EN 17992:2024
(Main)Food authenticity - Determination of the sum of 16-O-Methylcafestol, 16-O-Methylkahweol and their derivatives in roasted coffee by ¹H-qNMR
Food authenticity - Determination of the sum of 16-O-Methylcafestol, 16-O-Methylkahweol and their derivatives in roasted coffee by ¹H-qNMR
This document specifies a method for the determination of soluble 16-O-Methylcafestol and 16-O-Methylkahweol content (the sum of free forms and derivatives, e.g. fatty acid esters, henceforth abbreviated as 16-OMD = “diterpenes”) in roasted coffee (beans or ground), using quantitative proton nuclear magnetic resonance spectroscopy (1H-qNMR).
If complying with the experimental parameters described below, this test procedure has been proven for the following mass fraction range:
w16-OMD: 20 mg/kg to 2 000 mg/kg.
The mass fraction range can be expanded by suitable changes of the experimental parameters, e.g. a different weighed portion of ground coffee or the accumulation of more NMR-transients.
Lebensmittelauthentizität - Bestimmung des Gehalts von 16-O-Methylcafestol, 16-O-Methylkahweol und deren Derivaten als Summenparameter in Röstkaffee mittels ¹H-qNMR
Dieses Dokument legt ein Verfahren zur Bestimmung des Gehalts an löslichem 16 O Methylcafestol und 16 O Methylkahweol (Summe der freien Formen und Derivate, z. B. Fettsäureester, im Folgenden abgekürzt als 16 OMD = „Diterpene“) in geröstetem Kaffee (Bohnen oder gemahlen) mittels quantitativer Protonen-nuklearmagnetischer Resonanzspektroskopie (1H qNMR) fest.
Bei Einhaltung der nachstehend beschriebenen Versuchsparameter hat sich dieses Prüfverfahren für den folgenden Bereich der Massenanteile bewährt:
w16-OMD: 20 mg/kg bis 2 000 mg/kg.
Der Bereich der Massenanteile kann durch geeignete Änderungen der Versuchsparameter erweitert werden, z. B. durch eine andere Einwaage des gemahlenen Kaffees oder die Akkumulation von mehr NMR Transienten.
Authenticité des aliments - Détermination par résonance magnétique nucléaire quantitative du proton (RMN-¹H) de la somme des teneurs en 16-O-méthylcafestol, 16-O-méthylkahwéol et leurs dérivés dans le café torréfié
Le présent document spécifie une méthode de détermination de la teneur en 16-O-méthylcafestol et 16 O-méthylkahwéol solubles (somme des formes libres et des dérivés, par exemple esters d’acides gras, désormais abrégé 16-OMD = « diterpènes ») du café torréfié (en grains ou moulu), par spectroscopie par résonance magnétique nucléaire quantitative du proton (qRMN-1H).
En respectant les paramètres expérimentaux décrits ci-dessous, ce mode opératoire d’essai a été validé pour la gamme de fractions massiques suivantes :
w16-OMD : 20 mg/kg à 2 000 mg/kg.
La gamme de fractions massiques peut être élargie en modifiant de façon adéquate les paramètres expérimentaux, par exemple une prise d’essai différente de café moulu ou l’accumulation de plusieurs transitions RMN.
