EN ISO 8069:2007

SLOVENSKI STANDARD
01-oktober-2007
0OHNRYSUDKX'RORþHYDQMHYVHEQRVWLPOHþQHNLVOLQHLQODNWDWRY,62
Dried milk - Determination of content of lactic acid and lactates (ISO 8069:2005)
Milchpulver - Bestimmung des Gehalts an Milchsäure und Lactaten (ISO 8069:2005)
Lait sec - Determination de la teneur en acide lactique et en lactates (ISO 8069:2005)
Ta slovenski standard je istoveten z: EN ISO 8069:2007
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 8069
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2007
ICS 67.100.10
English Version
Dried milk - Determination of content of lactic acid and lactates
(ISO 8069:2005)
Lait sec - Determination de la teneur en acide lactique et en Milchpulver - Bestimmung des Gehalts an Milchsäure und
lactates (ISO 8069:2005) Lactaten (ISO 8069:2005)
This European Standard was approved by CEN on 19 May 2007.
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 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 Management Centre has the same status as the
official 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, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8069:2007: E
worldwide for CEN national Members.

Foreword
The text of ISO 8069:2005 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 8069:2007 by 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 December 2007, and conflicting national
standards shall be withdrawn at the latest by December 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, Finland, 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 8069:2005 has been approved by CEN as EN ISO 8069:2007 without any
modifications.
INTERNATIONAL ISO
STANDARD 8069
IDF
Second edition
2005-09-15
Dried milk — Determination of content of
lactic acid and lactates
Lait sec — Determination de la teneur en acide lactique et en lactates

Reference numbers
ISO 8069:2005(E)
IDF 69:2005(E)
©
ISO and IDF 2005
ISO 8069:2005(E)
IDF 69:2005(E)
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ii © ISO and IDF 2005 – All rights reserved

ISO 8069:2005(E)
IDF 69:2005(E)
Contents Page
Foreword. iv
1 Scope . 1
2 Terms and definitions. 1
3 Principle. 1
4 Reagents. 1
5 Apparatus . 3
6 Sampling. 3
7 Preparation . 4
7.1 Preparation of test sample. 4
7.2 Test portion . 4
7.3 Blank test. 4
7.4 Preparation of solution and deproteination. 4
8 Procedure . 4
8.1 Test to check the activity of reagents. 4
8.2 Determination. 5
9 Calculation and expression of results. 6
9.1 Calculation. 6
9.2 Expression of results . 7
10 Precision. 7
10.1 Interlaboratory test . 7
10.2 Repeatability. 7
10.3 Reproducibility. 8
11 Test report . 8
Annex A (normative) Good laboratory practice (GLP) rules for the performance of enzymatic
analyses. 9
Bibliography . 13

ISO 8069:2005(E)
IDF 69:2005(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.
International Standards 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
International 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 8069⎪IDF 69 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5,
Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO and
IDF.
This edition of ISO 8069⎪IDF 69 cancels and replaces ISO 8069:1986, which has been technically revised.

iv © ISO and IDF 2005 – All rights reserved

ISO 8069:2005(E)
IDF 69:2005(E)
Foreword
IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a National
Committee in every member country. Every National Committee has the right to be represented on the IDF
Standing Committees carrying out the technical work. IDF collaborates with ISO in the development of
standard methods of analysis and sampling for milk and milk products.
Draft International Standards adopted by the Action Teams and Standing Committees are circulated to the
National Committees for voting. Publication as an International Standard requires approval by at least 50 % of
the IDF National Committees casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. IDF shall not be held responsible for identifying any or all such patent rights.
ISO 8069⎪IDF 69 was prepared by the International Dairy Federation (IDF) and Technical Committee
ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It is being published jointly by IDF
and ISO.
All work was carried out by the Joint ISO-IDF Action Team on Lactose and lactate determination, of the
Standing Committee on Main components of milk, under the aegis of its project leader, Mr J Romero (US).
This edition of ISO 8069⎪IDF 69 cancels and replaces IDF 69:1987, which has been technically revised.
ISO 8069:2005(E)
INTERNATIONAL STANDARD
IDF 69:2005(E)
Dried milk — Determination of content of lactic acid and lactates
1 Scope
This International Standard specifies an enzymatic method for the determination of the lactic acid and lactates
content of all types of dried milk.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
lactic acid and lactates content
mass of substances determined by the procedure specified in this International Standard
NOTE It is expressed as milligrams of lactic acid per 100 g of non-fat solids.
3 Principle
A test portion of dried milk is dissolved in warm water. The fat and proteins are precipitated then filtered. The
filtrate is treated with the following enzymes and biochemical substances, added simultaneously, but acting in
sequence:
a) L-lactate dehydrogenase (L-LDH) and D-lactate dehydrogenase (D-LDH), in the presence of nicotinamide
adenine dinucleotide (NAD), to oxidize lactate to pyruvate and to convert NAD to its reduced form NADH;
b) glutamate pyruvate transaminase (GPT), in the presence of L-glutamate, to transform pyruvate into
L-alanine and to convert L-glutamate to α-ketoglutarate.
The amount of NADH produced is determined by spectrophotometric measurement at a wavelength of
340 nm, and is proportional to the lactic acid and lactates content.
4 Reagents
Use only reagents recognized analytical grade. The water used in the preparation of the enzyme solutions
shall be of at least doubly glass-distilled purity and the water used for other purposes shall be glass-distilled or
of at least equivalent purity.
4.1 Potassium hexacy
...