ISO/TS 17996:2023

Cheese — Determination of rheological properties by uniaxial compression at constant displacement rate

This document specifies a method for the determination of rheological properties by uniaxial compression at constant displacement rate in hard and semi-hard cheeses. The method provides standard conditions for sampling and testing, for data representation and general principles of calculation. NOTE Sampling can be difficult with some cheese varieties, e.g. caused by shortness, brittleness, stickiness and soft consistency. In these cases, reliable results cannot be achieved.

Fromage — Détermination des propriétés rhéologiques par compression uniaxiale à vitesse constante de translation

General Information

• Status: Published
• Publication Date: 05-Feb-2023
• ICS: 67.100.30 - Cheese
• Technical Committee: ISO/TC 34/SC 5 - Milk and milk products
• Drafting Committee: ISO/TC 34/SC 5 - Milk and milk products
• Current Stage: 6060 - International Standard published
• Start Date: 06-Feb-2023
• Due Date: 07-Dec-2023
• Completion Date: 06-Feb-2023

Relations

• Revises: ISO/TS 17996:2006 - Cheese — Determination of rheological properties by uniaxial compression at constant displacement rate
• Effective Date: 11-Jun-2022

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 17996
IDF/RM 205
Second edition
2023-02
Cheese — Determination of
rheological properties by uniaxial
compression at constant displacement
rate
Fromage — Détermination des propriétés rhéologiques par
compression uniaxiale à vitesse constante de translation
Reference numbers
ISO/TS 17996:2023(E)
IDF/RM 205 :2023(E)
© ISO and IDF 2023

---------------------- Page: 1 ----------------------
ISO/TS 17996:2023(E)
IDF/RM 205 :2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO and IDF 2023
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: [phone] Phone: [phone]
Fax: [phone]
Email: [e-mail] Email: [e-mail]
Website: www.iso.org Website: www.fil-idf.org
Published in Switzerland
ii
  © ISO and IDF 2023 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/TS 17996:2023(E)
IDF/RM 205 :2023(E)
Contents Page
Forewords .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 2
6 Sampling . 3
7 Procedure .4
7.1 Thermal equilibration of test samples . 4
7.2 Test portion . 4
7.2.1 Location . 4
7.2.2 Direction . 5
7.2.3 Geometry . 5
7.2.4 Cutting . 5
7.2.5 Delay . 6
7.3 Test conditions . 6
7.3.1 Relative deformation . 6
7.3.2 Crosshead speed . 6
7.3.3 Number of compression cycles . 6
7.3.4 Number of test portions . 7
7.3.5 Measuring temperature . 7
7.3.6 Nature of the interface between test portion and plates . 7
8 Analysis of the compression curves .7
8.1 Data representation and calculation . 7
8.1.1 Data representation . 7
8.1.2 Calculation of stress and strain . 8
8.2 Parameters characterizing the compression curves . 9
8.2.1 General . 9
8.2.2 Modulus of deformability . 9
8.2.3 Apparent fracture point . 9
8.2.4 Apparent fracture work . 10
8.3 Expression of results . 11
9 Precision .11
9.1 Interlaboratory test . . 11
9.2 Repeatability . 11
9.3 Reproducibility . 11
10 Test report .12
Annex A (normative) Non-standard sample conditions .13
Annex B (informative) Examples of compression curves .15
Annex C (informative) Results of interlaboratory trial with one sample .17
Bibliography .18
iii
© ISO and IDF 2023 – All rights reserved

---------------------- Page: 3 ----------------------
ISO/TS 17996:2023(E)
IDF/RM 205 :2023(E)
Forewords
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 second edition cancels and replaces the first edition (ISO/TS 17996:2006 | IDF/RM 205:2006),
which has been technically revised, with the following changes:
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 2023 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/TS 17996:2023(E)
IDF/RM 205 :2023(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 Processing Aids
and Indicators 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 on P18 of the Standing Committee on Analytical
Methods for Processing Aids and Indicators under the aegis of its project leader Mr P. Watkinson (NZ).
v
© ISO and IDF 2023 – All rights reserved

---------------------- Page: 5 ----------------------
ISO/TS 17996:2023(E)
TECHNICAL SPECIFICATION
IDF/RM 205 :2023(E)
Cheese — Determination of rheological properties by
uniaxial compression at constant displacement rate
1 Scope
This document specifies a method for the determination of rheological properties by uniaxial
compression at constant displacement rate in hard and semi-hard cheeses.
The method provides standard conditions for sampling and testing, for data representation and general
principles of calculation.
NOTE Sampling can be difficult with some cheese varieties, e.g. caused by shortness, brittleness, stickiness
and soft consistency. In these cases, reliable results cannot be achieved.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
rheological properties
deformation under compression of the test sample
Note 1 to entry: In accordance with the procedure specified in this document.
4 Principle
A cylindrical test sample, of defined dimensions, is compressed at a constant crosshead speed with a
compression tool up to a relative deformation sufficient to determine the apparent fracture point. The
force, which is the resistance of the cheese sample during compression, is measured with a load cell.
The displacement may be measured either from the position of the cross head or calculated from the
elapsed time multiplied by the displacement rate.
A schematic representation of the principle of the test is given in Figure 1.
1
© ISO and IDF 2023 – All rights reserved