Pristnost živil - Določanje vsote 16-O-metilkafestola, 16-O-metilkaveola in njunih derivatov v praženi kavi z metodo ¹H-qNMR
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN 17992:2023
01-september-2023
Pristnost živil - Določanje vsote 16-O-metilkafestola, 16-O-metilkaveola in njunih
derivatov v praženi kavi z metodo ¹H-qNMR
Food authenticity - Determination of the sum of 16-O-methylcafestol, 16-O-
Methylkahweol and their derivatives in roasted coffee by ¹H-qNMR
Lebensmittelauthentizität - Bestimmung des Gehalts von 16-O-Methylcafestol, 16-O-
Methylkahweol und deren Derivaten als Summenparameter in Röstkaffee mittels ¹H-
qNMR
Authenticité alimentaire du café - Détermination de la teneur en 16-O-méthylcafestol -
Méthode par NMR
Ta slovenski standard je istoveten z: prEN 17992
ICS:
67.140.20 Kava in kavni nadomestki Coffee and coffee substitutes
oSIST prEN 17992:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
oSIST prEN 17992:2023
oSIST prEN 17992:2023
DRAFT
EUROPEAN STANDARD
prEN 17992
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2023
ICS 67.140
English Version
Food authenticity - Determination of the sum of 16-O-
Methylcafestol, 16-O-Methylkahweol and their
derivatives in roasted coffee by H-qNM
Authenticité alimentaire du café - Détermination de la Lebensmittelauthentizität - Bestimmung des Gehalts
teneur en 16-O-méthylcafestol - Méthode par NMR von 16-O-Methylcafestol, 16-O-Methylkahweol und
deren Derivaten als Summenparameter in Röstkaffee
mittels H-qNMR
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 460.
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, Türkiye 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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 17992:2023 E
worldwide for CEN national Members.
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prEN 17992:2023 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Reagents . 8
5 Apparatus . 9
6 Measurement and test methods . 10
6.1 General. 10
6.2 Sampling . 11
6.3 Sample preparation . 11
6.4 NMR experiments . 12
6.5 Calibration and evaluation . 14
6.6 Determination of the PULCON factor . 15
6.7 Calculation of the analyte mass concentrations in coffee . 16
6.8 List of analytes and relevant parameters . 17
7 Accuracy . 17
7.1 Ring test / Interlaboratory comparison test . 17
7.2 Repeatability . 17
7.3 Reproducibility . 17
7.4 Limit of quantification (LOQ) . 18
8 Test report . 18
Annex A (informative) Summary of the statistical evaluation of the method validation study
“16-OMC in coffee” . 19
Annex B (informative) Common collaborative study of the NMR and HPLC methods (prEN
XXXX and prEN YYYY) . 22
B.1 Background of the collaborative study . 22
B.2 Explanation of systematic differences between the results of the NMR and HPLC
methods (prEN XXXX and prEN YYYY) . 22
Bibliography . 23
oSIST prEN 17992:2023
prEN 17992:2023 (E)
European foreword
This document (prEN 17992:2023) has been prepared by Technical Committee CEN/TC 460 “Food
authenticity”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
oSIST prEN 17992:2023
prEN 17992:2023 (E)
Introduction
This document was developed in response to demand for an efficient and reliable test method allowing
the confirmation of coffee authenticity both for commercial quality control and for official food control.
The coffee species with the greatest commercial importance are Coffea Arabica and Coffea canephora var.
robusta, commonly known as “arabica” and “robusta”. Within these species, Arabica coffees have a
significantly higher market value than robusta coffees. In unblended coffee the botanical origin of coffee
can be determined unambiguously by analysing the concentration of 16-O-methylcafestol and 16-O-
Methylkahweol and their derivatives (e.g. fatty acid esters) because these marker substances are present
in arabica coffee at very low concentrations (typically < 20 mg/kg). In robusta coffees the concentration
levels are significantly higher in the approximate range of 800 to 2 500 mg/kg. [1 – 5]
These published values are quoted as an orientation only and not intended as strict threshold recommendations.
oSIST prEN 17992:2023
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1 Scope
This document specifies a method for the determination of soluble 16-O-Methylcafestol and 16-O-Methyl
kahweol content (the sum of free forms and derivatives, e.g. fatty acid esters, henceforth abbreviated as
16-OMD = “diterpenes”) in roasted coffee (beans or ground), using quantitative proton nuclear magnetic
resonance spectroscopy ( H-qNMR).
If complying with the experimental parameters described below, this test procedure has been proven for
the following concentration range:
16-OMD: 20 mg/kg to 2 000 mg/kg.
