1、BRITISH STANDARDBS EN ISO 21415-1:2007Wheat and wheat flour Gluten content Part 1: Determination of wet gluten by a manual methodThe European Standard EN ISO 21415-1:2007 has the status of a British StandardICS 67.060g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54
2、g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN ISO 21415-1:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2007 BSI 2007ISBN 978 0 580 50581 2National fo
3、rewordThis British Standard was published by BSI. It is the UK implementation of EN ISO 21415-1:2007. It is identical with ISO 21415-1:2006. Together with BS EN ISO 21415-2, when published, will supersede BS 4317-12:1980.The UK participation in its preparation was entrusted to Technical Committee AW
4、/4, Cereals and pulses.A list of organizations represented on this committee can be obtained on request to its secretary.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 canno
5、t confer immunity from legal obligations.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 21415-1March 2007ICS 67.060English VersionWheat and wheat flour - Gluten content - Part 1: Determinationof wet gluten by a manual method (ISO 21415-
6、1:2006)Bl et farines de bl - Teneur en gluten - Partie 1:Dtermination du gluten humide par une mthode manuelle(ISO 21415-1:2006)Weizen und Weizenmehl - Glutengehalt - Teil 1: ManuelleMethode zur Bestimmung des Feuchtglutens (ISO 21415-1:2006)This European Standard was approved by CEN on 25 February
7、2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained o
8、n 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 translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Cen
9、tre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
10、 Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2007 CEN All rights of exploitation in any form and by any mea
11、ns reservedworldwide for CEN national Members.Ref. No. EN ISO 21415-1:2007: EForeword The text of ISO 21415-1:2006 has been prepared by Technical Committee ISO/TC 34 “Agricultural food products” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 21415-1:200
12、7 by Technical Committee CEN/TC 338 “Cereal and cereal products“, the secretariat 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 September 2007, and conflicting nationa
13、l standards shall be withdrawn at the latest by September 2007. 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 Republic, Denmark, Estonia, Finl
14、and, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Endorsement notice The text of ISO 21415-1:2006 has been approved by CEN as EN ISO
15、21415-1:2007 without any modifications. EN ISO 21415-1:2007Reference numberISO 21415-1:2006(E)INTERNATIONAL STANDARD ISO21415-1First edition2006-05-01Wheat and wheat flour Gluten content Part 1: Determination of wet gluten by a manual method Bl et farines de bl Teneur en gluten Partie 1: Dterminatio
16、n du gluten humide par une mthode manuelle EN ISO 21415-1:2007ii iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle. 1 5 Reagents 2 6 Apparatus 2 7 Sampling 3 8 Preparation of test sample. 3 9 Procedure 3 9.1 General. 3 9.2 Test
17、portion . 3 9.3 Dough preparation and leaving it to rest 3 9.4 Washing out 3 9.5 Removal of excess washing solution. 4 9.6 Determination of the mass of the wet gluten.4 9.7 Number of determinations . 4 10 Calculation and expression of results 4 11 Precision 5 11.1 Interlaboratory tests . 5 11.2 Repe
18、atability 5 11.3 Reproducibility 5 12 Test report . 5 Annex A (normative) Gluten press . 6 Annex B (normative) Preparation of ground wheat 7 Annex C (informative) Results of an interlaboratory test. 8 Bibliography . 9 EN ISO 21415-1:2007iv Foreword ISO (the International Organization for Standardiza
19、tion) 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 established has the right to be
20、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 standardization. International Standard
21、s 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. Publication as an Interna
22、tional 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 patent rights. ISO 21415-1 w
23、as prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 4, Cereals and pulses. This first edition of ISO 21415-1, together with ISO 21415-2 (to be published), cancels and replaces ISO 5531:1978, which has been technically revised. ISO 21415 consists of the following parts, under
24、 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 by mechanical means Part 3: Determination of dry gluten from wet gluten by an oven drying method Part 4: Determination of dry gluten from wet gluten by
25、a rapid drying method EN ISO 21415-1:2007vIntroduction The alternative techniques specified in this part of ISO 21415 and in ISO 21415-2 for the isolation of wet gluten (i.e. washing out by hand and mechanical washing out) do not usually give equivalent results. The reason is that, for complete deve
26、lopment of the gluten structure, it is necessary to rest the dough. Therefore, the result obtained by hand washing is usually higher than that obtained by mechanical washing, mainly in the case of wheat which has high gluten content. Consequently, the test report should always indicate the technique
27、 used. EN ISO 21415-1:2007blank1Wheat and wheat flour Gluten content Part 1: Determination of wet gluten by a manual method 1 Scope This part of ISO 21415 specifies a manual washing out method for the determination of the wet gluten content of wheat flour (Triticum aestivum L. and Triticum durum Des
28、f.). This method is directly applicable to flour. It is also applicable to semolina and wheat after grinding, if their particle size distribution meets the specification given in Table B.1. 2 Normative references The following referenced documents are indispensable for the application of this docume
29、nt. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 712, Cereals and cereal products Determination of moisture content Routine reference method 3 Terms and definitions For the purposes
30、 of this document, the following terms and definitions apply. 3.1 wet gluten visco-elastic substance, composed principally of two protein fractions (gliadin and glutenin) in a hydrated form, obtained as specified in this part of ISO 21415 or ISO 21415-2 3.2 ground wheat product of small-scale millin
