SIST EN ISO 707:2009
(Main)Milk and milk products - Guidance on sampling (ISO 707:2008)
Milk and milk products - Guidance on sampling (ISO 707:2008)
ISO 707|IDF 50:2008 gives guidance on methods of sampling milk and milk products for microbiological, chemical, physical and sensory analysis, except for (semi)automated sampling.
Milch und Milchprodukte - Leitfaden zur Probenahme (ISO 707:2008)
Diese Internationale Norm stellt einen Leitfaden zur Probenahme von Milch und Milcherzeugnissen für mikro¬biologische, chemische und physikalische Untersuchungen sowie für sensorische Prüfungen mit Ausnahme der (halb)automatischen Probenahme dar.
ANMERKUNG Siehe auch Literaturhinweis [9].
Lait et produits laitiers - Lignes directrices pour l'echantillonnage (ISO 707:2008)
L'ISO 707|FIL 50:2008 donne des lignes directrices relatives aux méthodes d'échantillonnage du lait et des produits laitiers destinés à une analyse microbiologique, chimique, physique et sensorielle, sauf pour l'échantillonnage (semi) automatisé.
Mleko in mlečni proizvodi - Navodila za vzorčenje (ISO 707:2008)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2009
1DGRPHãþD
SIST EN ISO 707:1999
0OHNRLQPOHþQLSURL]YRGL1DYRGLOD]DY]RUþHQMH ,62
Milk and milk products - Guidance on sampling (ISO 707:2008)
Milch und Milchprodukte - Leitfaden zur Probenahme (ISO 707:2008)
Lait et produits laitiers - Lignes directrices pour l'echantillonnage (ISO 707:2008)
Ta slovenski standard je istoveten z: EN ISO 707:2008
ICS:
67.100.01 0OHNRLQPOHþQLSURL]YRGLQD Milk and milk products in
VSORãQR general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN ISO 707
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2008
ICS 67.100.01 Supersedes EN ISO 707:1997
English Version
Milk and milk products - Guidance on sampling (ISO 707:2008)
Lait et produits laitiers - Lignes directrices pour Milch und Milcherzeugnisse - Leitfaden zur Probenahme
l'echantillonnage (ISO 707:2008) (ISO 707:2008)
This European Standard was approved by CEN on 14 August 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 707:2008: E
worldwide for CEN national Members.
Contents Page
Foreword.3
Foreword
This document (EN ISO 707:2008) 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 February 2009, and conflicting national standards shall be withdrawn
at the latest by February 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 707:1997.
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 707:2008 has been approved by CEN as a EN ISO 707:2008 without any modification.
INTERNATIONAL ISO
STANDARD 707
IDF
Third edition
2008-08-15
Milk and milk products — Guidance on
sampling
Lait et produits laitiers — Lignes directrices pour l'échantillonnage
Reference numbers
ISO 707:2008(E)
IDF 50:2008(E)
©
ISO and IDF 2008
ISO 707:2008(E)
IDF 50:2008(E)
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© 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.
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Published in Switzerland
ii © ISO and IDF 2008 – All rights reserved
ISO 707:2008(E)
IDF 50:2008(E)
Contents Page
Foreword. iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 General arrangements. 1
5 Apparatus . 3
6 Sampling. 5
7 Preservation of samples . 5
8 Storage and transport of samples . 5
9 Milk and liquid milk products . 6
10 Evaporated milk, sweetened condensed milk and milk concentrate . 9
11 Semi-solid and solid milk products except butter and cheese. 13
12 Edible ices, semi-processed (semi-finished) ices and other frozen milk products. 14
13 Dried milk and dried milk products. 16
14 Butter and related products. 17
15 Butterfat (butter oil) and related products . 19
16 Cheese . 21
Annex A (informative) Examples of sampling equipment and shapes of sampling. 24
Annex B (informative) Thermally insulated container for the transport of cooled, frozen and
quick-frozen food samples . 32
Annex C (informative) Additional information for the use of insulated transport containers. 36
Annex D (informative) Sampling report for cheese . 37
Bibliography . 40
ISO 707:2008(E)
IDF 50:2008(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 707⎪IDF 50 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 third edition of ISO 707⎪IDF 50 cancels and replaces the second edition (ISO 707:1997), which has been
technically revised.
iv © ISO and IDF 2008 – All rights reserved
ISO 707:2008(E)
IDF 50:2008(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 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 707⎪IDF 50 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 Sampling and sample preparation of the
Standing Committee on Quality assurance, statistics of analytical data and sampling under the aegis of its
project leader, Mr. T. Berger (CH).
