Wheat and wheat flour - Gluten content - Part 2: Determination of wet gluten and gluten index by mechanical means (ISO 21415-2:2015)

ISO 21415-2:2015 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 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.

Weizen und Weizenmehl - Glutengehalt - Teil 2: Bestimmung von Feuchtgluten und Glutenindex durch mechanische Verfahren (ISO 21415-2:2015)

Dieser Teil der ISO 21415 legt ein Verfahren zur Bestimmung des Gehalts an Feuchtgluten und des Glutenindex in Weizenmehlen (Triticum aestivum L. und Triticum durum Desf.) mit mechanischen Verfahrens-weisen fest. Dieses Verfahren ist direkt auf Mehle anwendbar. Es gilt auch für Weich  und Hartweizen nach dem Vermahlen, sofern deren Korngrößenverteilung den Spezifikationen nach Tabelle B.1 entspricht.

Blé et farines de blé - Teneur en gluten - Partie 2: Détermination du gluten humide et du gluten index par des moyens mécaniques (ISO 21415-2:2015)

ISO 21415-2:2015 spécifie une méthode de détermination de la teneur en gluten humide et du gluten index des farines de blé (Triticum aestivum L. et Triticum durum Desf.) par des moyens mécaniques. Cette méthode est directement applicable aux farines. Elle s'applique également au blé tendre et au blé dur après broyage, si leur granulométrie particulière satisfait aux spécifications données dans le Tableau B.1.

Pšenica in pšenična moka - Vsebnost glutena - 2. del: Določevanje mokrega glutena in indeksa glutena na mehanski način (ISO 21415-2:2015)

Ta del standarda ISO 21415 navaja metodo za določevanje vsebnosti mokrega glutena in
indeksa glutena za pšenične moke (Triticum aestivum L. in Triticum durum Desf.) na mehanski način. Ta
metoda se lahko neposredno uporablja za moke. Uporablja se tudi za navadno pšenico in pšenico durum po mletju, če
porazdelitev velikosti ustreza specifikaciji, podani v preglednici B.1.

General Information

Status
Published
Publication Date
27-Oct-2015
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
28-Oct-2015
Completion Date
28-Oct-2015

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SLOVENSKI STANDARD
SIST EN ISO 21415-2:2016
01-januar-2016
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SIST EN ISO 21415-2:2008
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Wheat and wheat flour - Gluten content - Part 2: Determination of wet gluten and gluten

index by mechanical means (ISO 21415-2:2015)
Weizen und Weizenmehl - Glutengehalt - Teil 2: Bestimmung von Feuchtgluten und
Glutenindex durch mechanische Verfahren (ISO 21415-2:2015)

Blé et farines de blé - Teneur en gluten - Partie 2: Détermination du gluten humide et du

gluten index par des moyens mécaniques (ISO 21415-2:2015)
Ta slovenski standard je istoveten z: EN ISO 21415-2:2015
ICS:
67.060 äLWDVWURþQLFHLQSURL]YRGLL] Cereals, pulses and derived
QMLK products
SIST EN ISO 21415-2:2016 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 21415-2:2016
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SIST EN ISO 21415-2:2016
EN ISO 21415-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2015
EUROPÄISCHE NORM
ICS 67.060 Supersedes EN ISO 21415-2:2008
English Version
Wheat and wheat flour - Gluten content - Part 2:
Determination of wet gluten and gluten index by
mechanical means (ISO 21415-2:2015)

Blé et farines de blé - Teneur en gluten - Partie 2: Weizen und Weizenmehl - Glutengehalt - Teil 2:

Détermination du gluten humide et du gluten index par Bestimmung von Feuchtgluten und Glutenindex durch

des moyens mécaniques (ISO 21415-2:2015) 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 Standard 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 (English, 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, Bulgaria, 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, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR 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 Ref. No. EN ISO 21415-2:2015 E

worldwide for CEN national Members.
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SIST EN ISO 21415-2:2016
EN ISO 21415-2:2015 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 21415-2:2016
EN ISO 21415-2:2015 (E)
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 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 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 standards 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, 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.
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SIST EN ISO 21415-2:2016
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SIST EN ISO 21415-2:2016
INTERNATIONAL ISO
STANDARD 21415-2
Second edition
2015-10-01
Wheat and wheat flour — Gluten
content —
Part 2:
Determination of wet gluten and
gluten index by mechanical means
Blé et farines de blé — Teneur en gluten —
Partie 2: Détermination du gluten humide et du gluten index par des
moyens mécaniques
Reference number
ISO 21415-2:2015(E)
ISO 2015
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SIST EN ISO 21415-2:2016
ISO 21415-2:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
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Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved
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SIST EN ISO 21415-2:2016
ISO 21415-2:2015(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Terms and definitions ..................................................................................................................................................................................... 1