The concentration range can be expanded by suitable changes of the experimental parameters, e.g. a
different weighed portion of ground coffee or the accumulation of more NMR-transients.
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 1042, Laboratory glassware - One-mark volumetric flasks (ISO 1042)
ISO 3310-1, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 3509, Coffee and coffee products — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3509 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
16-OMC and 16-OMK (= 16-O-Methyl Diterpene (“16-OMD”) derivatives content extractable with
chloroform
content in coffee, determined according to this test procedure and quoted as a mass fraction w in mg per
kg coffee, calculated as free 16-OMC
Note 1 to entry: An additional fraction of the total 16-OMD content (ca. 25 %) can only be extracted by vigorous
chemical processing.
Note 2 to entry: Approximately a mass fraction of 90 % of the 16-OMD is represented by 16-O-methylcafestol, and
16-O-methylkahweol represent the remaining mass fraction of 10 % of the mixture.
Note 3 to entry: The relative error due to differences in molar weight is 0,6 %.
[SOURCE: [1]]
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3.2
16-OMC
16-O-Methylcafestol
(CAS RN® : 108214-28-4), M = 330,5 g/mol
Note 1 to entry: The substance appears in its free form or esterified, see Figure 1.
3.3
16-OMK
16-O-Methylkahweol
(CAS RN®: not yet available), M = 328,5 g/mol
Note 1 to entry: The substance appears in its free form or esterified, see Figure 1.
a) 16-OMC b) 16-OMK
c) kahweol d) dehydrokahweol
Key
R residue (H or fatty acid)
NOTE The atom numbering is the same for the shown substances.
Figure 1 — Four diterpenes present in coffee
3.4
FID
free induction decay
time-domain NMR signal that results from the precession of the nuclear magnetization vector inside the
probe coil after application of an excitation RF pulse to a sample in a static magnetic field
[SOURCE: ISO 24583:2022, 3.6]
CAS Registry Number® is the trademark of a product supplied by CAS. This information is given for the
convenience of users of this document and does not constitute an endorsement by CEN of the product named.
Equivalent products may be used if they can be shown to lead to the same results.
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prEN 17992:2023 (E)
3.5
FWHM
full width at half maximum
width of a line shape at half the maximum signal intensity
Note 1 to entry: It is expressed in Hz.
[SOURCE: ISO 24583:2022, 3.9 – modified: Note 2 to entry deleted]
3.6
kahweol
1,2-Dehydrocafestol (CAS RN®: 6894-43-5)
Note 1 to entry: The substance appears in its free form or esterified, see Figure 1.
3.7
dehydrokahweol
1,2,15,16-bis-dehydrocafestol (CAS RN®: not yet available)
Note 1 to entry: It is a roasting product from kahweol.
Note 2 to entry: The substance appears in its free form or esterified, see Figure 1.
3.8
NMR
nuclear magnetic resonance spectroscopy
method based on the selective absorption of high frequency radio waves by atomic nuclei subjected to a
stationary magnetic field
Note 1 to entry: NMR provides chemical and structural properties of molecules.
[SOURCE: ISO 23118:2021, 3.10]
3.9
ppm
part per million
unit for the chemical shift (δ) of a resonance signal
Note 1 to entry: Dividing a signal’s real resonance frequency fres (in Hz, cycles per second) by the frequency rating
of the NMR spectrometer fspect and multiplying with 10 , a normalized shift measure is obtained that is independent
of the spectrometer’s field strength. See the following formula for explanation:
f
res
δ × 1 000 000
res
f
spect
3.10
PULCON
PUlse-Length-based CONcentration determination
quantitative NMR method with external standard factoring in the duration of the 90° excitation pulse into
the calculation of concentrations
=
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3.11
QuantRef
Quantification Reference
external standard to determine the spectrometer’s response (signal integral per amount of NMR-active,
measured nuclei)
Note 1 to entry: The QuantRef shall be a stable solution of one or more certified reference substances showing at
least one
...
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