BS ISO 11286-2004 Tea - Classification of grades by particle size analysis《茶 用粒度分析法进行等级分类》.pdf

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1、BRITISH STANDARD BS ISO 11286:2004 Tea Classification of grades by particle size analysis ICS 67.140.10 BS ISO 11286:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 16 February 2004 BSI 16 February 2004 ISBN 0 580 43377 3 National forewo

2、rd This British Standard reproduces verbatim ISO 11286:2004 and implements it as the UK national standard. It supersedes BS 6049-8:1998 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee AW/8, Tea, which has the responsibility to: A list of organizations

3、 represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence

4、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 British Standard does not of itself

5、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 the UK interests informed; monitor related international and European developments and prom

6、ulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 3 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publicatio

7、n Amd. No. Date Comments Reference number ISO 11286:2004(E) OSI 4002INTERNATIONAL STANDARD ISO 11286 Second edition 2004-02-15 Tea Classification of grades by particle size analysis Th Classification par catgories par analyse granulomtrique BSISO11286:2003BSISO11286:2004ISO 11286:2004(E) DPlcsid Fre

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12、euqer ehe.r ISO cirypothg fofice saCe tsopale 65 eneG 1121-HC 02 av leT. 4 + 10 947 22 1 11 xaF0 947 22 14 + 9 74 E-mial coirypthgis.o gro We bwww.is.o groii ISO 4002 Allr ithgsr esedevrBSISO11286:2003BSISO11286:2004ISO 11286:2004(E) I SO 4002 All irthgs ersedevr iiiForeword ISO (the International O

13、rganization 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 member body interested in a subject for which a technical committee has been estab

14、lished 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 Electrotechnical Commission (IEC) on all matters of electrotechnical standardizat

15、ion. 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 adopted by the technical committees are circulated to the member bodies for voting

16、. 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 be the subject of patent rights. ISO shall not be held responsible for identifying any or all such p

17、atent rights. ISO 11286 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 8, Tea. This second edition cancels and replaces the first edition (ISO 11286:1997), of which it constitutes a minor revision. The Scope has been modified to exclude large leafy grades of tea. BSISO

18、11286:2003BSISO11286:2004ISO 11286:2004(E) iv I SO 4002 All irthgs ersedevrIntroduction For many years the tea trade has used various systems for the grading nomenclature of teas according to the sieves used for sorting the teas. However, a designation given in one country does not always have the s

19、ame meaning in another and it was considered by some countries, in particular tea-producing countries, that a single, international method of classifying tea grades according to their particle size distributions would facilitate international trade. The method given in this International Standard pr

20、ovides such a system to supplement the existing traditional systems. BSISO11286:2003BSISO11286:2004INTENRATIONAL TSANDADR IS:68211 O4002(E)I SO 4002 All irthgs ersedevr 1Tea Classification of grades by particle size analysis 1 Scope This International Standard specifies a method for the classificati

21、on of grades of tea according to an analysis of their particle size. It is not applicable to large, leafy grades of tea. This method may not be suitable for blends of tea. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated refe

22、rences, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3310-1:1990, Test sieves Technical requirements and testing Part 1: Test sieves of metal wire cloth 3 Principle The tea is separated into different si

23、ze fractions using a series of sieves on a shaker. The tea particles retained on each sieve are weighed and the percentage by mass retained on each sieve is calculated. 4 Apparatus Usual laboratory apparatus and, in particular, the following. 4.1 Sieve shaker, capable of a vibration rate of 3 000 pe

24、r minute, a vibration stroke of up to 3 mm and a vibration angle of 30, with automatic timer 1) . 4.2 Test sieves, conforming to ISO 3310-1, of nominal diameter 200 mm and of nominal apertures sizes 2 mm, 1,4 mm, 1 mm, 710 m, 355 m, 250 m, 150 m and 75 m, together with a base pan (less than 75 m) an

25、d a clamp. 5 Sampling Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 1839 2) . 1) Endecotts Octagon 200 and Endecotts EFC Mark 1 are examples of suitable shakers available commercially. This information is given for the conv

26、enience of users of this International Standard and does not constitute an endorsement by ISO of the these products. 2) ISO 1839:1980, Tea Sampling. BSISO11286:20031 BSISO11286:2004ISO 11286:2004(E) 2 I SO 4002 All irthgs ersedevrIt is important that the laboratory receive a sample which is truly re

27、presentative and has not been damaged or changed during transport or storage. 6 Procedure 6.1 If sufficient of the sample is available, it is recommended that the analysis be carried out in duplicate. 6.2 Arrange the test sieves (4.2) in descending order of mesh size and fit them together. 6.3 Weigh

28、 100 g 1 g of the laboratory sample into a 400 ml beaker. Transfer the tea quantitatively to the top sieve and fit the cover. 6.4 Place the sieves onto the sieve shaker (4.1) and secure them using the clamp provided. Set an automatic timer to 10 min and start the shaker. 6.5 When the shaker stops, r

29、emove the test sieves and carefully separate them. 6.6 Transfer quantitatively the tea that has been retained on each sieve into a series of beakers, previously weighed to the nearest 0,01 g, and weigh to the nearest 0,01 g. 6.7 It is recommended that an appropriate brush be used to aid the transfer

30、 of the tea from the test sieves to the beakers. 7 Calculation Determine the percentage of tea retained on each test sieve and note the mesh sizes of the test sieves on which the largest amount (the peak) and the second largest amounts of tea were retained. 8 Classification Classify the tea into one

31、 of the grades listed in Table 1 in accordance with the definitions given. Each of the grades 1 to 6 in Table 1 may be divided into subgrades A, B and C, as follows: A: up to 2,0 % passing 355 m; B: more than 2,0 % passing 355 m; C: more than 5,0 % passing 355 m. Each of the grades 7 to 10 in Table

32、1 may be divided into subgrades A, B and C, as follows: A: up to 2,0 % passing 250 m; B: more than 2,0 % passing 250 m; C: more than 5,0 % passing 250 m. Each of the grades 11 to 15 in Table 1 may be divided into subgrades A, B and C, as follows: A: up to 2,0 % passing 150 m; B: more than 2,0 % and

33、up to 5,0 % passing 150 m; C: more than 5,0 % passing 150 m. BSISO11286:20032 BSISO11286:2004ISO 11286:2004(E) I SO 4002 All irthgs ersedevr 39 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

34、; c) the test method used, with reference to this International Standard; 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 results obtained. Table 1 Grade d

35、esignations Grade Definition 1 Peak in 2 mm 2 Peak in 1,4 mm and second highest peak in 2 mm 3 Peak in 1,4 mm and second highest peak in 1 mm 4 Peak in 1 mm and second highest peak in 1,4 mm 4.5 Peak in 1 mm and second highest peak in 2 mm 5 Peak in 1 mm and second highest peak in 710 m, and number

36、of sieves retaining 25 % = 1 6 Peak in 1 mm and second highest peak in 710 m, and number of sieves retaining 25 % = 2 or more 7 Peak in 710 m and second highest peak in 1 mm 8 Peak in 710 m and second highest peak in 355 m 9 Peak in 355 m and second highest peak in 710 m, and number of sieves retain

37、ing 25 % = 2 or more 9.5 Peak in 355 m and second highest peak in 1 mm 10 Peak in 355 m and second highest peak in 710 m, and number of sieves retaining 25 % = 1 11 Peak in 355 m and second highest peak in 250 m, and number of sieves retaining means greater than; means less than. BSISO11286:20033 BS

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