Paper and board intended to come into contact with foodstuffs - Calibration of the off-flavour test - Part 3: Dry food

This Technical Report specifies a written protocol to prepare calibration samples for assessment of off-flavour (given by benzaldehyde) in a test substance representative of dry food products (icing sugar). Essentially, this is meant to simulate the transfer of off-flavours from paper and board to a dry food product.
This Technical Report also specifies how to train the panel in the use of the calibration samples.
The general outline of the test procedure consists of sensory assessment of off-flavour in samples without formal training by a selected panel, followed by training of the panel, and finally sensory assessment of the samples after training by the same sensory panel.

Papier und Pappe vorgesehen für den Kontakt mit Lebensmitteln - Kalibrierung für die Geschmacksprüfung - Teil 3: Trockene Lebensmittel

Papiers et cartons destinés à entrer en contact avec les denrées alimentaires - Etalonnage des essais de flaveur atypique - Partie 3 : Aliments secs

Le présent Rapport technique spécifie un protocole écrit de préparation des échantillons d'étalonnage en vue de l'évaluation de la flaveur atypique (fournie par le benzaldéhyde) dans une substance d'essai représentative des produits alimentaires secs (sucre glace). Pour l'essentiel, ceci vise à simuler le transfert des flaveurs atypiques du papier et du carton vers un produit alimentaire sec.
Le présent Rapport technique spécifie également le mode d'entraînement du jury à l'utilisation des échantillons d'étalonnage.
De manière générale, le mode opératoire d’essai se décompose comme suit : une analyse sensorielle de la flaveur atypique dans des échantillons, sans entraînement formel préalable, par un jury sélectionné, suivie d’un entraînement du jury, puis une analyse sensorielle des échantillons par le même jury d'analyse sensorielle préalablement entraîné.

Papir, karton in lepenka v stiku z živili - Umerjanje za preskus neustreznega vonja ali okusa - 3. del: Suha živila

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SLOVENSKI STANDARD
SIST-TP CEN/TR 15645-3:2008
01-april-2008

Papir, karton in lepenka v stiku z živili - Umerjanje za preskus neustreznega vonja

ali okusa - 3. del: Suha živila

Paper and board intended to come into contact with foodstuffs - Calibration of the off-

flavour test - Part 3: Dry food

Papier und Pappe vorgesehen für den Kontakt mit Lebensmitteln - Kalibrierung für die

Geschmacksprüfung - Teil 3: Trockene Lebensmittel
Papiers et cartons destinés à entrer en contact avec les denrées alimentaires -
Etalonnage des essais de flaveur atypique - Partie 3 : Aliments secs
Ta slovenski standard je istoveten z: CEN/TR 15645-3:2008
ICS:
67.250 Materiali in predmeti v stiku z Materials and articles in
živili contact with foodstuffs
85.060 Papir, karton in lepenka Paper and board
SIST-TP CEN/TR 15645-3:2008 en,fr,de

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

---------------------- Page: 1 ----------------------
TECHNICAL REPORT
CEN/TR 15645-3
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
January 2008
ICS 67.250; 85.060
English Version
Paper and board intended to come into contact with foodstuffs -
Calibration of the off-flavour test - Part 3: Dry food

Papiers et cartons destinés à entrer en contact avec les Papier und Pappe vorgesehen für den Kontakt mit

denrées alimentaires - Etalonnage des essais de flaveur Lebensmitteln - Kalibrierung für die Geschmacksprüfung -

atypique - Partie 3 : Aliments secs Teil 3: Trockene Lebensmittel

This Technical Report was approved by CEN on 13 August 2007. It has been drawn up by the Technical Committee CEN/TC 172.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,

Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 15645-3:2008: E

worldwide for CEN national Members.
---------------------- Page: 2 ----------------------
CEN/TR 15645-3:2008 (E)
Contents Page

Foreword..............................................................................................................................................................4

Introduction .........................................................................................................................................................5

1 Scope ......................................................................................................................................................6

2 Normative references ............................................................................................................................6

3 Terms and definitions ...........................................................................................................................6

4 Principle..................................................................................................................................................8

5 Materials and reagents..........................................................................................................................8

5.1 General....................................................................................................................................................8

5.2 Test substance.......................................................................................................................................8

5.3 Spiking compound.................................................................................................................................8

5.4 Solvent ....................................................................................................................................................8

5.5 Silicone (optional)..................................................................................................................................9

5.6 Saturated sodium chloride solution ....................................................................................................9

6 Equipment ..............................................................................................................................................9

6.1 General....................................................................................................................................................9

6.2 Dessicators.............................................................................................................................................9

