1、BSI Standards PublicationBS EN ISO 21415-2:2015Wheat and wheat flour Gluten contentPart 2: Determination of wet gluten andgluten index by mechanical meansBS EN ISO 21415-2:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO 21415-2:2015.It supersedes BS EN
2、ISO 21415-2:2008 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee AW/4, Cereals and pulses.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprov
3、isions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 81868 4ICS 67.060Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published un
4、der the authority of theStandards Policy and Strategy Committee on 31 October 2015.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 21415-2 October 2015 ICS 67.060 Supersedes EN ISO 21415-2:2008English Version Wheat an
5、d wheat flour - Gluten content - Part 2: Determination of wet gluten and gluten index by mechanical means (ISO 21415-2:2015) Bl et farines de bl - Teneur en gluten - Partie 2: Dtermination du gluten humide et du gluten index par des moyens mcaniques (ISO 21415-2:2015) Weizen und Weizenmehl - Gluteng
6、ehalt - Teil 2: Bestimmung von Feuchtgluten und Glutenindex durch mechanische Verfahren (ISO 21415-2:2015) This European Standard was approved by CEN on 13 June 2015. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Sta
7、ndard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (Engli
8、sh, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, B
9、ulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
10、 Turkey andUnited Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Member
11、s. Ref. No. EN ISO 21415-2:2015 EBS EN ISO 21415-2:2015EN ISO 21415-2:2015 (E) 3 European foreword This document (EN ISO 21415-2:2015) has been prepared by Technical Committee ISO/TC 34 “Food products“ in collaboration with Technical Committee CEN/TC 338 “Cereal and cereal products” the secretariat
12、of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April 2016, and conflicting national standards shall be withdrawn at the latest by April 2016. Attention is drawn to the
13、possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 21415-2:2008. According to the CEN-CENELEC Internal Regulations, the national st
14、andards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
15、 Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 21415-2:2015 has been approved by CEN as EN ISO 21415-2:2015 without any modification. BS EN ISO 21415-2:2015ISO 21415
16、-2:2015(E)Foreword ivIntroduction v1 Scope . 12 Terms and definitions . 13 Principle 14 Reagents 15 Apparatus . 26 Sampling 37 Preparation of test sample . 38 Procedure. 38.1 General . 38.2 Testing 38.3 Paste preparation 38.4 Paste washing . 48.4.1 Detection of starch . 48.4.2 Flour . 48.4.3 Ground
17、wheat . 48.4.4 Special case . 48.5 Spinning and weighing the wet gluten . 48.6 Determining the gluten index 48.7 Number of measurements 59 Calculations and record of results 510 Precision . 510.1 Interlaboratory tests 510.2 Repeatability . 610.3 Reproducibility . 610.4 Critical difference 610.4.1 Co
18、mparison of two sets of measurements in the same laboratory 610.4.2 Comparison of two sets of measurements in two laboratories . 711 Test report . 7Annex A (informative) Washing chamber and mill of the Glutomatic unit and centrifuge 8Annex B (normative) Preparation of ground wheat 11Annex C (informa
19、tive) Results of interlaboratory tests .12Bibliography .15 ISO 2015 All rights reserved iiiContents PageBS EN ISO 21415-2:2015ISO 21415-2:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of pr
20、eparing International Standards is normally carried out through ISO 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, i
21、n liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IE
22、C Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility t
23、hat 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. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent
24、declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as informati
25、on about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 34, Food products, Subcommittee SC 4, Cereals and pulses.This second edition of ISO 21415-2 cancels
26、and replaces the first edition (ISO 21415-2-2006) which has been technically revised.ISO 21415 consists of the following parts, under the general title Wheat and wheat flour Gluten content : Part 1: Determination of wet gluten by a manual method Part 2: Determination of wet gluten and gluten index b
27、y mechanical means Part 3: Determination of dry gluten from wet gluten by using an oven-drying method Part 4: Determination of dry gluten from wet gluten by a rapid drying methodiv ISO 2015 All rights reservedBS EN ISO 21415-2:2015ISO 21415-2:2015(E)IntroductionThe alternative techniques specified i
28、n this part of ISO 21415 and in ISO 21415-1 for isolation of wet gluten (i.e. manual extraction and mechanical extraction) do not generally yield equivalent results. The reason for this is that for full development of the gluten structure the dough needs to be allowed to rest. Hence, the result obta
29、ined by manual extraction is usually greater than that obtained by mechanical extraction, especially in the case of wheat with high gluten content. Therefore, the test report should always state the technique used. ISO 2015 All rights reserved vBS EN ISO 21415-2:2015BS EN ISO 21415-2:2015Wheat and w
30、heat flour Gluten content Part 2: Determination of wet gluten and gluten index by mechanical means1 ScopeThis part of ISO 21415 specifies a method for determining the content of wet gluten and the gluten index for wheat flours (Triticum aestivum L. and Triticum durum Desf.) by mechanical means. This
31、 method is directly applicable to flours. It also applies to common and durum wheat after grinding, if their particular size distribution meets the specification given in Table B.1.2 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.2.1wet glutenviscoe