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ISO/TS 17996:2023(E)
IDF/RM 205 :2023(E)
Key
X displacement V constant displacement rate of the compression tool
Y force H initial sample height
0
1 compression tool ΔH variation in sample height
a
2 sample Apparent fracture point.
3 fixed base
Figure 1 — Schematic principle of uniaxial compression at constant displacement rate
5 Apparatus
Usual laboratory equipment and, in particular, the following.
5.1 Cork-borer, such as that shown in Figure 2 as an example.
It is recommended to mount the cork-borer on a drill-stand in order to drive it slowly and steadily
through the test sample.
2
  © ISO and IDF 2023 – All rights reserved

---------------------- Page: 7 ----------------------
ISO/TS 17996:2023(E)
IDF/RM 205 :2023(E)
Key
1 cork borer
2 cheese plug
Example A: d external diameter (d = 25 mm)
e e
 d internal diameter (d = 23 mm)
i i
 D cutting head diameter (D = 20 mm)
Example B: d external diameter (d = 16,5 mm)
e e
 D cutting head diameter (D = d is the internal diameter of 15,3 mm)
i
Figure 2 — Cork-borers for cutting cylindrical cheese plug
5.2 Parallel-wire cutting device, with a wire of diameter less than or equal to 0,4 mm and with a
system to keep the two wires parallel to each other and perpendicular to the plug. It should also include
a mechanically driven cutting system to cut the test sample to the required height.
5.3 Measuring cell, with a support and compression plate of the same stiff material, with smooth
and parallel surfaces, e.g. stainless steel, aluminium or polytetrafluoroethylene (PTFE), of diameter
larger (by 20 %) than that of the deformed test portion when at maximum compression. The load cell
capacity shall have a reasonable relationship to the expected maximum force.
5.4 Compression instrument, providing compression functions typically consisting of two (or
one) vertical columns on a platform and a crosshead connected perpendicular to these columns. This
crosshead is driven vertically up and down by a motor. The load cell is typically directly connected to
this crosshead and fixed to the compression tool (top plate) as shown in Figure 1. The fixed base in
Figure 1 (bottom plate) is connected to the platform.
6 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 document. A recommended sampling method is
[1]
given in ISO 707 | IDF 50 .
3
© ISO and IDF 2023 – All rights reserved

---------------------- Page: 8 ----------------------
ISO/TS 17996:2023(E)
IDF/RM 205 :2023(E)
7 Procedure
7.1 Thermal equilibration of test samples
If the storage temperature of the loaf of cheese is above that of the measuring temperature, then the loaf
of cheese shall be equilibrated at the measuring temperature for at least 50 h before further preparation
of the test sample because of the slow crystallization of milk fat in the cheese.
If the storage temperature of the loaf of cheese is below that of the measuring temperature, before any
preparation, store the loaf of cheese at the measuring temperature for at least 12 h. If there are specific
difficulties that can occur during the sample preparation at the measuring temperature, then sample at
the lower storage temperature and then equilibrate the test samples to the measurement temperature.
In this case, the sample thermal equilibration time may be less than 12 h.
NOTE Examples of specific sampling difficulties are that the cheese is hard to cut, or a heated loaf of cheese
changes the storage regime and therefore stops the use of the unsampled portions of the loaf of cheese for future
measurements.
The following shall be avoided:
a) dehydration of the test sample during the period of thermal equilibration;
b) deformation of the test sample due to its own mass.
7.2 Test portion
7.2.1 Location
Take the test portion from the loaf of the cheese with a plug about half a radius, either along a circle of a
cylindrical cheese, or along one side of a rectangular cheese (see Figure 3).
Cut the test portion in the plug in the area representing around half of the length (see Figure 4, plug A).
If the height of cheese is sufficient, two portions can be taken as shown in Figure 4, plug B and plug C.
a) Cheese with cylindrical form b) Cheese with parallelepipedal form
Key
R radius • plug in case 1
W width ° plug in case 2
L length
Figure 3 — Location of plug for cheese sampling
4
  © ISO and IDF 2023 – All rights reserved

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ISO/TS 17996:2023(E)
IDF/RM 205 :2023(E)
Key
1 sample
Figure 4 — Three types of sampling in plug
7.2.2 Direction
The standard direction for taking the test portion is parallel to the pressure axis in cheese making. See
Annex B for non-standard sampling conditions.
7.2.3 Geometry
The shape of the test portion shall be a cylinder with initial height/diameter ratio (h /d ) of between
0 0
1,1 and 1,5.
The initial height, h , of the test portion shall range from 12,5 mm to 25 mm. The diameter, d , for a
0 0
given height follows the above-mentioned ratio.
7.2.4 Cutting
Remove the rind or the plastic cover. Take a test portion using a cork-borer (5.1) with shapes shown in
Figure 2. For sticky cheeses, samples are easier to take with corer A than corer B. For cheese varieties
showing shortness or brittleness, form B as shown in Figure 2 is more appropriate than form A. It is
recommended to use a cork-borer mounted on a drill-stand in order to drive it slowly and steadily
through the test sample.
If it is difficult to obtain a good cylindrical form, it is recommended to use mineral oil of low viscosity
1)
(e.g. Vaseline® oil) to lubricate the cork-borer. Do not test samples with cracks, holes or other visible
defects.
1) Vaseline® is an example of a suitable product available commercially. This information is given for the
convenience of users of this document and does not constitute an endorsement by ISO of this product.
5
© ISO and IDF 2023 – All rights reserved

---------------------- Page: 10 ----------------------
ISO/TS 17996:2023(E)
IDF/RM 205 :2023(E)
Use a parallel-wire cutting device to cut the test sample to the required height. The wire diameter shall
be less than or equal to 0,4 mm. It is essential to have a system that keeps the two wires parallel to
each other and perpendicular to the plug. Preferably, use a mechanically driven cu
...

