Cheese and processed cheese products, caseins and caseinates - Determination of fat content - Gravimetric method (ISO/DIS 23319:2020)

Käse und Schmelzkäseprodukte, Kaseine und Kaseinate - Bestimmung des Fettgehaltes - Gravimetrisches Verfahren (ISO/DIS 23319:2020)

Dieses Dokument legt ein Verfahren für die Bestimmung des Fettgehaltes aller Arten von Käse und Schmelzkäse fest, die weniger als 5 % (Massenanteil) der fettfreien Feststoffe Lactose enthalten, und für alle Arten von Caseinen und Caseinaten.
Das Verfahren ist nicht auf Frischkäsearten anwendbar, die zum Beispiel Früchte, Sirup oder Müsli enthalten. Für derartige Produkte ist das Schmid-Bondzynski-Ratzlaff-(SBR-)Prinzip aufgrund hoher Konzentrationen von Zuckern nicht anwendbar. Für diese Produkte ist das Verfahren nach dem Weibull-Berntrop-Prinzip (ISO 8262 3) geeignet.

Fromages et fromages fondus, caséines et caséinates - Détermination de la teneur en matière grasse - Méthode gravimétrique (ISO/DIS 23319:2020)

Sir in topljeni sir, kazeini in kazeinati - Določevanje maščob - Gravimetrijska metoda (ISO/DIS 23319:2020) TC: Sir in topljeni sir, kazeini in kazeinati - Določevanje vsebnosti maščob - Gravimetrijska metoda (ISO/DIS 23319:2020)

General Information

Status
Not Published
Public Enquiry End Date
19-Sep-2020
Current Stage
4020 - Public enquire (PE) (Adopted Project)
Start Date
05-Aug-2020
Due Date
23-Dec-2020
Completion Date
13-Oct-2020

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SLOVENSKI STANDARD
oSIST prEN ISO 23319:2020
01-september-2020
Sir in topljeni sir, kazeini in kazeinati - Določevanje maščob - Gravimetrijska
metoda (ISO/DIS 23319:2020)

Cheese and processed cheese products, caseins and caseinates - Determination of fat

content - Gravimetric method (ISO/DIS 23319:2020)

Fromages et fromages fondus, caséines et caséinates - Détermination de la teneur en

matière grasse - Méthode gravimétrique (ISO/DIS 23319:2020)
Ta slovenski standard je istoveten z: prEN ISO 23319
ICS:
67.100.30 Sir Cheese
oSIST prEN ISO 23319:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 23319:2020
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oSIST prEN ISO 23319:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 23319
IDF 250
ISO/TC 34/SC 5 Secretariat: NEN
Voting begins on: Voting terminates on:
2020-03-26 2020-06-18
Cheese and processed cheese products, caseins
and caseinates — Determination of fat content —
Gravimetric method
ICS: 67.100.30
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
This document is circulated as received from the committee secretariat.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference numbers
NATIONAL REGULATIONS.
ISO/DIS 23319:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
IDF 250:2020(E)
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO and IDF 2020
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oSIST prEN ISO 23319:2020
ISO/DIS 23319:2020(E)
IDF 250:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO and IDF 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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 at the address

below or ISO’s member body in the country of the requester.
ISO copyright office International Dairy Federation
CP 401 • Ch. de Blandonnet 8 Silver Building • Bd Auguste Reyers 70/B
CH-1214 Vernier, Geneva B-1030 Brussels
Phone: +41 22 749 01 11 Phone: +32 2 325 67 40
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Email: copyright@iso.org Email: info@fil-idf.org
Website: www.iso.org Website: www.fil-idf.org
Published in Switzerland
ii © ISO and IDF 2020 – All rights reserved
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oSIST prEN ISO 23319:2020
ISO/DIS 23319:2020(E)
IDF 250:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 1

5 Reagents ........................................................................................................................................................................................................................ 2

6 Apparatus ..................................................................................................................................................................................................................... 2

