oSIST prEN 1787:2019

SLOVENSKI STANDARD
oSIST prEN 1787:2019
01-december-2019
Živila - Detekcija obsevane hrane, ki vsebuje celulozo, s spektroskopijo ESR

Foodstuffs - Detection of irradiated food containing cellulose by ESR spectroscopy

Produits alimentaires - Détection par spectroscopie RPE d'aliments ionisés contenant de

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

Produits alimentaires - Détection par spectroscopie Lebensmittel - ESR-spektroskopischer Nachweis von

RPE d'aliments ionisés contenant de la cellulose bestrahlten cellulosehaltigen Lebensmitteln

This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee

If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations

which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other

language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC

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

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

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1787:2019 E

European foreword .......................................................................................................................................................3

1 Scope ....................................................................................................................................................................4

2 Normative references ....................................................................................................................................4

3 Terms and definitions ....................................................................................................................................4

4 Principle ..............................................................................................................................................................4

5 Apparatus and equipment ............................................................................................................................5

6 Procedure ...........................................................................................................................................................5

6.1 Sample preparation ........................................................................................................................................5

6.1.1 General ................................................................................................................................................................5

6.1.2 Shells and stones ..............................................................................................................................................5

6.1.3 Spices ....................................................................................................................................................................5

6.1.4 Strawberries ......................................................................................................................................................6

6.2 ESR Spectroscopy .............................................................................................................................................6

6.2.1 Spectrometer settings ....................................................................................................................................6

6.2.2 Analysis of sample ...........................................................................................................................................7

7 Evaluation ...........................................................................................................................................................7

8 Limitations .........................................................................................................................................................7

9 Validation ...........................................................................................................................................................8

10 Test report .........................................................................................................................................................9

Annex A (normative) Figures................................................................................................................................. 10

Annex B (informative) Further information on the applicability ............................................................ 12

Bibliography ................................................................................................................................................................. 13

This document (prEN 1787:2019) has been prepared by Technical Committee CEN/TC 275 “Food

The predecessor of this document was elaborated on the basis of a protocol developed following a

concerted action supported by the Commission of European Union (XII C.5). Experts and

laboratories from EU and EFTA countries, contributed jointly to the development of this protocol.

— The scope contains the information that it has been shown that false-positive results can appear

— The clause on limitations was amended by the information that, having identified, that the

method yields false positives with certain matrices (e.g. bleached nuts), it is in the responsibility

of the analyst to ensure that the method is fit for purpose on the matrix on which it is applied.

— The clause on limitations was furthermore amended by the information that it has been shown

that with nuts in shells (hazelnuts, walnuts, pistachio), a bleaching can lead to comparable

— The Figures A.5 to A.8 were included to show how figures from non-irradiated but bleached

nutshells can be differentiated from irradiated shells from hazelnuts and walnuts.

This document specifies a method for the detection of foods containing cellulose which have been

treated with ionizing radiation, by analysing the electron spin resonance (ESR) spectrum, also called

Interlaboratory studies have been successfully carried out with pistachio nut shells, [14] to [18],

paprika powder [19] and [20] and fresh strawberries [21]. However, it has been shown that false-

positive results can appear when analysing bleached nuts. For further information, see Clause 7 on

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)

EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696:1987)

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

ESR spectroscopy detects paramagnetic centres (e.g. radicals). They are either due to irradiation, or

to other compounds present. An intense external magnetic field produces a difference between the

energy levels of the electron spins ms = + 1/2 and ms = −1/2, leading to resonance absorption of an

applied microwave beam in the spectrometer. ESR spectra are conventionally displayed as the first

The field and frequency values depend on the experimental arrangements (sample size, sample

holder and spectrometer specifications), while their ratio (i.e. g value) is an intrinsic characteristic

of the paramagnetic centre and its local coordination. For further information, see [1] to [13].

Radiation treatment produces specific radicals which can be mostly detected in solid and dry parts

of the food. The intensity of the signal obtained increases with the concentration of the

permanent), microwave bridge, console with field- controller and signal-channel, rectangular or

5.2 ESR tubes, suitable for the ESR spectrometer used (e.g. Suprasil quartz tubes,)

Do not grind the samples since grinding could either diminish the signal to noise ratio and can also

cause a change of the shape of the ESR spectrum or induce other ESR signals [25].

Remove pieces of suitable size (about 50 mg to 100 mg, e.g. 3,0 mm to 3,5 mm in diameter) from the

shells or stones of the food, e.g. using a scalpel or pincers. Drying (e.g. in a freeze-dryer or at

approximately 40 °C in a laboratory vacuum oven (5.4)) is usually not necessary in the case of

For example use about 150 mg to 200 mg of the spice sample. Drying (e.g. in a freeze-dryer or at

) Suprasil is an example of a product available commercially. This information is given for the

convenience of users of this Standard and does not constitute an endorsement of CEN of this product.

Strawberry samples should be measured immediately after receipt. Otherwise store the samples at

For ESR measurement about 200 mg of seeds (achenes) of strawberries are needed. These can be

For separation of the small seeds from the main fruit body either peel off the skin (recommendation:

in frozen state) or use the whole fruit (without stalks and leaves). Homogenize the strawberries in

an electric blender (5.5). Add 500 ml of water to the fruit pulp and stir thoroughly. Allow the seeds

to settle and decant most of the water together with the floating fruit pulp. Repeat this procedure

Place the seeds on filter paper to remove adhering water. Dry the seeds in a freeze dryer or at

Storing samples in the frozen state will not adversely affect the detection of treatment with

These following parameters have been proven to be successful in the interlaboratory test (see

Clause 8). They should be optimized as per sample and ESR spectrometer specifications.

Use a time constant and sweep rate (or sweep time) appropriate for an ESR signal with a peak to

peak linewidth of approximately 0,8 mT. For example, the following ESR spectrometer settings have

Microwave radiation: Frequency 9,78 GHz , power 0,4 mW (for e.g. pistachio nuts), to