© ISO and IDF 2022 – All rights reserved
ISO/DTS 17996 | IDF/RM 205:2022(E)
Date: 2022-09-2210-17
ISO TC 34/SC 5
Secretariat: NEN
Cheese — Determination of rheological properties by uniaxial
compression at constant displacement rate
Fromage — Détermination des propriétés rhéologiques par compression uniaxiale à vitesse
constante de translation

---------------------- Page: 1 ----------------------
ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)
© ISO and IDF 2022
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: [phone]                   Phone: + 32 2 325 67 40
                                           Fax: + 32 2 325 67 41
Email: [e-mail]                   Email: [e-mail]
Website: www.iso.org                      Website: www.fil-idf.org
Published in Switzerland.
ii © ISO and IDF 2022 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)
Contents
Forewords . iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 2
6 Sampling . 3
7 Procedure . 4
7.1 Thermal equilibration of test samples . 4
7.2 Test portion . 4
7.2.1 Location . 4
7.2.2 Direction . 5
7.2.3 Geometry . 5
7.2.4 Cutting . 5
7.2.5 Delay . 6
7.3 Test conditions . 6
7.3.1 Relative deformation . 6
7.3.2 Crosshead speed . 7
7.3.3 Number of compression cycles . 7
7.3.4 Number of test portions . 7
7.3.5 Measuring temperature . 7
7.3.6 Nature of the interface between test portion and plates . 7
8 Analysis of the compression curves . 7
8.1 Data representation and calculation . 7
8.1.1 Data representation . 7
8.1.2 Calculation of stress and strain . 8
8.2 Parameters characterizing the compression curves . 9
8.2.1 General . 9
8.2.2 Modulus of deformability . 9
8.2.3 Apparent fracture point . 10
8.2.4 Apparent fracture work . 11
8.3 Expression of results . 11
9 Precision . 11
9.1 Interlaboratory test . 11
9.2 Repeatability . 11
9.3 Reproducibility . 12
10 Test report . 12
Annex A (normative) Non-standard sample conditions . 18
Annex B (informative) Examples of compression curves . 20
Annex C (informative) Results of interlaboratory trial with one sample . 24
Bibliography . 25
© ISO and IDF 2022 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)
Forewords
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 second edition cancels and replaces the first edition (ISO/TS 17996:2006 | IDF/RM 205:2006),
which has been technically revised, with the following changes:
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 2022 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/DTS 17996:2022(E)
IDF/RM 205:2022(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 Processing Aids
and Indicators 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 on P18 of the Standing Committee on Analytical
Methods for Processing Aids and Indicators under the aegis of its project leader Mr P. Watkinson (NZ).
© ISO and IDF 2022 – All rights reserved v

---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)

Cheese — Determination of rheological properties by uniaxial
compression at constant displacement rate
1 Scope
This document describesspecifies a method for the determination of rheological properties by uniaxial
compression at constant displacement rate in hard and semi-hard cheeses.
The method provides standard conditions for sampling and testing, for data representation and general
principles of calculation.
NOTE Sampling mightcan be difficult with some cheese varieties, for examplee.g. caused by shortness,
brittleness, stickiness and soft consistency. In these cases, reliable results cannot be achieved.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminologicalterminology databases for use in standardization at the following
addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
rheological properties
deformation under compression of the test sample by the procedure specified in this document
Note 1 to entry. In accordance with the procedure specified in this document.
4 Principle
A cylindrical test sample, of defined dimensions, is compressed at a constant crosshead speed with a
compression tool up to a relative deformation sufficient to determine the apparent fracture point. The
force, which is the resistance of the cheese sample during compression, is measured with a load cell. The
displacement may be measured either from the position of the cross head or calculated from the elapsed
time multiplied by the displacement rate.
A schematic representation of the principle of the test is given in Figure A.1.
© ISO and IDF 2022 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)

Key
X displacement V constant displacement rate of the compression tool
Y force H initial sample height
0
1 compression tool ΔH variation in sample height
a
2 sample Apparent fracture point.
3 fixed base
Figure 1 — Schematic principle of uniaxial compression at constant displacement rate
5 Apparatus
Usual laboratory equipment and, in particular, the following.
5.1 Cork-borer, such as that shown in Figure A.4 2 as an example.
It is recommended to mount the cork-borer on a drill-stand in order to drive it slowly and steadily
through the test sample.
2 © ISO and IDF 2022 – All rights reserved

---------------------- Page: 7 ----------------------
ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)

