SIST EN ISO 14673-1:2002

Milk and milk products - Determination of nitrate and nitrite contents - Part 1: Method using cadmium reduction and spectrometry (ISO 14673-1:2001)

TC forecasts updated : delay with the directives ( TC forecasts updating exercise.sj 00-11-09)++

Milch und Milchprodukte - Bestimmung des Nitrat- und Nitritgehaltes - Teil 1: Verfahren mit Cadmiumreduktion und Spektrometrie (ISO 14673-1:2001)

Dieser Teil von ISO 14673/IDF 189 legt ein Verfahren zur Bestimmung des Nitrat- und Nitritgehaltes von Milch und Milchprodukten durch Cadmiumreduktion und Spektrometrie fest.
Das Verfahren gilt für
3 vollständig und teilentrahmte Milch und Magermilchpulver,
3 Hart-, Schnitt- und Weichkäse,
3 Schmelzkäse,
3 Molkenkäse, Caseine und Caseinate sowie Molkenpulver.
Das Verfahren kann unter Anwendung automatischer Geräte durchgeführt werden, besonders mit der segmen-tierten Fließanalyse (SFA) oder der Fließinjektionsanalyse (FIA), wodurch die Verunreinigung des Laborarbeits-platzes und des Abwassers mit Cadmium verringert wird.
ANMERKUNG   Diese Verfahren sind in ISO 14673-2/IDF 189-2 bzw. in ISO 14673-3/IDF 189-3 beschrieben.

Lait et produits laitiers - Détermination des teneurs en nitrates et en nitrites - Partie 1: Méthode par réduction au cadmium et spectrométrie (ISO 14673-1:2001)

Mleko in mlečni proizvodi - Določevanje nitratov in nitritov - 1. del: Spektrometrijska metoda po redukciji s kadmijem (ISO 14673-1:2001)

General Information

• Status: Withdrawn
• Publication Date: 31-May-2002
• Withdrawal Date: 31-Aug-2005
• ICS: 67.100.01 - Milk and milk products in general
• Technical Committee: KŽP - Agricultural food products
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 01-Sep-2005
• Due Date: 01-Sep-2005
• Completion Date: 01-Sep-2005
• Ref Project: EN ISO 14673-1:2001 - Milk and milk products - Determination of nitrate and nitrite contents - Part 1: Method using cadmium reduction and spectrometry (ISO 14673-1:2001)

Relations

• Replaced By: SIST EN ISO 14673-1:2004 - Milk and milk products - Determination of nitrate and nitrite contents - Part 1: Method using cadmium reduction and spectrometry (ISO 14673-1:2004)
• Effective Date: 22-Dec-2008
• Corrected By: SIST EN ISO 14673-1:2002/AC:2002 - Milk and milk products - Determination of nitrate and nitrite contents - Part 1: Method using cadmium reduction and spectrometry (ISO 14673-1:2001)
• Effective Date: 22-Dec-2008

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 14673-1:2002
01-junij-2002
0OHNRLQPOHþQLSURL]YRGL'RORþHYDQMHQLWUDWRYLQQLWULWRYGHO
6SHNWURPHWULMVNDPHWRGDSRUHGXNFLMLVNDGPLMHP,62
Milk and milk products - Determination of nitrate and nitrite contents - Part 1: Method
using cadmium reduction and spectrometry (ISO 14673-1:2001)
Milch und Milchprodukte - Bestimmung des Nitrat- und Nitritgehaltes - Teil 1: Verfahren
mit Cadmiumreduktion und Spektrometrie (ISO 14673-1:2001)
Lait et produits laitiers - Détermination des teneurs en nitrates et en nitrites - Partie 1:
Méthode par réduction au cadmium et spectrométrie (ISO 14673-1:2001)
Ta slovenski standard je istoveten z: EN ISO 14673-1:2001
ICS:
67.100.01 0OHNRLQPOHþQLSURL]YRGLQD Milk and milk products in
VSORãQR general
SIST EN ISO 14673-1:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 14673-1:2002