7 Sampling ........................................................................................................................................................................................................................ 4

8 Preparation of test sample ......................................................................................................................................................................... 4

8.1 Cheese ............................................................................................................................................................................................................. 4

8.2 Caseins and caseinates ..................................................................................................................................................................... 4

9 Procedure..................................................................................................................................................................................................................... 5

9.1 Test portion ................................................................................................................................................................................................ 5

9.2 Blank test ..................................................................................................................................................................................................... 5

9.3 Preparation of a fat-collecting vessel ................................................................................................................................... 5

9.4 Determination ......................................................................................................................................................................................... 5

10 Calculation and expression of results ............................................................................................................................................. 9

11 Precision ....................................................................................................................................................................................................................... 9

11.1 Interlaboratory test............................................................................................................................................................................. 9

11.2 Repeatability ............................................................................................................................................................................................. 9

11.3 Reproducibility ....................................................................................................................................................................................10

11.4 Test report ................................................................................................................................................................................................10

Annex A (normative) Additional procedures ...........................................................................................................................................11

Annex B (normative) Fat extraction tube model with siphon or wash-bottle fittings ...................................13

Annex C (normative) Interlaboratory test for cheeses ...................................................................................................................14

Annex D (normative) Interlaboratory test for caseins and caseinates ..........................................................................15

Bibliography .............................................................................................................................................................................................................................16

© ISO and IDF 2020 – All rights reserved iii
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oSIST prEN ISO 23319:2020
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IDF 250:2020(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.

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 (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 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 (see 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 of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document 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 first edition of ISO 23319 merges, cancels and replaces the following standards for the

determination of the fat content of milk and milk products using the SBR principle:

— ISO 1735:2004 | IDF 5:2004, Cheese and processed cheese products — Determination of fat content —

Gravimetric method (Reference method);

— ISO 5543:2004 | IDF 127:2004 Caseins and caseinates — Determination of fat content — Gravimetric

method (Reference method).

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO and IDF 2020 – All rights reserved
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oSIST prEN ISO 23319:2020
ISO/DIS 23319:2020(E)
IDF 250:2020(E)

IDF (the International Dairy Federation) is a non-profit private sector organization representing the

interests of various stakeholders in dairying at the global level. IDF members are organized in National

Committees, which are national associations composed of representatives of dairy-related national

interest groups including dairy farmers, dairy processing industry, dairy suppliers, academics and

governments/food control authorities.

ISO and IDF collaborate closely on all matters of standardization relating to methods of analysis

and sampling for milk and milk products. Since 2001, ISO and IDF jointly publish their International

Standards using the logos and reference numbers of both organizations.

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. 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 the convenience of users and does not

constitute an endorsement.

This document was prepared by the IDF Standing Committee on Analytical Methods for Composition and

ISO Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It is

being published jointly by ISO and IDF.

The work was carried out by the IDF/ISO Action Team (C34) of the Standing Committee on Analytical

Methods for Composition under the aegis of its project leader, Mr Philippe Trossat (FR).

© ISO and IDF 2020 – All rights reserved v
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oSIST prEN ISO 23319:2020
ISO/DIS 23319:2020(E)
DRAFT INTERNATIONAL STANDARD
IDF 250:2020(E)
Cheese and processed cheese products, caseins
and caseinates — Determination of fat content —
Gravimetric method

WARNING — The use of this document 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 to determine the applicability of regulatory limitations prior to use.
1 Scope

This document specifies a method for the determination of the fat content of all types of cheese and

processed cheese products containing lactose of below 5 % (mass fraction) of non-fat solids, and all

types of caseins and caseinates.