Key
1 cork borer
2 cheese plug
 Example A: d external diameter (d = 25 mm)
e e
  d internal diameter (d = 23 mm)
i i
  D cutting head diameter (D = 20 mm)
 Example B: d external diameter (d = 16,5 mm)
e e
  D cutting head diameter (D = d is the internal diameter of 15,3 mm)
i
Figure 2 — Cork-borers for cutting cylindrical cheese plug
5.2 Parallel-wire cutting device, with a wire of diameter less than or equal to 0,4 mm and with a system
to keep the two wires parallel to each other and perpendicular to the plug. It should also include a
mechanically driven cutting system to cut the test sample to the required height.
5.3 Measuring cell, with a support and compression plate of the same stiff material, with smooth and
parallel surfaces (, e.g. stainless steel, aluminium or polytetrafluoroethylene (PTFE), of diameter larger
(by 20 %) than that of the deformed test portion when at maximum compression. The load cell capacity
shall have a reasonable relationship to the expected maximum force.
5.4 Compression instrument, providing these compression functions typically consistsconsisting of
two (or one) vertical columns on a platform and a crosshead connected perpendicular to these columns.
This crosshead is driven vertically up and down by a motor. The load cell is typically directly connected
to this crosshead and fixed to the compression tool (top plate) as shown in Figure A.1. The fixed base in
Figure A.1 (bottom plate) is connected to the platform.
6 Sampling
A representative sample should have been sent to the laboratory. It should not have been damaged or
changed during transport or storage.
© ISO and IDF 2022 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)
Sampling is not part of the method specified in this document. A recommended sampling method is given
[1]
in ISO 707 | IDF 50 .
7 Procedure
7.1 Thermal equilibration of test samples
If the storage temperature of the loaf of cheese is above that of the measuring temperature, then the loaf
of cheese shall be equilibrated at the measuring temperature for at least 50 h before further preparation
of the test sample because of the slow crystallization of milk fat in the cheese.
If the storage temperature of the loaf of cheese is below that of the measuring temperature, before any
preparation, store the loaf of cheese at the measuring temperature for at least 12 h. If there are specific
difficulties that can occur during the sample preparation at the measuring temperature, then sample at
the lower storage temperature and then equilibrate the test samples to the measurement temperature.
In this case, the sample thermal equilibration time may be less than 12 h.
NOTE Examples of specific sampling difficulties are that the cheese is hard to cut, or a heated loaf of cheese
changes the storage regime and therefore stops the use of the unsampled portions of the loaf of cheese for future
measurements.
The following shall be avoided:
a) dehydration of the test sample during the period of thermal equilibration;
b) deformation of the test sample due to its own mass.
7.2 Test portion
7.2.1 Location
Take the test portion from the loaf of the cheese with a plug about half a radius, either along a circle of a
).
cylindrical cheese, or along one side of a rectangular cheese (see Figure A.2 3
Cut the test portion in the plug in the area representing around half of the length (see Figure A.3 4, plug A).
If the height of cheese is sufficient, two portions can be taken as shown in Figure A.3 4, plug B and plug C.


a) Cheese with cylindrical form b) Cheese with parallelepipedal form
Key
R radius • plug in case 1
W width ° plug in case 2
L length
Figure 3 — Location of plug for cheese sampling
4 © ISO and IDF 2022 – All rights reserved

---------------------- Page: 9 ----------------------
ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)

Key
1 sample
Figure 4 — Three types of sampling in plug
7.2.2 Direction
The standard direction for taking the test portion is parallel to the pressure axis in cheese making. See
Annex B for non-standard sampling conditions.
7.2.3 Geometry
The shape of the test portion shall be a cylinder with initial height/diameter ratio (h /d ) of between 1,1
0 0
and 1,5.
The initial height, h , of the test portion shall range from 12,5 mm to 25 mm. The diameter, d , for a given
0 0
height follows the above-mentioned ratio.
7.2.4 Cutting
Remove the rind or the plastic cover. Take a test portion using a cork-borer (5.1) with shapes shown in
Figure A.4 2. For sticky cheeses, samples are easier to take with corer A than corer B. For cheese varieties
showing shortness or brittleness, form B as shown in Figure A.4 2 is more appropriate than form A. It is
recommended to use a cork-borer mounted on a drill-stand in order to drive it slowly and steadily
through the test sample.
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ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)
If it is difficult to obtain a good cylindrical form, it is recommended to use mineral oil of low viscosity (e.g.
1
Vaseline® oil) to lubricate the cork-borer. Do not test samples with cracks, holes or other visible defects.
Use a parallel-wire cutting device to cut the test sample to the required height. The wire diameter shall
be less than or equal to 0,4 mm. It is essential to have a system that keeps the two wires parallel to each
other and perpendicular to the plug. Preferably, use a mechanically driven cutting system. Taking these
precautions into account reduces the lack in parallelism between the sample surface and the compression
plate.
7.2.5 Delay
A delay between the taking of a test portion and its testing allows stress relaxation of the test portion.
The recommended delay is between 10 min and 15 min. The upper limit is not strictly fixed but it should
not exceed 2 h. This recommendation is not relevant when sampling is done at a lower temperature than
the measuring temperature.
Store the test samples at the measuring temperature (see 7.3.5) and see Annex B for non-standard
conditions. Store samples in a pill-box or wrapped in plastic film to avoid dehydration during the delay
between sampling and testing.
7.3 Test conditions
7.3.1 Relative deformation
Perform the compression to just beyond the apparent fracture point (see Figure A.5, curve 1) or to a
predefined maximum deformation (see Figure A.5, curve 2).

Key
a
X deformation Apparent fracture point.
b
Y force Maximum deformation.
1 curve 1
2 curve 2
Figure 5 — Examples of compression curves

1 1
Vaseline® is an example of a suitable product available commercially. This information is given for the
convenience of users of this document and does not constitute an endorsement by ISO of this product.
6 © ISO and IDF 2022 – All rights reserved