31、g of whole wheat which meets the particle size distribution shown in Table B.1 3.3 semolina coarsely milled wheat endosperm 3.4 flour finely milled wheat endosperm with a particle size of less than 250 m 4 Principle Dough is prepared from a sample of flour or reground semolina or ground wheat and a
32、solution of sodium chloride. The dough is left to rest for the gluten structure to develop. The wet gluten is separated by hand EN ISO 21415-1:20072 washing the dough with sodium chloride solution, followed by removal of excess washing solution. The residue is weighed. 5 Reagents Use only reagents o
33、f recognized analytical grade, unless otherwise specified, and distilled or demineralized water or water of equivalent purity. 5.1 Sodium chloride solution, 20 g/l. Dissolve 200 g of sodium chloride (NaCl) in water then dilute it to 10 l. 5.2 Potassium iodide/iodine solution (Lugols solution). Disso
34、lve 2,54 g of potassium iodide (KI) in water. Add 1,27 g of iodine (I2) to this solution and, after complete dissolution of the integral parts, dilute to 100 ml with water. 6 Apparatus Usual laboratory apparatus and, in particular, the following. 6.1 Porcelain mortar, glazed inside, or enamelled met
35、al vessel of diameter 10 cm to 15 cm. 6.2 Burette, of capacity 25 ml, graduated in 0,1 ml. 6.3 Beaker, of capacity 250 ml. 6.4 Spatula, plastic or stainless steel, 18 cm to 20 cm in length. 6.5 Glass plate, about 40 cm 40 cm. 6.6 Gloves, of thin rubber and having a smooth surface. 6.7 Wooden frame,
36、about 30 cm 40 cm, covered with No. 56 grit gauze (308 m). 6.8 Container, with adjustable outflow, for the sodium chloride solution (5.1). 6.9 Filter paper1), of mass approximately 120 g/m2. 6.10 Stop-watch. 6.11 Balance, capable of weighing to the nearest 0,01 g. 6.12 Gluten press, see Annex A. 6.1
37、3 Watch-glass, of diameter 8 cm. 6.14 Small-scale mill, capable of milling to a particle size distribution that meets the requirements given in Table B.1. 1) For example, the Macherey Nagel No. 651 filter paper is suitable for this purpose. This information is given for the convenience of users of t
38、his part of ISO 21415 and does not constitute an endorsement by ISO of this product. EN ISO 21415-1:200737 Sampling A representative sample should have been sent to the laboratory. It should not have been damaged or changed during transport or storage. Sampling is not part of the method specified in
39、 this part of ISO 21415. A recommended sampling method is given in ISO 6644 or ISO 13690. 8 Preparation of test sample Homogenize the samples and determine their moisture content in accordance with ISO 712. Prior to the gluten content measurement, grind wheat grain and semolina using a small-scale m
40、ill (6.14) as specified in Annex B. To avoid changes in the moisture content of the samples, take special care during grinding and storage. 9 Procedure 9.1 General Use sodium chloride solution (5.1) for the preparation and washing of the dough. The test sample and the sodium chloride solution should
41、 be kept at least for one night in the laboratory where the procedure will be carried out. If the ambient temperature is lower than 20 C or higher than 25 C, the temperature of the test sample and the sodium chloride solution should be adjusted to between 20 C and 25 C. 9.2 Test portion Weigh about
42、24 g of the test sample to the nearest 0,01 g (m1) and transfer it quantitatively to the mortar or vessel (6.1). 9.3 Dough preparation and leaving it to rest 9.3.1 Add drop-by-drop 12 ml of the sodium chloride solution (5.1) from the burette (6.2), while continuously stirring the flour with the spat
43、ula (6.4). 9.3.2 After adding the sodium chloride solution, compress the mixture with the spatula and form a dough ball, taking care to avoid loss of flour. Dough residues adhering to the wall of the vessel or to the spatula shall be collected with the dough ball. 9.3.3 Preparation of the dough shou
44、ld not take longer than 3 min. 9.3.4 Place the dough ball on the glass plate (6.5). Cover the inside of a 250 ml beaker (6.3) with wet filter paper (6.9) and then use it to cover the dough ball. Leave the dough to rest for 30 min. 9.4 Washing out 9.4.1 The operations described in 9.4.2 and 9.4.3 sha
45、ll be carried out over the wooden frame covered with gauze (6.7) to avoid the possible loss of dough. During the operations, the hands shall be covered with rubber gloves (6.6) in order to protect the dough from warmth and perspiration from the hands. 9.4.2 After the resting period, weigh about 30 g
46、 from the dough ball (9.3) to the nearest 0,01 g (m2). Take it in the palm of one hand and allow the sodium chloride solution (5.1) to drip onto it from the container (6.8) at a flowing rate of 750 ml per 8 min. During this time, successively roll out and mould the dough ball with the thumb of the o
47、ther hand. EN ISO 21415-1:20074 9.4.3 The washing is considered to be complete when the sodium chloride solution pressed out from the gluten ball obtained as in 9.4.2 is practically free of starch. For the detection of starch, press out some drops of the washing solution from the gluten ball into a
48、watch-glass (6.13) and add a few drops of potassium iodide/iodine solution (5.2) to it. If the colour of the solution does not change, the washing out procedure is completed. If the colour of the solution turns blue, this indicates that starch is still present and the washing out procedure should be
49、 continued until it cannot be detected. 9.4.4 The washing out time depends on the gluten content, but in general is about 8 min. 9.5 Removal of excess washing solution 9.5.1 Eliminate most of the washing solution adhering to the gluten ball by holding it between the fingers of one hand and compressing it briefly three times. 9.5.2 Divide the gluten ball into two approximately equal parts, form them into a laminated shape and place them in the gluten press (6.12). Close the gluten press and re-open it after 5 s. Transfer the gluten leaves