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SIST EN ISO 14673-1:2002
EUROPEAN STANDARD
EN ISO 14673-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2001
ICS 67.100.01
English version
Milk and milk products - Determination of nitrate and nitrite
contents - Part 1: Method using cadmium reduction and
spectrometry (ISO 14673-1:2001)
Lait et produits laitiers - Détermination des teneurs en Milch und Milchprodukte - Bestimmung des Nitrat- und
nitrates et en nitrites - Partie 1: Méthode par réduction au Nitritgehaltes - Teil 1: Verfahren mit Cadmiumreduktion
cadmium et spectrométrie (ISO 14673-1:2001) und Spektrometrie (ISO 14673-1:2001)
This European Standard was approved by CEN on 1 November 2001.
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 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 Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, 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
© 2001 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14673-1:2001 E
worldwide for CEN national Members.

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SIST EN ISO 14673-1:2002
EN ISO 14673-1:2001 (E)
CORRECTED 2002-02-06
Foreword
This document (ISO 14673-1:2001) has been prepared by Technical Committee ISO/TC 34
"Agricultural 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 May 2002, and conflicting national
standards shall be withdrawn at the latest by May 2002.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,
Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United
Kingdom.
Endorsement notice
The text of the International Standard ISO 14673-1:2001 has been approved by CEN as a
European Standard without any modifications.
NOTE Normative references to International Standards are listed in annex ZA (normative).
2

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SIST EN ISO 14673-1:2002
EN ISO 14673-1:2001 (E)
Annex ZA
(normative)
Normative references to international publications
with their relevant European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions
of any of these publications apply to this European Standard only when incorporated in it by
amendment or revision. For undated references the latest edition of the publication referred to
applies (including amendments).
NOTE Where an International Publication has been modified by common modifications,
indicated by (mod.), the relevant EN/HD applies.
Publication Year Title EN Year
ISO 1042 1998 Laboratory glassware – One-mark EN ISO 1042 1999
volumetric flasks
3

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SIST EN ISO 14673-1:2002

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SIST EN ISO 14673-1:2002
INTERNATIONAL ISO
STANDARD 14673-1
IDF
189-1
First edition
2001-11-01
Milk and milk products — Determination
of nitrate and nitrite contents —
Part 1:
Method using cadmium reduction and
spectrometry
Lait et produits laitiers — Détermination des teneurs en nitrates et en
nitrites —
Partie 1: Méthode par réduction au cadmium et spectrométrie
Reference numbers
ISO 14673-1:2001(E)
IDF 189-1:2001(E)
©
ISO and IDF 2001

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SIST EN ISO 14673-1:2002
ISO 14673-1:2001(E)
IDF 189-1:2001(E)
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© ISO and IDF 2001
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO or IDF at the respective address below.
ISO copyright office International Dairy Federation
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Tel. + 41 22 749 01 11 Tel. + 32 2 733 98 88
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ii © ISO and IDF 2001 – All rights reserved

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SIST EN ISO 14673-1:2002
ISO 14673-1:2001(E)
IDF 189-1:2001(E)
Contents Page
Foreword.iv
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Principle.2
5 Reagents.2
6 Apparatus .4
7 Sampling.5
8 Preparation of test sample.5
8.1 Dried milk and dried whey .5
8.2 Caseins and caseinates .5
8.3 Cheese .5
8.4 Whey cheese .6
9 Procedure .6
9.1 Preparation of the copperized cadmium column .6
9.2 Checking the reducing capacity of the column.6
9.3 Regeneration of the column .7
9.4 Preparation of test portion.7
9.5 Extraction and deproteination.8
9.6 Reduction of nitrate to nitrite .8
9.7 Blank test.8
9.8 Determination.9
9.9 Preparation of calibration graph .9
10 Calculation and expression of results.9
10.1 Nitrite content.9
10.2 Nitrate content.10
11 Precision.10
11.1 General.10
11.2 Repeatability.10
12 Test report .11
Bibliography.13
© ISO and IDF 2001 – All rights reserved iii