6.3 Glass-weighting flasks..........................................................................................................................9

6.4 Glass rods ..............................................................................................................................................9

6.5 Plastic spoons........................................................................................................................................9

7 Preparation of calibration samples....................................................................................................10

7.1 General..................................................................................................................................................10

7.2 Stability of calibration samples..........................................................................................................10

7.3 Preparation of saturated sodium chloride solution .........................................................................10

7.4 Preparation of icing sugar test portions ...........................................................................................10

7.5 Preparation of spiking solutions........................................................................................................11

7.6 Preparation of calibration samples....................................................................................................11

8 Sensory tests .......................................................................................................................................13

8.1 General test conditions.......................................................................................................................13

8.2 Sensory panel ......................................................................................................................................13

8.3 Sample presentation ...........................................................................................................................13

8.4 Sensory evaluation of off-flavour.......................................................................................................14

9 Test procedure for sensory panel......................................................................................................14

9.1 General..................................................................................................................................................14

9.2 First step: Assessment before training.............................................................................................15

9.3 Second step: Training of the panel....................................................................................................15

9.4 Third step: Assessment after training...............................................................................................17

10 Data collection and reporting.............................................................................................................17

10.1 General..................................................................................................................................................17

10.2 Data format ...........................................................................................................................................17

11 Data analysis........................................................................................................................................18

Annex A (informative) Specifications of recommended dessicators ..........................................................19

Annex B (informative) Experimental design for sample evaluation before training (Rep 1) .....................20

Annex C (informative) Experimental design for sample evaluation before training (Rep 2) .....................21

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CEN/TR 15645-3:2008 (E)

Annex D (informative) Example of evaluation form for use during assessments (first step and

third step) .............................................................................................................................................22

Annex E (informative) Example of evaluation form for use during training (second step).......................23

Annex F (informative) Experimental design for sample evaluation after training (Rep 1) ........................24

Annex G (informative) Experimental design for sample evaluation after training (Rep 2)........................25

Annex H (informative) Example of data entry sheets for the first step .......................................................26

Annex I (informative) Example of data entry sheets for the third step........................................................30

Annex J (informative) Mood’s median test.....................................................................................................34

Annex K (informative) Tukey's Quick (Pocket) Test......................................................................................37

Annex L (informative) Method of chemical analysis .....................................................................................38

Bibliography......................................................................................................................................................41

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CEN/TR 15645-3:2008 (E)
Foreword

This document (CEN/TR 15645-3:2008) has been prepared by Technical Committee CEN/TC 172 “Pulp,

paper and board”, the secretariat of which is held by DIN.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

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CEN/TR 15645-3:2008 (E)
Introduction

Paper and board, intended to be in contact with food, may have characteristic off-flavours that can migrate via

the airspace to the food packed in it. The purpose of testing the off-flavour of food in contact with paper and

board is to establish whether the material to be tested possesses an inherent off-flavour when kept at room

temperature.

In order to gain reliable results from the sensory evaluation, the performance of a sensory panel assessing the

off-flavour within test material needs to be validated. This can be implemented through a training procedure by

using spiked calibration samples prepared according to the given instructions.
This document consists of:

 protocol to prepare the calibration samples (spiked icing sugar) for sensory evaluation of off-flavour;

 description of the training procedure for a sensory panel in the use of the calibration samples;

 instructions for sensory evaluation of calibration samples before and after training.

This guide is meant to be used in connection with the European Standard EN 1230-2. The guidance given in

this document is only a recommendation. Please note that the calibration samples, the preparation of which is

described, can be applied also in other ways than described in this document.

This guide has been devised and collaboratively tested in the context of the EU research project

CALIBSENSORY (Growth programme, Measurement and Testing activity, GRD2-2000-30015) and it is the

sole responsibility of its authors. It does in no way represent the views of the Commission or its services.

Published results of the project are available at http://www1.kcl.fi/euproj/calib.html .

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CEN/TR 15645-3:2008 (E)
1 Scope

This Technical Report specifies a written protocol to prepare calibration samples for assessment of off-flavour

(given by benzaldehyde) in a test substance representative of dry food products (icing sugar). Essentially, this

is meant to simulate the transfer of off-flavours from paper and board to a dry food product.

This Technical Report also specifies how to train the panel in the use of the calibration samples.

