ISO 22935-1:2023

Milk and milk products — Sensory analysis — Part 1: Recruitment, selection, training and monitoring of assessors

This document gives general guidance for the recruitment, selection, training, and monitoring of assessors for sensory analysis of milk and milk products. It specifies criteria for the selection, and procedures for the training and monitoring, of selected assessors and expert sensory assessors for milk and milk products. It supplements the information given in ISO 8586 that deals with expert assessors.

Lait et produits laitiers — Analyse sensorielle — Partie 1: Recrutement, sélection, entraînement et contrôle des sujets

Le présent document spécifie des recommandations pour le recrutement, la sélection, l’entraînement et le contrôle des sujets pour l’analyse sensorielle du lait et des produits laitiers. Il spécifie les critères de sélection et des modes opératoires pour l’entraînement et le contrôle des sujets qualifiés et des sujets experts sensoriels dans l’analyse sensorielle du lait et des produits laitiers. Il constitue également un complément aux informations données dans l’ISO 8586 traitant des sujets experts sensoriels.

Mleko in mlečni proizvodi - Senzorična analiza - 1. del: Splošne smernice za novačenje, izbiro, usposabljanje in spremljanje ocenjevalcev

General Information

• Status: Published
• Publication Date: 11-Apr-2023
• ICS: 03.100.30 - Management of human resources
• ICS: 67.100.01 - Milk and milk products in general
• 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: 12-Apr-2023
• Due Date: 21-Oct-2022
• Completion Date: 12-Apr-2023
• Ref Project: oSIST ISO/DIS 22935-1:2023 - Milk and milk products — Sensory analysis — Part 1: General guidance for the recruitment, selection, training and monitoring of assessors

Relations

• Revises: ISO 22935-1:2009 - Milk and milk products — Sensory analysis — Part 1: General guidance for the recruitment, selection, training and monitoring of assessors
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 22935-1
IDF 99-1
Second edition
2023-04
Milk and milk products — Sensory
analysis —
Part 1:
Recruitment, selection, training and
monitoring of assessors
Lait et produits laitiers — Analyse sensorielle —
Partie 1: Recrutement, sélection, entraînement et contrôle des sujets
Reference numbers
ISO 22935-1:2023(E)
IDF 99-1:2023(E)
© ISO and IDF 2023