3 Principle ........................................................................................................................................................................................................................ 1

4 Reagents ........................................................................................................................................................................................................................ 1

5 Apparatus ..................................................................................................................................................................................................................... 2

6 Sampling ........................................................................................................................................................................................................................ 3

7 Preparation of test sample ......................................................................................................................................................................... 3

8 Procedure..................................................................................................................................................................................................................... 3

8.1 General ........................................................................................................................................................................................................... 3

8.2 Testing ............................................................................................................................................................................................................ 3

8.3 Paste preparation.................................................................................................................................................................................. 3

8.4 Paste washing ........................................................................................................................................................................................... 4

8.4.1 Detection of starch ......................................................................................................................................................... 4

8.4.2 Flour ........................................................................................................................................................................................... 4

8.4.3 Ground wheat ..................................................................................................................................................................... 4

8.4.4 Special case ........................................................................................................................................................................... 4

8.5 Spinning and weighing the wet gluten ............................................................................................................................... 4

8.6 Determining the gluten index .................................................................................................................................................... 4

8.7 Number of measurements ............................................................................................................................................................ 5

9 Calculations and record of results...................................................................................................................................................... 5

10 Precision ....................................................................................................................................................................................................................... 5

10.1 Interlaboratory tests .......................................................................................................................................................................... 5

10.2 Repeatability ............................................................................................................................................................................................. 6

10.3 Reproducibility ....................................................................................................................................................................................... 6

10.4 Critical difference.................................................................................................................................................................................. 6

10.4.1 Comparison of two sets of measurements in the same laboratory ...................................... 6

10.4.2 Comparison of two sets of measurements in two laboratories ............................................... 7

11 Test report ................................................................................................................................................................................................................... 7

Annex A (informative) Washing chamber and mill of the Glutomatic unit and centrifuge ..........................8

Annex B (normative) Preparation of ground wheat ..........................................................................................................................11

Annex C (informative) Results of interlaboratory tests .................................................................................................................12

Bibliography .............................................................................................................................................................................................................................15

© ISO 2015 – All rights reserved iii
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SIST EN ISO 21415-2:2016
ISO 21415-2:2015(E)
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 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 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/IEC 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 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. 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 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 information about ISO’s adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

The 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 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 by 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 method
iv © ISO 2015 – All rights reserved
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SIST EN ISO 21415-2:2016
ISO 21415-2:2015(E)
Introduction

The alternative techniques specified in 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 obtained 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 v
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SIST EN ISO 21415-2:2016
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SIST EN ISO 21415-2:2016
INTERNATIONAL STANDARD ISO 21415-2:2015(E)
Wheat and wheat flour — Gluten content —
Part 2:
Determination of wet gluten and gluten index by
mechanical means
1 Scope

This 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

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 definitions
For the purposes of this document, the following terms and definitions apply.
2.1
wet gluten

viscoelastic 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 21415-1
2.2
gluten index
proportion of wet gluten remaining on the sieve after centrifugation
Note 1 to entry: The higher the index, the stronger the gluten is.
2.3
ground wheat

result of experimental grinding of whole wheat with the granulometry cited in Table B.1

2.4
flour
finely ground wheat endosperm with a granulometry of less than 250 µm
3 Principle

Preparation of a paste from a sample of flour or of ground wheat and a sodium chloride solution in

the equipment’s 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 sieve. The

percentage of wet gluten remaining on the sieve after centrifuging is defined as the gluten index.

4 Reagents

Use only reagents of recognized analytical grade, unless otherwise specified and distilled or

demineralized water, or water of equivalent purity.
© ISO 2015 – All rights reserved 1
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SIST EN ISO 21415-2:2016
ISO 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 22°C ± 2 °C.
It is advisable to prepare this solution specially every day.
4.2 Solution of iodine/potassium iodide (Lugol’s solution).

Dissolve 2,54 g of potassium iodide (KI) in water. Add 1,27 g of iodine (I ) to this solution and, when the

reagents have completely dissolved, dilute to 100 ml with
...

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