The general outline of the test procedure consists of sensory assessment of off-flavour in samples without

formal training by a selected panel, followed by training of the panel, and finally sensory assessment of the

samples after training by the same sensory panel.
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.
ISO 6658, Sensory analysis — Methodology — General guidance

ISO 8586-1, Sensory analysis — General guidance for the selection, training and monitoring of assessors —

Part 1: Selected assessors
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
assessor
any person taking part in a sensory test
[see ISO 5492:1992]
3.2
calibration procedure

protocol of calibration samples and written instructions to train selected assessors with calibration samples i.e.

calibrate the panel
3.3
calibration sample
test substance that is spiked with spiking compound at a certain concentration
3.4
control sample

a hidden reference sample served blind coded to the assessors among the calibration samples, and prepared

according the procedure of the calibration samples but without the spiking compound

3.5
flavour

complex combination of the olfactory, gustatory and trigeminal sensations perceived during tasting

NOTE The flavour may be influenced by tactile, thermal, painful and/or kinaesthesic effects

[see ISO 5492:1992]
---------------------- Page: 7 ----------------------
CEN/TR 15645-3:2008 (E)
3.6
multicomparison test

test where the assessor is asked to give a rating of the intensity of the difference in taste between test

portions for analysis and a known reference sample
3.7
off-flavour

a typical flavour often associated with deterioration or transformation of the product

[see ISO 5492:1992]
3.8
reference sample
calibration sample without any spiking compound.

NOTE This is presented to the assessors labelled as "Reference" and served to the assessors before tha calibration

samples.
3.9
selected assessor
assessor chosen for his/her ability to perform a sensory test
[see ISO 5492:1992]
3.10
spiking compound
volatile chemical compound having a specific flavour
NOTE In this case benzaldehyde is the selected spiking compound
3.11
spiking method
method for spiking the test substance with spiking compounds
3.12
taint
taste or odour foreign to the product
[see ISO 5492:1992]
3.13
taste

sensations perceived by the taste organ when stimulated by certain soluble substances

[see ISO 5492:1992]

NOTE For simplicity, taste and flavour are used as synonyms in the European Standard EN 1230-2, though this is

not exactly in accordance with ISO 5492. The same regards taint and off-flavour.
3.14
test portion
portion of the test sample, which is directly tested by the assessor
[see ISO 5492:1992]
3.15
test substance
substance to be assessed by the assessor
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CEN/TR 15645-3:2008 (E)

NOTE It may be the food product intended to be packed, or a suitable simulant that may absorb compounds from the

packaging materials. In this case icing sugar is the selected test substance.
4 Principle

A validation of the training process for a sensory panel has to be conducted with freshly made calibration

samples. Spiking solutions shall be prepared by diluting the spiking compound (benzaldehyde) in triacetin,

until required concentrations are reached. Calibration samples have to be prepared by exposure of icing sugar

to the different spiking solutions by an absorption procedure, using glass desiccators. The panel performance

in evaluating the off-flavour intensity within the calibration samples has to be determined before and after a

formal training step. The effectiveness of training can then be determined.
The test procedure consists of 3 steps:
a) first step: assessment of calibration samples before training;
b) second step: training procedure;
c) third step: assessment of calibration samples after training.

Detailed instructions for general test procedure, sample preparation and sensory evaluation are provided

within this Technical Report, and must be carefully followed to ensure validity of results.

5 Materials and reagents
5.1 General

Icing sugar is the test substance used to absorb different concentrations of the spiking compound diluted with

the solvent. In this Technical Report, benzaldehyde shall be used as the spiking compound and triacetin as

the solvent.

Every substance and reagent shall be certified for use in foodstuffs in accordance with European Standards

and free from off-flavours.
5.2 Test substance

Icing sugar that is free from off-flavour is used as the test substance. It should be stored in an odourless

environment, with storage conditions recommended as follows:
 Temperature: 18 °C to 25 ºC;
 Relative Humidity: 20 % to 60 %.
5.3 Spiking compound
Food grade benzaldehyde with purity of ≥ 99 % is used as the spiking compound.
5.4 Solvent

Triacetin (glyceryl triacetate) shall be used as a solvent for diluting the spiking compound. The CAS number of

triacetin is 102-76-1. Recommended purity of 97 % to 100 %.
---------------------- Page: 9 ----------------------
CEN/TR 15645-3:2008 (E)
5.5 Silicone (optional)

Silicone may be used to seal the cap of the glass-weighting flasks. If silicone is used, it should be chemically

pure and odourless (or very weak odour). Note that the use of silicone is optional.

5.6 Saturated sodium chloride solution

Pure NaCl (sodium chloride) has to be used to create batches of saturated sodium chloride solutions. NaCl

shall be free from off-flavours.
6 Equipment
6.1 General

All equipment used shall be free from odour and only in use for sensory analysis (see ISO 6658). Minimum-

odour cleaning agents for cleaning shall be used. Equipment and glassware shall be cleaned between

sessions. Any glassware used shall be washed with minimum-odour cleaning agents and dried by placement

in an oven at a temperature > 100 °C and left to evaporate for at least 2 h. All other equipment (including

dessicators) shall be washed with minimum-odour cleaning agents and left to dry at room temperature.