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ISO 22935-1:2023(E)
IDF 99-1:2023(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
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Contents Page
Forewords .iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Recruitment . 2
5 Screening. 2
5.1 Screening form and requirements . 2
5.2 Preparation of test samples for screening . 3
5.3 Screening tests, materials and methods . 4
5.3.1 General . 4
5.3.2 Odour recognition . 4
5.3.3 Basic taste recognition . 4
5.3.4 Ranking tests . 5
5.3.5 Difference testing . 6
5.3.6 Descriptive ability and group discussion . 9
5.3.7 Marking schedule summary . . 10
6 Selection .11
7 Requirements for assessors in the panel .12
8 Training and monitoring of assessors for dairy products .12
8.1 General .12
8.2 References. 13
9 Performance .16
Bibliography .17
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ISO 22935-1:2023(E)
IDF 99-1:2023(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 22935-1 | IDF 99-1:2009), which has been
technically revised.
The main changes are as follows:
— the Normative references have been updated;
— a few changes have been made to reference materials.
A list of all parts in the ISO 22935 series can be found on the ISO website.
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.
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ISO 22935-1:2023(E)
IDF 99-1:2023(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 Statistics and Automation 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 S17 of the Standing Committee on Statistics and
Automation under the aegis of its project leader Dr H. Kraggerud (NO).
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Introduction
The purpose of the ISO 22935 | IDF 99 series is to give guidance on methodology for sensory analysis
and the use of a common nomenclature of terms for milk and milk products.
To achieve that, the ISO 22935 | IDF 99 series is divided into three parts.
ISO 6658 should be consulted for an overview of sensory methods other than the one provided in
ISO 22935-3 | IDF 99-3.
The principles described are largely derived from various International Standards on the topic.
It is important that safety issues are handled during sensory evaluations (see ISO 20613).
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ISO 22935-1:2023(E)
INTERNATIONAL STANDARD
IDF 99-1:2023(E)
Milk and milk products — Sensory analysis —
Part 1:
Recruitment, selection, training and monitoring of
assessors
1 Scope
This document gives general guidance for the recruitment, selection, training, and monitoring of
assessors for sensory analysis of milk and milk products.
It specifies criteria for the selection, and procedures for the training and monitoring, of selected
assessors and expert sensory assessors for milk and milk products. It supplements the information
given in ISO 8586 that deals with expert assessors.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 4120, Sensory analysis — Methodology — Triangle test
ISO 4121, Sensory analysis — Guidelines for the use of quantitative response scales
ISO 5492, Sensory analysis — Vocabulary
ISO 5496, Sensory analysis — Methodology — Initiation and training of assessors in the detection and
recognition of odours
ISO 6658, Sensory analysis — Methodology — General guidance
ISO 8586:2012, Sensory analysis — General guidelines for the selection, training and monitoring of selected
assessors and expert sensory assessors
ISO 8587, Sensory analysis — Methodology — Ranking
ISO 8589, Sensory analysis — General guidance for the design of test rooms
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4121, ISO 5492, ISO 5496,
ISO 6658, ISO 8586 and ISO 8589 and the following 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/
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
3.1
sensory analysis
science involved with the assessment of the sensory attributes of a product by the senses
[SOURCE: ISO 5492:2008, 1.1, modified — “sensory” replaced “organoleptic” in the definition.]
3.2
expert sensory assessor
selected assessor with a demonstrated sensory sensitivity and with considerable training and
experience in sensory testing, who is able to make consistent and repeatable sensory assessments of
various products
Note 1 to entry: Examples of “various products” are “dairy products”.
[SOURCE: ISO 5492:2008, 1.8, modified — Note 1 to entry added.]
3.3
appearance
all the visible attributes of a substance or object
Note 1 to entry: For a dairy product, the visual attributes are both internal and external, and include shape,
colour, loose liquid, phase separation, wanted or unwanted particles, and openings.
[SOURCE: ISO 5492:2008, 3.1, modified — Note 1 to entry added.]
3.4
fingerfeel
mixed experience derived from sensations on the fingers that relate to physical properties of a stimulus
3.5
flavour
complex combination of the olfactory, gustatory and trigeminal sensations perceived during tasting
[SOURCE: ISO 5492:2008, 3.20, modified — Note 1 to entry deleted.]
4 Recruitment
Assessors can be recruited from within a company (laboratory staff, production staff, administration
staff, etc.), who are not involved with project work, or from outside a company. Outside assessors can be
recruited by advertisement or by word of mouth. The panel candidates should have an understanding
of the amount of time that will be required for the screening process and for actual panel work. A large
enough pool of available candidates should be screened in order to have enough assessors available to
select from when forming a panel. The trainee assessor should have satisfactory personal qualifications
for assessments and should be pre-selected by:
a) the use of screening tests to assess the ability of candidates to perceive, discriminate and describe
sensory attributes;
b) a general understanding of the concepts of sensory evaluation;
c) a general liking or interest in dairy products.
5 Screening
5.1 Screening form and requirements
Potential applicants should go through two forms of screening via an interview and sensory screening
tests. During the interview, the applicants should fill out a pre-screening form which indicates the times
that they are available for panels and any health issues they can have, e.g. arthritis which can interfere
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
with the evaluation of product texture in-hand (fingerfeel), lactose intolerance, food allergies, wearing
of dentures, smoking status, and any other issues of concern.
Flavoured water solutions and dairy products should be used to indicate if the potential assessor can
recognize specific tastes or flavours at different intensities. The potential evaluator shall be able to
detect certain flavours within complex dairy products. The following three sessions each take assessors
approximately 45 min to 1 h to complete. These screening exercises are suggestions only and may be
adapted to the application area of the assessors. The sessions described in Tables 1 to 3 may be broken
down into smaller or larger sessions depending on how much time is available.
Table 1 — Session 1 — Basic odour and taste recognition
Test Reference Result
1 5.3.2 Odour recognition
2 5.3.3 Basic taste recognition
3 5.3.4, Table 8 Ranking of basic taste — sweet
4 5.3.4, Table 9 Ranking of basic taste — sour
5 5.3.4, Table 10 Ranking of basic taste — salty
6 5.3.4, Table 11 Ranking of basic taste — bitter
Table 2 — Session 2 — Milk powder and cream products
Test Reference Result
7 5.3.5, Table 14 Triangle test — milk powder
8 5.3.5, Table 15 Triangle test — butter
9 5.3.5, Table 16 Triangle test — salted butter
10 5.3.6.3 Round table discussion — cream evaluation
11 5.3.4, Table 12 Ranking of texture — body/creaminess
12 5.3.5, Table 13 Triangle test — aged milk powder
Table 3 — Session 3 — Cheese
Test Reference Result
13 5.3.5, Table 16 Triangle test — cheese
14 5.3.6.2 Round table discussion — cheese evaluation
15 5.3.5, Table 16 Triangle test — bitter cheese
16 5.3.5, Table 17 Triangle test — cheese firmness
17 5.3.5, Table 17 Triangle test — cheese smoothness
Mark each section as per each marking schedule. Other examples of screening exercises can be found in
ISO 8586.
5.2 Preparation of test samples for screening
5.2.1 If possible, prepare test samples on the day of the evaluation.
5.2.2 For screening purposes, it is easier to serve test samples in the same order to all assessors.
5.2.3 If appropriate, use test sample questionnaires for all screening exercises found in ISO 4120
(triangle test), ISO 8587 (ranking test), ISO 6658 and ISO 4121 (scales).
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
5.3 Screening tests, materials and methods
5.3.1 General
The screening tests, materials and methods presented in this clause are recommendations only. They
can be adapted to suit the needs of an individual company.
5.3.2 Odour recognition
Follow the instructions outlined in ISO 8586:2012, 5.4.1, for details on how to prepare the test samples
and conduct this test. Table 4 suggests other aromas that can be used.
Table 4 — Examples of olfactory materials for odour description test
Blind code Sample preparation
(example)
981 Citronella oil (lemon, cleaning fluid)
194 Orange
229 Caramel
371 Butyric acid
926 Acetic acid
174 Ammonia
a
746 (Z)-hex-3-en-1-ol
831 Oct-1-en-3-ol
556 Vanilla
a
In older literature, known as cis-hex-3-en-1-ol.
Candidates are graded according to performance, as shown in Table 5. For each sample, a total of three
points can be achieved. If the assessor uses words other than those listed in Table 5, score appropriately.
Table 5 — Marking schedule for odour recognition
Correct answer
Sample
3 points 2 points 1 point
Citronella oil Citronella oil Lemony, cleaning fluid Citrus, fruity
Orange Orange Lemon Citrus, fruity
Caramel Caramel Vanilla, malt, toasted Sweet
Butyric acid Rancid butter Parmesan cheese Vomit, baby burp
Acetic acid Acetic acid Vinegar Sour/off milk
Ammonia Ammonia Cleaning fluid, urine Pungent
(Z)-hex-3-en-1-ol Green grass Green beans Green vegetable
Oct-1-en-3-ol Mushroom Cellar, musty Mouldy
Vanilla Vanilla Custard, dessert Sweets, candy
5.3.3 Basic taste recognition
The solutions can be prepared as shown in Table 6. Present the solutions to the assessors in the same
order, and one of the solutions twice. Ask the assessor to identify the basic taste that is represented by
the solution.
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Table 6 — Basic taste solutions
Blind code Answer Concentration Sample preparation
(examples)
10 g/l sucrose
683 Sweet 10 g sucrose + 1 l water
(1 % mass fraction)
2 g/l NaCl
429 Salty 2 g NaCl + 1 l water
(0,2 % mass fraction)
0,3 g/l citric acid
662 Sour 0,3 g citric acid + 1 l water
(0,03 % mass fraction)
0,3 g/l caffeine
353 Bitter 0,3 g caffeine + 1 l water
(0,03 % mass fraction)
0,6 g monosodium glutamate or 0,18 g umami mixture
0,6 g/l monosodium
Umami (50 % mass fraction monosodium glutamate, 25 % mass
768 glutamate
(optional) fraction 5′- guanylic acid, 25 % mass fraction inosinic
(0,06 % mass fraction)
acid) + 1 l water with 0,5 g NaCl
418 Water water
Candidates are graded according to performance on the scale shown in Table 7.
Table 7 — Gradation scale I
Points Result
6 all correct
5 five correct
4 four correct
3 three correct
2 two correct
1 one correct
0 none correct
5.3.4 Ranking tests
A minimum of four test samples should be ranked in order of increasing intensity. This test will indicate
whether the assessor can tell the difference between samples for certain basic tastes.
Samples for ranking of sweetness, sourness, saltiness, bitterness and creamy flavour are given in
Tables 8, 9, 10, 11 and 12, respectively.
This test can also indicate the threshold levels of assessors (i.e. if the assessor did not correctly identify
the order of the lower intensities, that would indicate that this assessor cannot taste at lower levels for
this particular attribute).
NOTE All samples are randomized, but are presented to all the assessors in the same order.
Table 8 — Sweet ranking
Blind code Correct Concentration Sample preparation
(examples) ranking
478 3 10 g/l sucrose (1 % mass per volume) 10 g sucrose + 1 l water
753 1 Water Water
578 4 15 g/l sucrose (1,5 % mass per volume) 15 g sucrose + 1 l water
248 2 5 g/l sucrose (0,5 % mass per volume) 5 g sucrose + 1 l water
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Table 9 — Sour ranking
Blind code Correct Concentration Sample preparation
(examples) ranking
145 2 0,10 g/l citric acid (0,01 % mass per vol- 0,10 g citric
ume) acid + 1 l water
249 4 0,5 g/l citric acid (0,05 % mass per volume) 0,5 g citric
acid + 1 l water
871 1 Water Water
675 3 0,3 g/l citric acid (0,03 % mass per volume) 0,3 g citric
acid + 1 l water
Table 10 — Salt ranking
Blind code Correct Concentration Sample preparation
(examples) ranking
985 2 1 g/l NaCl (0,1 % mass per volume) 1 g NaCl + 1 l water
813 1 Water Water
713 4 2 g/l NaCl (0,2 % mass per volume) 2 g NaCl + 1 l water
632 3 1,5 g/l NaCl (0,15 % mass per volume) 1,5 g NaCl + 1 l water
Table 11 — Bitter ranking
Blind code Correct Concentration Sample preparation
(examples) ranking
268 2 0,1 g/l caffeine (0,01 % mass per volume) 0,1 g caffeine + 1 l water
634 1 Water Water
919 4 0,5 g/l caffeine (0,05 % mass per volume) 0,5 g caffeine + 1 l water
752 3 0,3 g/l caffeine (0,03 % mass per volume) 0,3 g caffeine + 1 l water
Table 12 — Creamy flavour ranking
Blind code (examples) Correct ranking Sample preparation
268 1 Ultra high temperature (UHT) non-fat
634 4 UHT full fat + 20 % volume fraction UHT cream
919 3 UHT full fat + 3 % volume fraction UHT cream
752 2 UHT full fat
Candidates are graded according to performance on the scale shown in Table 13.
Table 13 — Gradation scale II
Points Result
4 Four correct
3 Adjacent switch
1 One correct
0 None correct
5.3.5 Difference testing
Difference testing indicates if the individual can detect small differences between samples for certain
flavours or textures.
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
The test samples should be selected so that they test the capability of the assessor to discriminate
between the samples based only on flavour or texture. An expert assessor can be used to select the
samples to be used in the tests. Examples of samples for difference testing are listed in Table 14 to
Table 17.
“Paired comparison” or “triangle” testing should be conducted on a series of products. If the assessor
thinks the samples are different, they can be asked to indicate what the difference is. This indicates if
assessors can accurately identify differences between products and name the difference.
All test samples are to be presented to all assessors in the same randomized order.
It is recommended that each set of samples be presented to the assessors twice to check if assessors can
replicate their results.
Table 14 — Suggested milk powder samples for difference testing — Flavour
Product Blind code Answer Sample preparation
(examples) (30 g per assessor)
100 % mass fraction
737 Skim milk powder
Milk powder sample set No. 1 932 Skim milk powder
895 Different Whole milk powder
769 Skim milk powder
Milk powder sample set No. 2 862 Different Whole milk powder
374 Skim milk powder
a
191 Different Oxidized milk powder
Aged milk powder sample set No. 1 748 Fresh milk powder
651 Fresh milk powder
426 Fresh milk powder
Aged milk powder sample set No. 2 621 Fresh milk powder
a
848 Different Oxidized milk powder
a
Refer to Table 28 for instructions on preparing oxidized milk samples.
Table 15 — Suggested butter samples for difference testing — Flavour
Product Blind code Answer Sample preparation
(examples) (1 cube per assessor)
148 Butter type 1
a
Butter sample set No. 1 897 Butter type 1
198 Different Butter type 2
539 Butter type 1
a
Butter sample set No. 2 575 Different Butter type 2
272 Butter type 1
514 Unsalted butter
Salted butter sample set No. 1 796 Unsalted butter
244 Different Salted butter
868 Unsalted butter
Salted butter sample set No. 2 364 Unsalted butter
968 Different Salted butter
a
The butters used in this test can be two different brands of butter, butter with known flavour differences or “spiked”
butter samples [e.g. regular butter and a grassy butter (butter with 1,5 % mass fraction hexanal)].
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Table 16 — Suggested cheese samples for difference testing — Flavour
Product Blind code Answer Sample preparation
(examples) (30 g per assessor)
345 Cheese type 1
Cheese sample set No. 1 223 Different Cheese type 2
466 Cheese type 1
342 Cheese type 1
a
Cheese sample set No. 2 555 Cheese type 1
314 Different Cheese type 2
871 Non-bitter cheese
Bitter cheese sample set No. 1 914 Non-bitter cheese
557 Different Bitter cheese
997 Non-bitter cheese
Bitter cheese sample set No. 2 663 Different Bitter cheese
783 Non-bitter cheese
a
The cheese samples used in this test can be collected from two different brands of cheese or cheeses with known
flavour differences.
Table 17 — Suggested cheese samples for difference testing — Texture
Product Blind code Answer Sample preparation
(examples)
278 Cheese firmness — brand 1
Cheese — firmness sample set No. 1 921 Different Cheese firmness — brand 2
461 Cheese firmness — brand 1
476 Different Cheese firmness — brand 2
Cheese — firmness sample set No. 2 133 Cheese firmness — brand 1
931 Cheese firmness — brand 1
119 Different Cheese smoothness — brand 1
Cheese — smoothness sample set No. 1 346 Cheese smoothness — brand 2
278 Cheese smoothness — brand 2
563 Cheese smoothness — brand 2
Cheese — smoothness sample set No. 2 572 Different Cheese smoothness — brand 1
588 Cheese smoothness — brand 2
Candidates are graded according to performance on scale III (see Table 18).
Table 18 — Gradation scale III
Points Result
6 Correct response for both sample set #1 and sample set #2
4 Correct response for either sample set #1 or sample set #2
0 Incorrect response for both sample set #1 and sample set #2
0,5 Correct description of difference
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
5.3.6 Descriptive ability and group discussion
5.3.6.1 General
During a group discussion, the candidates taste a product and generate descriptive terms for that
product by themselves. The candidates discuss their result with the other assessors (minimum of eight
in a group). This indicates if a candidate can break a product down into descriptive terms and how the
candidate interacts within group discussions.
Choose two types of dairy products for the descriptive discussion groups. This document gives examples
for cheese and cream samples; other samples can be selected depending on the types of products that
are commonly evaluated by panels. Ask the candidates to evaluate the samples presented and write
down all the descriptive words they can think of for the odour, texture and flavour of the products.
Once the evaluation has been conducted, get the group to discuss the samples and their differences.
5.3.6.2 Cheese
Samples are proposed in Table 19.
Table 19 — Suggested cheese samples for discussion groups
Blind code (examples) Sample preparation
524 Mild Cheddar cheese
831 Blue vein cheese
Candidates are graded according to performance on scale IV (see Table 20). Check all the descriptors
that the candidates generated and give them appropriate marks based on how many de
...

