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SLOVENSKI STANDARD
01-junij-2022
Nadomešča:
SIST EN 13708:2002
Živila - Določevanje obsevanosti živil, ki vsebujejo kristalni sladkor, s
spektroskopijo ESR
Foodstuffs - Detection of irradiated foodstuff containing crystalline sugar by ESR
spectroscopy
Lebensmittel - ESR-spektroskopischer Nachweis von bestrahlten Lebensmitteln, die
kristallinen Zucker enthalten
Produits alimentaires - Détection par spectroscopie RPE d’aliments ionisés contenant
des sucres cristallisés
Ta slovenski standard je istoveten z: EN 13708:2022
ICS:
67.050 Splošne preskusne in General methods of tests and
analizne metode za živilske analysis for food products
proizvode
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN 13708
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2022
EUROPÄISCHE NORM
ICS 67.050 Supersedes EN 13708:2001
English Version
Foodstuffs - Detection of irradiated foodstuff containing
crystalline sugar by ESR spectroscopy
Produits alimentaires - Détection par spectroscopie Lebensmittel - ESR-spektroskopischer Nachweis von
RPE d'aliments ionisés contenant des sucres bestrahlten Lebensmitteln, die kristallinen Zucker
cristallisés enthalten
This European Standard was approved by CEN on 14 February 2022.
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. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists 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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 13708:2022 E
worldwide for CEN national Members.
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
7 Evaluation . 6
8 Limitations . 8
9 Validation . 8
10 Test report . 9
Annex A (informative) Example Figures . 10
Bibliography . 12
European foreword
This document (EN 13708:2022) has been prepared by Technical Committee CEN/TC 275 “Food
analysis - Horizontal methods”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by September 2022, and conflicting national standards shall
be withdrawn at the latest by September 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 13708:2001.
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.). Experts and laboratories from
E.U. and EFTA countries, contributed jointly to the development of this protocol.
In comparison with the previous edition, the entire document was editorially revised according to
current rules. Additionally, the following technical modifications have been made:
a) clause “Normative references” was added;
b) clause “Terms and Definitions” was added;
c) former 3.2 was scientifically refined and converted into a footnote;
d) section “Sample preparation” was slightly extended and modified by conversion of the NOTE and
WARNING into main text;
e) section “Spectrometer settings” was scientifically refined, its normative character (i.e. provisions set
out) modified towards more exemplary/suggestive expressions of provision and aligned with
EN 1787;
f) clause “Evaluation” was amended by restructuring the subsections (subsection “G-value calculation”
became 7.1 and “Identification of irradiated samples” 7.2), including refinement of the given
information, designations and abbreviations including the alignment with the Annexes and EN 1787;
g) clause “Limitations” was extended;
h) layout of Figures A.1 to A.4 were revised and Figures A.5 to A.7 for irradiated fructose, glucose and
saccharose were added including alignment of the given information with the main text and EN 1787;
i) the Bibliography was updated and extended by entry [8], [9] and [10].
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: 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 the United
Kingdom.
1 Scope
This document specifies a method for the detection of foodstuff containing crystalline sugars which have
been treated with ionizing radiation, by analysing the electron spin resonance (ESR) spectrum, also called
electron paramagnetic resonance (EPR) spectrum, of the foodstuff, see [1] to [7].
Interlaboratory studies have been successfully carried out on dried figs, dried mangoes, dried papayas
and raisins, see [1] to [3].
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No 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
— ISO Online browsing platform: available at
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 m = +½ and m = -½, leading to resonance absorption of an applied
s s
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 magnetic field and microwave frequency values depend on the experimental arrangements (sample
size and sample holder), while their ratio (i.e. g value) is an intrinsic characteristic of the paramagnetic
centre and its local co-ordination. For further information, see [1] to [7].
Radiation treatment produces radicals, which can be mostly detected in solid and dry parts of the
foodstuff. The intensity of the signal obtained increases with the concentration of the paramagnetic
compounds and thus with the applied dose.
5 Apparatus and equipment
Usual laboratory apparatus and, in particular, the following.
5.1 Commercially available X-Band ESR spectrometer including magnet, microwave bridge, console
with field-controller and signal-channel, rectangular or cylindrical cavity .
