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1、Reference number ISO 15793:2000(E) ISO 2000 INTERNATIONAL STANDARD ISO 15793 First edition 2000-12-15 Durum wheat semolinas Determination of the undersize fraction Semoules de bl dur Dtermination du taux daffleurement Copyright International Organization for Standardization Provided by IHS under lic
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7、ail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2000 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 09:02:02 MDTNo reproduction or networking permitted witho
8、ut license from IHS -,-,- ISO 15793:2000(E) ISO 2000 All rights reservediii 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
9、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 committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates clo
10、sely with the International 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 3. Draft International Standards adopted by the technical committees are circulated
11、 to the member bodies 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 International Standard may be the subject of patent rights. ISO shall not be held
12、 responsible for identifying any or all such patent rights. InternationalStandardISO 15793waspreparedbyTechnicalCommitteeISO/TC 34,Foodproducts, Subcommittee SC 4, Cereals and pulses. Annex A of this International Standard is for information only. Copyright International Organization for Standardiza
13、tion Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 09:02:02 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9
14、980755100 Not for Resale, 04/23/2007 09:02:02 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARDISO 15793:2000(E) ISO 2000 All rights reserved1 Durum wheat semolinas Determination of the undersize fraction 1Scope This International Standard specifies a m
15、ethod for the determination of the undersize fraction of durum wheat semolinas, which is an important characteristic. It is applicable to samples of at least 1 kg of durum wheat semolina obtained solely by comminution, without subsequent combination, having a moisture content higher than 10 % and pa
16、ckaged in fully filled airtight packaging. It is not applicable to determinations carried out using sieves of aperture size below 160 ?m. NOTEDetermination of the undersize fraction is sometimes termed “granulation of semolinas“. 2Normative reference The following normative document contains provisi
17、ons which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate
18、the possibility of applying the most recent edition of the normative document indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 712, Cereals and cereal p
19、roducts Determination of moisture content Routine reference method. 3Term and definition For the purposes of this International Standard, the following term and definition applies. 3.1 undersize fraction of semolina by convention, the percentage of semolina which passes through the sieve specified f
20、or the semolina in question, under the operating conditions described in this International Standard 4Principle The semolina under test is sieved using a chosen sieve of specified aperture size, in accordance with the procedure described in this International Standard. 5Apparatus Usual laboratory eq
21、uipment and, in particular, the following. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 09:02:02 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15793:2000(E) 2 I
22、SO 2000 All rights reserved 5.1Laboratory sieving machine1?, capable of being set at 200 r/min ? 5 r/min as well as at sieving amplitudes of 30 mm ? 2 mm and 60 mm ? 2 mm, and equipped with a sieve blocking system. 5.2Circular sieve, with sieving medium, cover and receiver, in stainless steel or sim
23、ilar material, having the following characteristics: a)frame diameter: 200 mm; b)useful diameter of sieving medium: 185 mm ? 5 mm, corresponding to a sieving surface area of approximately 270 cm2; c)height: 20 mm minimum; d)aperture size (or void): the following list gives examples of aperture sizes
24、2?of sieving media currently used in European and international transactions: ?160 ?m ? 6,9 ?m, ?180 ?m ? 7,6 ?m, ?200 ?m ? 8,3 ?m, ?250 ?m ? 9,9 ?m, ?300 ?m ? 11 ?m, ?315 ?m ? 12 ?m, ?425 ?m ? 15 ?m, ?500 ?m ? 18 ?m. 5.3Rubber balls (eight), having a diameter of 18 mm ? 1 mm and a mass of 5 g ? 0,5
25、 g. 5.4Spatula. 5.5Soft-haired brush. 5.6Flat container, having a capacity of approximately 2 litres, made of a non-electrostatic material. 5.7Dishes (two), of suitable dimensions, made of a non-electrostatic material. 5.8Analytical balance, capable of being read to the nearest 0,001 g. 5.9Chronomet
26、er, capable of being read to the nearest 1 s. 6Sampling Sampling is not a part of the method specified in this International Standard. A recommended sampling method is given in ISO 13690 ?2?. 1?ROTACHOC is an example of a suitable apparatus and is supplied by Tripette et Renaud (France). This inform
27、ation is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO of this apparatus. Equivalent apparatus may be used if it can be shown to give the same results. 2?The tolerances are as given in ISO 3310-1 ?1?. Copyright International Organizat
28、ion for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 09:02:02 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15793:2000(E) ISO 2000 All rights reserved3 It is important that the laboratory receive a sam
29、ple which is truly representative and has not been damaged or changed during transport or storage. 7Preparation of test sample Pour the entire contents of a package of approximately 1 kg of semolina into the container (5.6). Mix it carefully in order to make it as homogeneous as possible. The homoge
