SIST EN ISO 1736:2009

Dried milk and dried milk products - Determination of fat content - Gravimetric method (Reference method) (ISO 1736:2008)

This International Standard specifies the reference method for the determination of the fat content of dried milk and dried milk products. The method is also applicable to dried milk wit h a fat content of 40 % mass fraction or more, dried whole, dr ied partially skimmed, and dried skimmed milk, dried whey, dri ed buttermilk and dried butter serum. The method is not applic able when the powder contains hard lumps which do not dissolve in ammonia solution or free fatty acids in significant quantities.

Milchpulver und Trockenmilcherzeugnisse - Bestimmung des Fettgehaltes - Gravimetrisches Verfahren (Referenzverfahren) (ISO 1736:2008)

Diese Internationale Norm legt das Referenzverfahren für die Bestimmung des Fettgehaltes von Milchpulver und Trockenmilcherzeugnissen fest. Das Verfahren gilt für Milchpulver mit einem Fettgehalt von mindestens 40 % (Massenanteil), Vollmilchpulver, teilentrahmtes Milchpulver und Magermilchpulver, Molkenpulver, Buttermilchpulver und Butterserumpulver.
Dieses Verfahren ist nicht auf Pulver anwendbar, die sich nicht vollständig in Ammoniak lösen oder die freie Fettsäuren in signifikanten Mengen enthalten.
ANMERKUNG   Falls das Pulver feste Klumpen enthält, die sich nicht in Ammoniaklösung auflösen, oder in signifikanter Menge freie Fettsäuren enthält, die an einem ausgeprägten Geruch zu erkennen sind, fällt das Bestimmungsergebnis zu niedrig aus. Bei derartigen Produkten ist ein Verfahren geeignet, das nach dem Weibull-Berntrop-Prinzip arbeitet (siehe ISO 8262-3|IDF 124-3 [3]).

Lait sec et produits à base de lait sec - Détermination de la teneur en matière grasse - Méthode gravimétrique (Méthode de référence) (ISO 1736:2008)

L'ISO 1736|FIL 9:2008 spécifie la méthode de référence pour la détermination de la teneur en matière grasse du lait sec et des produits à base de lait sec. La méthode est applicable au lait sec d'une teneur en matière grasse de 40 % (fraction massique) ou plus, au lait entier sec, au lait partiellement écrémé sec, au lait écrémé sec, au lactosérum sec, au babeurre sec et au sérum de beurre sec.
La méthode n'est pas applicable aux poudres contenant des grumeaux compacts qui ne se dissolvent pas dans une solution d'hydroxyde d'ammonium ou qui contiennent des acides gras libres en quantité significative.

Mleko v prahu in suhi mlečni proizvodi - Določevanje maščob - Gravimetrijska metoda (Referenčna metoda) (ISO 1736:2008)

General Information

• Status: Published
• Publication Date: 24-Mar-2009
• ICS: 67.100.10 - Milk and processed milk products
• Technical Committee: KŽP - Agricultural food products
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 23-Mar-2009
• Due Date: 28-May-2009
• Completion Date: 25-Mar-2009
• Ref Project: EN ISO 1736:2008 - Dried milk and dried milk products - Determination of fat content - Gravimetric method (Reference method)(ISO 1736:2008)

Relations

• Replaces: SIST EN ISO 1736:2001 - Dried milk and dried milk products - Determination of fat content - Gravimetric method (Reference method) (ISO 1736:2000)
• Effective Date: 01-May-2009

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 1736:2009
01-maj-2009
1DGRPHãþD
SIST EN ISO 1736:2001
0OHNRYSUDKXLQVXKLPOHþQLSURL]YRGL'RORþHYDQMHPDãþRE*UDYLPHWULMVND
PHWRGD5HIHUHQþQDPHWRGD,62
Dried milk and dried milk products - Determination of fat content - Gravimetric method
(Reference method) (ISO 1736:2008)
Milchpulver und Trockenmilcherzeugnisse - Bestimmung des Fettgehaltes -
Gravimetrisches Verfahren (Referenzverfahren) (ISO 1736:2008)
Lait sec et produits à base de lait sec - Détermination de la teneur en matière grasse -
Méthode gravimétrique (Méthode de référence) (ISO 1736:2008)
Ta slovenski standard je istoveten z: EN ISO 1736:2008
ICS:
67.100.10 0OHNRLQSUHGHODQLPOHþQL Milk and processed milk
SURL]YRGL products
SIST EN ISO 1736:2009 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN ISO 1736:2009