This edition of ISO 707⎪IDF 50 cancels and replaces IDF 50:1995, which has been technically revised.
ISO 707:2008(E)
IDF 50:2008(E)
Introduction
Sampling is an operation that requires most careful attention; emphasis cannot be too strongly laid on the
necessity of obtaining a properly representative sample. Written sampling procedures are demanded by
[6]
ISO/IEC 17025 if sampling is performed by laboratories. Written procedures are also required for
subsampling steps in the laboratory, e.g. the preparation of test portions. The sampling procedure is part of
the measurement procedure, but not of the measurement itself. It therefore does not contribute to the
measurement uncertainty. Variations resulting from sampling procedures handled by the laboratory contribute
to the uncertainty of the reported result and have therefore to be added to the measurement uncertainty.
Reference [10] is a guidance document on this issue.
The procedures described in this International Standard are recognized as good practice to be followed
whenever practicable. However, it is impossible to lay down fixed rules to be followed in every case, and,
however explicit, they cannot fully take the place of judgement, skill and experience. In particular, unforeseen
circumstances may render some modifications desirable. Whenever special requirements are given for
sampling and/or arise from a specific analysis to be performed, these requirements should be followed.
Heterogeneity in cheese provides particular challenges for sampling. Sampling uncertainty is mainly
influenced by the heterogeneity of the sample, the sample size and the sampling method.
There are significant consequences for both microbiological as well as for chemical analyses in cheese.
Normally the cheese curd is moulded into a specific shape and dimensions and this can affect the
development. During ripening of the moulded cheese curd under regular conditions or in environments in
which the humidity, temperature, and possibly composition of the atmosphere are controlled, the outside of
the cheese will develop into a semi-closed layer with a lower moisture content, the rind, often initiated by
brining. Due to the influence of the salt gradient in the brine, of oxygen, of drying out and of other reactions,
the rind successively becomes of a somewhat different composition than the interior of the cheese.
Rennet and microorganisms, added as selected cultures or naturally available, by enzymatic and
microbiological activity, change the structure and composition of the inner zone of the cheese. Moreover,
microorganisms are often not homogeneously distributed throughout the cheese.
Ripening is influenced by storage temperature, time, humidity, and salt gradients. During or after ripening, the
cheese rind can be treated or can be naturally colonized with desired cultures of microorganisms. The
resulting layer, in the latter case referred to as smear, will have further influence on the ripening of the border
zone. To be able to make correct decisions on the sampled material, specific knowledge of cheese ripening is
necessary. Depending on the desired conclusion, it has to be decided where a sample is to be taken and how
many samples are necessary.
For these reasons, ISO 707⎪IDF 50 has been written in the form of guidance rather than as an “imperative”
standard.
The test samples obtained by the methods described in this International Standard are “laboratory samples”
[1]
as defined in ISO 78-2:1999 , 3.1. The “test portion” obtained by the methods described is also defined in
[1]
ISO 78-2:1999 , 3.3.
vi © ISO and IDF 2008 – All rights reserved
ISO 707:2008(E)
INTERNATIONAL STANDARD
IDF 50:2008(E)
Milk and milk products — Guidance on sampling
1 Scope
This International Standard gives guidance on methods of sampling milk and milk products for microbiological,
chemical, physical and sensory analysis, except for (semi)automated sampling.
NOTE See also Reference [9].
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 7002, Agricultural food products — Layout for a standard method of sampling from a lot
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7002, and the following, apply.
3.1
laboratory sample
sample as prepared for sending to the laboratory and intended for inspection or testing
[1]
[ISO 78-2:1999 , 3.1]
3.2
test portion
quantity of material drawn from the laboratory sample on which the test or observation is actually carried out
[1]
[Adapted from ISO 78-2:1999 , 3.3]
NOTE It is possible that test portions of milk and milk products may require further processing, e.g. removal of parts
that impair the test result, aseptic extraction of parts or grating.
