EN ISO 27971-2015 en Cereals and cereal products - Common wheat (Triticum aestivum L ) - Determination of alveograph properties of dough at constant hydration from commercial or te.pdf

1、BSI Standards PublicationBS EN ISO 27971:2015Cereals and cereal products Common wheat (Triticumaestivum L.) Determinationof alveograph properties ofdough at constant hydrationfrom commercial or test floursand test milling methodologyBS EN ISO 27971:2015 BRITISH STANDARDNational forewordThis British

2、Standard is the UK implementation of EN ISO 27971:2015. It supersedes BS EN ISO 27971:2008 which iswithdrawn.The UK participation in its preparation was entrusted to Technical Committee AW/4, Cereals and pulses.A list of organizations represented on this committee can be obtained on request to its s

3、ecretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 84004 3 ICS 67.060 Compliance with a British Standard cann

4、ot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 June 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 27971 Ju

5、ne 2015 ICS 67.060 Supersedes EN ISO 27971:2008English Version Cereals and cereal products - Common wheat (Triticum aestivum L.) - Determination of alveograph properties of dough at constant hydration from commercial or test flours and test milling methodology (ISO 27971:2015) Crales et produits cra

6、liers - Bl tendre (Triticum aestivum L.) - Dtermination des proprits alvographiques dune pte hydratation constante de farine industrielle ou dessai et mthodologie pour la mouture dessai (ISO 27971:2015) Getreide und Getreideerzeugnisse - Weizen (Triticum aestivum L.) - Bestimmung der Eigenschaften v

7、on Teig bei konstanter Flssigkeitszufuhr zu handelsblichen Mehlen oder Versuchsmehlen bei gleichen Versuchsmahlverfahren mittels Alveograph (ISO 27971:2015) This European Standard was approved by CEN on 16 April 2015. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which st

8、ipulate 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 Europea

9、n 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 t

10、he 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, Roman

11、ia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United 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

12、any means reserved worldwide for CEN national Members. Ref. No. EN ISO 27971:2015 EBS EN ISO 27971:2015EN ISO 27971:2015 (E) 3 Foreword This document (EN ISO 27971:2015) has been prepared by Technical Committee ISO/TC 34 “Food products“in collaboration with Technical Committee CEN/TC 338 “Cereal and

13、 cereal products” the secretariat of whichis held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identicaltext or by endorsement, at the latest by December 2015, and conflicting national standards shall be withdrawnat the latest by Dece

14、mber 2015. Attention is drawn to the possibility that some of the elements of this document may be the subject of patentrights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 27971:2008. According to the CEN-CENELEC Int

15、ernal Regulations, the national standards organizations of the followingcountries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, CzechRepublic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,Hungary, Iceland, Ire

16、land, 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 27971:2015 has been approved by CEN as EN ISO 27971:2015 without any modification. BS EN

17、 ISO 27971:2015ISO 27971:2015(E)Foreword vIntroduction vi1 Scope . 12 Normative references 13 Principle 14 Reagents 15 Apparatus . 26 Sampling 97 Preparation of the wheat for laboratory milling. 107.1 Cleaning the laboratory sample 107.2 Test portion . 107.3 Wheat moisture content determination 107.

18、4 Wheat preparation 107.4.1 General. 107.4.2 Wheat with initial moisture content between 13 % and 15 % (one-stage moistening) .107.4.3 Wheat with a moisture content less than 13 % (two-stage moistening) .107.4.4 Wheat with a moisture content greater than 15 % (preliminary drying followed by moisteni

19、ng, as described above) 118 Laboratory milling .118.1 General 118.2 Milling procedure 118.2.1 Breaking . 118.2.2 Reduction 118.2.3 Flour homogenization 128.2.4 Storage of the flour128.3 Expression of milling results 129 Preparation and alveograph test 139.1 Preliminary checks . 139.2 Preliminary ope

20、rations . 149.3 Kneading 159.4 Preparation of dough test pieces 169.5 Alveograph test 209.5.1 Initial preparation209.5.2 First operation: Adjusting the dough test piece .219.5.3 Second operation: biaxial extension 229.6 Expression of alveograph test results 239.6.1 General. 239.6.2 Maximum pressure

21、parameter, P 239.6.3 Mean abscissa at rupture, L . 239.6.4 Swelling index, G . 249.6.5 Elasticity index .249.6.6 Curve configuration ratio, P/L 249.6.7 Deformation work, W . 2410 Precision 2410.1 Interlaboratory tests . 2410.2 Repeatability limits 2510.2.1 Commercial flour: limits established by the

22、 interlaboratory test 2510.2.2 Flour obtained from laboratory milling 2510.3 Reproducibility limits 25 ISO 2015 All rights reserved iiiContents PageBS EN ISO 27971:2015ISO 27971:2015(E)10.3.1 Commercial flour: Limits established by the proficiency tests .2510.3.2 Flour obtained from laboratory milli

23、ng 2610.4 Uncertainty 2611 Test report 26Annex A (informative) Characteristics of the Chopin-Dubois CD1 mill .27Annex B (normative) Quantity of water to be added to wheat for conditioning29Annex C (informative) Sample milling sheet .31Annex D (informative) Conversion table from L to G 32Annex E (inf

