BS ISO 24557-2009 Pulses - Determination of moisture content - Air-oven method《豆类植物 水分含量的测定 热空气箱方法》.pdf

1、BS ISO24557:2009ICS 67.060NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDPulses Determination ofmoisture content Air-oven methodThis British Standardwas published underthe authority of theStandards Policy andStrategy Committee on 30November 2009. BSI 2009ISBN 9

2、78 0 580 56150 4Amendments/corrigenda issued since publicationDate CommentsBS ISO 24557:2009National forewordThis British Standard is the UK implementation of ISO 24557:2009.The UK participation in its preparation was entrusted to TechnicalCommittee AW/4, Cereals and pulses.A list of organizations r

3、epresented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.BS ISO 245

4、57:2009Reference numberISO 24557:2009(E)ISO 2009INTERNATIONAL STANDARD ISO24557First edition2009-10-01Pulses Determination of moisture content Air-oven method Lgumineuses Dtermination de la teneur en eau Mthode par schage ltuve BS ISO 24557:2009ISO 24557:2009(E) PDF disclaimer This PDF file may cont

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7、ameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2009 All r

8、ights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of

9、the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2009 All rights reservedBS ISO 24557:2009ISO 24557:2009(E) ISO 2009 All rights reserved iiiForeword ISO (the Inte

10、rnational 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 member body interested in a subject for which a technical committee has

11、 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 Electrotechnical Commission (IEC) on all matters of electrotechnical s

12、tandardization. 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

13、 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 be the subject of patent rights. ISO shall not be held responsible for identifying any or

14、 all such patent rights. ISO 24557 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 4, Cereals and pulses. BS ISO 24557:2009BS ISO 24557:2009INTERNATIONAL STANDARD ISO 24557:2009(E) ISO 2009 All rights reserved 1Pulses Determination of moisture content Air-oven method 1

15、Scope This International Standard specifies a routine reference method for the determination of moisture content of pulses. The procedure is applicable to chickpeas, lentils, peas, and all classes of beans with the exception of soybeans. NOTE The method is based on AACC approved method 44-174. 2 Ter

16、ms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 moisture content loss of mass fraction undergone by the product under the conditions specified in this International Standard NOTE The moisture content is expressed as a percentage mass fraction. 3 P

17、rinciple The method determines moisture content as the loss of mass fraction, expressed as a percentage, of a sample when heated under specified conditions. A preconditioning stage is used to minimize moisture loss during the grinding stage. 4 Apparatus 4.1 Laboratory mill1), capable of grinding wit

18、hout undue exposure to atmosphere and without appreciable heating. The mill shall be able to grind large-seeded pulses, such as beans. Required particle size, d, after grinding: d 0,5 mm: more than 20 % mass fraction; d 1,0 mm: 70 % mass fraction; d 1,7 mm: 100 % mass fraction. NOTE Grinders operati

19、ng at speeds higher than 3 600 r/min are unsatisfactory due to excessive moisture loss during grinding, which results in moisture values lower than actual. 1) The Thomas Wiley model ED5 with a 1 mm sieve (1 260 r/min) and the laboratory mill 3303 produced by Perten Instruments, with settings 0 to 4

20、(3 600 r/min), are examples of suitable devices available commercially. This information is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO of these products. Other equipment may be used if it can be shown to give comparable results. BS

21、 ISO 24557:2009ISO 24557:2009(E) 2 ISO 2009 All rights reserved4.2 Oven, either gravity-convection or mechanical-convection, capable of being maintained at 130 C 1 C uniformly throughout. A thermometer should be situated in the oven so the tip is no more than 100 mm from the top of the moisture dish

22、es. Determine the effectiveness of the ventilation using durum wheat semolina, of maximum particle size 1 mm, as the test material. The ventilation shall be such that, after insertion of the maximum number of test portions that the oven can accommodate, and drying at a temperature of 130 C 1 C, the

23、results, after heating the same test portions for 2 h and then for a further 1 h, do not differ by more than 0,15 g of moisture per 100 g of sample. 4.3 Moisture dishes, of heavy gauge aluminium and provided with tightly fitting covers. Identify both dish and cover using the same number and clean th

24、em between uses with a vacuum or soft cloth. 4.4 Drying trays, made of a non-absorbent material such as heavy gauge aluminium, of dimensions about 100 mm 130 mm with tapered 15 mm sides. 4.5 Airtight desiccator, with an effective desiccant. 4.6 Analytical balance, capable of being read to at least t

25、he nearest 1 mg. 5 Sampling Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 243333. Ensure that the laboratory receives a sample that is truly representative and that has not been damaged or changed during transport and stora

26、ge. 6 Procedure 6.1 General If sample moisture content is within the range 9 % mass fraction to 11 % mass fraction, proceed directly to 6.3. Perform two single determinations per laboratory sample under the conditions specified in 8.2. If the absolute difference between the two results is more than

27、the repeatability limit, r, repeat the determination until the results meet this requirement. 6.2 Preconditioning of laboratory sample 6.2.1 Mix the sample thoroughly and weigh approximately 50 g of a representative portion of unground laboratory sample into a drying tray or moisture dish (preferabl

28、y a drying tray to limit sample to a single layer). Record the mass of sample, mL0, to the nearest 0,001 g. 6.2.2 Precondition the sample by either of the methods below. a) Preferred procedure: remove the lids from the moisture dishes and dry the laboratory samples (as specified in 6.2.1) in the ove

29、n (4.2) at 130 C 1 C for 15 min; then cool moisture dishes uncovered to room temperature without use of a desiccator, for 2 h. b) Optional procedure: remove the lids from the moisture dishes and air dry the laboratory samples in a well-ventilated drying cabinet or any location where they are not dis