© ISO and IDF 2023 – All rights reserved
revISO/DIS 22935-1 | IDF 99-1:20222023(E)
Date: 2023-01-1202-13
ISO TC 34/SC 5
Secretariat: NEN
Milk and milk products — Sensory analysis — Part 1:
Recruitment, selection, training and monitoring of assessors
Lait et produits laitiers — Analyse sensorielle — Partie 1: Le recrutement, la sélection,
l'entraînement et le contrôle des sujets
DIS stage

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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
© 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: + 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.
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Contents
Forewords . iv
Introduction. vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Recruitment . 2
5 Screening . 3
5.1 Screening form and requirements . 3
5.2 Preparation of test samples for screening . 4
5.3 Screening tests, materials and methods . 4
5.3.1 General . 4
5.3.2 Odour recognition . 4
5.3.3 Basic taste recognition . 5
5.3.4 Ranking tests . 6
5.3.5 Difference testing . 7
5.3.6 Descriptive ability and group discussion . 10
5.3.7 Marking schedule summary . 12
6 Selection . 12
7 Requirements for assessors in the panel . 13
8 Training and monitoring of assessors for dairy products . 14
8.1 General . 14
8.2 References . 14
9 Performance . 18
Bibliography . 19
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ISO 22935-1:2023(E)
IDF 99-1:2023(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 22935-1 | IDF 99-1:2009), which has been
technically revised.
The main changes are as follows:
— the Normative references have been updated;
— a few changes have been made to reference materials.
A list of all parts in the ISO 22935 series can be found on the ISO website.
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

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ISO 22935-1:2023(E)
IDF 99-1:2023(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 Statistics and Automation 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 S17 of the Standing Committee on Statistics and
Automation under the aegis of its project leader Dr H. Kraggerud (NO).
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Introduction
The purpose of the ISO 22935 | IDF 99 series is to give guidance on methodology for sensory analysis and
the use of a common nomenclature of terms for milk and milk products.
To achieve that, the ISO 22935 | IDF 99 series is divided into three parts.
ISO 6658 should be consulted for an overview of sensory methods other than the one provided in
ISO 22935-3 | IDF 99-3.
The principles described are largely derived from various International Standards on the topic.
It is important that safety issues are handled during sensory evaluations (see ISO 20613).
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INTERNATIONAL STANDARD ISO 22935-1:2023(E)
IDF 99-1:2023(E)