The method is not applicable to fresh cheese type containing e.g. fruits, syrup or muesli. For such

products the Schmid–Bondzynski–Ratzlaff (SBR) principle is not applicable due to high concentrations

of sugars. For these products, the method using the Weibull-Berntrop principle (ISO 8262-3) is

appropriate.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 3889, Milk and milk products — Specification of Mojonnier-type fat extraction flasks

ISO 565, Test sieves — Metal wire cloth, perforated metal plate and electroformed sheet — Nominal sizes

of openings
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
fat content

mass fraction of substances determined by the procedure specified in this document

Note 1 to entry: The fat content is expressed as a percentage by mass.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Principle

A test portion is digested with hydrochloric acid, then ethanol is added. The acid-ethanolic solution

is subsequently extracted with diethyl ether and light petroleum. The solvents are removed by

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IDF 250:2020(E)

distillation or evaporation. The mass of the substances extracted, which are soluble in light petroleum,

is determined.
NOTE This is usually known as the Schmid-Bondzynski-Ratzlaff principle.
5 Reagents

Use only reagents of recognized analytical grade, unless otherwise specified, and 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 Annex A).

5.1 Hydrochloric acid, containing a mass fraction of HCl of approximately 36 % (ρ20 = 1,18 g/ml)

5.2 Dilute hydrochloric acid, containing a mass fraction of approximately 25 % (ρ20 = 1,125 g/ml)

Dilute 675 ml of concentrated hydrochloric acid (5.2) to 1 000 ml with water and mix.

5.3 Ethanol, (C H OH), at least 94 % (volume fraction)
2 5

Ethanol denatured otherwise than by methanol may be used provided that the denaturant does not

affect the result of the determination (see A5).

5.4 Diethyl ether (C H OC H ), free from peroxides (see A3) and containing none or not more than

2 5 2 5
7 mg/kg of antioxidants (see A4)

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.
3 2 3 3

5.6 Mixed solvent, prepared shortly before use by mixing 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.

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 around 80 g to 90 g at

the outer end of the flasks or tubes.
NOTE The use of the centrifuge is optional but recommended (see 9.4.7).

6.3 Distillation or evaporation apparatus to enable the solvents and ethanol to be distilled from the

fat-collecting flasks or to be evaporated from beakers and dishes 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 the working space, alternatively, a vacuum drying oven,

capable of being maintained at 72,5 ± 2,5 °C, and a pressure less than 600 mbar (50 mmHg) may be used.

The oven shall be fitted with a suitable thermometer.
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6.5 Boiling water bath or hot plate
6.6 Fat-extraction flasks
6.6.1 Mojonnier-type fat-extraction flasks, as specified in ISO 3889 | IDF 219
6.6.2 Extraction tubes-type fat extraction flask

It is also possible to use fat extraction tubes with siphon or wash-bottle fittings. For an example, see

model in Annex B.
6.6.3 Stoppers

The flasks or tubes shall be provided with stoppers of different material, such as bark cork, silicone

rubber, polytetrafluoroethylene (PTFE) or glass, unaffected by the reagents used. Bark corks shall be

washed with the diethyl ether (5.4), kept in water at 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, to hold the fat-extraction flasks or tubes.

6.8 Wash bottle, suitable for use with the mixed solvent (5.6). A plastic wash bottle shall not be used.

6.9 Fat-collecting vessels
For example:
— boiling flasks, flat-bottomed, of capacity 125 ml to 250 ml;
— conical flasks, of capacity 250 ml;
— metal dishes.

If metal dishes are used, they shall preferably be of stainless steel, and shall be flat-bottomed, preferably

with a spout, and shall have a diameter of 80 mm to 100 mm and a height of approximately 50 mm. Do

not use aluminium dishes.

6.10 Boiling aids, fat-free, of non-porous porcelain or silicon carbide, or glass beads. The use of glass

beads is optional in the case of metal dishes.
6.11 Measuring cylinders of capacities 5 ml and 25 ml.
6.12 Pipettes, graduated, to deliver 10 ml.
6.13 Tongs, made of metal, capable of holding flasks, beakers or dishes.

