DIN EN ISO 712-2010 Cereals and cereal products - Determination of moisture content - Reference method (ISO 712 2009) German version EN ISO 712 2009《谷类和谷类制品 湿气含量的测定 参照法》.pdf

《DIN EN ISO 712-2010 Cereals and cereal products - Determination of moisture content - Reference method (ISO 712 2009) German version EN ISO 712 2009《谷类和谷类制品 湿气含量的测定 参照法》.pdf》由会员分享，可在线阅读，更多相关《DIN EN ISO 712-2010 Cereals and cereal products - Determination of moisture content - Reference method (ISO 712 2009) German version EN ISO 712 2009《谷类和谷类制品 湿气含量的测定 参照法》.pdf（21页珍藏版）》请在麦多课文档分享上搜索。

1、April 2010 Translation by DIN-Sprachendienst.English price group 12No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS

2、67.060!$aZr“1625579www.din.deDDIN EN ISO 712Cereals and cereal products Determination of moisture content Reference method (ISO 712:2009)English translation of DIN EN ISO 712:2010-04Getreide und Getreideerzeugnisse Bestimmung des Feuchtegehaltes Referenzverfahren (ISO 712:2009)Englische bersetzung v

3、on DIN EN ISO 712:2010-04Crales et produits craliers Dtermination de la teneur en eau Mthode de rfrence (ISO 712:2009)Traduction anglaise de DIN EN ISO 712:2010-04SupersedesDIN 10350:1967-09www.beuth.deIn case of doubt, the German-language original shall be considered authoritative.Document comprise

4、s 21 pages03.10 DIN EN ISO 712:2010-04 2 A comma is used as the decimal marker. National foreword This standard has been prepared by Technical Committee ISO/TC 34 “Food products” (Secretariat: AFNOR, France), Subcommittee SC 4 “Cereals and pulses” (Secretariat: SAC, China) in collaboration with Tech

5、nical Committee CEN/TC 338 “Cereal and cereal products” (Secretariat: AFNOR, France) and has been published in accordance with the result of the voting procedure within the scope of the Agreement on technical cooperation between ISO and CEN (Vienna Agreement) to adopt, without alteration, Internatio

6、nal Standard ISO 712:2009 as a European Standard. The responsible German body involved in its preparation was the Normenausschuss Lebensmittel und landwirtschaftliche Produkte (Food and Agricultural Products Standards Committee), Working Committee NA 057-05-06 AA Getreide und Getreideerzeugnisse. Am

7、endments This standard differs from DIN 10350:1967-09 as follows: a) Conforming to this standard a laboratory sample, requiring grinding if necessary, is weighed into a dish (with lid) and dried at 131,5 C 1,5 C for two hours (90 minutes when drying flour). b) The requirements for the analytical bal

8、ance, the grinding mill and the constant-temperature oven have been extended. The dish is made only of metal. The grinding and drying procedure has been described more in detail. Previous editions DIN 10350: 1967-09 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 712 November 2009 ICS 67.06

9、0 English Version Cereals and cereal products - Determination of moisture content - Reference method (ISO 712:2009) Crales et produits craliers - Dtermination de la teneur en eau - Mthode de rfrence (ISO 712:2009) Getreide und Getreideerzeugnisse - Bestimmung des Feuchtegehaltes - Referenzverfahren

10、(ISO 712:2009) This European Standard was approved by CEN on 14 November 2009. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bib

11、liographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibilit

12、y of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, I

13、reland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marni

14、x 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 712:2009: EContents DIN EN ISO 712:2010-04 EN ISO 712:2009 (E) 2 Page Foreword .3 1 Scope4 2 Terms and definitions .4 3 Principle .4 4 Apparatus.4 5 Sam

15、pling 5 6 Preparation of the test sample.5 6.1 Products not requiring grinding 5 6.2 Products requiring grinding.6 6.2.1 General .6 6.2.2 Grinding without preconditioning .6 6.2.3 Grinding with preconditioning .6 7 Procedure.6 7.1 Number of determinations6 7.2 Test portion6 7.3 Drying .7 7.4 Weighin

16、g 7 8 Expression of results7 8.1 Without preconditioning.7 8.2 With preconditioning.7 9 Precision 8 9.1 Interlaboratory test8 9.2 Repeatability 8 9.3 Reproducibility 8 9.4 Comparison of two groups of measurements in one laboratory .8 9.5 Comparison of two groups of measurements in two laboratories 9

