1、November 2016 English price group 15No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 67.060!%uv“2588283www.din.deDIN
2、 EN ISO 16634-2Food products Determination of the total nitrogen content by combustion according to theDumas principle and calculation of the crude protein content Part 2: Cereals, pulses and milled cereal products (ISO 166342:2016);English version EN ISO 166342:2016,English translation of DIN EN IS
3、O 16634-2:2016-11Lebensmittelerzeugnisse Bestimmung des Gehaltes an Gesamtstickstoff mit dem Verbrennungsverfahren nach Dumas und Berechnung des Gehaltes an Rohprotein Teil 2: Getreide, Hlsenfrchte und gemahlene Getreideerzeugnisse (ISO 166342:2016);Englische Fassung EN ISO 166342:2016,Englische ber
4、setzung von DIN EN ISO 16634-2:2016-11Produits alimentaires Dtermination de la teneur en azote total par combustion selon le principe Dumas et calcul de la teneur en protines brutes Partie 2: Crales, lgumineuses et produits craliers de mouture (ISO 166342:2016);Version anglaise EN ISO 166342:2016,Tr
5、aduction anglaise de DIN EN ISO 16634-2:2016-11SupersedesDIN SPEC 1138(DIN ISO/TS 166342):201002www.beuth.deDocument comprises 33 pagesDTranslation by DIN-Sprachendienst.In case of doubt, the German-language original shall be considered authoritative.11.16 DIN EN ISO 16634-2:2016-11 2 A comma is use
6、d as the decimal marker. National foreword This document (EN ISO 16634-2:2016) has been prepared by Technical Committee ISO/TC 34 “Food products” in collaboration with Technical Committee CEN/TC 338 “Cereal and cereal products” (Secretariat: AFNOR, France). The responsible German body involved in it
7、s preparation was DIN-Normenausschuss Lebensmittel und landwirtschaftliche Produkte (DIN Standards Committee Food and Agricultural Products), Working Committee NA 057-05-06 AA Getreide und Getreideerzeugnisse. The DIN Standards corresponding to the International Standards referred to in this documen
8、t are as follows: ISO 712 DIN EN ISO 712 ISO 5725-1 DIN ISO 5725-1 ISO 5725-2 DIN ISO 5725-2 ISO 5725-6 DIN ISO 5725-6 ISO 6540 DIN EN ISO 6540 ISO 14891 DIN EN ISO 14891 ISO 20483 DIN EN ISO 20483 ISO 24333 DIN EN ISO 24333 Amendments This standard differs from DIN SPEC 1138 (DIN ISO/TS 16634-2):20
9、10-02 as follows: a) the status of the document is now that of a DIN Standard; b) the former Annex D (informative) “Examples of factors for converting nitrogen content to protein content” has been deleted; c) the standard has been editorially revised and brought in line with the current rules of pre
10、sentation. Previous editions DIN SPEC 1138 (DIN ISO/TS 16634-2): 2010-02 DIN EN ISO 16634-2:2016-11 3 National Annex NA (informative) Bibliography DIN EN ISO 712, Cereals and cereal products Determination of moisture content Reference method DIN EN ISO 6540, Maize Determination of moisture content (
11、on milled grains and on whole grains) DIN EN ISO 14891, Milk and milk products Determination of nitrogen content Routine method using combustion according to the Dumas principle DIN EN ISO 20483, Cereals and pulses Determination of the nitrogen content and calculation of the crude protein content Kj
12、eldahl method DIN EN ISO 24333, Cereals and cereal products Sampling DIN ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results Part 1: General principles and definitions DIN ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic meth
13、od for the determination of repeatability and reproducibility of a standard measurement method DIN ISO 5725-6, Accuracy (trueness and precision) of measurement methods and results Part 6: Use in practice of accuracy values DIN EN ISO 16634-2:2016-11 4 This page is intentionally blank EUROPEAN STANDA
14、RD NORME EUROPENNE EUROPISCHE NORM EN ISO 16634-2 June 2016 ICS 67.060; 67.050 Supersedes CEN ISO/TS 16634-2:2009English Version Food products - Determination of the total nitrogen content by combustion according to the Dumas principle and calculation of the crude protein content - Part 2: Cereals,
15、pulses and milled cereal products(ISO 16634-2:2016) Produits alimentaires - Dtermination de la teneur en azote total par combustion selon le principe Dumas et calcul de la teneur en protines brutes - Partie 2: Crales, lgumineuses et produits craliers de mouture (ISO 16634-2:2016) Lebensmittelerzeugn
16、isse - Bestimmung des Gehaltes an Gesamtstickstoff mit dem Verbrennungsverfahren nach Dumas und Berechnung des Gehaltes an Rohprotein - Teil 2: Getreide, Hlsenfrchte und gemahlene Getreideerzeugnisse (ISO 16634-2:2016) This European Standard was approved by CEN on 12 May 2016. CEN members are bound
17、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-
18、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
19、 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, Lux
20、embourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, 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 Brus
21、sels 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 16634-2:2016 EForeword 4Introduction 51 Scope . 62 Normative references 63 Terms and definitions . 64 Principle 75 Reagents 76 Apparatus . 87 Sampling 88 Preparation of
22、the test sample . 89 Procedure. 99.1 General . 99.2 Test portion 99.3 Control of oxygen supply 99.4 Calibration . 109.5 Determination 109.6 Detection and data processing . 1010 Calculation and expression of results 1110.1 Calculation . 1110.1.1 Nitrogen content . 1110.1.2 Crude protein content 1110.