Milk and milk products — Sensory analysis — Part 1:
Recruitment, selection, training and monitoring of assessors
1 Scope
This document gives general guidance for the recruitment, selection, training, and monitoring of
assessors for sensory analysis of milk and milk products.
It specifies criteria for the selection, and procedures for the training and monitoring, of selected assessors
and expert sensory assessors for milk and milk products. It supplements the information given in
ISO 8586 that deals with expert assessors.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 4120, Sensory analysis — Methodology — Triangle test
ISO 4121, Sensory analysis — Guidelines for the use of quantitative response scales
ISO 5492, Sensory analysis — Vocabulary
ISO 5496, Sensory analysis — Methodology — Initiation and training of assessors in the detection and
recognition of odours
ISO 6658, Sensory analysis — Methodology — General guidance
ISO 8586:2012, Sensory analysis — General guidelines for the selection, training and monitoring of selected
assessors and expert sensory assessors
ISO 8587, Sensory analysis — Methodology — Ranking
ISO 8589, Sensory analysis — General guidance for the design of test rooms
ISO 20613, Sensory analysis — General guidance for the application of sensory analysis in quality control
ISO 22935-2 | IDF 99-2, Milk and milk products — Sensory analysis: Part 2: Recommended methods for
sensory evaluation
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4121, ISO 5492, ISO 5496,
ISO 6658, ISO 8586 and ISO 8589 and the following 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
sensory analysis
science involved with the assessment of the sensory attributes of a product by the senses
[SOURCE: ISO 5492:2008, 1.1, modified — “sensory” replaced “organoleptic” in the definition.]
3.2
expert sensory assessor
selected assessor (3.2) with a demonstrated sensory sensitivity and with considerable training and
experience in sensory testing, who is able to make consistent and repeatable sensory assessments of
various products
Note 1 to entry: Examples of “various products” are “dairy products”.
[SOURCE: ISO 5492:2008, 1.8, modified — Note 1 to entry added.]
3.3
appearance
all the visible attributes of a substance or object.
Note 1 to entry: For a dairy product, the visual attributes are both internal and external, and include shape, colour,
loose liquid, phase separation, wanted or unwanted particles, and openings.
[SOURCE: ISO 5492:2008, 3.1, modified — Note 1 to entry added.]
3.4
fingerfeel
mixed experience derived from sensations on the fingers that relate to physical properties of a stimulus
3.5
flavour
complex combination of the olfactory, gustatory and trigeminal sensations perceived during tasting
[SOURCE: ISO 5492:2008, 3.20, modified — Note 1 to entry deleted.]
4 Recruitment
Assessors can be recruited from within a company (laboratory staff, production staff, administration staff,
etc.), who are not involved with project work, or from outside a company. Outside assessors can be
recruited by advertisement or by word of mouth. The panel candidates should have an understanding of
the amount of time that will be required for the screening process and for actual panel work. A large
enough pool of available candidates should be screened in order to have enough assessors available to
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
select from when forming a panel. The trainee assessor should have satisfactory personal qualifications
for assessments and should be pre-selected by:
a) the use of screening tests to assess the ability of candidates to perceive, discriminate and describe
sensory attributes;
b) a general understanding of the concepts of sensory evaluation;
c) a general liking or interest in dairy products.
5 Screening
5.1 Screening form and requirements
Potential applicants should go through two forms of screening via an interview and sensory screening
tests. During the interview, the applicants should fill out a pre-screening form which indicates the times
that they are available for panels and any health issues they can have, e.g. arthritis which can interfere
with the evaluation of product texture in-hand (fingerfeel), lactose intolerance, food allergies, wearing of
dentures, smoking status, and any other issues of concern.
Flavoured water solutions and dairy products should be used to indicate if the potential assessor can
recognize specific tastes or flavours at different intensities. The potential evaluator shall be able to detect
certain flavours within complex dairy products. The following three sessions each take assessors
approximately 45 min to 1 h to complete. These screening exercises are suggestions only and may be
adapted to the application area of the assessors. The sessions described in Tables 1 to 3 may be broken
down into smaller or larger sessions depending on how much time is available.
Table 1 — Session 1 — Basic odour and taste recognition
Test Reference Result
1 5.3.2 Odour recognition
2 5.3.3 Basic taste recognition
3 5.3.4, Table 8 Ranking of basic taste — sweet
4 5.3.4, Table 9 Ranking of basic taste — sour
5 5.3.4, Table 10 Ranking of basic taste — salty
6 5.3.4, Table 11 Ranking of basic taste — bitter
Table 2 — Session 2 — Milk powder and cream products
Test Reference Result
7 5.3.5, Table 14 Triangle test — milk powder
8 5.3.5, Table 15 Triangle test — butter
9 5.3.5, Table 16 Triangle test — salted butter
10 5.3.6.3 Round table discussion — cream evaluation
11 5.3.4, Table 12 Ranking of texture — body/creaminess
12 5.3.5, Table 13 Triangle test — aged milk powder
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Table 3 — Session 3 — Cheese
Test Reference Result
13 5.3.5, Table 16 Triangle test — cheese
14 5.3.6.2 Round table discussion — cheese evaluation
15 5.3.5, Table 16 Triangle test — bitter cheese
16 5.3.5, Table 17 Triangle test — cheese firmness
17 5.3.5, Table 17 Triangle test — cheese smoothness
Mark each section as per each marking schedule. Other examples of screening exercises can be found in
ISO 8586.
5.2 Preparation of test samples for screening
5.2.1 If possible, prepare test samples on the day of the evaluation.
5.2.2 For screening purposes, it is easier to serve test samples in the same order to all assessors.
5.2.3 If appropriate, use test sample questionnaires for all screening exercises found in ISO 4120
(triangle test), ISO 8587 (ranking test), ISO 6658 and ISO 4121 (scales).
5.3 Screening tests, materials and methods
5.3.1 General
The screening tests, materials and methods presented in this clause are recommendations only. They can
be adapted to suit the needs of an individual company.
5.3.2 Odour recognition
Follow the instructions outlined in ISO 8586:2012, 5.4.1, for details on how to prepare the test samples
and conduct this test. Table 4 suggests other aromas that can be used.
Table 4 — Examples of olfactory materials for odour description test
Blind code Sample preparation
(example)
981 Citronella oil (lemon, cleaning fluid)
194 Orange
229 Caramel
371 Butyric acid
926 Acetic acid
174 Ammonia
a
746 (Z)-hex-3-en-1-ol
831 Oct-1-en-3-ol
556 Vanilla
a
In older literature, known as cis-hex-3-en-1-ol.
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Candidates are graded according to performance, as shown in Table 5. For each sample, a total of three
points can be achieved. If the assessor uses words other than those listed in Table 5, score appropriately.
Table 5 — Marking schedule for odour recognition
Correct answer
Sample
3 points 2 points 1 point
Citronella oil Citronella oil Lemony, cleaning fluid Citrus, fruity
Orange Orange Lemon Citrus, fruity
Caramel Caramel Vanilla, malt, toasted Sweet
Butyric acid Rancid butter Parmesan cheese Vomit, baby burp
Acetic acid Acetic acid Vinegar Sour/off milk
Ammonia Ammonia Cleaning fluid, urine Pungent
(Z)-hex-3-en-1-ol Green grass Green beans Green vegetable
Oct-1-en-3-ol Mushroom Cellar, musty Mouldy
Vanilla Vanilla Custard, dessert Sweets, candy
5.3.3 Basic taste recognition
The solutions can be prepared as shown in Table 6. Present the solutions to the assessors in the same
order, and one of the solutions twice. Ask the assessor to identify the basic taste that is represented by
the solution.
Table 6 — Basic taste solutions
Blind code Answer Concentration Sample preparation
(examples)
10 g/l sucrose
683 Sweet 10 g sucrose + 1 l water
(1 % mass fraction)
2 g/l NaCl
429 Salty 2 g NaCl + 1 l water
(0,2 % mass fraction)
0,3 g/l citric acid
662 Sour 0,3 g citric acid + 1 l water
(0,03 % mass fraction)
0,3 g/l caffeine
353 Bitter 0,3 g caffeine + 1 l water
(0,03 % mass fraction)
0,6 g monosodium glutamate or 0,18 g umami mixture
0,6 g/l monosodium
Umami (50 % mass fraction monosodium glutamate, 25 % mass
768 glutamate
(optional) fraction 5′- guanylic acid, 25 % mass fraction inosinic
(0,06 % mass fraction)
acid) + 1 l water with 0,5 g NaCl
418 Water  water
Candidates are graded according to performance on the scale shown in Table 7.
Table 7 — Gradation scale I
Points Result
6 all correct
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Points Result
5 five correct
4 four correct
3 three correct
2 two correct
1 one correct
0 none correct
5.3.4 Ranking tests
A minimum of four test samples should be ranked in order of increasing intensity. This test will indicate
whether the assessor can tell the difference between samples for certain basic tastes.
Samples for ranking of sweetness, sourness, saltiness, bitterness and creamy flavour are given in
Tables 8, 9, 10, 11 and 12, respectively.
This test can also indicate the threshold levels of assessors (i.e. if the assessor did not correctly identify
the order of the lower intensities, that would indicate that this assessor cannot taste at lower levels for
this particular attribute).
NOTE All samples are randomized, but are presented to all the assessors in the same order.
Table 8 — Sweet ranking
Blind code (examples) Correct Concentration Sample preparation
ranking
478 3 10 g/l sucrose (1 % mass per volume) 10 g sucrose + 1 l water
753 1 Water Water
578 4 15 g/l sucrose (1,5 % mass per volume) 15 g sucrose + 1 l water
248 2 5 g/l sucrose (0,5 % mass per volume) 5 g sucrose + 1 l water
Table 9 — Sour ranking
Blind code (examples) Correct Concentration Sample preparation
ranking
145 2 0,10 g/l citric acid (0,01 % mass per 0,10 g citric
volume) acid + 1 l water
249 4 0,5 g/l citric acid (0,05 % mass per volume) 0,5 g citric
acid + 1 l water
871 1 Water Water
675 3 0,3 g/l citric acid (0,03 % mass per volume) 0,3 g citric
acid + 1 l water
Table 10 — Salt ranking
Blind code (examples) Correct Concentration Sample preparation
ranking
985 2 1 g/l NaCl (0,1 % mass per volume) 1 g NaCl + 1 l water
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Blind code (examples) Correct Concentration Sample preparation
ranking
813 1 Water Water
713 4 2 g/l NaCl (0,2 % mass per volume) 2 g NaCl + 1 l water
632 3 1,5 g/l NaCl (0,15 % mass per volume) 1,5 g NaCl + 1 l water
Table 11 — Bitter ranking
Blind code (examples) Correct Concentration Sample preparation
ranking
268 2 0,1 g/l caffeine (0,01 % mass per volume) 0,1 g caffeine + 1 l water
634 1 Water Water
919 4 0,5 g/l caffeine (0,05 % mass per volume) 0,5 g caffeine + 1 l water
752 3 0,3 g/l caffeine (0,03 % mass per volume) 0,3 g caffeine + 1 l water
Table 12 — Creamy flavour ranking
Blind code (examples) Correct ranking Sample preparation
Ultra High Temperaturehigh temperature (UHT)
268 1
non-fat
634 4 UHT full fat + 20 % volume fraction UHT cream
919 3 UHT full fat + 3 % volume fraction UHT cream
752 2 UHT full fat
Candidates are graded according to performance on the scale shown in Table 13.
Table 13 — Gradation scale II
Points Result
4 Four correct
3 Adjacent switch
1 One correct
0 None correct
5.3.5 Difference testing
Difference testing indicates if the individual can detect small differences between samples for certain
flavours or textures.
The test samples should be selected so that they test the capability of the assessor to discriminate
between the samples based only on flavour or texture. An expert assessor can be used to select the
samples to be used in the tests. Examples of samples for difference testing are listed in Table 14 to
Table 17.
“Paired comparison” or “triangle” testing should be conducted on a series of products. If the assessor
thinks the samples are different, they can be asked to indicate what the difference is. This indicates if
assessors can accurately identify differences between products and name the difference.
All test samples are to be presented to all assessors in the same randomized order.
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
It is recommended that each set of samples be presented to the assessors twice to check if assessors can
replicate their results.
Table 14 — Suggested milk powder samples for difference testing — Flavour
Product Blind code Answer Sample preparation
(examples) (30 g per assessor)
100 % mass fraction
737  Skim milk powder
Milk powder sample set No. 1 932  Skim milk powder
895 Different Whole milk powder
769  Skim milk powder
Milk powder sample set No. 2 862 Different Whole milk powder
374  Skim milk powder
Oxidized milk
191 Different
a
powder
Aged milk powder sample set No. 1
748  Fresh milk powder
651  Fresh milk powder
426  Fresh milk powder
621  Fresh milk powder
Aged milk powder sample set No. 2
Oxidized milk
848 Different
a
powder

a
Refer to Table 28 for instructions on preparing oxidized milk samples.
Table 15 — Suggested butter samples for difference testing — Flavour
Product Blind code Answer Sample preparation
(examples) (1 cube per assessor)
148  Butter type 1
a
Butter sample set No. 1 897  Butter type 1
198 Different Butter type 2
539  Butter type 1
a
Butter sample set No. 2 575 Different Butter type 2
272  Butter type 1
514  Unsalted butter
Salted butter sample set No. 1 796  Unsalted butter
244 Different Salted butter
868  Unsalted butter
Salted butter sample set No. 2 364  Unsalted butter
968 Different Salted butter
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Product Blind code Answer Sample preparation
(examples) (1 cube per assessor)
a
The butters used in this test can be two different brands of butter, butter with known flavour differences or

“spiked” butter samples [e.g. regular butter and a grassy butter (butter with 1,5 % mass fraction hexanal)].
Table 16 — Suggested cheese samples for difference testing — Flavour
Product Blind code Answer Sample preparation
(examples) (30 g per assessor)
345  Cheese type 1
Cheese sample set No. 1 223 Different Cheese type 2
466  Cheese type 1
342  Cheese type 1
a
Cheese sample set No. 2 555  Cheese type 1
314 Different Cheese type 2
871  Non-bitter cheese
Bitter cheese sample set No. 1 914  Non-bitter cheese
557 Different Bitter cheese
997  Non-bitter cheese
Bitter cheese sample set No. 2 663 Different Bitter cheese
783  Non-bitter cheese
a
The cheese samples used in this test can be collected from two different brands of cheese or cheeses with
known flavour differences.
Table 17 — Suggested cheese samples for difference testing — Texture
Product Blind code Answer Sample preparation
(examples)
278  Cheese firmness — brand 1
Cheese — firmness sample set No. 1 921 Different Cheese firmness — brand 2
461  Cheese firmness — brand 1
476 Different Cheese firmness — brand 2
Cheese — firmness sample set No. 2 133  Cheese firmness — brand 1
931  Cheese firmness — brand 1
119 Different Cheese smoothness — brand 1
Cheese — smoothness sample set No. 1 346  Cheese smoothness — brand 2
278  Cheese smoothness — brand 2
563  Cheese smoothness — brand 2
Cheese — smoothness sample set No. 2 572 Different Cheese smoothness — brand 1
588  Cheese smoothness — brand 2
Candidates are graded according to performance on scale III (see Table 18).
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Table 18 — Gradation scale III
Points Result
6 Correct response for both sample set #1 and sample set #2
4 Correct response for either sample set #1 or sample set #2
0 Incorrect response for both sample set #1 and sample set #2
0,5 Correct description of difference
5.3.6 Descriptive ability and group discussion
5.3.6.1 General
During a group discussion, the candidates taste a product and generate descriptive terms for that product
by themselves. The candidates discuss their result with the other assessors (minimum of eight in a
group). This indicates if a candidate can break a product down into descriptive terms and how the
candidate interacts within group discussions.
Choose two types of dairy products for the descriptive discussion groups. This document gives examples
for cheese and cream samples; other samples can be selected depending on the types of products that are
commonly evaluated by panels. Ask the candidates to evaluate the samples presented and write down all
the descriptive words they can think of for the odour, texture and flavour of the products. Once the
evaluation has been conducted, get the group to discuss the samples and their differences.
5.3.6.2 Cheese
Samples are prop
...