6.2 Dessicators

The absorption process has to be carried out in a glass dessicator fitted with a porcelain plate. One dessicator

is used per concentration of the spiking compound, five in total. Ensure the same dessicator is used to

make the same concentration of sample at each session. Specifications for the recommended dessicator

are given in Annex A.
6.3 Glass-weighting flasks

Glass-weighting flasks with ground glass cap that fits into an internally ground glass body.

Dimensions: diameter 50 mm
height 35 mm

If these flasks are not available, glass flasks of similar dimensions may be used, as long as they do not

introduce off-flavours or absorb odour.

Each test portion should be prepared and served in a separate glass-weighting flask. Six glass flasks are

required for each assessor on the panel. E.g. if there are eight assessors on the panel, then 48 flasks have to

be required.

NOTE Five extra glass-weighting flasks should be required for the spiking solutions. If possible, these should be of

identical dimensions, i.e. 50 mm diameter × 35 mm height.
6.4 Glass rods
Glass rods to stir the samples.
6.5 Plastic spoons

Each sample should be assessed using a separate spoon. At each session, every assessor will need one

plastic spoon for each sample.
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CEN/TR 15645-3:2008 (E)
7 Preparation of calibration samples
7.1 General

In general, six samples will be needed to be prepared. These are summarised, along with their concentrations

of benzaldehyde, see Table 1.

During the assessment sessions (first and third step), all six calibration samples will be needed to be

prepared. During the training session (second step), only four of the samples will be needed to be prepared

(reference, S1, S2 and S4). This will impact on the amount of icing sugar test portions that is needed to be

prepared, as well as which spiking solutions are needed to be made.

Table 1 — Samples and their concentrations of benzaldehyde (ppm = mg benzaldehyde/g sugar)

sample benzaldehyde concentration first step second third step
determined by the chemical step
analyses
ppm
reference 0 x x x
S0 (control sample) 0 x x
S1 3,22 ± 0,19 x x x
S2 6,44 ± 0,26 x x x
S3 14,63 ± 0,60 x x
S4 30,32 ± 1,39 x x x
7.2 Stability of calibration samples

The concentration of benzaldehyde significantly decreases in the calibration samples within 3 d of preparation.

Sample preparation shall begin 24 h prior to assessment (see details above).

If the dimensions of the used dessicator and the porcelain plate are not exactly the same as described in

Annex A, it is strongly recommended that the concentrations of benzaldehyde in calibration samples are

checked by chemical analyses (see Annex L) to be within the limits presented in Table1.

7.3 Preparation of saturated sodium chloride solution

NaCl has to be used to create batches of saturated sodium chloride solutions. One batch is required for each

dessicator (five batches in total). For each batch, heat 1 l of distilled water up to 90 ºC, add 500 g of pure NaCl

and stir using a magnetic stirrer until dissolved. Once it has cooled to room temperature, the solution has to be

placed in the dessicators, providing a saturated solution of NaCl standing over excess salt. A relative humidity

of 75 % will prevail in the dessicators with the aid of this solution.
7.4 Preparation of icing sugar test portions

First individual test portions of icing sugar shall be prepared. For each session, as many icing sugar samples

as you need (one 4,8 g sample of icing sugar for each sample for each assessor) have to prepared.

a) prior to measure test portions of icing sugar, the container with the 470 g of icing sugar for that session

has to be shaken for approximately 30 s for homogenisation;
b) weigh (4,8 ± 0,02) g of icing sugar in each glass-weighting flask;
---------------------- Page: 11 ----------------------
CEN/TR 15645-3:2008 (E)
c) the glass-weighting flasks have to be closed immediately;

NOTE The containers may be sealed by smearing silicone around the cap (optional);

d) surface of the sample is levelled out by gently knocking each container on the work surface (table).

Keep the icing sugar samples ready, but do not place them in the dessicators until after the following step.

7.5 Preparation of spiking solutions

Once the icing sugar is ready, the spiking solutions for each concentration should be prepared.

NOTE 1 The mixtures should be prepared immediately prior to introducing the glass-weighting flasks with the icing

sugar in the dessicators.

The spiking solutions have to be prepared in glass-weighting flasks (the same size and specifications as the

glass-weighting flasks used for the icing sugar).