6.14 Sheets of cellulose film, unlacquered, soluble in hydrochloric acid, of thickness of thickness 0,03

mm to 0,05 mm, of dimensions 50 mm × 75 mm approximately. The sheets shall be inert under the test

conditions.

6.15 Grinding or grating device, for grinding or grating the laboratory sample if necessary. This device

should be such that no undue heat will be developed and no loss of moisture occurs. A hammer mill shall

not be used.

6.16 Test sieve, of woven wire cloth, diameter 200 mm, nominal size of opening 500 µm, with receiver,

complying with the requirements of ISO 565.
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6.17 Container with lid, airtight, of capacity such that the test sample can be mixed by shaking.

6.18 Beaker of flask, of capacity of 100 ml.
7 Sampling

A representative sample should be sent to the laboratory. It should not be damaged or changed during

transport or storage. The laboratory sample shall be stored in a securely closed airtight container.

Sampling is not part of the method specified in this International Standard. A recommended sampling

[1]
method is given in ISO 707 .

From the time of sampling to the time of commencing the procedure, the test samples shall be kept at

a temperature of between 2 °C and 6 °C for cheese and at room temperature for casein and caseinates.

8 Preparation of test sample
8.1 Cheese

Prior to analysis, remove the rind, the smear or the mouldy surface layer of the cheese in such a way as

to obtain a test sample representative of the cheese.

Grind or grate the test sample by using an appropriate grinding or grating device (6.15). Mix the ground

mass quickly and, if necessary for semi-hard and hard cheeses, grind it a second time and again mix

thoroughly. Preferably, cut hard and semi-hard cheeses into cubes of about 15 mm × 15 mm. Mix the

cubes by shaking in a container. Grind or grate the test sample as specified before. Clean the device

after preparing each sample.

If the test sample cannot be ground or grated, mix it thoroughly by intensive kneading, for example

with a pestle in a mortar. Care should be taken to avoid moisture loss.

Store the test sample in an airtight container until commencing the analysis, which shall be carried out

as soon as possible after grinding.

If, however, a delay is unavoidable, take all precautions to ensure proper preservation of the test

sample. When refrigerated, bring the test sample to room temperature. Thoroughly mix the sample

to obviate the well-documented transfer of moisture within the cheese that occurs during cooling and

warming. Ensure that any condensation of moisture on the inside surface of the container is thoroughly

and uniformly re-incorporated into the test sample. Do not examine ground cheese showing unwanted

mould growth or signs of deterioration.

All sample preparation should be carried out in a manner which minimizes moisture loss. Such moisture

loss will have the effect of increasing the apparent fat content.
8.2 Caseins and caseinates

Thoroughly mix the laboratory sample, if necessary after transferring all of it to an airtight container of

suitable capacity, by repeatedly shaking and inverting the container.

Transfer 50 g of the laboratory sample to the test sieve (6.16). If it does not pass completely through the

sieve, use the grinding device to achieve this condition. Immediately transfer all the sieved sample to the

container (6.17) and mix thoroughly in the closed container. During these operations, take precautions

to avoid any change in the water content of the product.

After the test sample has been prepared, proceed with the determination (9.4) as soon as possible.

If the 50 g portion directly passes through the sieve, or nearly completely passes, use the prepared test

sample for the determination.
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9 Procedure
9.1 Test portion

Mix the test sample by gently stirring. Immediately weigh, to the nearest 1 mg, directly or by difference,

1 g to 3 g of test sample for cheese and 2 g to 3 g for caseins and caseinates into a fat-extraction flask

(6.6), a 100 ml beaker or flask (6.18).

For cheeses having a mass fraction of fat of more than 30 %, adapt the mass of the test portion so as to

obtain a mass of extracted fat of between 750 mg and 1 000 mg.

The test portion may also be weighed on a sheet of cellulose film (6.14), which is subsequently folded and

introduced into the chosen vessel. For the Mojonnier type flask, deliver the test portion as completely

as possible into the lower (small) bulb of the fat-extraction flask.
9.2 Blank test

Carry out a blank test simultaneously with the determination, using the same procedure and same

reagents but omitting the test portion.