17、 9.6 Uncertainty.9 10 Test report9 Annex A (informative) Results of interlaboratory test 10 Annex B (informative) Cereals and cereal products Determination of moisture content Absolute method .12 Bibliography19 Foreword held by AFNOR. This European Standard shall be given the status of a national st

18、andard, either by publication of an identical text or by endorsement, at the latest by May 2010, and conflicting national standards shall be withdrawn at the latest by May 2010. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN

19、and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Repu

20、blic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 712:2009 has bee

21、n approved by CEN as a EN ISO 712:2009 without any modification. DIN EN ISO 712:2010-04 EN ISO 712:2009 (E) 3 This document (EN ISO 712:2009) has been prepared by Technical Committee ISO/TC 34 “Food products” in collaboration with Technical Committee CEN/TC 338 “Cereal and cereal products” the secre

22、tariat of which is 1 Scope This International Standard specifies a routine reference method for the determination of the moisture content of cereals and cereal products. This International Standard applies to: wheat, rice (paddy, husked and milled), barley, millet (Panicum miliaceum), rye, oats, tri

23、ticale, sorghum in the form of grains, milled grains, semolina or flour. The method is not applicable to maize and pulses. NOTE For moisture content determination in maize, see ISO 65405; and for pulses, see ISO 245577. 2 Terms and definitions For the purposes of this document, the following terms a

24、nd definitions apply. 2.1 moisture content mass loss undergone by a product under the conditions specified in this International Standard NOTE Moisture content is expressed as a percentage. 3 Principle If necessary, a laboratory sample is ground, after conditioning, if required. A test portion is dr

25、ied at a temperature between 130 C and 133 C, under conditions which enable a result to be obtained which corresponds to that obtained by the absolute method described in Annex B. 4 Apparatus 4.1 Analytical balance, capable of weighing to an accuracy of 0,001 g. 4.2 Grinding mill, having the followi

26、ng characteristics: a) made of material which does not absorb moisture; b) easy to clean and having as little dead space as possible; c) enabling grinding to be carried out rapidly and uniformly, without appreciable development of heat (difference of temperatures before and after grinding smaller th

27、an or equal to 5 C); NOTE A grinding mill fitted with a cooling device can comply with this requirement. d) tightness to air to avoid water exchange between sample and external air; e) adjustable so as to obtain particles of the dimensions indicated in Table 1. DIN EN ISO 712:2010-04 EN ISO 712:2009

28、 (E) 4 4.3 Metal dish, non-corrodible under the test conditions, or glass dish, with a lid and having an effective surface area enabling the test portion to be distributed so as to give a mass per unit area of not more than 0,3 g/cm2. 4.4 Constant-temperature oven, electrically heated, controlled in

29、 such a way that, during normal working, the temperature of the air and of the shelves carrying the test portions is maintained within the range 130 C to 133 C in the vicinity of the test portions. The oven shall have a heat capacity such that, when initially adjusted to a temperature of 131 C, it c

30、an regain this temperature in less than 30 min after insertion of the maximum number of test portions that can be dried simultaneously. The effectiveness of the ventilation shall be determined using durum wheat semolina, of maximum particle size of 1 mm, as the test material. The ventilation shall b

31、e such that, after insertion of the maximum number of test portions that the oven can accommodate, and drying at a temperature of 130 C to 133 C, the 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

32、.5 Desiccator, containing an effective desiccant. 5 Sampling Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 243336. A representative sample, in an airtight packaging, should have been sent to the laboratory. It should not ha

33、ve been damaged or changed during transport or storage. 6 Preparation of the test sample 6.1 Products not requiring grinding Products having particle size characteristics indicated in Table 1 do not need to be ground before the determination. Mix the laboratory sample thoroughly before taking the te

34、st portion (7.2). Table 1 Particle size characteristics of products not requiring grinding Particle size characteristics mm Proportion % u 1,7 (1,8)a100 1,0 (1,0)bu 10 0,5 (0,56)aW 50 a Nominal size of openings, ISO 3310-11, that does not retain this particle size. b Nominal size of openings, ISO 33