32、lastic substance consisting mainly of two protein fractions (gliadin and glutenin) in hydrated form, obtained in the way indicated in this part of ISO 21415 or in ISO 21415-12.2gluten indexproportion of wet gluten remaining on the sieve after centrifugationNote 1 to entry: The higher the index, the
33、stronger the gluten is.2.3ground wheatresult of experimental grinding of whole wheat with the granulometry cited in Table B.12.4flourfinely ground wheat endosperm with a granulometry of less than 250 m3 PrinciplePreparation of a paste from a sample of flour or of ground wheat and a sodium chloride s
34、olution in the equipments chamber; separation of the wet gluten by washing this paste with a sodium chloride solution, followed by removal of excess washing solution by centrifugation and weighing the residue. The gluten index is obtained after centrifuging to force the wet gluten through a special
35、sieve. The percentage of wet gluten remaining on the sieve after centrifuging is defined as the gluten index.4 ReagentsUse only reagents of recognized analytical grade, unless otherwise specified and distilled or demineralized water, or water of equivalent purity.INTERNATIONAL STANDARD ISO 21415-2:2
36、015(E) ISO 2015 All rights reserved 1BS EN ISO 21415-2:2015ISO 21415-2:2015(E)4.1 Sodium chloride solution, 20 g/l.Dissolve 200 g of sodium chloride (NaCl) in water, then dilute to 10 l. When using this, it is recommended that the temperature of the solution be 22C 2 C.It is advisable to prepare thi
37、s solution specially every day.4.2 Solution of iodine/potassium iodide (Lugols solution).Dissolve 2,54 g of potassium iodide (KI) in water. Add 1,27 g of iodine (I2) to this solution and, when the reagents have completely dissolved, dilute to 100 ml with water.5 ApparatusUsual laboratory apparatus a
38、nd, in particular, the following items.5.1 Automatic gluten separation unit 1), (single or double) consisting of a washing/mixing chamber, mill(s) (see Figures A.1 and A.2) and an electronically controlled distribution device for extracting the gluten.5.1.1 Mixing/washing chamber(s), fitted with rep
39、laceable chrome-plated sieve support(s) with polyester sieves with an 88 m mesh gap and polyamide sieves with an 840 m mesh gap.The distance between the milling hook and the chrome-plated sieve support shall be 0,7 mm 0,05 mm. This value should be checked with the calibrated thickness shims supplied
40、.5.1.2 10 l plastic drum, to contain the sodium chloride solution (4.1) connected to the equipment by a plastic tube.5.1.3 Distribution system, consisting of a peristaltic pump allowing the sodium chloride solution (4.1) used for washing the gluten to be delivered at a constant rate of between 50 ml
41、/min and 56 ml/min.For a detailed description of the unit and for detailed operating instructions, users of this part of ISO 21415 should consult the leaflet of the maker of the equipment used.5.2 Dispenser, for the sodium chloride solution, permitting delivery of 3 ml to 10 ml with an accuracy of 0
42、,1 ml.5.3 Centrifuge, capable of maintaining a rotational frequency of 6 000 5 per minute and producing a radial acceleration of 2 000 g, fitted with 2 perforated plates with holes of diameter 600 m and/or 2 receptacles 22 mm in diameter equipped with a grid containing 600 m holes, to determine the
43、gluten index (cf. Figures A.3 and A.4).5.4 Balance, calibrated to 0,01 g.5.5 Stainless steel spatula.5.6 Beakers with 500 ml capacity (to catch the rinsing water).5.7 Stainless steel or plastic grippers.1) The Glutomatic unit (types 2100 and 2200) made by Perten Instruments AB (Sweden) is the mechan
44、ical device most widely used at present for this purpose. This information is given for the benefit of users of this part of ISO 21415 and in no way implies that ISO approves or recommends exclusive use of this device. Other equipment may also be used if it yields similar results to those of the Glu
45、tomatic unit or those of the method described in ISO 21415-1.2 ISO 2015 All rights reservedBS EN ISO 21415-2:2015ISO 21415-2:2015(E)5.8 Lab crusher, capable of producing a ground product with a granulometry meeting the requirements of Table B.1.5.9 Watch glass.6 SamplingIt is important for the labor
46、atory to receive a truly representative sample which has not been damaged or altered during transport or storage.The method specified in this part of ISO 21415 does not cover sampling. A recommended sampling method is given in ISO 24333.7 Preparation of test sampleHomogenize the samples. Before meas
47、uring the gluten content, grind the wheat grains and crush them with a lab crusher (5.8), as indicated in Annex B. Special precautions should be taken during grinding and storing to prevent any alteration to the moisture content of samples.8 Procedure8.1 GeneralThe operations of preparation and wash
48、ing of the dough are carried out continuously with automatic equipment (5.1). Follow the instructions supplied by the manufacturer of the equipment used.8.2 TestingWeigh 10 g of the sample to within 0,01 g for testing and transfer to the units washing/mixing chamber (5.1.1). Ensure that the washing
49、chamber is fitted with a suitable sieve, which has been previously cleaned and moistened.When testing flour samples, one or more fine polyester sieve(s) (88 m aperture) is/are used. When testing ground wheat, chrome-plated sieve supports fitted with a slotted ring are also required with polyamide sieves with a mesh gap of 840 m. In that case, the test starts with the fine sieve and in addition a coarse sieve is used for the second step in the method.The gluten index is generally measured using only 88 m polyester sieves and 840 m