4 General arrangements
This International Standard is not suitable as a basis for formulating legal obligations between contracting
parties. In such cases, additional written requirements are necessary.
The number of units to be selected for sampling by inspection by attributes may be determined according to
[3]
ISO 5538⎪IDF 113 . Sampling for inspection by variables may be determined according to lSO 8197
[5]
(IDF 136A) .
ISO 707:2008(E)
IDF 50:2008(E)
The following instructions are not necessarily applicable for routine sampling:
a) the parties concerned or their representatives should be given the opportunity to be present when
sampling is performed;
b) whenever special requirements are given for the sampling and/or arise from a specific analysis to be
performed, these requirements should be followed.
1)
4.1 Sampling personnel
An authorized person, properly trained in the appropriate technique, e.g. for microbiological purposes, and
free from any infectious disease, shall perform sampling.
4.2 Sealing and labelling of samples
Samples should be sealed (if this is a legal requirement or if agreed between the parties concerned) and a
label attached, reproducing integrally the identification of product, the nature of the product and, at least, the
identification number, name and signature (or initials) of the authorized person (4.1) responsible for taking the
samples.
If necessary, additional information may be included, such as the purpose of sampling, the mass or volume of
sample, and the unit from which the sample was taken and the condition of product and storage conditions at
the moment of sampling.
4.3 Replicate samples
Samples should be taken in duplicate, or in greater numbers, if this is a legal requirement or if agreed
between the parties concerned.
It is recommended that additional sets of samples be taken and retained for arbitration purposes, if agreed
between the interested parties.
4.4 Sampling report
Samples should be accompanied by a report, signed or initialled by the authorized sampling personnel (4.1)
and countersigned — as far as necessary or agreed by the parties concerned — by witnesses present.
The report should include at least the following information:
a) the place, date and time of sampling (the time only being required when agreed between the parties
concerned);
b) the names and designations of the authorized sampling personnel and of any witnesses;
c) the precise method of sampling, including sample preparation and homogenization techniques;
d) the nature and number of units constituting the consignment, together with their batch code markings,
where available;
e) the identification number and any code markings of the batch from which the samples were taken;
f) the number of samples duly identified as to the batches from which they were taken;
g) if necessary, the place to which the samples are to be sent;
h) if possible, the name and address of the producer or trader or of the persons responsible for packing the
product.
1) In some countries it is the practice to employ a sworn person for sampling.
2 © ISO and IDF 2008 – All rights reserved
ISO 707:2008(E)
IDF 50:2008(E)
When appropriate, the report should also include any relevant conditions or circumstances (e.g. the condition
of the product containers and their surroundings, temperature and humidity of the atmosphere, the age of the
product, method of sterilization of the sampling equipment, whether a preservative substance has been added
to the samples), and any special information relating to the product being sampled, e.g. difficulty in achieving
homogeneity of the product.
Test portion size and handling vary according to the test(s) intended and are found under the appropriate
headings in the individual International Standards specifying the tests.
Sampling also includes preparation of the laboratory sample. Therefore, the sampling report or a separate
laboratory report should clearly state how the laboratory samples were prepared. Sampling reports are
transmitted to the appropriate authority together with the test report. The example of a sampling report for
cheese is given in Annex D (see also 16.3).
5 Apparatus
5.1 Sampling equipment
5.1.1 General
Sampling equipment should be made of stainless steel, or other suitable material of adequate strength, which
does not bring about a change in the sample which could affect the results of subsequent examinations.
All surfaces should be smooth and free from crevices. All corners should be rounded except in the case of
method D mentioned in 5.1.2. The equipment should be dry prior to use.
5.1.2 For microbiological examination
Sampling equipment for microbiological examination should be clean and sterilized prior to use. Disposable
plastics equipment should be sterile.
If solder is used in the manufacture of the equipment, it should be capable of withstanding a temperature of
180 °C. If possible, sterilization should be performed by one of the three following methods:
[4]
a) Method A: Exposure to hot air at 170 °C for at least 1 h or equivalent (see ISO 7218 );
b) Method B: Exposure to steam in an autoclave set at 121 °C ± 1 °C for at least 15 min (see
[4]
ISO 7218 );
c) Method C: Exposure to a sufficient dose of γ-radiation.
After sterilization by one of methods A, B or C, the sampling equipment should be stored under conditions to
ensure sterility until ready to sample.