35、10-11, that retains this particle size. DIN EN ISO 712:2010-04 EN ISO 712:2009 (E) 5 6.2 Products requiring grinding 6.2.1 General If the products do not have the particle size characteristics mentioned in Table 1, they shall be ground either without preconditioning (6.2.2) or with preconditioning (

36、6.2.3), as required. 6.2.2 Grinding without preconditioning For products that are not likely to undergo variations in moisture content during grinding (in general, products with a moisture content between 9 % and 15 %), grind without preconditioning. NOTE The range of moisture contents given for con

37、ditioning products before grinding corresponds approximately in the laboratory to a temperature of 20 C and a relative humidity of 40 % to 70 %. Adjust the grinding mill (4.2) to obtain particles of the dimensions indicated in Table 1. Then, quickly grind a quantity of the laboratory sample accordin

38、g to the apparatus used and at least slightly greater than that required for the test portion (about 5 g), and immediately proceed in accordance with 7.2. 6.2.3 Grinding with preconditioning Products which are likely to undergo changes in moisture content during the course of grinding (in general, p

39、roducts with a moisture content greater than 15 % or less than 9 %) shall be preconditioned so as to bring their moisture content to between 9 % and 15 % before grinding. If the moisture content is more than 15 % (the most frequent case), weigh, to the nearest 0,001 g, a sufficient quantity of the l

40、aboratory sample to provide a test portion slightly greater than 5 g (see 6.2.2). Record the mass of the test portion before preconditioning and dish as m2. Pre-dry in accordance with 7.3, except that the time of heating in the oven (4.4) shall be 7 min to 10 min and the product shall be cooled to l

41、aboratory temperature with the dish (4.3) uncovered and without a desiccator, for at least 2 h. NOTE It is possible that these times are not be suitable for all products, e.g. paddy rice. For products having moisture contents of less than 9 %, weigh, to the nearest 0,001 g, a sufficient quantity of

42、the laboratory sample to provide a test portion slightly greater than 5 g (see 6.2.2). Record the mass of the test portion before preconditioning and dish as m2. Place in a suitable atmosphere (generally that of the laboratory) and leave until a moisture content within the limits indicated above is

43、obtained. After conditioning, weigh the sample to the nearest 0,001 g. Record the mass of the test portion after preconditioning and dish as m3. Grind immediately, adjusting the grinder so as to obtain particles of the dimensions indicated in Table 1, and immediately proceed in accordance with 6.2.2

44、. 7 Procedure 7.1 Number of determinations Carry out separate determinations on two test portions taken from the laboratory sample in accordance with 7.2 and 7.3. If the absolute difference between the two values obtained is greater than the repeatability limit given in Clause 9, repeat the determin

45、ation until requirements are satisfied. 7.2 Test portion Rapidly weigh, to the nearest 0,001 g, a quantity of 5 g 1 g of the laboratory sample (6.2.2 or 6.2.3) in the dish (4.3). Record the mass of the undried test portion and dish as m0. Previously dry and tare the dish, together with its lid, and

46、record the mass, md, to the nearest 0,001 g. DIN EN ISO 712:2010-04 EN ISO 712:2009 (E) 6 7.3 Drying Place the open dish containing the test portion (7.2), together with the lid, in the oven (4.4) and leave for 120 min 5 min (90 min for flours). In certain cases and particularly in hot and dry count

47、ries, the drying period may be reduced to 60 min 5 min, which is sufficient time for the test portions to attain constant mass. Review these times regularly. Do not open the door of the oven during drying and do not place moist products in the oven before removing the dry test portions, as this will

48、 result in partial rehydration of the latter. After drying, quickly remove the dish from the oven, cover, and place in the desiccator (4.5). When several tests are being carried out, never place dishes on top of one another in the desiccator, but place them side by side. 7.4 Weighing When the dish h

49、as cooled to laboratory temperature (generally between 30 min and 45 min after it has been placed in the desiccator), weigh to the nearest 0,001 g. Record the mass of the dried test portion and dish as m1. 8 Expression of results 8.1 Without preconditioning The moisture content, wH2O, expressed in grams per 100 g of the product as received, is given by: 12HO01 100mw m= where m0= m0 mdis the mass, in grams, of the test portion (7.2); m1= m1 mdis the mass, in grams, of the test portion after drying (7.4). Ca