When a batch of test samples is analysed, the number of drying cycles may differ between different

samples. If one blank sample is used for the entire batch, ensure that the blank value, used in the

calculation of the fat content of any individual sample, was obtained under the same conditions as 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

done recently (see A.1). Corrections for values of more than 2,5 mg in the blank test shall be reported in

the test report (see A.2).
9.3 Preparation of a fat-collecting vessel

Dry a fat-collecting vessel (6.9) with a few boiling aids (6.10) in the drying oven (6.4) for 1 h.

NOTE Boiling aids are desirable to promote gentle boiling during the subsequent removal of solvent,

especially in the case of glass vessels; their use is optional in the case of metal dishes.

Allow the fat-collecting vessel to cool (protected from dust) to the temperature of the weighing room

(glass 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 to place the fat-collecting vessel on the balance to avoid, in particular, temperature variations.

Weigh the dish to the nearest 1 mg.
9.4 Determination

9.4.1 Depending on the shape of the extraction apparatus and the size of the test portion, add 8 ml to

10 ml for cheese and 7.5 ml to 10 ml for caseins and caseinates of dilute hydrochloric acid (5.2). Add the

hydrochloric acid so as to wash the test portion and for Mojonnier type flask into the small bulb of the

fat-extraction flask (6.6) or onto the bottom of the beaker or flask (6.18), and mix.

9.4.2 Heat by gently moving the fat-extraction flask or vessel (to avoid charring) in a boiling water

bath or on a hot plate (6.5), until all particles are completely dissolved.

9.4.3 Allow the fat-extraction flask or vessel to stand for 20 min to 30 min in the boiling water bath

(6.5) or keep it gently boiling on the hot plate (6.5) for 10 min. Cool under running water.

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9.4.4 If the digestion has been carried out in the fat-extraction flask apparatus, add 10 ml of ethanol

(5.4). Mix gently but thoroughly by allowing the contents of the flask to flow backwards and forwards

and for Mojonnier type flask, between the two bulbs while not bringing the liquid too near to the neck..

Alternatively, if the digestion has been carried out in a vessel other than the fat-extraction flask (6.6),

pour the contents of the vessel into a fat-extraction flask (6.6). Rinse the vessel successively with 10

ml of ethanol (5.3). Mix gently as described above. Then rinse the vessel with 25 ml of diethyl ether

(5.4) and pour the vessel contents into the fat-extraction flask, while rinsing the tip or rim with some

additional diethyl ether or mixed solvent (5.6). Close the fat-extraction flask with a stopper (6.6.3) and

shake as described in 9.4.5. Finally rinse the vessel again with 25 ml of light petroleum (5.5) or mixed

solvent (5.6) and pour that solvent into the fat-extraction flask, while also rinsing the tip or rim with

some additional light petroleum. Close the fat-extraction flask again and shake its contents as described

in 9.4.6. Then continue with the centrifugation procedure as in 9.4.7.

9.4.5 Add 25 ml of diethyl ether (5.4). Close the fat-extraction flask with a stopper (6.6.3).

Shake the flask vigorously for 1 min, but not so vigorously as to cause formation of a persistent emulsion.

For Mojonnier type flask only, while shaking, keep the flask in a horizontal position with the small bulb

extending upwards, periodically allowing the liquid in the large bulb to run into the small bulb.

If necessary, cool the flask under running water.

Carefully remove 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 fat-extraction flask.

9.4.6 Add 25 ml of the light petroleum (5.5). Close the fat-extraction flask with the stopper.

Gently shake the flask as described in 9.4.5, but for 30 s only.
-1 -1

9.4.7 Centrifuge the closed fat-extraction flask at a rotational frequency of 500 min to 600 min for 1

min to 5 min. If a centrifuge is
...

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