2
5.2 ESR tubes, with an internal diameter of about 4,0 mm (e.g. Suprasil quartz tubes).
5.3 Balance, accuracy of 1 mg (optional).
5.4 Laboratory vacuum oven, or freeze dryer.
5.5 Scalpel.
6 Procedure
6.1 Sample preparation
Prepare suitable pieces (50 mg to 100 mg) of the fruits, e.g. using a scalpel. Avoid grinding of samples.
Various parts of the fruits can contain different quantities of crystalline sugars. It can be advantageous to
take the test sample from the outer parts of the fruits.
Transfer a test portion directly into the ESR tube (5.2) and start the measurement.
Difficulties in tuning the spectrometer cavity can be experienced if the sample is insufficiently dry. In this
case either reduce the sample quantity or dry it further. Samples should be dried in a laboratory vacuum
oven at approximately 40 °C under reduced pressure or in a freeze-dryer.
Temperatures significantly higher than 40 °C can reduce the signal.
6.2 ESR Spectroscopy
6.2.1 Spectrometer settings
The parameters shown in Table 1 have been found to be successful in interlaboratory tests (see Clause 9).
The values shown (Table 1) are given as examples and should be optimized per sample and ESR
spectrometer as required.
Use a time constant and sweep rate (or sweep time) appropriate for an ESR signal with a peak to peak
linewidth of approximately 0,2 mT to 0,4 mT.
g-value calculation unit including frequency counter magnetic field probe (magnetic resonance Teslameter) or
any other built in g-value calculation unit.
2
Suprasil is an example of a suitable product available commercially. This information is only given for the
convenience of users of this document and does not constitute an endorsement by CEN or CENELEC of this product.
Table 1 — Example for ESR spectrometer settings
Parameter Setting
a
Microwave radiation:
Frequency 9,78 GHz , power 5 mW.
a
Magnetic field:
348 mT centre field , sweep width 10,0 mT to 20,0 mT.
Signal channel: 50 kHz or 100 kHz modulation frequency;
0,15 mT to 0,4 mT modulation amplitude;
b −1
100 ms to 200 ms time constant , sweep rate 5 mT min to 10 mT min
−1
or accumulation of 3 to 5 spectra at greater sweep rate and shorter
time constant.
4 6
Gain:
Between approximately 10 and 10 .
Temperature: Ambient temperature.
a
These values are for the specified microwave frequency and magnetic field; if the frequency is higher
(lower) the magnetic field strength will be higher (lower).
b
These values are for the specified sweep rate.
6.2.2 Analysis of sample
Analyse the sample prepared as described in 6.1 in an ESR tube (5.2).
7 Evaluation
7.1 G-value calculation
For calculating the g-value of the centre (i.e. zero point) of the multicomponent ESR spectra (Figures A.1
to A.4) it is necessary to measure the frequency v (e.g. frequency counter) and the field B (e.g. gaussmeter)
at this point.
A g-value of a signal, g (g ), is calculated using Formula (1):
signal
S
71, 448⋅ν
ESR
g = (1)
S
B
where
ν is the microwave frequency, in Gigahertz (GHz);
ESR
B is the magnetic flux density (magnetic field setting of the spectrometer), in Millitesla (mT);
(10 Gauss = 10 G = 1 mT).
7.2 Identification of irradiated samples
7.2.1 General
Irradiated foodstuff containing crystalline sugar show typical multicomponent ESR spectra reflecting the
presence of radiation-induced radicals in the sample. Dried fruits often contain sugar particles in
crystalline form, and therefore the appearance of a typical multicomponent ESR spectrum (see Annex A)
indicates radiation treatment. Due to different mono- and disaccharides and due to the changes in
saccharide composition various ESR spectrum types can occur.
Other irradiated sugar-containing foodstuff reveal ESR spectra that have similar structures. Since the
overall spectrum structure depends on the radical composition and on the crystallinity of the mono- and
disaccharides present in the sample, variations in the spectrum characteristics occur.
For monocrystalline samples, the orientation within the ESR cavity can influence the relative intensities
of the ESR lines and thus the spectral shape. However, in t
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