INTERNATIONAL ISO
STANDARD 22935-1
IDF 99-1
Second edition
Milk and milk products — Sensory
analysis —
Part 1:
Recruitment, selection, training and
monitoring of assessors
PROOF/ÉPREUVE
Reference numbers
ISO 22935-1:2023(E)
IDF 99-1:2023(E)
© ISO and IDF 2023

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ISO 22935-1:2023(E)
IDF 99-1:2023(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]
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Website: www.iso.org Website: www.fil-idf.org
Published in Switzerland
ii
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Contents Page
Forewords .iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Recruitment . 2
5 Screening. 2
5.1 Screening form and requirements . 2
5.2 Preparation of test samples for screening . 3
5.3 Screening tests, materials and methods . 4
5.3.1 General . 4
5.3.2 Odour recognition . 4
5.3.3 Basic taste recognition . 4
5.3.4 Ranking tests . 5
5.3.5 Difference testing . 6
5.3.6 Descriptive ability and group discussion . 9
5.3.7 Marking schedule summary . . 10
6 Selection .11
7 Requirements for assessors in the panel .12
8 Training and monitoring of assessors for dairy products .12
8.1 General .12
8.2 References. 13
9 Performance .16
Bibliography .17
iii
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ISO 22935-1:2023(E)
IDF 99-1:2023(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 22935-1 | IDF 99-1:2009), which has been
technically revised.
The main changes are as follows:
— the Normative references have been updated;
— a few changes have been made to reference materials.
A list of all parts in the ISO 22935 series can be found on the ISO website.
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 22935-1:2023(E)
IDF 99-1:2023(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 Statistics and Automation 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 S17 of the Standing Committee on Statistics and
Automation under the aegis of its project leader Dr H. Kraggerud (NO).
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Introduction
The purpose of the ISO 22935 | IDF 99 series is to give guidance on methodology for sensory analysis
and the use of a common nomenclature of terms for milk and milk products.
To achieve that, the ISO 22935 | IDF 99 series is divided into three parts.
ISO 6658 should be consulted for an overview of sensory methods other than the one provided in
ISO 22935-3 | IDF 99-3.
The principles described are largely derived from various International Standards on the topic.
It is important that safety issues are handled during sensory evaluations (see ISO 20613).
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ISO 22935-1:2023(E)
INTERNATIONAL STANDARD
IDF 99-1:2023(E)
Milk and milk products — Sensory analysis —
Part 1:
Recruitment, selection, training and monitoring of
assessors
1 Scope
This document gives general guidance for the recruitment, selection, training, and monitoring of
assessors for sensory analysis of milk and milk products.
It specifies criteria for the selection, and procedures for the training and monitoring, of selected
assessors and expert sensory assessors for milk and milk products. It supplements the information
given in ISO 8586 that deals with expert assessors.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 4120, Sensory analysis — Methodology — Triangle test
ISO 4121, Sensory analysis — Guidelines for the use of quantitative response scales
ISO 5492, Sensory analysis — Vocabulary
ISO 5496, Sensory analysis — Methodology — Initiation and training of assessors in the detection and
recognition of odours
ISO 6658, Sensory analysis — Methodology — General guidance
ISO 8586:2012, Sensory analysis — General guidelines for the selection, training and monitoring of selected
assessors and expert sensory assessors
ISO 8587, Sensory analysis — Methodology — Ranking
ISO 8589, Sensory analysis — General guidance for the design of test rooms
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4121, ISO 5492, ISO 5496,
ISO 6658, ISO 8586 and ISO 8589 and the following 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/
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
3.1
sensory analysis
science involved with the assessment of the sensory attributes of a product by the senses
[SOURCE: ISO 5492:2008, 1.1, modified — “sensory” replaced “organoleptic” in the definition.]
3.2
expert sensory assessor
selected assessor with a demonstrated sensory sensitivity and with considerable training and
experience in sensory testing, who is able to make consistent and repeatable sensory assessments of
various products
Note 1 to entry: Examples of “various products” are “dairy products”.
[SOURCE: ISO 5492:2008, 1.8, modified — Note 1 to entry added.]
3.3
appearance
all the visible attributes of a substance or object
Note 1 to entry: For a dairy product, the visual attributes are both internal and external, and include shape,
colour, loose liquid, phase separation, wanted or unwanted particles, and openings.
[SOURCE: ISO 5492:2008, 3.1, modified — Note 1 to entry added.]
3.4
fingerfeel
mixed experience derived from sensations on the fingers that relate to physical properties of a stimulus
3.5
flavour
complex combination of the olfactory, gustatory and trigeminal sensations perceived during tasting
[SOURCE: ISO 5492:2008, 3.20, modified — Note 1 to entry deleted.]
4 Recruitment
Assessors can be recruited from within a company (laboratory staff, production staff, administration
staff, etc.), who are not involved with project work, or from outside a company. Outside assessors can be
recruited by advertisement or by word of mouth. The panel candidates should have an understanding
of the amount of time that will be required for the screening process and for actual panel work. A large
enough pool of available candidates should be screened in order to have enough assessors available to
select from when forming a panel. The trainee assessor should have satisfactory personal qualifications
for assessments and should be pre-selected by:
a) the use of screening tests to assess the ability of candidates to perceive, discriminate and describe
sensory attributes;
b) a general understanding of the concepts of sensory evaluation;
c) a general liking or interest in dairy products.
5 Screening
5.1 Screening form and requirements
Potential applicants should go through two forms of screening via an interview and sensory screening
tests. During the interview, the applicants should fill out a pre-screening form which indicates the times
that they are available for panels and any health issues they can have, e.g. arthritis which can interfere
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
with the evaluation of product texture in-hand (fingerfeel), lactose intolerance, food allergies, wearing
of dentures, smoking status, and any other issues of concern.
Flavoured water solutions and dairy products should be used to indicate if the potential assessor can
recognize specific tastes or flavours at different intensities. The potential evaluator shall be able to
detect certain flavours within complex dairy products. The following three sessions each take assessors
approximately 45 min to 1 h to complete. These screening exercises are suggestions only and may be
adapted to the application area of the assessors. The sessions described in Tables 1 to 3 may be broken
down into smaller or larger sessions depending on how much time is available.
Table 1 — Session 1 — Basic odour and taste recognition
Test Reference Result
1 5.3.2 Odour recognition
2 5.3.3 Basic taste recognition
3 5.3.4, Table 8 Ranking of basic taste — sweet
4 5.3.4, Table 9 Ranking of basic taste — sour
5 5.3.4, Table 10 Ranking of basic taste — salty
6 5.3.4, Table 11 Ranking of basic taste — bitter
Table 2 — Session 2 — Milk powder and cream products
Test Reference Result
7 5.3.5, Table 14 Triangle test — milk powder
8 5.3.5, Table 15 Triangle test — butter
9 5.3.5, Table 16 Triangle test — salted butter
10 5.3.6.3 Round table discussion — cream evaluation
11 5.3.4, Table 12 Ranking of texture — body/creaminess
12 5.3.5, Table 13 Triangle test — aged milk powder
Table 3 — Session 3 — Cheese
Test Reference Result
13 5.3.5, Table 16 Triangle test — cheese
14 5.3.6.2 Round table discussion — cheese evaluation
15 5.3.5, Table 16 Triangle test — bitter cheese
16 5.3.5, Table 17 Triangle test — cheese firmness
17 5.3.5, Table 17 Triangle test — cheese smoothness
Mark each section as per each marking schedule. Other examples of screening exercises can be found in
ISO 8586.
5.2 Preparation of test samples for screening
5.2.1 If possible, prepare test samples on the day of the evaluation.
5.2.2 For screening purposes, it is easier to serve test samples in the same order to all assessors.
5.2.3 If appropriate, use test sample questionnaires for all screening exercises found in ISO 4120
(triangle test), ISO 8587 (ranking test), ISO 6658 and ISO 4121 (scales).
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
5.3 Screening tests, materials and methods
5.3.1 General
The screening tests, materials and methods presented in this clause are recommendations only. They
can be adapted to suit the needs of an individual company.
5.3.2 Odour recognition
Follow the instructions outlined in ISO 8586:2012, 5.4.1, for details on how to prepare the test samples
and conduct this test. Table 4 suggests other aromas that can be used.
Table 4 — Examples of olfactory materials for odour description test
Blind code Sample preparation
(example)
981 Citronella oil (lemon, cleaning fluid)
194 Orange
229 Caramel
371 Butyric acid
926 Acetic acid
174 Ammonia
a
746 (Z)-hex-3-en-1-ol
831 Oct-1-en-3-ol
556 Vanilla
a
In older literature, known as cis-hex-3-en-1-ol.
Candidates are graded according to performance, as shown in Table 5. For each sample, a total of three