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ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)
7.3.2 Crosshead speed
The standard value of the crosshead speed or displacement rate is 50 mm/min (or 0,83 mm/s) for initial
height 12,5 mm ≤ h ≤ 25 mm.
0
7.3.3 Number of compression cycles
Perform one compression cycle.
7.3.4 Number of test portions
Measure at least four test portions, but preferably carry out more than this.
7.3.5 Measuring temperature
Measure at the standardized measuring temperature of 15 °C ± 1 °C.
NOTE Although the chosen test temperature of 15 °C is a good compromise for a single temperature, the
challenge remains that many studies will use other temperatures for good reasons, as outlined in Annex BA.
SeeFollow Annex B A for non-standard conditions.
7.3.6 Nature of the interface between test portion and plates
Use a low viscosity mineral oil as lubricant between the test portion and the plates. Apply the oil as a very
thin layer on the plates.
8 Analysis of the compression curves
8.1 Data representation and calculation
8.1.1 Data representation
Raw data files contain data pairs (s , F ) with displacement data, s , of the compression plate and force
i i i
data, F , in units depending on the system. If the displacement of the plate is recorded right from the
i
beginning of the test (i.e. before the plate is in contact with the sample), then compute the absolute
deformation data, |Δh |, of the sample before any other calculation is performed. Let |s | be the absolute
i 0
displacement of the plate when the force becomes significantly different from zero (indicating the start
of the compression of the sample). Then calculate the absolute sample deformation data, |Δh |, using
i
:
Formula (1)
∆hs− s (1)
ii 0
where
 |s | is the absolute displacement of the plate when the force becomes significantly different from
0
zero;
 |s | is the absolute displacement of the plate.
i
The correct sample deformation data, Δh , is then found using the Formula (2):
i
∆hh=−∆ (2)
ii
For further processing, it may be useful to remove data from the free precontact displacement of the
compression plate.
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ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)
If the measuring system automatically records the absolute deformation |Δh| of the sample (starting with
zero as soon as the contact force becomes significant), then |s | is equal to |Δh | and no correction has to
i i
be applied. However, the sign assignment Δh = – |Δh | may still be necessary.
i i
The deformation/force data (Δh, F) shall be transformed to the normalized measures strain and stress in
order to be comparable. Graphical representations, numerical values and computed parameters of
compression curves are given in terms of strain and stress. Both of the following representations to
evaluate the curves are recommended options. Either one or both of these options may be used:
a) engineering stress, σ , versus Cauchy strain, ε ;
u C
b) corrected stress, σ , versus Hencky strain, ε
c H.
Strain has no dimension; stress is given in pascals (Pa) or kilopascals (kPa).
Examples of compression curves from some cheese varieties are given in Annex C B.
NOTE The symbol σ is also known as “uncorrected stress;”; ε is the engineering strain or relative
u C
deformation. The terms ‘“true stress’stress” and ‘“true strain’strain” to denote corrected stress σ , and
c
Hencky strain ε , respectively, are not recommended.
H
Stress correction is based on the cylindrical shape and volume constancy of the sample during the test,
allowing the calculation of the cross-section, A , at each time point.
t
This changing cross-section, A , is calculated using Formula (3):
t
Ah⋅
0 0
A A∆h (3)
( )
t
ht( )
where
 h is the initial sample height;
0
 A is the initial cross-section;
0
 h(t) is the height at each time point is derived from h and the deformation Δh, h(t) = h + Δh.
0 0
Under compression, Δh is a negative quantity (Δh ≤ 0) because the deformation reduces the
height of the sample, thus h(t) = h -– |Δh| (see Reference [4]).
0
8.1.2 Calculation of stress and strain
The following FormulasFormulae (4), (5), (6) and (7) assume that Δh ≤ 0.
The transformations of force into stress and of deformation into strain are applied to all data points (Δh,
F).
F
t
σ = (4)
u
A
0
∆h
ε = (5)
C
h
0
F Fh F
t tt t
σ= = ⋅ = ⋅+11εσ= ⋅+ε (6)
( ) ( )
c Cu C
A Ah A
t 0 0 0
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ISO/DTS 17996:2022(E)
IDF/RM 205:2022(E)
h hh+∆
  
t 0
εε ln ln ln 1+ (7)
( )
H    C
hh
  
0 0
NOTE 1 According to Formulas Formulae (5) and (6), compressive strain is a negative quantity (see Reference [4]).
Although rheologically correct, it is not common practice to indicate the minus sign in graphical representations or
in the computed parameters of the compression curves. The use of the sign maycan be useful if results from
compression (ε < 0) and tension (ε > 0) need to be distinguished.
NOTE 2 The application of stress correction according to Formula (6) (see Reference [5]) induces a shift of the
apparent fracture point towards lower absolute strain values (apart from decreasing the numerical stress values).
This shift is a transformation property of the correction factor (1 + εC), applied to curves with local maxima (see
Reference [7]).
8.2 Parameters characterizing the compression curves
8.2.1 General
Descriptive mechanical parameters of the compression curves are evaluated from stress/strain data
calculated according to Formulas Formulae (4) to (7), respectively.). The parameters characterize the
first part of the curves and that part where fracture occurs. The apparent fracture work characterizes the
curve up to the apparent fracture point.
The following four parameters are recommended to characterize the compression curves (see Annex
C B):
a) M , which is the modulus of deformability;
D
b) ε , which is the fracture strain (strain at the apparent fracture point);
f
c) σ , which is the fracture stress (stress at the apparent fracture point);
f
d) W , which is the fracture work (total deformation work up to the apparent fracture point, divided by
f
the initial sample volume V; its value is equal to the area under the stress/strain curve from zero
strain to strain at apparent fracture).
8.2.2 Modulus of deformability
The slope of the approximately linear part at small absolute strain values is an estimate of the apparent
elastic modulus, also called “modulus of deformability,”, M .
D
A well-defined estimate of M is accessible by the maximum of the first derivative of the compression
D
curve at |ε | < 0,1 using Formula (8):
∂σ
(8)
M = max
D 
∂ε

ε<0,1
The calculation is applied to (ε , σ ) and to (ε , σ ) data.
C U H c
The modulus of deformability, M , is given in pascals (Pa) or kilopascals (kPa).
D
NOTE 1 The estimation of the modulus of deformability, M , according to Formula (8) is justified by the
D
experimentally observed fact that there always exists a maximum of the first derivative at very low
absolute strain. Although F
...