---------------------- Page: 2 ----------------------

SIST EN ISO 1736:2009
EUROPEAN STANDARD
EN ISO 1736
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2008
ICS 67.100.10 Supersedes EN ISO 1736:2000
English Version
Dried milk and dried milk products - Determination of fat content
- Gravimetric method (Reference method) (ISO 1736:2008)
Lait sec et produits à base de lait sec - Détermination de la Milchpulver und Trockenmilcherzeugnisse - Bestimmung
teneur en matière grasse - Méthode gravimétrique des Fettgehaltes - Gravimetrisches Verfahren
(Méthode de référence) (ISO 1736:2008) (Referenzverfahren) (ISO 1736:2008)
This European Standard was approved by CEN on 14 October 2008.
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
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 1736:2008: E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------

SIST EN ISO 1736:2009
EN ISO 1736:2008 (E)
Contents Page
Foreword.3

2

---------------------- Page: 4 ----------------------

SIST EN ISO 1736:2009
EN ISO 1736:2008 (E)
Foreword
This document (EN ISO 1736:2008) 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 April 2009, and conflicting national standards shall be withdrawn at the
latest by April 2009.
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 1736:2000.
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 the United Kingdom.
Endorsement notice
The text of ISO 1736:2008 has been approved by CEN as a EN ISO 1736:2008 without any modification.

3

---------------------- Page: 5 ----------------------

SIST EN ISO 1736:2009

---------------------- Page: 6 ----------------------

SIST EN ISO 1736:2009


INTERNATIONAL ISO
STANDARD 1736
IDF
9
Fourth edition
2008-10-15


Dried milk and dried milk products —
Determination of fat content —
Gravimetric method (Reference method)
Lait sec et produits à base de lait sec — Détermination de la teneur en
matière grasse — Méthode gravimétrique (Méthode de référence)




Reference numbers
ISO 1736:2008(E)
IDF 9:2008(E)
©
ISO and IDF 2008

---------------------- Page: 7 ----------------------

SIST EN ISO 1736:2009
ISO 1736:2008(E)
IDF 9:2008(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. Neither the ISO Central
Secretariat nor the IDF accepts any liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies
and IDF national committees. In the unlikely event that a problem relating to it is found, please inform the ISO Central Secretariat at the
address given below.


COPYRIGHT PROTECTED DOCUMENT


©  ISO and IDF 2008
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
Case postale 56 • CH-1211 Geneva 20 Diamant Building • Boulevard Auguste Reyers 80 • 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 [e-mail] E-mail [e-mail]
Web www.iso.org Web www.fil-idf.org
Published in Switzerland

ii © ISO and IDF 2008 – All rights reserved

---------------------- Page: 8 ----------------------

SIST EN ISO 1736:2009
ISO 1736:2008(E)
IDF 9:2008(E)
Contents Page
Foreword. iv
Foreword. v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Principle.2
5 Reagents.2
6 Apparatus .2
7 Sampling.3
8 Preparation of test sample.4
9 Procedure .4
9.1 Test portion .4
9.2 Blank tests.4
9.3 Preparation of fat-collecting vessel.5
9.4 Determination.5
10 Calculation and expression of results.7
10.1 Calculation.7
10.2 Expression of results .8
11 Precision.8
11.1 Interlaboratory test .8
11.2 Repeatability.8
11.3 Reproducibility.8
12 Test report .8
Annex A (informative) Notes on procedures .9
Annex B (informative) Alternative procedure using fat-extraction tubes with siphon or wash-bottle
fittings .11
Bibliography .14
© ISO and IDF 2008 – All rights reserved iii

---------------------- Page: 9 ----------------------

SIST EN ISO 1736:2009
ISO 1736:2008(E)
IDF 9:2008(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 1736⎪IDF 9 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 fourth edition of ISO 1736⎪IDF 9 cancels and replaces the third edition (ISO 1736:2000), of which it
constitutes a minor revision.
iv © ISO and IDF 2008 – All rights reserved

---------------------- Page: 10 ----------------------

SIST EN ISO 1736:2009
ISO 1736:2008(E)
IDF 9:2008(E)
Foreword
IDF (the International Dairy Federation) is a non-profit organization representing the dairy sector worldwide.
IDF membership comprises National Committees in every member country as well as regional dairy
associations having signed a formal agreement on cooperation with IDF. All members of IDF have the right to
be represented at 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 1736⎪IDF 9 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 Fat of the Standing Committee on Main
components in milk under the aegis of its project leader, Mr G.J. Beutick (NL).
This edition of ISO 1736⎪IDF 9 cancels and replaces IDF 9:1987, of which it constitutes a minor revision.
© ISO and IDF 2008 – All rights reserved v