If, in a particular situation, sterilization by methods A, B or C is impossible, one the following alternative
methods might be used provided that the sampling equipment is used immediately after treatment. However,
these methods should be regarded as secondary methods only.
d) Method D: Exposure of all working surfaces of the sampling equipment to a suitable flame;
e) Method E: Immersion in ethanol of at least 70 % volume fraction (see 5.5.1) followed by 5 min drying
time;
f) Method F: Ignition with ethanol of 96 % volume fraction (see 5.5.2).
After treatment by either method D or method F, the sampling equipment should be cooled under appropriate
conditions to maintain sanitation before sampling.
ISO 707:2008(E)
IDF 50:2008(E)
5.1.3 For chemical and physical analysis and for sensory examination
Sampling equipment should be clean and dry and should not influence the properties, such as odour, flavour,
consistency, and composition, of the product. In some cases, equipment treated as described in 5.1.2 is
required to avoid microbial contamination of the product.
The marking of samples should not influence the properties or composition of the product. Odourless marking
equipment should be used, e.g. odourless permanent ink or felt-tip pens.
5.2 Sample containers
Sample containers and closures should be of material and construction that adequately protect the sample
and which do not bring about a change in the sample which could affect the results of subsequent analyses or
examinations. Appropriate materials include glass, some metallic materials (e.g. stainless steel) and some
plastics (e.g. polypropylene).
The containers should preferably be opaque. If necessary, transparent filled containers should be stored in a
dark place. Containers and closures should be dry, clean and either sterile or suitable for treatment by one of
the methods described in 5.1.2. The use of glass containers for sampling inside production areas should be
avoided.
The shape and capacity of the containers should be appropriate to the particular requirements for the product
to be sampled. Single-service plastic containers as well as aluminium foil of adequate strength (sterile and
non-sterile) and suitable plastic bags, with appropriate methods of closure, may also be used.
Sample containers other than plastic bags should be securely closed either by using a suitable stopper or a
screw cap of metallic or plastics material. The latter should have, if necessary, a liquid-tight plastic liner which
is insoluble, non-absorbent and greaseproof and which will not influence the composition, properties or the
odour and flavour of the sample. If stoppers are used, they should be made from, or covered with,
non-absorbent, odourless and flavourless material. Sample containers need to be airtight/sealed to prevent
contamination and air ingress.
Containers for samples for microbiological examinations should not be closed with cork stoppers or caps with
cork seals, even if provided with liners. Containers for solid, semi-solid or viscous products should be
wide-mouthed.
Small retail containers are considered as sample containers; the sample should consist of the contents of one
or more intact, unopened containers.
Requirements for insulated containers for transport of cooled, frozen or quick-frozen samples are given in
Annex B.
5.3 Sample preparation equipment
The technical equipment for sample preparation should be described in the specific method of analysis.
5.4 Thermometer specifications
Thermometers used in the sampling procedure should be validated and of sufficient accuracy.
5.5 Ethanol
5.5.1 Ethanol, undenatured, with a volume fraction of 70 %.
5.5.2 Ethanol, undenatured, with a volume fraction of 96 %.
CAUTION — This solution is hygroscopic and may change its concentration over a long period of time.
Use freshly prepared solutions.
4 © ISO and IDF 2008 – All rights reserved
ISO 707:2008(E)
IDF 50:2008(E)
6 Sampling
Sampling should be done in such a way as to get representative samples of the product.
If laboratory samples for microbiological, chemical and physical analyses and sensory examinations are taken
separately, those for microbiological examinations should be taken first using aseptic techniques and sterilized
equipment and containers (see 5.1.2).
Care should be taken to ensure that when taking samples for sensory examinations, the flavour of the
samples is not adversely affected by the use of sampling equipment or sampling cocks, e.g. method E or F
(5.1.2).
The precise method of sampling and the mass or volume of product to be taken varies according to the nature
of the product and the purpose for which samples are required.
For details of the requirements, see Clauses 9 to 16. If products contain coarse particles, it may be necessary
to increase the minimum sample size. The sample container should be closed immediately after sampling.
For small retail containers, the sample consists of one or more unopened containers.
If necessary, a further sample is taken for temperature control during transportation to the testing laboratory.