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SIST EN ISO 14673-1:2002
ISO 14673-1:2001(E)
IDF 189-1:2001(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 3.
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 part of ISO 14673�IDF 189 may be the subject
of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 14673-1�IDF 189-1 was prepared by Technical Committee ISO/TC 34, Food products,
Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF), in collaboration with
AOAC International. It is being published jointly by ISO and IDF and separately by AOAC International.
This first edition of ISO 14673-1�IDF 189-1, together with ISO 14673-2�IDF 189-2 and ISO 14673-3�IDF 189-3,
cancels and replaces ISO 4099:1984, ISO 6736:1982, ISO 6739:1988, ISO 6740:1985 and ISO 8195:1987, which
have been technically revised.
ISO 14673�IDF 189 consists of the following parts, under the general title Milk and milk products — Determination
of nitrate and nitrite contents:
— Part 1: Method using cadmium reduction and spectrometry
— Part 2: Method using segmented flow analysis (Routine method)
— Part 3: Method using cadmium reduction and flow injection analysis with in-line dialysis (Routine method)
iv © ISO and IDF 2001 – All rights reserved

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SIST EN ISO 14673-1:2002
ISO 14673-1:2001(E)
IDF 189-1:2001(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 and AOAC International 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 National
Committees casting a vote.
International Standard ISO 14673-1�IDF 189-1 was prepared by Technical Committee ISO/TC 34, Food products,
Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF), in collaboration with
AOAC International. It is being published jointly by ISO and IDF and separately by AOAC International.
All work was carried out by the Joint ISO/IDF/AOAC Action Team, Minerals and minor compounds,of the
Standing Committee on Minor components characterization of physical properties, under the aegis of its project
leader Mr G. Bråthen (NO).
© ISO and IDF 2001 – All rights reserved v

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SIST EN ISO 14673-1:2002

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SIST EN ISO 14673-1:2002
ISO 14673-1:2001(E)
INTERNATIONAL STANDARD
IDF 189-1:2001(E)
Milk and milk products — Determination of nitrate and nitrite
contents —
Part 1:
Method using cadmium reduction and spectrometry
WARNING — The use of this International Standard may involve hazardous materials, operations and
equipment. This standard does not purport to address all the safety problems associated with its use. It is
the responsibility of the user of this standard to establish safety and health practices and determine the
applicability of regulatory limitations prior to use.
1 Scope
This part of ISO 14673�IDF 189 specifies a method for the determination of the nitrate and nitrite contents of milk
and milk products by cadmium reduction and spectrometry. The method is applicable to
� whole and partly skimmed and skimmed dried milk;
� hard, semi-hard and soft cheeses;
� processed cheese;
� whey cheese, caseins and caseinates and dried whey.
The method may be performed using automatic equipment, in particular by segmented flow analysis (SFA) or flow
injection analysis (FIA), thus reducing cadmium contamination in laboratory work places and waste water.
NOTE These methods are described in ISO 14673-2�IDF 189-2 and ISO 14673-3�IDF 189-3, respectively.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 14673�IDF 189. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this part of ISO 14673�IDF 189 are
encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated
below. For undated references, the latest edition of the normative document referred to applies. Members of ISO
and IEC maintain registers of currently valid International Standards.
ISO 565, Test sieves — Metal wire cloth, perforated metal plate and electroformed sheet — Nominal sizes of
openings
ISO 648, Laboratory glassware — One-mark pipettes
ISO 835-1, Laboratory glassware — Graduated pipettes — Part 1: General requirements
ISO 1042, Laboratory glassware — One-mark volumetric flasks
© ISO and IDF 2001 – All rights reserved 1