FINAL
TECHNICAL ISO/DTS
DRAFT
SPECIFICATION 17996
IDF/RM 205
ISO/TC 34/SC 5
Cheese — Determination of
Secretariat: NEN
rheological properties by uniaxial
Voting begins on:
2022-11-01 compression at constant displacement
rate
Voting terminates on:
2022-12-27
Fromage — Détermination des propriétés rhéologiques par
compression uniaxiale à vitesse constante de translation
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference numbers
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/DTS 17996:2022(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
IDF/RM 205 :2022(E)
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO and IDF 2022

---------------------- Page: 1 ----------------------
ISO/DTS 17996:2022(E)
FINAL
TECHNICAL ISO/DTS
DRAFT
SPECIFICATION 17996
IDF/RM 205
ISO/TC 34/SC 5
Cheese — Determination of
Secretariat: NEN
rheological properties by uniaxial
Voting begins on:
compression at constant displacement
rate
Voting terminates on:
Fromage — Détermination des propriétés rhéologiques par
compression uniaxiale à vitesse constante de translation
COPYRIGHT PROTECTED DOCUMENT
© ISO and IDF 2022
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
RECIPIENTS OF THIS DRAFT ARE INVITED TO
CP 401 • Ch. de Blandonnet 8 Silver Building • Bd Auguste Reyers 70/B
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
CH-1214 Vernier, Geneva B-1030 Brussels
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
Phone: [phone] Phone: [phone]
DOCUMENTATION.
Fax: [phone]
IN ADDITION TO THEIR EVALUATION AS
Reference numbers
Email: [e-mail] Email: [e-mail]
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/DTS 17996:2022(E)
Website: www.iso.org Website: www.fil-idf.org
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
IDF/RM 205 :2022(E)
Published in Switzerland
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
ii
  © ISO and IDF 2022 – All rights reserved
NATIONAL REGULATIONS. © ISO and IDF 2022