The spiking compound (benzaldehyde) has to be dissolved and diluted in the solvent (triacetin), (3 ± 0,003) g

total weight. The amount of benzaldehyde and triacetin for each calibration sample, along with the final

concentrations, can be found in Table 2.

Table 2 — Concentration of spiking compound in solvent ((3 ± 0,003) g total weight)

sample benzaldehyde triacetin benzaldehyde in
solvent
g g
reference and S0 0,000 3,000 0
S1 0,045 2,955 1,5
S2 0,090 2,910 3
S3 0,210 2,790 7
S4 0,480 2,520 16

NOTE 2 The reference and control sample (S0) should be made simultaneously in the same dessicator, so only one

3 g batch of solution (triacetin only) is required to make both of these samples.

As soon as the spiking solution is ready, the container for each spiking solution by placing the lid on the glass-

weighting flask should be closed.
7.6 Preparation of calibration samples

For each session, fresh calibration samples have to be prepared. Prepare each set of calibration samples

using a separate dessicator for each concentration, following the steps below:

a) prepare the saturated NaCl solution as described in 7.3, pour the solution in the dessicators;

b) prepare the icing sugar samples as described in 7.4;
c) prepare the spiking solutions as described in 7.5;

d) closed container with the spiking compound has to be placed immediately in the centre of the porcelain

plate inside the dessicator. Dessicators should be labelled to identify the concentration inside.

Ensure the same dessicator is used to make the same concentration of sample at each session;

 each concentration of spiking solution has to be placed in a separate dessicator;

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CEN/TR 15645-3:2008 (E)

 one spiking solution only will be needed for the reference and control samples, which have to be

made in the same dessicator;

e) the containers with icing sugar are opened (lids removed), and placed in the dessicator, arranged around

the walls of the dessicator;

 for the spiked samples (S1, S2, S3, S4), up to fifteen icing sugar samples can be placed in one

dessicator (flasks may not be stacked);

 for the non-spiked samples (the reference and control samples), both sets of test portions (maximum

of 15 each, 30 in total) can be made simultaneously in the same dessicator (flasks are allowed to be

stacked);

f) the glass-weighting flask with the spiking compound is opened and is immediately followed by closure of

the dessicator, which is stored for 24 h at room temperature (20 ± 1) °C.
After the 24 h storage period:

g) dessicator is opened and the containers with the spiking compound and the icing sugar samples are

immediately closed. This has to be done for each dessicator, one at a time;

h) bottles containing the icing sugar are then coded with the appropriate 3-digit blinding codes (as identified

by the dessicator) from the experimental design, using an odourless marker. This has to be done one

dessicator at a time to ensure samples are correctly labelled.
Key
1 Dessicator
2 Container with the spiking solution
3 Porcelain plate
4 Container with the icing sugar
5 Sodium chloride saturated solution
Figure 1 — Arrangement of icing sugar samples in the dessicator
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CEN/TR 15645-3:2008 (E)

During the entire preparation procedure samples should be handled with care to avoid any movement that

might disturb the sample. Furthermore following completion of the spiking procedure the lids on the spiked

calibration samples should not be removed until ready for dilution with water and the sensory assessment that

follows.

The calibrated samples should be evaluated within 2 h of removing the spiked samples from the dessicator.

Immediately prior to sensory assessment: the spiked icing sugar samples should be diluted by adding

1,2 ml of mineral water to each sample using a pipette. Each lid should be replaced after the water has been

added.

Each sample then must be stirred for 30 s. It may save some preparation time to ask the assessors to

perform this task. In this case, for one sample at a time, instruct the assessors to remove the lid, stir for 30 s

then replace the lid. This has to be done for each sample. Once all samples have been stirred, the sensory

assessment may begin as described in clause 8.

NOTE The instructions in Annex D and Annex E assume that the assessors should stir the samples themselves. If

this is not the case, remove this from their instructions.
8 Sensory tests
8.1 General test conditions

Basic information on general requirements, test methods and analysis of results in sensory evaluation is given

in ISO 6658 as a general guidance.

For the design of, and the conditions in, the room in which tests are conducted ISO 8589 should be consulted.

In general, the evaluation shall be carried out at room temperature in a quiet, well-ventilated room that is free

from odours.

The containers and equipment used shall be odourless and should not have any influence on the test results.

8.2 Sensory panel

Guidelines concerning the selection and training of assessors are given in ISO 8586-1. The assessors shall

be in good health and shall not suffer from the common cold at the time of the test.

Only selected, trained assessors shall be used in the sensory evaluations. The availability of assessors, their

interest and motivation, and capacity to concentrate should be ascertained prior the training procedure. The

recommended
...

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