is accepted for publication if i
24、t is approved by at least 50 % of the committee members casting a vote. A Reviewed method is equal to an ISO/PAS or ISO/TS and will, therefore, also be published jointly under ISO conditions. Attention is drawn to the possibility that some of the elements of this document may be the subject of paten
25、t rights. IDF shall not be held responsible for identifying any or all such patent rights. ISO/TS 17996|IDF/RM 205 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 ID
26、F and ISO. All work was carried out by the Joint ISO-IDF Action Team on Physical properties and rheological tests, of the Standing Committee on Minor compounds and characterization of physical properties, under the aegis of its former project leader, Mrs Y. Nol (FR), who performed most of the work,
27、and its present project leader, Mr P. Watkinson (NZ). DD ISO/TS 17996:2006blank1Cheese Determination of rheological properties by uniaxial compression at constant displacement rate 1 Scope This Technical Specification describes a method for the determination of rheological properties by uniaxial com
28、pression at constant displacement rate in hard and semi-hard cheeses. The method provides standard conditions for sampling and testing, for data representation and general principles of calculation. NOTE Sampling might be difficult with some cheese varieties, for example caused by shortness, brittle
29、ness, stickiness and soft consistency. In these cases, reliable results cannot be achieved. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 rheological properties deformation under compression of the test sample by the procedure specified in
30、this Technical Specification 3 Principle A cylindrical test sample, of defined dimensions, is compressed at a constant crosshead speed with a compression tool up to a relative deformation sufficient to determine the apparent fracture point. The force, which is the resistance of the cheese sample dur
31、ing compression, is measured with a load cell. The displacement may be measured either from the position of the cross head or calculated from the elapsed time multiplied by the displacement rate. A schematic representation of the principle of the test is given in Figure A.1. 4 Apparatus Usual labora
32、tory apparatus and, in particular, the following. 4.1 Cork-borer, such as that shown in Figure A.4 as an example. It is recommended to mount the cork-borer on a drill-stand in order to drive it slowly and steadily through the test sample. 4.2 Parallel-wire cutting device, with a wire of diameter les
33、s than or equal to 0,4 mm and with a system to keep the two wires parallel to each other and perpendicular to the plug. It should also include a mechanically driven cutting system to cut the test sample to the required height. DD ISO/TS 17996:20062 4.3 Measuring cell, with a support and compression
34、plate of the same stiff material, with smooth and parallel surfaces (e.g. stainless steel, aluminium or Teflon), of diameter larger (by 20 %) than that of the deformed test portion when at maximum compression. The load cell capacity shall have a reasonable relationship to the expected maximum force.
35、 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 Technical Specification. A recommended sampling method is given in ISO 707|IDF 50. 6 Procedure 6.1
36、 Thermal equilibration of test samples If the storage temperature of the loaf of cheese is above that of the measuring temperature, then the loaf of cheese shall be equilibrated at the measuring temperature for at least 50 h before further preparation of the test sample because of the slow crystalli
37、zation of milk fat in the cheese. If the storage temperature of the loaf of cheese is below that of the measuring temperature, before any preparation store the loaf of cheese at the measuring temperature for at least 12 h. If there are specific difficulties that can occur during the sample preparati
38、on at the measuring temperature, then sample at the lower storage temperature and then equilibrate the test samples to the measurement temperature. In this case, the sample thermal equilibration time may be less than 12 h. NOTE Examples of specific sampling difficulties are that the cheese is hard t
39、o cut, or a heated loaf of cheese changes the storage regime and therefore stops the use of the unsampled portions of the loaf of cheese for future measurements. The following shall be avoided: a) dehydration of the test sample during the period of thermal equilibration; b) deformation of the test s
40、ample due to its own mass. 6.2 Test portion 6.2.1 Location Take the test portion from the loaf of the cheese with a plug about half a radius, either along a circle of a cylindrical cheese, or along one side of a rectangular cheese (see Figure A.2). Cut the test portion in the plug in the area repres
41、enting around half of the length (see Figure A.3, plug A). If the height of cheese is sufficient, two portions can be taken as shown in Figure A.3, plug B and plug C. 6.2.2 Direction The standard direction for taking the test portion is parallel to the pressure axis in cheese making. See Annex B for
42、 non-standard sampling conditions. 6.2.3 Geometry The shape of the test portion shall be a cylinder with initial height/diameter ratio (h0/d0) of between 1,1 and 1,5. DD ISO/TS 17996:20063The initial height, h0, of the test portion shall range from 12,5 mm to 25 mm. The diameter, d0, for a given hei
43、ght follows the above-mentioned ratio. 6.2.4 Cutting Remove the rind or the plastic cover. Take a test portion using a cork-borer (4.1) with shapes shown in Figure A.4. For sticky cheeses, samples are easier to take with corer A than corer B. For cheese varieties showing shortness or brittleness, fo
44、rm B shown in Figure A.4 is more appropriate than form A. It is recommended to use a cork-borer mounted on a drill-stand in order to drive it slowly and steadily through the test sample. If it is difficult to obtain a good cylindrical form, it is recommended to use mineral oil of low viscosity (e.g.
45、 Vaseline oil) to lubricate the cork-borer. Do not test samples with cracks, holes or other visible defects. Use a parallel-wire cutting device to cut the test sample to the required height. The wire diameter shall be less than or equal to 0,4 mm. It is essential to have a system that keeps the two
46、wires parallel to each other and perpendicular to the plug. Preferably, use a mechanically driven cutting system. Taking these precautions into account reduces the lack in parallelism between the sample surface and the compression plate. 6.2.5 Delay A delay between the taking of a test portion and i
47、ts testing allows stress relaxation of the test portion. The recommended delay is between 10 min and 15 min. The upper limit is not strictly fixed but it should not exceed 2 h. This recommendation is not relevant when sampling is done at a lower temperature than the measuring temperature. Store the
48、test samples at the measuring temperature (6.3.5) and see Annex B for non-standard conditions. Store samples in a pill-box or wrapped in plastic film to avoid dehydration during the delay between sampling and testing. 6.3 Test conditions 6.3.1 Relative deformation Perform the compression to just bey
49、ond the apparent fracture point (Figure A.5, curve 1) or to a predefined maximum deformation (Figure 5, curve 2). 6.3.2 Crosshead speed The standard value of the crosshead speed or displacement rate is 50 mm/min (or 0,83 mm/s) for initial height 12,5 mm u h0u 25 mm. 6.3.3 Number of compression cycles Perform one compression cycle. 6.3.4 Number of test portions Measure at least four test portions, but preferably carry out more than this. 6.3.5 Measuring temperature Measure at the standardized measuring temperature of 15 C 1 C. NOTE
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