points can be achieved. If the assessor uses words other than those listed in Table 5, score appropriately.
Table 5 — Marking schedule for odour recognition
Correct answer
Sample
3 points 2 points 1 point
Citronella oil Citronella oil Lemony, cleaning fluid Citrus, fruity
Orange Orange Lemon Citrus, fruity
Caramel Caramel Vanilla, malt, toasted Sweet
Butyric acid Rancid butter Parmesan cheese Vomit, baby burp
Acetic acid Acetic acid Vinegar Sour/off milk
Ammonia Ammonia Cleaning fluid, urine Pungent
(Z)-hex-3-en-1-ol Green grass Green beans Green vegetable
Oct-1-en-3-ol Mushroom Cellar, musty Mouldy
Vanilla Vanilla Custard, dessert Sweets, candy
5.3.3 Basic taste recognition
The solutions can be prepared as shown in Table 6. Present the solutions to the assessors in the same
order, and one of the solutions twice. Ask the assessor to identify the basic taste that is represented by
the solution.
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Table 6 — Basic taste solutions
Blind code Answer Concentration Sample preparation
(examples)
10 g/l sucrose
683 Sweet 10 g sucrose + 1 l water
(1 % mass fraction)
2 g/l NaCl
429 Salty 2 g NaCl + 1 l water
(0,2 % mass fraction)
0,3 g/l citric acid
662 Sour 0,3 g citric acid + 1 l water
(0,03 % mass fraction)
0,3 g/l caffeine
353 Bitter 0,3 g caffeine + 1 l water
(0,03 % mass fraction)
0,6 g monosodium glutamate or 0,18 g umami mixture
0,6 g/l monosodium
Umami (50 % mass fraction monosodium glutamate, 25 % mass
768 glutamate
(optional) fraction 5′- guanylic acid, 25 % mass fraction inosinic
(0,06 % mass fraction)
acid) + 1 l water with 0,5 g NaCl
418 Water water
Candidates are graded according to performance on the scale shown in Table 7.
Table 7 — Gradation scale I
Points Result
6 all correct
5 five correct
4 four correct
3 three correct
2 two correct
1 one correct
0 none correct
5.3.4 Ranking tests
A minimum of four test samples should be ranked in order of increasing intensity. This test will indicate
whether the assessor can tell the difference between samples for certain basic tastes.
Samples for ranking of sweetness, sourness, saltiness, bitterness and creamy flavour are given in
Tables 8, 9, 10, 11 and 12, respectively.
This test can also indicate the threshold levels of assessors (i.e. if the assessor did not correctly identify
the order of the lower intensities, that would indicate that this assessor cannot taste at lower levels for
this particular attribute).
NOTE All samples are randomized, but are presented to all the assessors in the same order.
Table 8 — Sweet ranking
Blind code Correct Concentration Sample preparation
(examples) ranking
478 3 10 g/l sucrose (1 % mass per volume) 10 g sucrose + 1 l water
753 1 Water Water
578 4 15 g/l sucrose (1,5 % mass per volume) 15 g sucrose + 1 l water
248 2 5 g/l sucrose (0,5 % mass per volume) 5 g sucrose + 1 l water
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Table 9 — Sour ranking
Blind code Correct Concentration Sample preparation
(examples) ranking
145 2 0,10 g/l citric acid (0,01 % mass per vol- 0,10 g citric
ume) acid + 1 l water
249 4 0,5 g/l citric acid (0,05 % mass per volume) 0,5 g citric
acid + 1 l water
871 1 Water Water
675 3 0,3 g/l citric acid (0,03 % mass per volume) 0,3 g citric
acid + 1 l water
Table 10 — Salt ranking
Blind code Correct Concentration Sample preparation
(examples) ranking
985 2 1 g/l NaCl (0,1 % mass per volume) 1 g NaCl + 1 l water
813 1 Water Water
713 4 2 g/l NaCl (0,2 % mass per volume) 2 g NaCl + 1 l water
632 3 1,5 g/l NaCl (0,15 % mass per volume) 1,5 g NaCl + 1 l water
Table 11 — Bitter ranking
Blind code Correct Concentration Sample preparation
(examples) ranking
268 2 0,1 g/l caffeine (0,01 % mass per volume) 0,1 g caffeine + 1 l water
634 1 Water Water
919 4 0,5 g/l caffeine (0,05 % mass per volume) 0,5 g caffeine + 1 l water
752 3 0,3 g/l caffeine (0,03 % mass per volume) 0,3 g caffeine + 1 l water
Table 12 — Creamy flavour ranking
Blind code (examples) Correct ranking Sample preparation
268 1 Ultra high temperature (UHT) non-fat
634 4 UHT full fat + 20 % volume fraction UHT cream
919 3 UHT full fat + 3 % volume fraction UHT cream
752 2 UHT full fat
Candidates are graded according to performance on the scale shown in Table 13.
Table 13 — Gradation scale II
Points Result
4 Four correct
3 Adjacent switch
1 One correct
0 None correct
5.3.5 Difference testing
Difference testing indicates if the individual can detect small differences between samples for certain
flavours or textures.
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
The test samples should be selected so that they test the capability of the assessor to discriminate
between the samples based only on flavour or texture. An expert assessor can be used to select the
samples to be used in the tests. Examples of samples for difference testing are listed in Table 14 to
Table 17.
“Paired comparison” or “triangle” testing should be conducted on a series of products. If the assessor
thinks the samples are different, they can be asked to indicate what the difference is. This indicates if
assessors can accurately identify differences between products and name the difference.
All test samples are to be presented to all assessors in the same randomized order.
It is recommended that each set of samples be presented to the assessors twice to check if assessors can
replicate their results.
Table 14 — Suggested milk powder samples for difference testing — Flavour
Product Blind code Answer Sample preparation
(examples) (30 g per assessor)
100 % mass fraction
737 Skim milk powder
Milk powder sample set No. 1 932 Skim milk powder
895 Different Whole milk powder
769 Skim milk powder
Milk powder sample set No. 2 862 Different Whole milk powder
374 Skim milk powder
a
191 Different Oxidized milk powder
Aged milk powder sample set No. 1 748 Fresh milk powder
651 Fresh milk powder
426 Fresh milk powder
Aged milk powder sample set No. 2 621 Fresh milk powder
a
848 Different Oxidized milk powder
a
Refer to Table 28 for instructions on preparing oxidized milk samples.
Table 15 — Suggested butter samples for difference testing — Flavour
Product Blind code Answer Sample preparation
(examples) (1 cube per assessor)
148 Butter type 1
a
Butter sample set No. 1 897 Butter type 1
198 Different Butter type 2
539 Butter type 1
a
Butter sample set No. 2 575 Different Butter type 2
272 Butter type 1
514 Unsalted butter
Salted butter sample set No. 1 796 Unsalted butter
244 Different Salted butter
868 Unsalted butter
Salted butter sample set No. 2 364 Unsalted butter
968 Different Salted butter
a
The butters used in this test can be two different brands of butter, butter with known flavour differences or “spiked”
butter samples [e.g. regular butter and a grassy butter (butter with 1,5 % mass fraction hexanal)].
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
Table 16 — Suggested cheese samples for difference testing — Flavour
Product Blind code Answer Sample preparation
(examples) (30 g per assessor)
345 Cheese type 1
Cheese sample set No. 1 223 Different Cheese type 2
466 Cheese type 1
342 Cheese type 1
a
Cheese sample set No. 2 555 Cheese type 1
314 Different Cheese type 2
871 Non-bitter cheese
Bitter cheese sample set No. 1 914 Non-bitter cheese
557 Different Bitter cheese
997 Non-bitter cheese
Bitter cheese sample set No. 2 663 Different Bitter cheese
783 Non-bitter cheese
a
The cheese samples used in this test can be collected from two different brands of cheese or cheeses with known
flavour differences.
Table 17 — Suggested cheese samples for difference testing — Texture
Product Blind code Answer Sample preparation
(examples)
278 Cheese firmness — brand 1
Cheese — firmness sample set No. 1 921 Different Cheese firmness — brand 2
461 Cheese firmness — brand 1
476 Different Cheese firmness — brand 2
Cheese — firmness sample set No. 2 133 Cheese firmness — brand 1
931 Cheese firmness — brand 1
119 Different Cheese smoothness — brand 1
Cheese — smoothness sample set No. 1 346 Cheese smoothness — brand 2
278 Cheese smoothness — brand 2
563 Cheese smoothness — brand 2
Cheese — smoothness sample set No. 2 572 Different Cheese smoothness — brand 1
588 Cheese smoothness — brand 2
Candidates are graded according to performance on scale III (see Table 18).
Table 18 — Gradation scale III
Points Result
6 Correct response for both sample set #1 and sample set #2
4 Correct response for either sample set #1 or sample set #2
0 Incorrect response for both sample set #1 and sample set #2
0,5 Correct description of difference
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ISO 22935-1:2023(E)
IDF 99-1:2023(E)
5.3.6 Descriptive ability and group discussion
5.3.6.1 General
During a group discussion, the candidates taste a product and generate descriptive terms for that
product by themselves. The candidates discuss their result with the other assessors (minimum of eight
in a group). This indicates if a candidate can break a product down into descriptive terms and how the
candidate interacts within group discussions.
Choose two types of dairy products for the descriptive discussion groups. This document gives examples
for cheese and cream samples; other samples can be selected depending on the types of products that
are commonly evaluated by panels. Ask the candidates to evaluate the samples presented and write
down all the descriptive words they can think of for the odour, texture and flavour of the products.
Once the evaluation has been conducted, get the group to discuss the samples and their differences.
5.3.6.2 Cheese
Samples are proposed in Table 19.
Table 19 — Suggested cheese samples for discussion groups
Blind code (examples) Sample preparation
524 Mild Cheddar cheese
831 Blue vein cheese
Candidates are graded according to performance on scale IV (see Table 20). Check all the descriptors
that the candidates generate
...