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ISO/DTS 17996:2022(E)
IDF/RM 205 :2022(E)
Contents Page
Forewords .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 2
6 Sampling . 3
7 Procedure .4
7.1 Thermal equilibration of test samples . 4
7.2 Test portion . 4
7.2.1 Location . 4
7.2.2 Direction . 5
7.2.3 Geometry . 5
7.2.4 Cutting . 5
7.2.5 Delay . 6
7.3 Test conditions . 6
7.3.1 Relative deformation . 6
7.3.2 Crosshead speed . 6
7.3.3 Number of compression cycles . 6
7.3.4 Number of test portions . 7
7.3.5 Measuring temperature . 7
7.3.6 Nature of the interface between test portion and plates . 7
8 Analysis of the compression curves .7
8.1 Data representation and calculation . 7
8.1.1 Data representation . 7
8.1.2 Calculation of stress and strain . 8
8.2 Parameters characterizing the compression curves . 9
8.2.1 General . 9
8.2.2 Modulus of deformability . 9
8.2.3 Apparent fracture point . 9
8.2.4 Apparent fracture work . 10
8.3 Expression of results . 11
9 Precision .11
9.1 Interlaboratory test . . 11
9.2 Repeatability . 11
9.3 Reproducibility . 11
10 Test report .12
Annex A (normative) Non-standard sample conditions .13
Annex B (informative) Examples of compression curves .15
Annex C (informative) Results of interlaboratory trial with one sample .17
Bibliography .18
iii
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ISO/DTS 17996:2022(E)
IDF/RM 205 :2022(E)
Forewords
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 non­governmental, 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 second edition cancels and replaces the first edition (ISO/TS 17996:2006 | IDF/RM 205:2006),
which has been technically revised, with the following changes:
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
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ISO/DTS 17996:2022(E)
IDF/RM 205 :2022(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 Processing Aids
and Indicators 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 on P18 of the Standing Committee on Analytical
Methods for Processing Aids and Indicators under the aegis of its project leader Mr P. Watkinson (NZ).
v
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ISO/DTS 17996:2022(E)
TECHNICAL SPECIFICATION
IDF/RM 205 :2022(E)
Cheese — Determination of rheological properties by
uniaxial compression at constant displacement rate
1 Scope
This document specifies a method for the determination of rheological properties by uniaxial
compression at constant displacement rate in hard and semi­hard cheeses.
The method provides standard conditions for sampling and testing, for data representation and general
principles of calculation.
NOTE Sampling can be difficult with some cheese varieties, e.g. caused by shortness, brittleness, stickiness
and soft consistency. In these cases, reliable results cannot be achieved.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
rheological properties
deformation under compression of the test sample
Note 1 to entry: to entry. In accordance with the procedure specified in this document.
4 Principle
A cylindrical test sample, of defined dimensions, is compressed at a constant crosshead speed with a
compression tool up to a relative deformation sufficient to determine the apparent fracture point. The
force, which is the resistance of the cheese sample during compression, is measured with a load cell.
The displacement may be measured either from the position of the cross head or calculated from the
elapsed time multiplied by the displacement rate.
A schematic representation of the principle of the test is given in Figure 1.
1
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ISO/DTS 17996:2022(E)
IDF/RM 205 :2022(E)
Key
X displacement V constant displacement rate of the compression tool
Y force H initial sample height
0
1 compression tool ΔH variation in sample height
a
2 sample Apparent fracture point.
3 fixed base
Figure 1 — Schematic principle of uniaxial compression at constant displacement rate
5 Apparatus
Usual laboratory equipment and, in particular, the following.
5.1 Cork-borer, such as that shown in Figure 2 as an example.
It is recommended to mount the cork-borer on a drill-stand in order to drive it slowly and steadily
through the test sample.
2
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ISO/DTS 17996:2022(E)
IDF/RM 205 :2022(E)
Key
1 cork borer
2 cheese plug
Example A: d external diameter (d = 25 mm)
e e
 d internal diameter (d = 23 mm)
i i
 D cutting head diameter (D = 20 mm)
Example B: d external diameter (d = 16,5 mm)
e e
 D cutting head diameter (D = d is the internal diameter of 15,3 mm)
i
Figure 2 — Cork-borers for cutting cylindrical cheese plug
5.2 Parallel-wire cutting device, with a wire of diameter less than or equal to 0,4 mm and with a
system to keep the two wires parallel to each other and perpendicular to the plug. It should also include
a mechanically driven cutting system to cut the test sample to the required height.
5.3 Measuring cell, with a support and compression plate of the same stiff material, with smooth
and parallel surfaces, e.g. stainless steel, aluminium or polytetrafluoroethylene (PTFE), of diameter
larger (by 20 %) than that of the deformed test portion when at maximum compression. The load cell
capacity shall have a reasonable relationship to the expected maximum force.
5.4 Compression instrument, providing compression functions typically consisting of two (or
one) vertical columns on a platform and a crosshead connected perpendicular to these columns. This
crosshead is driven vertically up and down by a motor. The load cell is typically directly connected to
this crosshead and fixed to the compression tool (top plate) as shown in Figure 1. The fixed base in
Figure 1 (bottom plate) is connected to the platform.
6 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 document. A recommended sampling method is
[1]
given in ISO 707 | IDF 50 .
3
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ISO/DTS 17996:2022(E)
IDF/RM 205 :2022(E)
7 Procedure
7.1 Thermal equilibration of test samples
If the storage temperature of the loaf of cheese is above that of the measuring temperature, then the loaf
of cheese shall be equilibrated at the measuring temperature for at least 50 h before further preparation
of the test sample because of the slow crystallization of milk fat in the cheese.
If the storage temperature of the loaf of cheese is below that of the measuring temperature, before any
preparation, store the loaf of cheese at the measuring temperature for at least 12 h. If there are specific
difficulties that can occur during the sample preparation at the measuring temperature, then sample at
the lower storage temperature and then equilibrate the test samples to the measurement temperature.
In this case, the sample thermal equilibration time may be less than 12 h.
NOTE Examples of specific sampling difficulties are that the cheese is hard to cut, or a heated loaf of cheese
changes the storage regime and therefore stops the use of the unsampled portions of the loaf of cheese for future
measurements.
The following shall be avoided:
a) dehydration of the test sample during the period of thermal equilibration;
b) deformation of the test sample due to its own mass.
7.2 Test portion
7.2.1 Location
Take the test portion from the loaf of the cheese with a plug about half a radius, either along a circle of a
cylindrical cheese, or along one side of a rectangular cheese (see Figure 3).
Cut the test portion in the plug in the area representing around half of the length (see Figure 4, plug A).
If the height of cheese is sufficient, two portions can be taken as shown in Figure 4, plug B and plug C.
a) Cheese with cylindrical form b) Cheese with parallelepipedal form
Key
R radius • plug in case 1
W width ° plug in case 2
L length
Figure 3 — Location of plug for cheese sampling
4
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ISO/DTS 17996:2022(E)
IDF/RM 205 :2022(E)
Key
1 sample
Figure 4 — Three types of sampling in plug
7.2.2 Direction
The standard direction for taking the test portion is parallel to the pressure axis in cheese making. See
Annex B for non­standard sampling conditions.
7.2.3 Geometry
The shape of the test portion shall be a cylinder with initial height/diameter ratio (h /d ) of between
0 0
1,1 and 1,5.
The initial height, h , of the test portion shall range from 12,5 mm to 25 mm. The diameter, d , for a
0 0
given height follows the above­mentioned ratio.
7.2.4 Cutting
Remove the rind or the plastic cover. Take a test portion using a cork­borer (5.1) with shapes shown in
Figure 2. For sticky cheeses, samples are easier to take with corer A than corer B. For cheese varieties
showing shortness or brittleness, form B as shown in Figure 2 is more appropriate than form A. It is
recommended to use a cork-borer mounted on a drill-stand in order to drive it slowly and steadily
through the test sample.
If it is difficult to obtain a good cylindrical form, it is recommended to use mineral oil of low viscosity
1)
(e.g. Vaseline® oil) to lubricate the cork­borer. Do not test samples with cracks, holes or other visible
defects.
1) Vaseline® is an example of a suitable product available commercially. This information is given for the
convenience of users of this document and does not constitute an endorsement by ISO of this product.
5
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ISO/DTS 17996:2022(E)
IDF/RM 205 :2022(E)
Use a parallel-wire cutting device to cut the test sample to the required height. The wire diameter shall
be less than or equal to 0,4 mm. It is essential to have a system that keeps the two wires parallel to
each other and perpendicular to the plug. Preferably, use a mechanically driven cutting system. Taking
these precautions into account reduces the lack in parallelism between the sample surface and the
compression plate.
7.2.5 Delay
A delay between the taking of a test portion and its testing allows stress relaxation of the test portion.
The recommended delay is between 10 min and 15 min. The upper limit is not strictly fixed but it should
not exceed 2 h. This recommendation is not relevant when sampling is done at a lower temperature
than the measuring temperature.
Store the test samples at the measuring temperature (see 7.3.5) and see Annex B for non­standard
conditions. Store samples in a pill-box or wrapped in plastic film to avoid dehydration during the delay
between sampling and testing.
7.3 Test conditions
7.3.1 Relative deformation
Perform the compression to just beyond the apparent fracture point (see Figure 5, curve 1) or to a
predefined maximum deformation (see Figure 5, curve 2).
Key
a
X deformation Apparent fracture point.
b
Y force Maximum deformation.
1 curve 1
2 curve 2
Figure 5 — Examples of compression curves
7.3.2 Crosshead speed
The standard value of the crosshead speed or displacement rate is 50 mm/min (or 0,83 mm/s) for initial
height 12,5 mm ≤ h ≤ 25 mm.
0
7.3.3 Number of compression cycles
Perform one compression cycle.
6
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ISO/DTS 17996:2022(E)
IDF/RM 205 :2022(E)
7.3.4 Number of test portions
Measure at least four test portions, but preferably carry out more than this.
7.3.5 Measuring temperature
Measure at the standardized measuring temperature of 15 °C ± 1 °C.
NOTE Although the chosen test temperature of 15 °C is a good compromise for a single temperature, the
challenge remains that many studies will use other temperatures for good reasons, as outlined in Annex A.
Follow Annex A for non­standard conditions.
7.3.6 Nature of the interface between test portion and plates
Use a low viscosity mineral oil as lubricant between the test portion and the plates. Apply the oil as a
very thin layer on the plates.
8 Analysis of the compression curves
8.1 Data representation and calculation
8.1.1 Data representation
Raw data files contain data pairs (s , F ) with displacement data, s , of the compression plate and force
i i i
data, F , in units depending on the system. If the displacement of the plate is recorded right from the
i
beginning of the test (i.e. before the plate is in contact with the sample), then compute the absolute
deformation data, |Δh |, of the sample before any other calculation is performed. Let |s | be the absolute
i 0
displacement of the plate when the force becomes significantly different from zero (indicating the start
of the compression of the sample). Then calculate the absolute sample deformation data, |Δh |, using
i
Formula (1):
Δhs=− s (1)
ii 0
where
|s | is the absolute displacement of the plate when the force becomes significantly different from
0
zero;
|s | is the absolute displacement of the plate.
i
The correct sample deformation data, Δh , is then found using Formula (2):
i
ΔΔhh=− (2)
ii
For further processing, it may be useful to remove data from the free precontact displacement of the
compression plate.
If the measuring system automatically records the absolute deformation |Δh| of the sample (starting
with zero as soon as the contact force becomes significant), then |s | is equal to |Δh | and no correction
i i
has to be applied. However, the sign assignment Δh = – |Δh | may still be necessary.
i i
The deformation/force data (Δh, F) shall be transformed to the normalized measures strain and stress
in order to be comparable. Graphical representations, numerical values and computed parameters of
compression curves are given in terms of strain and stress. Both of the following representations to
evaluate the curves are recommended options. Either one or both of these options may be used:
a) engineering stress, σ , versus Cauchy strain, ε ;
u C
7
© ISO and IDF 2022 – All rights reserved