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SIST EN ISO 14673-1:2002
ISO 14673-1:2001(E)
IDF 189-1:2001(E)
3 Terms and definitions
For the purposes of this part of ISO 14673�IDF 189, the following terms and definitions apply.
3.1
nitrate content
mass fraction of nitrate determined by the procedure specified in this part of ISO 14673�IDF 189
–
NOTE The nitrate content is expressed as the mass in milligrams of nitrate ions (NO ) per kilogram of product.
3
3.2
nitrite content
mass fraction of nitrite determined by the procedure specified in this part of ISO 14673�IDF 189
–
NOTE The nitrite content is expressed as the mass in milligrams of nitrite ions (NO ) per kilogram of product.
2
4Principle
A test portion is dispersed in warm water, with precipitation of the fat and proteins, then filtration. The nitrate ions
are reduced to nitrite ions in a portion of the filtrate by means of copperized cadmium.
A red colour is developed in portions of both unreduced filtrate and the reduced solution, by addition of
sulfanilamide and N-1-naphthyl ethylenediamine dihydrochloride. Spectrometric measurements are carried out at a
wavelength of 538 nm.
The nitrite content of the sample and the total nitrite content after reduction of nitrate ions are calculated by
comparing the measured absorbances with those of a set of sodium nitrite calibration solutions. The nitrate content
is calculated from the difference between these two contents.
5 Reagents
Use only reagents of recognized analytical grade unless otherwise specified.
5.1 Water, distilled or deionized, or water of equivalent purity, free from nitrate and nitrite ions.
To avoid the possible inclusion of small gas bubbles in the copperized cadmium column (9.1.6), freshly boil the
distilled or deionized water and cool to room temperature. Use the thus-prepared water for the preparation of the
column (9.1), to check the reducing capacity of the column (9.2), and to regenerate the column (9.3).
5.2 Cadmium granules, of diameter 0,3 mm to 0,8 mm.
Prepare cadmium granules, if not available commercially, as follows.
Place a suitable number of zinc rods in a beaker. Cover the rods with cadmium sulfate solution (5.3). Scrape the
cadmium sponge from the rods from time to time over a period of 24 h. Remove the zinc rods and decant the liquid
until only sufficient remains to cover the cadmium sponge. Wash the sponge two or three times with water. Transfer
the cadmium sponge to a laboratory blender together with 400 mm of the hydrochloric acid working solution (5.7)
and blend for a few seconds to obtain granules of the required size. Return the contents of the blender to the
beaker and leave to stand for several hours, while stirring occasionally to remove bubbles. Decant most of the
liquid and immediately copperize the granules as described in 9.1.
WARNING — Because of its toxicity, the used cadmium should be delivered as chemical waste to the
relevant authorities.
2 © ISO and IDF 2001 – All rights reserved