---------------------- Page: 11 ----------------------

SIST EN ISO 1736:2009

---------------------- Page: 12 ----------------------

SIST EN ISO 1736:2009
ISO 1736:2008(E)
INTERNATIONAL STANDARD
IDF 9:2008(E)

Dried milk and dried milk products — Determination of fat
content — Gravimetric method (Reference method)
WARNING — The use of this International Standard may involve hazardous materials, operations and
equipment. This International Standard does not purport to address all the safety problems associated
with its use. It is the responsibility of the user of this International Standard to establish safety and
health practices and determine the applicability of regulatory limitations prior to use.
1 Scope
This International Standard specifies the reference method for the determination of the fat content of dried
milk and dried milk products. The method is also applicable to dried milk with a fat content of 40 % mass
fraction or more, dried whole, dried partially skimmed, and dried skimmed milk, dried whey, dried buttermilk
and dried butter serum.
The method is not applicable when the powder contains hard lumps which do not dissolve in ammonia
solution or free fatty acids in significant quantities.
NOTE When the powder contains hard lumps which do not dissolve in ammonia solution or contains free fatty acids
in significant quantities, noticeable by a distinct smell, the result of the determination will be too low. With such products, a
[3]
method using the Weibull-Berntrop principle is suitable (see ISO 8262-3⎪IDF 124-3 ).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 835, Laboratory glassware — Graduated pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3889⎪IDF 219, Milk and milk products — Specification of Mojonnier-type fat extraction flasks
ISO 4788, Laboratory glassware — Graduated measuring cylinders
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
fat content of dried milk and dried milk products
mass fraction of substances determined by the procedure specified in this International Standard
NOTE The fat content is expressed as a percentage mass fraction.
© ISO and IDF 2008 – All rights reserved 1

---------------------- Page: 13 ----------------------

SIST EN ISO 1736:2009
ISO 1736:2008(E)
IDF 9:2008(E)
4 Principle
An ammoniacal ethanolic solution of a test portion is extracted with diethyl ether and light petroleum. The
solvents are removed by distillation or evaporation. The mass of the substances extracted is determined.
NOTE This is usually known as the Röse-Gottlieb principle.
5 Reagents
Use only reagents of recognized analytical grade, unless otherwise specified, and only distilled or
demineralized water or water of equivalent purity.
The reagents shall leave no appreciable residue when the determination is carried out by the method
specified (see 9.2.2).
5.1 Ammonia solution, containing a mass fraction of NH of approximately 25 % (ρ = 910 g/l).
3 20
NOTE If ammonia solution of this concentration is not available, a more concentrated solution of known concentration
may be used (see 9.4.2).
5.2 Ethanol (C H OH), or ethanol denatured by methanol, containing a volume fraction of ethanol of at
2 5
least 94 %. (See Clause A.5.)
5.3 Congo red solution.
Dissolve 1 g of Congo red (C H N Na O S ) in water in a 100 ml one-mark volumetric flask (6.14). Make
32 22 6 2 6 2
up to the mark with water.
NOTE The use of this solution, which allows the interface between the solvent and aqueous layers to be seen more
clearly, is optional (see 9.4.4). Other aqueous indicator solutions can be used provided that they do not affect the result of
the determination.
5.4 Diethyl ether (C H OC H ), free from peroxides (see Clause A.3), containing no more than 2 mg/kg of
2 5 2 5
antioxidants, and complying with the requirements for the blank test (see 9.2.2, Clauses A.1 and A.4).
WARNING — The use of diethyl ether can lead to hazardous situations. Observe current safety
precautions for handling, use, and disposal.
5.5 Light petroleum, with any boiling range between 30 °C and 60 °C or, as equivalent, pentane
(CH [CH ] CH ) with a boiling point of 36 °C and complying with the requirements for the blank test (see
3 2 3 3
9.2.2, Clauses A.1 and A.4).
The use of pentane is recommended because of its higher purity and consistent quality.
5.6 Mixed solvent.
Shortly before use, mix equal volumes of diethyl ether (5.4) and light petroleum (5.5).
6 Apparatus
WARNING — Since the determination involves the use of volatile flammable solvents, all electrical
apparatus employed shall comply with legislation relating to the hazards in using such solvents.
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.
2 © ISO and IDF 2008 – All rights reserved