SLOVENSKI STANDARD
oSIST ISO/DIS 22935-1:2023
01-februar-2023
Mleko in mlečni proizvodi - Senzorična analiza - 1. del: Splošne smernice za
novačenje, izbiro, usposabljanje in spremljanje ocenjevalcev
Milk and milk products — Sensory analysis — Part 1: General guidance for the
recruitment, selection, training and monitoring of assessors
Lait et produits laitiers — Analyse sensorielle — Partie 1: Lignes directrices générales
pour le recrutement, la sélection, l'entraînement et le contrôle des sujets
Ta slovenski standard je istoveten z: ISO/DIS 22935-1
ICS:
03.100.30 Vodenje ljudi Management of human
resources
67.100.01 Mleko in mlečni proizvodi na Milk and milk products in
splošno general
oSIST ISO/DIS 22935-1:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST ISO/DIS 22935-1:2023

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oSIST ISO/DIS 22935-1:2023
DRAFT INTERNATIONAL STANDARD
ISO/DIS 22935-1
IDF 99-1
ISO/TC 34/SC 5 Secretariat: NEN
Voting begins on: Voting terminates on:
2022-03-22 2022-06-14
Milk and milk products — Sensory analysis —
Part 1:
General guidance for the recruitment, selection, training
and monitoring of assessors
Lait et produits laitiers — Analyse sensorielle —
Partie 1: Lignes directrices générales pour le recrutement, la sélection, l'entraînement et le contrôle des
sujets
ICS: 67.100.01; 03.100.30
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
This document is circulated as received from the committee secretariat.
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference numbers
NATIONAL REGULATIONS.
ISO/DIS 22935-1:2022(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
IDF 99-1:2022(E)
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. © ISO and IDF 2022