30、turbed. Air dry for 48 h. The room temperature and humidity affect the level to which the sample dries. 6.2.3 If using moisture dishes, place lids on dishes and reweigh the laboratory sample after preconditioning. Record the mass of sample, mL1, to the nearest 0,001 g. BS ISO 24557:2009ISO 24557:200

31、9(E) ISO 2009 All rights reserved 3Ensure that the moisture content after preconditioning has been reduced to between 9 % mass fraction and 11 % mass fraction; therefore, check the value periodically. Checking is even more important for the optional procedure 6.2.2 b) as different locations vary in

32、humidity, which affects the desired preconditioned moisture levels. 6.3 Grinding and test portion Grind the remaining preconditioned sample using the laboratory mill (4.1). Rapidly mix the sample with a spoon or spatula and immediately transfer a test portion of 2 g to 3 g into a previously dried an

33、d tared moisture dish. Cover the moisture dish and weigh, and record the mass of the test portion, mt0, to the nearest 0,001 g. Clean the mill between samples. If it is not possible to weigh the test portion immediately after grinding, store the ground laboratory sample in a moisture-proof container

34、 until it is weighed. 6.4 Drying Place open dishes containing the test portion (6.3), together with the lid, in the oven (4.2) at 130 C 1 C and heat for 120 min after the oven regains its temperature. The oven should regain temperature within 15 min to 20 min after insertion of a full load (24 moist

35、ure dishes). Do not use the oven if it requires a longer time to recover. Remove dishes from the oven, cover rapidly, and transfer to a desiccator as quickly as possible. Weigh dishes and contents after they have reached room temperature (normally 45 min to 60 min) and record the mass of the test po

36、rtion, mt1. 7 Calculation and expression of results 7.1 Calculation Use the equation to determine the total loss of mass fraction, expressed as a percentage, due to moisture removal, wH2O: 2t1 L1HOt0 L01 100mmwmm= where mL0is the mass, in grams, of the laboratory sample before preconditioning; mL1is

37、 the mass, in grams, of the laboratory sample after preconditioning; mt0is the mass, in grams, of the test portion before oven drying; mt1is the mass, in grams, of the test portion after oven drying. 7.2 Expression of results Calculate the arithmetic mean of two determinations satisfying the repeata

38、bility conditions (8.2). Round the result to the nearest one decimal place. BS ISO 24557:2009ISO 24557:2009(E) 4 ISO 2009 All rights reserved8 Precision 8.1 Interlaboratory test Details of an interlaboratory test on the precision of the method are summarized in Annex A. The values derived from this

39、interlaboratory test may not be applicable to concentration ranges and matrices other than those given. 8.2 Repeatability The absolute difference between two independent single test results, obtained using the same method on identical test material in the same laboratory by the same operator using t

40、he same equipment within a short interval of time, shall in not more than 5 % of cases be greater than 0,3 %, which is the repeatability limit, r, given in Annex A (Tables A.1 and A.2 and Figure A.1). 8.3 Reproducibility The absolute difference between two single test results, obtained using the sam

41、e method on identical test material in different laboratories with different operators using different equipment, shall in not more than 5 % of cases be greater than 0,5 %, which is the reproducibility limit, R, given in Annex A (Tables A.1 and A.2 and Figure A.1). 8.4 Critical difference, CD 8.4.1

42、General Critical difference is the difference between two averaged values obtained from two test results under repeatability conditions. 8.4.2 Comparison of two groups of measurements in one laboratory The critical difference (CD) between two averaged values obtained from two test results under repe

43、atability conditions is given by: 1211 1CD 2,8 2,8 1,98 0,2222 2rrrsssnn=+=where sris the standard deviation of repeatability; n1and n2are the number of test results corresponding to each of the averaged values. 8.4.3 Comparison of two groups of measurements in two laboratories The critical differen

44、ce (CD) between two averaged values obtained in two different laboratories from two test results under repeatability conditions is given by: 22 2 21211CD 2,8 1 2,8 0,55 0, 4522Rr R rss s snn=+=where sris the standard deviation of repeatability; sRis the standard deviation of reproducibility; n1and n

45、2are the number of test results corresponding to each of the averaged values. BS ISO 24557:2009ISO 24557:2009(E) ISO 2009 All rights reserved 58.5 Uncertainty, U Uncertainty, U, attached to results for laboratories under repeatability conditions is equal to: 20,36RUs= where sRis the standard deviati

46、on of reproducibility. 9 Test report The test report shall contain at least the following information: 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 ope

47、rating details not specified in this International Standard, or regarded as optional, together with details of any incidents which may have influenced the test results; e) the test results obtained, clearly mentioning the method of expression used. BS ISO 24557:2009ISO 24557:2009(E) 6 ISO 2009 All r

48、ights reservedAnnex A (informative) Results of an interlaboratory test An international collaborative test involving 13 laboratories was carried out on pulse samples including peas, lentils, kidney beans, and navy beans. The test was organized by AACC International in August 2003 and the results obt

49、ained were subjected to statistical analysis in accordance with ISO 5725-11and ISO 5725-22to give the precision data shown in Tables A.1 and A.2. There is no statistical link between r or R value and the moisture content (Figure A.1) and it has been chosen to take constant values for the repeatability limit, r (mean of r values), and the reproducibility limit, R (mean of R values). Table A.1 Results in peas (six samples) Parameter Pea 1 Pea 2 Pea 3 Pea 4 Pea 5 Pea 6 Number o