24、ormative) Interlaboratory and proficiency test data for commercial flours 34Annex F (informative) Interlaboratory data for laboratory milled flour 44Annex G (informative) Routine maintenance instructions for the alveograph .61Annex H (informative) Assessment of proteolytic activity in wheat (T. aest

25、ivum L.) or flour 63Bibliography .65iv ISO 2015 All rights reservedBS EN ISO 27971:2015ISO 27971:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normal

26、ly 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

27、 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 d

28、ifferent 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

29、 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/pa

30、tents). 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 ISOs adherence to the WTO princ

31、iples 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 pulse.This second edition cancels and replaces the first edition (ISO 27971:2008), which h

32、as been technically revised. ISO 2015 All rights reserved vBS EN ISO 27971:2015ISO 27971:2015(E)IntroductionThe end-use value of wheat is determined by a number of properties that are useful in the manufacture of baked products such as bread, rusks, and biscuits.Such properties include the important

33、 viscoelastic (rheological) properties of dough formed as a result of flour hydration and kneading. An alveograph is used to study the main parameters by subjecting a dough test piece to biaxial extension (producing a dough bubble) by inflating it with air, which is similar to the deformation to whi

34、ch it is subjected during panary fermentation.Recording the pressure generated inside the bubble throughout the deformation of the dough test piece until it ruptures provides information on the following:a) the resistance of the dough to deformation, or its strength. It is expressed by the maximum p

35、ressure parameter, P;b) the extensibility or the possibility of inflating the dough to form a bubble; It is expressed by the parameters of extensibility, L, or swelling, G;c) the elasticity of the dough during biaxial extension. It is expressed by the elasticity index, Ie;d) the work required to def

36、orm the dough bubble until it ruptures, which is proportional to the area of the alveogram (sum of the pressures throughout the deformation process). It is expressed by the parameter, W.The P/L ratio is a measurement of the balance between strength and extensibility.Alveographs are commonly used thr

37、oughout the wheat and flour industry, for the following purposes: selecting and assessing different varieties of wheat and marketing batches of wheat; blending different batches of wheat or flour to produce a batch with given values for the alveographic criteria (W, P, and L) complying with the prop

38、ortional laws of blending.Alveographs are used both on the upstream side of the industry for marketing, selecting and assessing the different wheat varieties and on the downstream side throughout the baking industries (see Bibliography).vi ISO 2015 All rights reservedBS EN ISO 27971:2015Cereals and

39、cereal products Common wheat (Triticum aestivum L.) Determination of alveograph properties of dough at constant hydration from commercial or test flours and test milling methodology1 ScopeThis International Standard specifies a method of determining, using an alveograph, the rheological properties o

40、f different types of dough obtained from common wheat flour (Triticum aestivum L.) produced by industrial milling or laboratory milling.It describes the alveograph test and how to use a laboratory mill to produce flour in two stages: stage 1: preparation of the wheat grain for milling to make it eas

41、ier to separate the bran from the endosperm (see Clause 7); stage 2: the milling process, including breaking between three fluted rollers, reduction of particle size between two smooth rollers and the use of a centrifugal sieving machine to grade the products (see Clause 8).2 Normative referencesThe

42、 following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 660, An

43、imal and vegetable fats and oils Determination of acid value and acidityISO 712, Cereals and cereal products Determination of moisture content Reference methodISO 12099, Animal feeding stuffs, cereals and milled cereal products Guidelines for the application of near infrared spectrometry3 PrincipleT

44、he behaviour of dough obtained from a mixture of different types of flour and salt water is evaluated during deformation. A dough disk is subjected to a constant air flow; at first it withstands the pressure. Subsequently, it inflates into a bubble, according to its extensibility, and ruptures. The

45、change in the dough is measured and recorded in the form of a curve called an alveogram.4 ReagentsUnless otherwise specified, use only reagents of recognized analytical grade, and only distilled or demineralized water or water of equivalent purity.4.1 Sodium chloride solution, obtained by dissolving

46、 (25 0,2) g of sodium chloride (NaCl) in water and then making the volume up to 1 000 ml. This solution shall not be stored for more than 15 d and its temperature shall be (20 2) C when used.INTERNATIONAL STANDARD ISO 27971:2015(E) ISO 2015 All rights reserved 1BS EN ISO 27971:2015ISO 27971:2015(E)4

47、.2 Refined vegetable oil, low in polyunsaturates, such as peanut oil. It is possible to use olive oil if its acid value is less than 0,4 (determined according to ISO 660). Store in a dark place in a closed container and replace regularly (at least every three months).Alternatively, liquid paraffin (

48、also known as “soft petroleum paraffin”), with an acid value of less than or equal to 0,05 and the lowest possible viscosity maximum 60 mPas (60 cP) at 20 C.4.3 Cold degreasing agent, optimum safety.5 ApparatusUsual laboratory apparatus and, in particular, the following.5.1 Mechanical cleaner, fitte

49、d with sieves for wheat cleaning, in accordance with the manufacturers instructions.5.2 Conical or riffle sample divider.5.3 Analytical balance, accurate to 0,01 g.5.4 Glass burette, of 50 ml in capacity, graduated in 1 ml divisions.5.5 Rotary blender1), for grain conditioning and flour homogenization, including the following components:5.5.1 Constant speed stirrer.5.5.2 Two worm screws integral with the flask, possibly via the stopper (one for wheat preparation, the other for flour homogenization).5.5.3 Several wide-n