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oSIST ISO/DIS 22935-1:2023
ISO/DIS 22935-1:2022(E)
IDF 99-1:2022(E)
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
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
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oSIST ISO/DIS 22935-1:2023
ISO/DIS 22935-1:2022(E)
IDF 99-1:2022(E)
Contents Page
Foreword .iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Recruitment . 3
5 Screening. 3
5.1 Screening form and requirements . 3
5.1.1 General . 3
5.1.2 Session 1 – Basic odour and taste recognition . 4
5.1.3 Session 2 – Milk powder and cream products. 4
5.1.4 Session 3 – Cheese . 4
5.2 Preparation of test samples for screening . 4
5.3 Screening tests, materials and methods . 4
5.3.1 Odour recognition . 5
5.3.2 Basic taste recognition . 5
5.3.3 Ranking tests . 6
5.3.4 Difference testing . 7
5.3.5 Descriptive ability and group discussion . 9
5.3.6 Marking schedule summary . . 11
6 Selection .12
7 Requirements for assessors in the panel .13
8 Training and monitoring of assessors for dairy products .13
8.1 General .13
8.2 References. 13
9 Performance .16
Bibliography .18
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oSIST ISO/DIS 22935-1:2023
ISO/DIS 22935-1:2022(E)
IDF 99-1:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national
standards bodies (ISO member bodies). The work of preparing International Standards is normally
carried out through ISO technical committees. Each member body interested in a subject for which
a technical committee has been established has the right to be represented on that committee.
International organizations, governmental and non-governmental, in liaison with ISO, also take part
in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all
matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5,
Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO
and IDF.
This second edition cancels and replaces the first edition (ISO 22935-1|IDF 99-1:2009), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— corrections in normative references
— a few changes in reference materials
A list of all parts in the ISO 22935 series can be found on the ISO website.
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.
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oSIST ISO/DIS 22935-1:2023
ISO/DIS 22935-1:2022(E)
IDF 99-1:2022(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 Statistics and Automation 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 S17 of the Standing Committee on Statistics and
Automation under the aegis of its project leader Dr H. Kraggerud (NO).
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oSIST ISO/DIS 22935-1:2023
ISO/DIS 22935-1:2022(E)
IDF 99-1:2022(E)
Introduction
The purpose of ISO 22935|IDF 99 (all parts) is to give guidance on methodology for sensory analysis
and the use of a common nomenclature of terms for milk and milk products.
To achieve that, ISO 22935|IDF 99 has been divided into three parts.
ISO 6658 should be consulted for an overview of sensory methods other than the one provided in
ISO 22935-3|IDF 99-3.
Evaluation of labelling and packaging is not covered by ISO 22935|IDF 99 (all parts).
The principles described are largely derived from various International Standards on the topic.
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oSIST ISO/DIS 22935-1:2023
ISO/DIS 22935-1:2022(E)
DRAFT INTERNATIONAL STANDARD
IDF 99-1:2022(E)
Milk and milk products — Sensory analysis —
Part 1:
General guidance for the recruitment, selection, training
and monitoring of assessors
1 Scope
This part of ISO 22935|IDF 99 gives general guidance for the recruitment, selection, training, and
monitoring of assessors for sensory analysis of milk and milk products.
It specifies criteria for the selection, and procedures for the training and monitoring, of selected
assessors and expert sensory assessors for milk and milk products. It supplements the information
given in ISO 8586 that deals with expert assessors.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 4120, Sensory analysis — Methodology — Triangle test
ISO 4121, Sensory analysis — Guidelines for the use of quantitative response scales
ISO 5492, Sensory analysis — Vocabulary
ISO 5496, Sensory analysis — Methodology — Initiation and training of assessors in the detection and
recognition of odours
ISO 6658, Sensory analysis — Methodology — General guidance
ISO 8586, Sensory analysis — General guidelines for the selection, training and monitoring of selected
assessors and expert sensory assessors
ISO 8587, Sensory analysis — Methodology — Ranking
ISO 8589, Sensory analysis — General guidance for the design of test rooms
ISO 22935-2, |IDF 99-2, Milk and milk products — Sensory analysis: Part 2: Recommended methods for
sensory evaluation
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4121, ISO 5492, ISO 5496,
ISO 6658, ISO 8586 and ISO 8589 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
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oSIST ISO/DIS 22935-1:2023
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IDF 99-1:2022(E)
3.1
sensory analysis
science involved with the assessment of the sensory attributes of a product by the senses
[SOURCE: ISO 5492:2008, 1.1]
3.2
selected assessor
assessor chosen for his/her ability to perform a sensory test
[SOURCE: ISO 5492:2008, 1.6]
3.3
expert sensory assessor
selected assessor with a demonstrated sensory sensitivity and with considerable training and
experience in sensory testing, who is able to make consistent and repeatable sensory assessments of
various products
[SOURCE: ISO 5492:2008, 1.8]
Note 1 to entry: Examples of “various products” are “dairy products”.
3.4
sensory panel
group of assessors participating in a sensory test
[SOURCE: ISO 5492:2008, 1.9]
3.5
scoring
evaluation of a product (or of attributes of a product) by assigning numbers that have some mathematical
relationship to the product or attributes being evaluated
[SOURCE: ISO 5492:2008, 4.7]
3.6
product specification
document stating requirements of a product
Note 1 to entry: Adapted from ISO 9000:2005 [2].
3.7
classification
method of sorting into categories
[SOURCE: ISO 5492:2008, 4.5]
3.8
attribute
perceptible characteristic
[SOURCE: ISO 5492:2008, 1.3]
3.9
appearance
all the visible attributes of a substance or object
[SOURCE: ISO 5492:2008, 3.1]
Note 1 to entry: For a dairy product, the visual attributes are both internal and external, and include shape,
colour, loose liquid, phase separation, wanted or unwanted particles, and openings.
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oSIST ISO/DIS 22935-1:2023
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3.10
consistency
mechanical attribute detected by stimulation of the tactile or visual receptors
[SOURCE: ISO 5492:2008, 3.49]
3.11
mouthfeel
mixed experience derived from sensations in the mouth that relate to physical or chemical properties
of a stimulus
[SOURCE: ISO 5492:2008, 3.62]
3.12
fingerfeel
mixed experience derived from sensations on the fingers that relate to physical properties of a stimulus
3.13
flavour
complex combination of the olfactory, gustatory and trigeminal sensations perceived during tasting
[SOURCE: ISO 5492:2008, 3.20]
3.14
odour
sensation perceived by means of the olfactory organ in sniffing certain volatile substances
[SOURCE: ISO 5492:2008, 3.18]
4 Recruitment
Assessors can be recruited from within a company (laboratory staff, production staff, administration
staff, etc.), who are not involved with project work, or from outside a company. Outside assessors can be
recruited by advertisement or by word of mouth. The panel candidates should have an understanding
of the amount of time that will be required for the screening process and for actual panel work. A large
enough pool of available candidates should be screened in order to have enough assessors available to
select from when forming a panel. The trainee assessor should have satisfactory personal qualifications
for assessments and should be pre-selected by:
a) the use of screening tests to assess the ability of candidates to perceive, discriminate, and describe
sensory attributes;
b) a general understanding of the concepts of sensory evaluation;
c) a general liking or interest in dairy products.
5 Screening
5.1 Screening form and requirements
5.1.1 General
Potential applicants should go through two forms of screening via an interview and sensory screening
tests. During the interview, the applicants should fill out a pre-screening form which indicates the times
that they are available for panels and any health issues they may have: arthritis which could interfere
with the evaluation of product texture in-hand (fingerfeel), lactose intolerance, wearing of dentures,
smoking status, and any other issues of concern.
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oSIST ISO/DIS 22935-1:2023
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IDF 99-1:2022(E)
Flavoured water solutions and dairy products should be used to indicate if the potential assessor can
recognize specific tastes or flavours at different intensities. The potential evaluator shall be able to
detect certain flavours within complex dairy products. The following three sessions each take assessors
approximately 45 min to 1 h to complete. These screening exercises are suggestions only and may be
adapted to the application area of the assessors. The sessions described in 5.1.2 to 5.1.4 may be broken
down into smaller or larger sessions depending on how much time is available.
5.1.2 Session 1 – Basic odour and taste recognition
Test Reference Result
1 5.3.1 Odour recognition
2 5.3.2 Basic taste recognition
3 5.3.3, Table 5 Ranking of basic taste — sweet
4 5.3.3, Table 6 Ranking of basic taste — sour
5 5.3.3, Table 7 Ranking of basic taste — salty
6 5.3.3, Table 8 Ranking of basic taste — bitter
5.1.3 Session 2 – Milk powder and cream products
Test Reference Result
7 5.3.4, Table 11 Triangle test — milk powder
8 5.3.4, Table 12 Triangle test — butter
9 5.3.4, Table 12 Triangle test — salted butter
10 5.3.5.2 Round table discussion — cream evaluation
11 5.3.3, Table 9 Ranking of texture — body/creaminess
12 5.3.4, Table 11 Triangle test — aged milk powder
5.1.4 Session 3 – Cheese
Test Reference Result
13 5.3.4, Table 13 Triangle test — cheese
14 5.3.5.1 Round table discussion — cheese evaluation
15 5.3.4, Table 13 Triangle test — bitter cheese
16 5.3.4, Table 14 Triangle test — cheese firmness
17 5.3.4, Table 14 Triangle test — cheese smoothness
Mark each section as per each marking schedule. Other examples of screening exercises can be found in
ISO 8586.
5.2 Preparation of test samples for screening
5.2.1 If possible, prepare test samples on the day of the evaluation.
5.2.2 For screening purposes, it is easier to serve test samples in the same order to all assessors.
5.2.3 If appropriate, use test sample questionnaires for all screening exercises found in ISO 4120
(triangle test), ISO 8587 (ranking test), ISO 6658 and ISO 4121 (scales).
5.3 Screening tests, materials and methods
The screening tests, materials and methods presented in this section are recommendations only. They
can be adapted to suit the needs of an individual company.
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oSIST ISO/DIS 22935-1:2023
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IDF 99-1:2022(E)
5.3.1 Odour recognition
Follow the instructions outlined in ISO 8586:2012, 5.4.1 for details on how to prepare the test samples
and conduct this test. Table 1 suggests other aromas that can be used.
Table 1 — Examples of olfactory materials for odour description test
Blind code (ex-
Sample Preparation
ample)
981 Citronella oil (lemon, cleaning fluid)
194 Orange
229 Caramel
371 Butyric acid
926 Acetic acid
174 Ammonia
a
746 (Z)-hex-3-en-1-ol
831 Oct-1-en-3-ol
556 Vanilla
a
In older literature, known as cis-hex-3-en-1-ol.
Candidates are graded according to performance, as shown in Table 2. For each sample, a total of three
points can be achieved. If the assessor uses words other than those listed in Table 2, score appropriately.
Table 2 — Marking schedule for odour recognition
Correct Answer
Sample
3 points 2 points 1 point
Citronella oil Citronella oil Lemony, cleaning fluid Citrus, fruity
Orange Orange Lemon Citrus, fruity
Caramel Caramel Vanilla, malt, toasted Sweet
Butyric acid Rancid butter Parmesan cheese Vomit, baby burp
Acetic acid Acetic acid Vinegar Sour/off milk
Ammonia Ammonia Cleaning fluid, urine Pungent
(Z)-hex-3-en-1-ol Green grass Green beans Green vegetable
Oct-1-en-3-ol Mushroom Cellar, musty Mouldy
Vanilla Vanilla Custard, dessert Sweets, candy
5.3.2 Basic taste recognition
The solutions can be prepared as shown in Table 3. Present the solutions to the assessors in the same
order, and one of the solutions twice. Ask the assessor to identify the basic taste that is represented by
the solution.
Table 3 — Basic taste solutions
Blind code
Answer Concentration Sample preparation
(examples)
10 g/l sucrose
683 Sweet 10 g sucrose + 1 l water
(1 % mass fraction)
2 g/l NaCl
429 Salty 2 g NaCl + 1 l water
(0,2 % mass fraction)
0,3 g/l citric acid
662 Sour 0,3 g citric acid + 1 l water
(0,03 % mass fraction)
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oSIST ISO/DIS 22935-1:2023
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IDF 99-1:2022(E)
Table 3 (continued)
Blind code
Answer Concentration Sample preparation
(examples)
0,3 g/l caffeine
353 Bitter 0,3 g caffeine + 1 l water
(0,03 % mass fraction)
0,6 g monosodium glutamate or 0,18 g umami mixture
0,6 g/l monosodium
Umami (50 % mass fraction monosodium glutamate, 25 % mass
768 glutamate
(optional) fraction 5'- guanylic acid, 25 % mass fraction inosinic
(0,06 % mass fraction)
acid) + 1 l water with 0,5 g NaCl
418 Water water
Candidates are graded according to performance on the scale shown in Table 4.
Table 4 — Gradation scale I
Points Result
6 all correct
5 five correct
4 four correct
3 three correct
2 two correct
1 one correct
0 none correct
5.3.3 Ranking tests
A minimum of four test samples should be ranked in order of increasing intensity. This test will indicate
whether the assessor can tell the difference between samples for certain basic tastes.
Samples for ranking of sweetness, sourness, saltiness, bitterness, and creamy flavour are given in
Tables 5, 6, 7, 8, and 9, respectively.
This test can also indicate the threshold levels of assessors (i.e. if the assessor did not correctly identify
the order of the lower intensities, that would indicate that this assessor cannot taste at lower levels for
this particular attribute).
NOTE All samples are randomized, but are presented to all the assessors in the same order.
Table 5 — Sweet ranking
Correct
Blind code (examples) Concentration Sample preparation
ranking
478 3 10 g/l sucrose (1 % mass per volume) 10 g sucrose + 1 l water
753 1 Water Water
578 4 15 g/l sucrose (1,5 % mass per volume) 15 g sucrose + 1 l water
248 2 5 g/l sucrose (0,5 % mass per volume) 5 g sucrose + 1 l water
Table 6 — Sour ranking
Correct
Blind code (examples) Concentration Sample preparation
ranking
145 2 0,10 g/l citric acid (0,01 % mass per vol- 0,10 g citric
ume) acid + 1 l water
249 4 0,5 g/l citric acid (0,05 % mass per volume) 0,5 g citric
acid + 1 l water
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oSIST ISO/DIS 22935-1:2023
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IDF 99-1:2022(E)
Table 6 (continued)
Correct
Blind code (examples) Concentration Sample preparation
ranking
871 1 Water Water
675 3 0,3 g/l citric acid (0,03 % mass per volume) 0,3 g citric
acid + 1 l water
Table 7 — Salt ranking
Correct
Blind code (examples) Concentration Sample preparation
ranking
985 2 1 g/l NaCl (0,1 % mass per volume) 1 g NaCl + 1 l water
813 1 Water Water
713 4 2 g/l NaCl (0,2 % mass per volume) 2 g NaCl + 1 l water
632 3 1,5 g/l NaCl (0,15 % mass per volume) 1,5 g NaCl + 1 l water
Table 8 — Bitter ranking
Correct
Blind code (examples) Concentration Sample preparation
ranking
268 2 0,1 g/l caffeine (0,01 % mass per volume) 0,1 g caffeine + 1 l water
634 1 Water Water
919 4 0,5 g/l caffeine (0,05 % mass per volume) 0,5 g caffeine + 1 l water
752 3 0,3 g/l caffeine (0,03 % mass per volume) 0,3 g caffeine + 1 l water
Table 9 — Creamy flavour ranking
Blind code (examples) Correct ranking Sample preparation
268 1 UHT non-fat
634 4 UHT full fat + 20 % volume fraction UHT cream
919 3 UHT full fat + 3 % volume fraction UHT cream
752 2 UHT full fat
Candidates are graded according to performance on the scale shown in Table 10.
Table 10 — Gradation scale II
Points Result
4 Four correct
3 Adjacent switch
1 One correct
0 None correct
5.3.4 Difference testing
Difference testing indicates if the individual can detect small differences between samples for certain
flavours or textures.
The test samples should be selected so that they test the capability of the assessor to discriminate
between the samples based only on flavour or texture. An expert assessor can be used to select the
samples to be used in the tests.
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oSIST ISO/DIS 22935-1:2023
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IDF 99-1:2022(E)
“Paired comparison” or “triangle” testing should be conducted on a series of products. If the assessor
thinks the samples are different, they can be asked to indicate what the difference is. This indicates if
assessors can accurately identify differences between products and name the difference.
All test samples are to be presented to all assessors in the same randomized order. Refer to
ISO 22935-2|IDF 99-2:2009, 9.2, for instructions on how to prepare milk powder samples.
It is recommended that each set of samples be presented to the assessors twice to check if assessors can
replicate their results.
Table 11 — Suggested milk powder samples for difference testing — Flavour
Sample preparation
Blind code
(30 ml per assessor)
Product Answer
(examples)
100 % mass fraction
737 Skim milk powder
Milk powder sample set No. 1 932 Skim milk powder
895 Different Whole milk powder
769 Skim milk powder
Milk powder sample set No. 2 862 Different Whole milk powder
374 Skim milk powder
Oxidized milk pow-
191 Different
a
der
Aged milk powder sample set No.
1 748 Fresh milk powder
651 Fresh milk powder
426 Fresh milk powder
Aged milk powd
...