7 Preservation of samples
Preservatives should normally not be added to samples intended for microbiological or sensory examination
but may be added to some milk products, provided that:
a) an instruction to do so is issued by the testing laboratory;
b) the preservative is of a nature that does not interfere with subsequent analyses, and testing of texture
and flavour should not be performed;
c) the nature and quantity of preservative are stated in the sampling report and, preferably, indicated on the
label;
d) the safety instructions for the preservative used are followed.
In certain cases, the preservative will interfere with the analyte. In such cases, a suitable correction should be
used.
8 Storage and transport of samples
Storage and dispatch of the samples should be such that the state of the sample at the time of sampling
remains essentially unaltered until the time of starting the test procedure.
During transport, where necessary, precautions should be taken to prevent exposure to off-odours, direct
sunlight and other adverse conditions. If cooling is necessary, the minimum requirements to be met are the
temperature ranges which are either legally requested or prescribed by the manufacturer. The storage
temperature after sampling should be attained as quickly as possible. The time and temperature should be
considered in combination and not independently.
Storage temperatures are given in Table 1.
Samples should be dispatched immediately after sampling to the testing laboratory. The time for dispatch of
the samples to the testing laboratory should be as short as possible, preferably within 24 h. If requested,
samples should be dispatched as instructed by the testing laboratory.
After preparation of the test portion, analysis should be carried out immediately.
ISO 707:2008(E)
IDF 50:2008(E)
Table 1 — Sample preservation, storage temperature and minimum sample size
Sampling Product Preservation Storage Minimum
a
according permitted for temperature recombined
b
to Clause samples intended also used before sample size
for chemical and and during
physical analysis transport
°C
9 Non-sterilized milk and liquid milk products Yes 1 to 5 100 ml or 100 g
9 Sterilized milk, UHT milk and sterilized liquid No Ambient, max. 30 100 ml or 100 g
milk products in original, unopened containers
9 Sterilized milk, UHT milk and sterilized liquid Yes 1 to 5 100 ml or 100 g
milk products after sampling from the production
line or from one or more original pack(s)
10 Evaporated milk, sweetened condensed milk, No Ambient, max. 30 100 g
milk concentrates, and sterilized concentrates
11 Semi-solid and solid milk products except butter No 1 to 5 100 g
and cheese
12 Edible ices and semi-finished ice products No u −18 100 g
13 Dried milk and dried milk products No Ambient, max. 30 100 g
14 Butter and butter products No 1 to 5 (in the dark) 50 g
15 Butterfat (butter oil and similar products) No 1 to 5 (in the dark) 50 g
16 Fresh cheese No 1 to 5 100 g
16 Processed cheese No 1 to 5 100 g
16 Other cheeses No 1 to 5 100 g
a [4]
These temperatures are meant as general guidelines (see ISO 7218 ). For specific analytical purposes, other temperatures can
be more appropriate. It may be, under certain practical conditions, not always easy or even impossible to maintain the “ideal” or
desirable temperatures specified here especially during transportation. It is therefore recommended to use suitable containers in all
cases where it is necessary (see also Annex B) and to monitor and record temperatures in a suitable way.
b
In certain cases, it will be necessary to take a number of samples to produce a composite of corresponding minimum sample size.
A larger sample size for laboratory samples may be necessary according to the tests required and the type of product. Smaller sample
sizes are possible if no analytical and statistical arguments are against it. For the measurement of zonal differences, e.g. in cheese, it
may even be necessary to take smaller sample sizes.
9 Milk and liquid milk products
9.1 Applicability
The instructions given in this clause are applicable to raw and heat-treated milk, whole, partly skimmed and
skimmed milk, flavoured milk, cream, fermented milk, buttermilk, liquid whey and similar products.
9.2 Sampling equipment
Sampling equipment should comply with the requirements of Clause 5.
9.2.1 Apparatus for manual mixing
Apparatus for mixing liquids in bulk should have a surface sufficient to produce adequate disturbance of the
products. In view of the different shapes and sizes of containers, no specific design of apparatus can be
recommended for all purposes, but they should be designed in such a way as to avoid damage of the inner
surface of the container during mixing.