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SIST EN ISO 14673-1:2002
ISO 14673-1:2001(E)
IDF 189-1:2001(E)
5.3 Cadmium sulfate solution, c(CdSO ·8H O) = 40 g/l.
4 2
Dissolve 40 g of cadmium sulfate solution in water in a 1 000 ml volumetric flask (6.4). Dilute to the mark with water
and mix.
5.4 Copper(II) sulfate solution, c(CuSO ·5H O) = 20 g/l.
4 2
Dissolve 20 g of copper(II) sulfate in water in a 1 000 ml volumetric flask (6.4). Dilute to the mark with water and
mix.
5.5 Hydrochloric acid (HCl), (� = 1,19 g/ml).
20
5.6 Dilute hydrochloric acid, c(HCl)�2mol/l.
Carefully add 160 ml of hydrochloric acid (5.5) to about 700 ml of water in a 1 000 ml volumetric flask (6.4) while
regularly swirling the contents. Cool the contents to room temperature. Dilute to the mark with water and mix
carefully.
5.7 Hydrochloric acid working solution, c(HCl)� 0,1 mol/l.
Add 50 ml of dilute hydrochloric acid (5.6) to a 1 000 ml volumetric flask (6.4). Dilute to the mark with water and
mix.
5.8 Zinc sulfate solution, c(ZnSO ·7H O) = 535 g/l.
4 2
Dissolve 53,5 g of zinc sulfate in water in a 100 ml volumetric flask (6.4). Dilute to the mark with water and mix.
5.9 Potassium hexacyanoferrate(II) solution, c(K [Fe(CN) ]·3H O) = 172 g/l.
4 6 2
Dissolve 17,2 g of potassium hexacyanoferrate(II) trihydrate in water in a 100 ml volumetric flask (6.4). Dilute to the
mark with water and mix.
5.10 Disodium ethylenediaminetetraacetate dihydrate (EDTA) solution (Na C H N O ·2H O).
2 10 14 2 8 2
Dissolve 33,5 g of EDTA in about 900 ml water in a 1 000 ml volumetric flask (6.4). Dilute to the mark with water
and mix.
5.11 Solution I.
Carefully add 450 ml of hydrochloric acid (5.5) to a 1 000 ml volumetric flask (6.4). Dilute to the mark with water
and mix.
5.12 Solution II.
Dissolve by heating on a water bath (6.15) 0,5 g of sulfanilamide (NH C H SO NH ) in a mixture of 75 ml of water
2 6 4 2 2
and 5 ml of hydrochloric acid (5.5) in a 100 ml volumetric flask (6.4). Cool to room temperature. Dilute to the mark
with water and mix. Filter the obtained solution, if necessary.
5.13 Solution III.
Dissolve 0,1 g of N-1-naphthyl ethylenediamine dihydrochloride (C H NHCH CH NH ·2HCl) in water in a 100 ml
10 7 2 2 2
volumetric flask (6.4). Dilute to the mark with water and mix. Filter the obtained solution, if necessary.
The solution may be stored for up to 1 week in a well-stoppered brown bottle in a refrigerator.
5.14 Sodium nitrite stock solution (NaNO ).
2
Dry a few grams of sodium nitrite in an oven (6.16) at 110 °Cto 120 °C to constant mass (i.e. until the difference
between two successive weighings does not exceed 1 mg). Dissolve 0,150 g of the sodium nitrite in water in a
1 000 ml volumetric flask (6.4). Dilute to the mark with water and mix.
© ISO and IDF 2001 – All rights reserved 3

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SIST EN ISO 14673-1:2002
ISO 14673-1:2001(E)
IDF 189-1:2001(E)
5.15 Sodium nitrite standard working solution.
Prepare the sodium nitrite standard working solution on the day of use. Transfer with a pipette (6.5), 10 ml of the
stock solution (5.14) and 20 ml of the buffer solution (5.19) to a 1 000 ml volumetric flask (6.4). Dilute to the mark
with water and mix. The nitrite content of the sodium nitrite standard working solution is 1�g/ml.
5.16 Potassium nitrate stock solution (KNO ).
3
Dry a few grams of potassium nitrate in an oven (6.16) at 110 °Cto 120 °C to constant mass (i.e. until the
difference between two successive weighings does not exceed 1 mg). Dissolve 1,468 g of the potassium nitrate in
water in a 1 000 ml volumetric flask (6.4). Dilute to the mark with water and mix.
5.17 Potassium nitrate working standard solution.
Prepare the potassium nitrate working standard solution on the day of use. Transfer with a pipette (6.5), 5 ml of the
potassium nitrate stock solution (5.16) and 20 ml of the buffer solution (5.19) to a 1 000 ml volumetric flask (6.4).
Dilute to the mark with water and mix. The nitrate content of the potassium nitrate working standard solution is
4,50�g/l.
5.18 Ammonia solution (NH ), (� =0,91g/ml).
3 20
If an ammonia solution of above-mentioned concentration is not available, an equivalent amount of a more
concentrated ammonia solution may be used in 5.19 [e.g. 103 ml of a 35 % (mass fraction) ammonia solution
(� = 1,19 g/ml)].
20
5.19 Buffer solution, pH 9,6 to 9,7.
Dilute 50 ml of hydrochloric acid (5.5) with 600 ml of water in a conical flask (6.3) and mix. Add 135 ml of the
ammonia solution (5.18) and dilute to 1 000 ml with 215 ml of water and mix. Adjust the pH, if necessary, to
between 9,6 to 9,7.
6 Apparatus
Clean all glassware thoroughly and rinse with distilled water to ensure that it is free from nitrate and nitrite ions.
Usual laboratory equipment and, in particular, the following.
6.1 Analytical balance, capable of weighing to the nearest 1 mg, with a readability of 0,1 mg.
6.2 Sample container, provided with an airtight lid.
6.3 Conical flasks, of capacity 250 ml, 500 ml and 1 000 ml.
6.4 Volumetric flasks, of nominal capacity 100 ml, 500 ml and 1 000 ml respectively, complying with the
requirements of ISO 1042, class B.
6.5 Pipettes, capable of delivering 2 ml, 4 ml, 5 ml, 6 ml, 8 ml, 10 ml, 12 ml, 20 ml and 25 ml respectively,
complying with the requirements of ISO 648, class A, or ISO 835-1. Where appropriate, burettes may be used
instead of pipettes.
6.6 Measuring cylinders, of capacities 5 ml, 10 ml, 25 ml, 100 ml, 250 ml, 500 ml and 1 000 ml respectively.
6.7 Glass funnels,of diameter 7cm,withshortstem.
6.8 Filter paper, medium grade, of diameter about 15 cm, free from nitrate and nitrite ions.
6.9 Reduction column, made of glass, an example of which is given in Figure 1.
4 © ISO and IDF 2001 – All rights reserved