30、nization may be carried out by a mixing device if its container is made of non-electrostatic material. 8Determination of moisture content of the sample Determine separately the moisture content of the prepared test sample (clause 7) in accordance with ISO 712. The moisture content shall be between 1
31、0 % and 15,50 %. If this is not the case, the procedure described in clause 9 is not applicable (in accordance with clause 1). 9Procedure 9.1General The operations described in 9.2 to 9.3.8 inclusive shall be carried out in less than 15 min. 9.2Test portion From the test sample prepared according to
32、 clause 7, immediately take, using a spatula (5.4), a test portion of 50 g ? 0,5 g, weighed to the nearest 0,01 g (m0). 9.3Determination 9.3.1Place the sieve, appropriate for the type of semolina to be tested, on the receiver (5.2) and put eight rubber balls (5.3) in the sieve. 9.3.2Pour the test po
33、rtion (9.2) into the sieve and put on the cover. Place the assembly on the sieving machine (5.1) which is set at an amplitude of 60 mm. Block using the tightening system and disengage the sieve cleaning system if the appliance is equipped with one. 9.3.3Start the chronometer (5.9) and the sieving ma
34、chine (5.1) simultaneously. Sieve the test portion for 5 min ? 5 s. 9.3.4As soon as the sieving machine stops, release the tightening system and remove the assembly. 9.3.5Remove the cover. Brush off (5.5) the particles of semolina adhering to the underside of the sieve into the receiver to avoid los
35、s. 9.3.6Discard the semolina remaining on the sieve. 9.3.7Transfer quantitatively the contents of the receiver (the undersize fraction) into a dish (5.7), then weigh to the nearest 0,01 g (m). 9.3.8Conduct a new determination by sampling another test portion (9.2) and proceeding as described in 9.3.
36、1 to 9.3.7. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 09:02:02 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15793:2000(E) 4 ISO 2000 All rights reserved 9.4
37、Calculation Calculate the undersize fraction (T) of each test portion of the semolina according to the following equation: 0 100 % m T m ? where mis the mass, in grams, of the undersize fraction obtained; m0is the mass, in grams, of the test portion. Calculate the arithmetic mean of the two determin
38、ations and express the results to the nearest 0,01 %. 10 Expression of results 10.1Examine the repeatability of the measurements by taking the following criteria into consideration. a)If the mean value is higher than 15 % Accept the result only if both values do not differ by more than?1,0 % (i.e.?0
39、,50 g). b)If the mean value is lower than 15 % Accept the result only if both values do not differ by more than?0,5 % (i.e.?0,25 g). If the result does not meet the criteria given in a) and b), repeat all of the operations with two other test portions. 10.2If the repeatability conditions are fulfill
40、ed, examine whether the mean value obtained is higher or lower than 15 % (i.e. 7,5 g). a)If the mean value is higher than 15 % Accept this value as the final result of the test and express it to the nearest 0,1 %. b)If the mean value is lower than 15 % Repeat the operations with two other test porti
41、ons following the same procedure as previously described (see 9.2 to 9.4), but modifying the operating conditions as follows: ?in 9.2: using a spatula (5.4), take a test portion of 100 g?0,50 g, weighed to the nearest 0,01 g; ?in 9.3.1: put four rubber balls (5.3) into the sieve; ?in 9.3.2: set the
42、sieving machine (5.1) at an amplitude of 30 mm?2 mm. Proceed as before on two test portions. Calculate the arithmetical mean of the two results and express it to the nearest 0,01 %. Examine the repeatability of the measurements taking the following criteria into consideration. 1)If the mean value is
43、 higher than 15 %:accept the result only if both values do not differ by more than ?1,0 % (i.e.?1,0 g). Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 09:02:02 MDTNo reproduction or networking p
44、ermitted without license from IHS -,-,- ISO 15793:2000(E) ISO 2000 All rights reserved5 2)If the mean value is lower than 15 %: accept the result only if both values do not differ by more than ? 0,5 % (i.e. ? 0,50 g). 10.3If the result does not meet these criteria, repeat all of the operations with
45、two other test portions proceeding as described in 10.2 b). Otherwise, take the arithmetical mean as the final result and express it to the nearest 0,01 %. 11 Precision 11.1 Interlaboratory test Details of an interlaboratory test on the precision of the method are summarized in annex A. The values d
46、erived from this interlaboratory test may not be applicable to concentration ranges and matrices other than those given. 11.2 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 sam
47、e operator using the same equipment within a short interval of time, will in not more than 5 % of cases be greater than the values specified, as appropriate, in 10.1 or 10.2 b). 11.3 Reproducibility The absolute difference between two single test results, obtained using the same method on identical
48、test material in different laboratories with different operators using different equipment, will in not more than 5 % of cases be greater than 25 % of the arithmetic mean of the two results, with minimum and maximum tolerances of 2 g and 10 g respectively. NOTEThese values correspond to what can be currently obtained, account being taken of the “rules of the game“. Indeed, if a certain scattering of results is observed, it is not solely due to the method, but also results from the tolerances author