6 © ISO and IDF 2008 – All rights reserved
ISO 707:2008(E)
IDF 50:2008(E)
9.2.1.1 Apparatus for manual mixing in small vessels
For mixing liquids in small vessels (e.g. in buckets and cans) a stirrer (plunger) of the design and dimensions
shown in Figure A.1 is suitable. The length should be adjusted to the depth of the vessel.
9.2.1.2 Apparatus for manual mixing in large vessels
A stirrer (plunger) of the design and dimensions shown in Figure A.2 is suitable for use for larger vessels
(e.g. road and farm tanks).
9.2.2 Apparatus for mechanical agitation
9.2.2.1 Built-in agitators
The product to be stirred in the tank or vessel determines the technical data and construction of built-in
agitators. Various types of agitators are used but no attempt has been made to describe any of them, within
this International Standard.
9.2.2.2 Removable agitators
Removable agitators are mostly provided with a propeller and are introduced into transport, road and rail tanks
through the inspection port. Best stirring results are achieved at a depth corresponding to 0,7 of the filling
height. It is recommended that the agitator be inclined by 5° to 20° as this provides a horizontal as well as
vertical component to the resultant stirring motion of the liquor liquid.
9.2.3 Apparatus for taking samples
9.2.3.1 Apparatus for sampling
A dipper of the shape and size shown in Figure A.3 is suitable for sampling. The tapered form of the cup
permits nesting of the dippers.
9.2.3.2 Sample containers
The capacity of the sample containers should be such that they are almost completely filled by the sample and
allow proper mixing of the content before testing, but avoid churning during transport.
9.2.3.3 Thermally insulated transport container
See Annex B.
9.3 Sampling
Thoroughly mix all liquids, by inverting, stirring, by pouring to and from one product container to another of the
same volume, until sufficient homogeneity is obtained but avoid foaming. The equipment described in 9.2.1
and 9.2.2 may be used.
Take the sample immediately after mixing. Refer to Table 1 for minimum sample size and acceptable
sampling temperatures.
9.3.1 Sampling for microbiological examination
Samples for microbiological examination should always be taken first using aseptic techniques. Whenever
possible, they should be taken from the same product containers as those for chemical and physical analysis
and for sensory examination.
Treat the sampling equipment and sample containers as described in 5.1.2.
Proceed as described in 9.3.2 but using aseptic techniques.
ISO 707:2008(E)
IDF 50:2008(E)
9.3.2 Sampling for chemical and physical analysis and sensory examination
In certain cases, sampling equipment and sample containers should be treated as described in 5.1.2 for
chemical and physical analysis and sensory examination.
9.3.2.1 Small vessels, milk buckets and cans
Thoroughly mix the milk, e.g. by transfer, stirring or plunging (plunger).
9.3.2.2 Milk tanks or vats
Mechanically stir the milk for at least 5 min until sufficient homogeneity is obtained. If the tank is equipped with
a periodical, time-programmed agitation system, sampling may be carried out after only a short duration of
agitation (1 min to 2 min). In those instances where the propeller of the agitator is close to the surface of the
milk, the agitator should not be used, as that is likely to lead to the formation of foam.
9.3.2.3 Weighing bowl
To obtain a representative milk sample, it is essential that the milk be adequately mixed in the weighing bowl.
A sufficient degree of mixing is not achieved when the milk being tipped into the weighing bowl varies and
does not allow proper sampling. In that case, it is essential to supplement the mixing by additional agitation.
The amount of additional agitation should be determined by experiment. When the volume of milk to be
sampled exceeds the capacity of the weighing bowl, a sample representative of the whole consignment
should be obtained.
9.3.2.4 Large vessels, storage, rail and road tanks
In each case, thoroughly mix the milk by an appropriate method before sampling, e.g. by mechanical agitation,
by stirring with clean compressed air without foaming or by the use of a plunger. When compressed air is
used, any adverse influence on the product to be mixed should be avoided.
The extent of mixing should be appropriate to the period of time over which the milk has been at rest.
An agitator propeller too close to the surface of the milk is likely to lead to the formation of foam. Do not use
an agitator if foam production cannot be avoided.
Mixing by using a plunger or a removable agitator in road, rail tanks or vessels of similar size should be
performed as follows.
a) When samples are taken within 30 min after filling the container, the milk should be mixed for at least
5 min by plunging or stirring with an agitator. When the milk has been stored in the tank for a longer
period of time, mixing should be extended to at least 15 min.
b) When the tank is completely filled as is normally the case with transport, road and rail tanks, proper
mixing of milk showing pronounced creaming phenomena can only be achieved by mechanical agitation.