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SIST EN ISO 14673-1:2002
ISO 14673-1:2001(E)
IDF 189-1:2001(E)
6.10 Spectrometer, suitable for measuring absorbance at a wavelength of 538 nm, with cells of optical path
length 1 cm to 2 cm.
6.11 Grinding device, appropriate for grinding the test sample, if necessary. To avoid loss of moisture, the device
should not produce undue heat. A hammer shall not be used.
6.12 Laboratory mixer or homogenizer, with glass containers of capacity 250 ml or 400 ml, suitable for
suspending test portions of cheese and whey cheese.
6.13 Test sieve, of woven wire cloth, of diameter 200 mm, nominal size of openings 500�m, and a receiver
complying with the requirements of ISO 565.
6.14 Magnetic stirrer.
6.15 Water bath, capable of boiling water.
6.16 Oven, capable of maintaining a temperature of between 110 °Cand120 °C.
7 Sampling
Sampling is not part of the method specified in this part of ISO 14673�IDF 189. A recommended sampling method
is giveninISO 707.
It is important that the laboratory receive a sample which is truly representative and has not been damaged or
changed during transport or storage.
Store the test sample in such a way that deterioration and change in composition are prevented.
8 Preparation of test sample
8.1 Dried milk and dried whey
Transfer the test sample to a sample container (6.2) of capacity about twice the volume of the test sample. Close
the container immediately. Mix the test sample thoroughly by repeatedly shaking and inverting the container until a
homogeneous sample is obtained.
8.2 Caseins and caseinates
8.2.1 Thoroughly mix the test sample, if necessary after transferring all of it to a sample container (6.2) of
suitable capacity, by repeatedly shaking and inverting the container.
8.2.2 Transfer 50 g of the test sample to the test sieve (6.13). If the 50 g portion directly passes, or nearly
completely passes the sieve, pass the whole mixed test sample (8.2.1) through the sieve.
8.2.3 If the test sample does not pass completely through the sieve, use the grinding device (6.11) to achieve
that condition. Immediately transfer all the sieved test sample to the sample container (6.2) and mix thoroughly in
the closed container. During these operations, take precautions to avoid any change in the water content of the
product.
8.2.4 After the test sample has been prepared, proceed with the preparation of the test portion (9.4) as soon as
possible.
8.3 Cheese
8.3.1 Prior
...