---------------------- Page: 14 ----------------------

SIST EN ISO 1736:2009
ISO 1736:2008(E)
IDF 9:2008(E)
6.2 Centrifuge, capable of holding the fat-extraction flasks or tubes (6.6) and capable of spinning at a
−1 −1
rotational frequency of 500 min to 600 min to produce a radial acceleration of 80g to 90g at the outer end
of the flasks or tubes.
The use of the centrifuge is optional but recommended (see 9.4.7).
6.3 Distillation or evaporation apparatus, for distilling the solvents and ethanol from the boiling or conical
flasks, or evaporating from beakers and dishes (see 9.4.14) at a temperature not exceeding 100 °C.
6.4 Drying oven, electrically heated, with ventilation port(s) fully open, capable of being maintained at a
temperature of 102 °C ± 2 °C throughout its working space.
The oven shall be fitted with a suitable thermometer.
6.5 Water bath, capable of being maintained at a temperature of 65 °C ± 5 °C.
6.6 Mojonnier-type fat-extraction flasks, as specified in ISO 3889⎪IDF 219.
NOTE It is also possible to use fat-extraction tubes with siphon or wash-bottle fittings, but then the procedure is
different. The alternative procedure is given in Annex B.
The fat-extraction flasks shall be provided with good quality cork bungs or stoppers of another material (e.g.
silicone rubber or polytetrafluoroethylene) unaffected by the reagents used. Cork bungs shall be extracted
with the diethyl ether (5.4), kept in water at a temperature of 60 °C or more for at least 15 min, and shall then
be allowed to cool in the water so that they are saturated when used.
6.7 Rack, for holding the fat-extraction flasks (or tubes) (6.6).
6.8 Wash bottle, suitable for use with the mixed solvent (5.6).
A plastics wash bottle shall not be used.
6.9 Fat-collecting vessels, such as boiling flasks (flat-bottomed), of capacities 125 ml to 250 ml, conical
flasks, of capacity 250 ml, or metal dishes.
If metal dishes are used, they shall be of stainless steel, flat-bottomed with a diameter of 80 mm to 100 mm
and a height of approximately 50 mm.
6.10 Boiling aids, fat-free, of non-porous porcelain or silicon carbide (optional when metal dishes are used).
6.11 Measuring cylinders, of capacities 5 ml and 25 ml, complying with the requirements of ISO 4788,
class A, or any other apparatus suitable for the product concerned.
6.12 Pipettes, graduated, of capacity 10 ml, complying with the requirements of ISO 835, class A.
6.13 Tongs, made of metal, for holding flasks, beakers or dishes.
6.14 Volumetric flask, one-mark, of capacity 100 ml, complying with the requirements of ISO 1042, class A.
7 Sampling
A representative sample should have been sent to the laboratory. It should not have been damaged or
changed during transport or storage.
Sampling is not part of the method specified in this International Standard. A recommended sampling method
[1]
is given in ISO 707⎪IDF 50 .
Store laboratory samples at a temperature between 2 °C and 6 °C from the time of sampling to the time of
commencing the procedure.
© ISO and IDF 2008 – All rights reserved 3

---------------------- Page: 15 ----------------------

SIST EN ISO 1736:2009
ISO 1736:2008(E)
IDF 9:2008(E)
8 Preparation of test sample
Thoroughly mix the test sample by repeatedly rotating and inverting the sample container. If necessary,
transfer all of the test sample to an airtight container of approximately twice the volume of the test sample to
allow this operation to be carried out.
9 Procedure
NOTE 1 If it is required to check whether the repeatability limit (11.2) is met, carry out two single determinations in
accordance with 9.1 to 9.4.
NOTE 2 An alternative procedure using fat-extraction tubes with siphon or wash-bottle fittings (see Note to 6.6) is given
in Annex B.
9.1 Test portion
Mix the test sample (Clause 8) by gently stirring or rotating and inverting the container several times.
Immediately weigh, to the nearest 1 mg, directly or by difference, in a fat-extraction flask (6.6), one of the
following test portions:
a) about 1,000 g of dried high-fat milk, of dried whole milk or of dried butter serum;
b) about 1,500 g of dried partially skimmed milk;
c) about 1,500 g of dried skimmed milk;
d) about 1,500 g of dried whey;
e) about 1,500 g of dried buttermilk.
Transfer the test portion as completely as possible into the lower (small) bulb of the fat-extraction flask.
9.2 Blank tests
9.2.1 Blank test for method
Carry out a blank test simultaneously with the determination using the same procedure and the same
reagents, but replacing the dispersed test portion in 9.4.1 by 10 ml of water (see Clause A.2).
When one blank sample is used for a batch of test samples of which the individual samples may not have
exactly the same conditions, ensure that the procedure for obtaining the value of the blank used in the
calculation of the result corresponds exactly to that of the individual test sample.
If the value obtained in the blank test regularly exceeds 1,0 mg, check the reagents if this has not been
recently done (9.2.2). Corrections of more than 2,5 mg should be mentioned in the test report.
9.2.2 Blank test for reagents
To test the quality of the reagents, carry out a blank test as specified in 9.2.1. Additionally, use an empty fat-
collecting vessel, prepared as specified in 9.3, for mass control purposes. The reagents shall leave no residue
greater than 1,0 mg (see Clause A.1).
If the residue of the complete reagent blank test is greater than 1,0 mg, determine the residue of the solvents
separately by distilling 100 ml of the diethyl ether (5.4) and light petroleum (5.5), respectively. Use an empty
fat-collecting vessel, prepared for control purposes as in the preceding paragraph, to obtain the real mass of
residue which shall not exceed 1,0 mg.
4 © ISO and IDF 2008 – All rights reserved