In a large vessel with a bottom discharge outlet or a sampling cock installed at another place, there may be, at
the discharge outlet, a small quantity of milk which is not representative of the whole content even after mixing.
Accordingly, samples should preferably be taken through the inspection port. If samples are taken from the
discharge outlet valve or the sampling cock, discharge sufficient milk to ensure that the samples are
representative of the whole.
The efficiency of the method of mixing applied in any particular circumstances should be demonstrated as
being adequate for the purposes of the analysis envisaged; the criterion of mixing efficiency is the repeatability
of analytical results from samples taken either from different parts of the whole, or from the outlet of the tank
at intervals during discharge.
9.3.2.5 Containers of different design
To take samples from shallow containers, special equipment is required.
8 © ISO and IDF 2008 – All rights reserved
ISO 707:2008(E)
IDF 50:2008(E)
9.3.2.6 Subdivided quantities
Unless a part of the bulk is tested individually, a representative quantity should be taken from each container
after mixing the content and the quantity and container related to the sample noted in the sampling report (4.4).
Mix portions of each representative quantity in amounts which are proportional to the quantity of the container
from which they are taken. Samples from the aggregate sample thus obtained should be taken after mixing.
9.3.2.7 Sampling from closed systems
For taking samples from closed systems (e.g. UHT plants, aseptic techniques) and in particular for
microbiological analysis, the working instructions for the installed sampling equipment should be observed.
9.3.2.8 Retail containers
The content of intact and unopened containers constitute the sample.
9.3.3 Applicability to products other than milk
9.3.3.1 Buttermilk, fermented milk, flavoured milk
Choose a suitable method from those described for milk and take a sample before fat or other solid matter has
had time to separate. If the latter has occurred, proceed to ensure a representative sample from a
homogeneous product as described in 9.3.1.
9.3.3.2 Cream
When using a plunger or a mechanical agitator for mixing cream thoroughly, mix the cream at the bottom of
the container with the upper layers.
To avoid foaming, whipping or churning of the cream, do not raise the disc of the plunger above the surface of
the cream during plunging. The equipment described in 9.2.1 (see Figures A.1 and A.2) may be used. When
mechanical agitators are used, the incorporation of air should be avoided.
9.3.3.3 Whey
Choose a suitable method from those described for milk.
9.4 Preservation, storage and dispatch of samples
See Clauses 7 and 8.
10 Evaporated milk, sweetened condensed milk and milk concentrate
10.1 Applicability
The instructions given in this clause are applicable to evaporated milk, sweetened condensed milk and milk
concentrates and similar products.
10.2 Sampling equipment
See 5.1.
10.2.1 Apparatus for manual mixing, see 9.2.1 and 9.2.2.
10.2.2 Stirrers, broad bladed, of sufficient length to reach the bottom of the product container and having
one edge shaped to the contour of the container (see Figure A.4).
ISO 707:2008(E)
IDF 50:2008(E)
10.2.3 Dippers, see 9.2.3.1.
10.2.4 Rods, of length about 1 m and diameter about 35 mm.
10.2.5 Containers, for subsampling, of capacity 5 l, with a wide mouth and meeting the requirements of 5.2.
10.2.6 Spoons or spatula, broad bladed.
10.2.7 Sample containers, see 5.2.
The capacity of the sample containers should be such that they are almost completely filled by the sample and
allow proper mixing of the contents before testing.
10.3 Sampling evaporated milk
Take the sample immediately after mixing, avoid foaming. Refer to Table 1 for minimum sample size and
acceptable sampling temperatures.
10.3.1 Sampling for microbiological examination
Samples for microbiological examination should always be taken first by using aseptic techniques. Whenever
possible, they should be taken from the same product containers as those for chemical and physical analysis
and for sensory examination.
Treat the sampling equipment and sample containers as described in 5.1.2.
Proceed as described in 10.3.2, but using aseptic techniques.
10.3.2 Sampling for chemical and physical analysis and for sensory examination
In certain cases, the sampling equipment and sample containers should also be treated as described in 5.1.2
for chemical and physical analys
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