prEN 1787
(Main)Foodstuffs - Detection of irradiated food containing cellulose by ESR spectroscopy
Foodstuffs - Detection of irradiated food containing cellulose by ESR spectroscopy
This European Standard 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 electron paramagnetic resonance (EPR) spectrum, of the food.
Interlaboratory studies have been successfully carried out with pistachio nut shells, paprika powder and fresh strawberries. However, it has been shown that false positive results can appear when analysing bleached nuts. For further information, see Clause 7 on limitations.
Lebensmittel - ESR-spektroskopischer Nachweis von bestrahlten cellulosehaltigen Lebensmitteln
Dieses Dokument legt ein Verfahren zum Nachweis von mit ionisierender Strahlung behandelten cellulosehaltigen Lebensmitteln fest. In diesem Verfahren wird das ESR (Elektronen-Spin-Resonanz) – auch bekannt als EPR (Elektronen-Paramagnetische-Resonanz)-Spektrum des Lebensmittels analysiert, siehe [1] bis [13].
Dieses Verfahren wurde im Ringversuch erfolgreich an Pistazienschalen [14] bis [18], an Paprikapulver [19] und [20] und an frischen Erdbeeren [21] geprüft. Es hat sich jedoch gezeigt, dass das Verfahren bei der Untersuchung von gebleichten Nüssen zu falsch positiven Ergebnissen führen kann. Weitere Informationen siehe Abschnitt 7 zu den Grenzen des Verfahrens.
Produits alimentaires - Détection par spectroscopie RPE d'aliments ionisés contenant de la cellulose
Le présent document spécifie une méthode de détection de traitement ionisant appliquée à des produits
alimentaires contenant de la cellulose, par analyse du spectre de résonance de spin électronique (RSE)
aussi appelé spectre de résonance paramagnétique électronique (RPE) des aliments ; voir [1] à [13].
Des essais interlaboratoires ont été réalisés sur des écales de pistache [14] à [18], du paprika en poudre
[19] et [20], et des fraises fraîches [21]. Toutefois, il a été démontré que des résultats faux positifs peuvent
être obtenus lors de l’analyse de noix en coque blanchies. Pour de plus amples informations, voir
l’Article 7 relatif aux limites.
Živila - Detekcija obsevane hrane, ki vsebuje celulozo, s spektroskopijo ESR TC: Živila - Dokazovanje obsevanosti hrane, ki vsebuje celulozo, s spektroskopijo ESR
General Information
RELATIONS
Standards Content (sample)
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
Lebensmittel - ESR-spektroskopischer Nachweis von bestrahlten cellulosehaltigenLebensmitteln
Produits alimentaires - Détection par spectroscopie RPE d'aliments ionisés contenant de
la celluloseTa slovenski standard je istoveten z: prEN 1787
ICS:
67.050 Splošne preskusne in General methods of tests and
analizne metode za živilske analysis for food products
proizvode
oSIST prEN 1787:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 1787:2019
DRAFT
EUROPEAN STANDARD
prEN 1787
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2019
ICS Will supersede EN 1787:2000
English Version
Foodstuffs - Detection of irradiated food containing
cellulose by ESR spectroscopy
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
CEN/TC 275.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
Management Centre has the same status as the official versions.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
United Kingdom.Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1787:2019 E
worldwide for CEN national Members.---------------------- Page: 3 ----------------------
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prEN 1787:2019 (E)
Contents Page
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
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prEN 1787:2019 (E)
European foreword
This document (prEN 1787:2019) has been prepared by Technical Committee CEN/TC 275 “Food
analysis - Horizontal methods”, the secretariat of which is held by DIN.This document will supersede EN 1787:2000.
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 changes between this document and the previous edition are as follows:— The scope contains the information that it has been shown that false-positive results can appear
when analysing bleached nuts.— 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
positive signals which can be mixed up with radiation induced signals.— 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 new version was editorially updated according to current rules.---------------------- Page: 5 ----------------------
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1 Scope
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
electron paramagnetic resonance (EPR) spectrum, of the food, see [1] to [13].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
limitations.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.EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696:1987)
3 Terms and definitionsNo terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/• ISO Online browsing platform: available at http://www.iso.org/obp
4 Principle
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
derivative of the absorption with respect to the applied magnetic field.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
paramagnetic compounds and thus with the applied dose.---------------------- Page: 6 ----------------------
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5 Apparatus and equipment
Usual laboratory apparatus and, in particular, the following:
5.1 Commercially available X-Band ESR spectrometer including magnet (electro or
permanent), microwave bridge, console with field- controller and signal-channel, rectangular or
cylindrical cavity.5.2 ESR tubes, suitable for the ESR spectrometer used (e.g. Suprasil quartz tubes,)
5.3 Balance, accurate to the nearest 1 mg (optional)5.4 Laboratory vacuum oven or freeze dryer
5.5 Electric blender
5.6 Filter paper
5.7 Scalpel, pincers
5.8 Water of at least grade 3 according to EN ISO 3696
6 Procedure
6.1 Sample preparation
6.1.1 General
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].
6.1.2 Shells and stonesRemove 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
nutshells but recommended for pips and kernels of fruits.6.1.3 Spices
For example use about 150 mg to 200 mg of the spice sample. Drying (e.g. in a freeze-dryer or at
approximately 40 °C in a laboratory vacuum oven (5.4)) is usually not necessary.1 ®
) 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.
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6.1.4 Strawberries
Strawberry samples should be measured immediately after receipt. Otherwise store the samples at
approximately - 18 °C until analysis.For ESR measurement about 200 mg of seeds (achenes) of strawberries are needed. These can be
gained usually from about 80 g of strawberries.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
once or twice to remove any remaining fruit pulp.Place the seeds on filter paper to remove adhering water. Dry the seeds in a freeze dryer or at
approximately 40 °C in a laboratory vacuum oven (5.4) e.g. for 2 h.Storing samples in the frozen state will not adversely affect the detection of treatment with
radiation.6.2 ESR Spectroscopy
6.2.1 Spectrometer settings
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
been found to be satisfactory:Microwave radiation: Frequency 9,78 GHz , power 0,4 mW (for e.g. pistachio nuts), to
0,8 mW (for e.g. paprika powder or strawberries) ;Magnetic field: 348 mT centre field ), sweep width 20 mT;
Signal channel: 50 kHz or 100 kHz modulation frequency;
0,4 mT to 1,0 mT modulation amplitude;
4 −1
100 ms to 200 ms time con
...
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