23、2 Expression of results . 1111 Precision 1111.1 Interlaboratory tests . 1111.2 Repeatability 1211.3 Reproducibility 1211.4 Critical difference. 1211.4.1 Comparison of two groups of measurements in the same laboratory . 1211.4.2 Comparison of two groups of measurements in two different laboratories .
24、 1311.5 Uncertainty 1312 Test report 13Annex A (informative) Flowchart for a basic Dumas apparatus .14Annex B (informative) Schematic diagrams of suitable types of Dumas apparatus 15Annex C (informative) Equipment calibration 18Annex D (informative) Results of interlaboratory tests 20Bibliography .2
25、7Contents Page2EN ISO 16634-2:2016 (E) DIN EN ISO 16634-2:2016-11 European foreword .3European Foreword This document (EN ISO 16634-2:2016) has been prepared by Technical Committee ISO/TC 34 “Food products“ in collaboration with Technical Committee CEN/TC 338 “Cereal and cereal products” the secreta
26、riat 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 December 2016, and conflicting national standards shall be withdrawn at the latest by December 2016. Attention is dr
27、awn 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 CEN ISO/TS 16634-2:2009. According to the CEN-CENELEC Internal Regulations,
28、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, Lat
29、via, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 16634-2:2016 has been approved by CEN as EN ISO 16634-2:2016 without any modification. 3EN ISO 16634-2:
30、2016 (E) DIN EN ISO 16634-2:2016-11 ForewordISO (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 in
31、terested 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 Electrotechni
32、cal 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 doc
33、uments 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 responsi
34、ble 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
35、 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 principles in the Technical Barriers to Trade (TBT) see the following URL:
36、 Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 34, Food products, Subcommittee SC 4, Cereals and pulses.This first edition cancels and replaces ISO/TS 16634-2:2009, which has been technically revised.ISO 16634 consists of the following parts, under the gen
37、eral title, Food products Determination of the total nitrogen content by combustion according to the Dumas principle and calculation of the crude protein content: Part 1: Oilseeds and animal feeding stuffs Part 2: Cereals, pulses and milled cereal products4EN ISO 16634-2:2016 (E) DIN EN ISO 16634-2:
38、2016-11 IntroductionFor a long time, the Kjeldahl method has been the most frequently used method for the determination of the protein content of food products. In recent years, the Dumas method has gained importance compared to the Kjeldahl method because it is faster and does not use dangerous che
39、micals. Although the principles of the two methods are different, both measure the nitrogen content of the product. Nitrogen content can be converted into protein content by using an appropriate factor. The value of this factor varies depending on the relative amounts of different proteins and their
40、 amino-acid composition in a given product.Neither the Dumas nor the Kjeldahl method distinguishes between protein and non-protein nitrogen. In most cases, results obtained by the Dumas method are slightly higher than those of the Kjeldahl method. This is because the Dumas method measures almost all
41、 of the non-protein nitrogen, whereas the Kjeldahl method measures only a part of it.Taking into consideration that the protein content of a product calculated by both methods only approximates to the true value, it is a matter of discretion which one is accepted. The best solution is to use a secon
42、d factor for the elimination of the systematic error caused by the non-protein nitrogen content of the different products.However, this second factor has to be determined for each product like the existing factors which indicate the ratio of the protein content to the nitrogen content.5EN ISO 16634-
43、2:2016 (E) DIN EN ISO 16634-2:2016-11 1 ScopeThis part of ISO 16634 specifies a method for the determination of the total nitrogen content and the calculation of the crude protein content of cereals, pulses and milled cereal products.This method, like the Kjeldahl method (see References 1 and 6), do
44、es not distinguish between protein nitrogen and non-protein nitrogen. For the calculation of the protein content, various conversion factors are used (see 3.2).2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for it
45、s application. 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 Reference methodISO 6540, Maize Determination of moistu
46、re content (on milled grains and on whole grains)ISO 24557, Pulses Determination of moisture content Air-oven method3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1nitrogen contentmass fraction of the total nitrogenNote 1 to entry: Determined by
47、 the procedure specified in this part of ISO 16634.Note 2 to entry: The mass fraction is expressed as a percentage.3.2crude protein contentnitrogen content (3.1) multiplied by a factorNote 1 to entry: A 5,7 factor is generally used for cereals for human food (such as wheat, rye and their milled prod
48、ucts) and 6,25 for malting barley and cereals for feed and other products falling within the scope of this part of ISO 16634.Note 2 to entry: The factors for calculation of the crude protein content from the total nitrogen content are derived from the Kjeldahl method, which is the reference method f
49、or the determination of total nitrogen content.6EN ISO 16634-2:2016 (E) DIN EN ISO 16634-2:2016-11 4 PrincipleSamples are converted into gases by heating in a combustion tube. Interfering components are removed from the resulting gas mixture. The nitrogen compounds in the gas mixture, or a representative part of them, are converted to molecular nitrogen which is quantitatively determined by a thermal-conductivity detec
