EN ISO 8968-1:2014

SLOVENSKI STANDARD
01-april-2014
1DGRPHãþD
SIST EN ISO 8968-1:2002
SIST EN ISO 8968-2:2002
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Milk and milk products - Determination of nitrogen content - Part 1: Kjeldahl principle and
crude protein calculation (ISO 8968-1:2014)
Milch und Milcherzeugnisse - Bestimmung des Stickstoffgehaltes - Teil 1: Kjeldahl-
Verfahren und Berechnung des Rohproteingehaltes (ISO 8968-1:2014)
Lait et produites laitieres - Détermination de la teneur en azote et calcul de protéine brute
- Partie 1: Méthode Kjeldahl (ISO/FDIS 8968-1:2013)
Ta slovenski standard je istoveten z: EN ISO 8968-1:2014
ICS:
67.100.10 0OHNRLQSUHGHODQLPOHþQL Milk and processed milk
SURL]YRGL products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 8968-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2014
ICS 67.100.10 Supersedes EN ISO 8968-1:2001, EN ISO 8968-2:2001
English Version
Milk and milk products - Determination of nitrogen content - Part
1: Kjeldahl principle and crude protein calculation (ISO 8968-
1:2014)
Lait et produits laitiers - Détermination de la teneur en azote Milch und Milcherzeugnisse - Bestimmung des
- Partie 1: Méthode Kjeldahl et calcul de la teneur en Stickstoffgehaltes - Teil 1: Kjeldahl-Verfahren und
protéines brutes (ISO 8968-1:2014) Berechnung des Rohproteingehaltes (ISO 8968-1:2014)
This European Standard was approved by CEN on 18 January 2014.

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
© 2014 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8968-1:2014 E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 8968-1:2014) has been prepared by Technical Committee ISO/TC 34 “Food
products” in collaboration with Technical Committee CEN/TC 302 “Milk and milk products - Methods of
sampling and analysis” the secretariat of which is held by NEN.
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 August 2014, and conflicting national standards shall be withdrawn at
the latest by August 2014.
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 8968-1:2001, EN ISO 8968-2:2001.
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 8968-1:2014 has been approved by CEN as EN ISO 8968-1:2014 without any modification.

INTERNATIONAL ISO
STANDARD 8968-1
IDF
20-1
Second edition
2014-02-01
Milk and milk products —
Determination of nitrogen content —
Part 1:
Kjeldahl principle and crude protein
calculation
Lait et produits laitiers — Détermination de la teneur en azote —
Partie 1: Méthode Kjeldahl et calcul de la teneur en protéines brutes
Reference numbers
ISO 8968-1:2014(E)
IDF 20-1:2014(E)
©
ISO and IDF 2014
ISO 8968-1:2014(E)
IDF 20-1:2014(E)
© ISO/IDF 2014
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 or IDF at the respective address below or ISO’s member body in the
country of the requester.
ISO copyright office International Dairy Federation
Case postale 56 • CH-1211 Geneva 20 Silver Building • Bd Auguste Reyers 70/B • B-1030 Brussels
Tel. + 41 22 749 01 11 Tel. + 32 2 733 98 88
Fax + 41 22 749 09 47 Fax + 32 2 733 04 13
E-mail copyright@iso.org E-mail info@fil-idf.org
Web www.iso.org Web www.fil-idf.org
Published in Switzerland
ii © ISO and IDF 2014 – All rights reserved

ISO 8968-1:2014(E)
IDF 20-1:2014(E)
Contents Page
Forewords .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents . 2
6 Apparatus . 3
7 Sampling . 5
8 Preparation of test sample . 5
8.1 Whole, partially skimmed or skimmed liquid milk . 5
8.2 Hard, semi-hard and processed cheese . 5
8.3 Dried milk and dried milk products . 5
9 Procedures . 6
9.1 Traditional method . 6
9.2 Block digestion method . 7
9.3 Blank test . 9
9.4 Recovery tests .10
10 Calculation and expression of results .11
10.1 Calculation .11
10.2 Expression of results .12
11 Precision .13
11.1 Interlaboratory tests .13
11.2 Liquid milk, whole milk and skimmed milk .13
11.3 Hard, semi-hard and processed cheese .14
11.4 Dried milk and dried milk products .14
12 Test report .14
Annex A
(informative)
Test portion .15
Annex B
(informative)
Collaborative trials .16
Bibliography .18
ISO 8968-1:2014(E)
IDF 20-1:2014(E)
Forewords
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. 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. 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 and food products, Subcommittee SC 5,
Milk and milk products and the International Dairy Federation (IDF) and is being published jointly by ISO
and IDF.
This second edition of ISO 8968-1
...