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ISO/DTS 17996:2022(E)
IDF/RM 205 :2022(E)
b) corrected stress, σ , versus Hencky strain, ε
c H.
Strain has no dimension; stress is given in pascals (Pa) or kilopascals (kPa).
Examples of compression curves from some cheese varieties are given in Annex B.
The symbol σ is also known as “uncorrected stress”; ε is the engineering strain or relative
u C
deformation. The terms “true stress” and “true strain” to denote corrected stress σ , and Hencky strain
c
ε , respectively, are not recommended.
H
Stress correction is based on the cylindrical shape and volume constancy of the sample during the test,
allowing the calculation of the cross­section, A , at each time point.
t
This changing cross­section, A , is calculated using Formula (3):
t
Ah⋅
00
AA= Δh = (3)
()
t
ht()
where
h is the initial sample height;
0
A is the initial cross-section;
0
h(t) is the height at each time point is derived from h and the deformation Δh, h(t) = h + Δh.
0 0
Under compression, Δh is a negative quantity (Δh ≤ 0) because the deformation reduces the
height of the sample, thus h(t) = h – |Δh| (see Reference [4]).
0
8.1.2 Calculation of stress and strain
Formulae (4), (5), (6) and (7) assume that Δh ≤ 0.
The transformations of force into stress and of deformation into strain are applied to all data points
(Δh, F).
F
t
σ = (4)
u
A
0
Δh
ε = (5)
C
h
0
F F h F
t tt t
σε== ⋅= ⋅+11=⋅σε+ (6)
() ()
cC uC
A A h A
t 00 0
h hh+Δ
   
t 0
εε = ln = ln =+ln()1 (7)
HC   
h h
 0   0 
NOTE 1 According to Formulae (5) and (6), compressive strain is a negative quantity (see Reference [4]).
Although rheologically correct, it is not common practice to indicate the minus sign in graphical representations
or in the computed parameters of the compression curves. The use of the sign can be useful if results from
compression (ε < 0) and tension (ε > 0) need to be distinguished.
NOTE 2 The application of stress correction according to Formula (6) (see Reference [5]) induces a shift of
the apparent fracture point towards lower absolute strain values (apart from decreasing the numerical stre
...