---------------------- Page: 16 ----------------------

SIST EN ISO 1736:2009
ISO 1736:2008(E)
IDF 9:2008(E)
Very occasionally, the solvents may contain volatile matter which is strongly retained in fat. If there are
indications of the presence of such substances, carry out blank tests on all the reagents and for each solvent
using a fat-collecting vessel with about 1 g of anhydrous butterfat. If necessary, redistil solvents in the
presence of 1 g of anhydrous butterfat per 100 ml of solvent. Use the solvents only shortly after the
redistillation.
Replace unsatisfactory reagents and solvents, or redistil solvents.
9.3 Preparation of fat-collecting vessel
Dry a fat-collecting vessel (6.9) with a few boiling aids (6.10) in the oven (6.4) maintained at 102 °C for 1 h.
NOTE 1 Boiling aids are desirable to promote gentle boiling during the subsequent removal of solvents, especially
when using glass fat-collecting vessels; their use is optional with metal dishes.
Protect the fat-collecting vessel from dust and allow it to cool to the temperature of the weighing room (glass
fat-collecting vessel for at least 1 h; metal dish for at least 30 min).
To avoid insufficient cooling or unduly long cooling times, the fat-collecting vessel should not be placed in a
desiccator.
Use tongs (6.13) to place the fat-collecting vessel on the balance. Weigh the fat-collecting vessel to the
nearest 1,0 mg.
NOTE 2 The use of tongs effectively avoids, in particular, inducing temperature variations.
9.4 Determination
9.4.1 Carry out the determination without delay.
Add about 10 ml of preheated water at a temperature of 65 °C ± 5 °C to the test portion in the fat-extraction
flask (9.1) to obtain a total volume of 10 ml to 11 ml. Use the water to wash the test portion into the small bulb
of the fat-extraction flask. Mix thoroughly with the test portion in the small bulb until the test portion is
completely dispersed.
9.4.2 Add 2 ml of ammonia solution (5.1) to the test portion (9.4.1), or an equivalent volume of a more
concentrated ammonia solution (see Note to 5.1). Mix thoroughly with the test portion in the small bulb of the
fat-extraction flask.
9.4.3 Heat the flask to 65 °C ± 5 °C in the water bath (6.5) for 15 min to 20 min with occasional shaking.
Cool in running water to room temperature.
9.4.4 Add 10 ml of ethanol (5.2). Mix gently but thoroughly by allowing the contents of the fat-extraction
flask to flow backwards and forwards between the small and large bulb. Avoid bringing the liquid too near to
the neck of the flask. If desired, add 2 drops of the Congo red solution (5.3).
9.4.5 Add 25 ml of diethyl ether (5.4). Close the fat-extraction flask with a cork bung saturated with water or
with a stopper of other material wetted with water (6.6). Shake the flask vigorously, but not excessively, for
1 min to avoid the formation of persistent emulsions.
While shaking, keep the fat-extraction flask in a horizontal position with the small bulb extending upwards,
periodically allowing the liquid to run from the large bulb into the small bulb. If necessary, cool the flask in
running water to about room temperature. Carefully remove the bung or stopper and rinse it and the neck of
the flask with a little mixed solvent (5.6). Use the wash bottle (6.8) so that the rinsings run into the flask.
9.4.6 Add 25 ml of the light petroleum (5.5). Close the fat-extraction flask with the rewetted (by dipping into
water) bung or stopper. Mix gently again for 30 s as specified in 9.4.4. Proceed with shaking as specified in
9.4.5.
© ISO and IDF 2008 – All rights reserved 5

---------------------- Page: 17 ----------------------

SIST EN ISO 1736:2009
ISO 1736:2008(E)
IDF 9:2008(E)
9.4.7 Centrifuge the closed fat-extraction flask for between 1 min and 5 min at a radial acceleration of 80g
to 90g. If a centrifuge (6.2) is not available, allow the closed flask to stand in the rack (6.7) for at least 30 min
...