EN ISO 3656:2011
(Main)Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction (ISO 3656:2011)
Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction (ISO 3656:2011)
ISO 3656:2011 specifies a method for the determination of the absorbance at ultraviolet wavelengths of animal and vegetable fats and oils.
Tierische und pflanzliche Fette und Öle - Bestimmung der Ultraviolett-Absorption, ausgedrückt als spezifische UV-Extinktion (ISO 3656:2011)
Diese Internationale Norm legt ein Verfahren zur Bestimmung der Absorption von tierischen und pflanzlichen
Fetten und Ölen bei Wellenlängen im ultravioletten Bereich fest.
Corps gras d'origines animale et végétale - Détermination de l'absorbance dans l'ultraviolet, exprimée sous la forme d'extinction spécifique en lumière ultraviolette (ISO 3656:2011)
L'ISO 3656:2011 spécifie une méthode pour la détermination de l'absorbance des corps gras d'origines animale et végétale, aux longueurs d'onde ultraviolettes.
Rastlinske in živalske maščobe in olja - Določanje ultravijolične absorpcije, izražene kot specifična UV-ekstinkcija (ISO 3656:2011)
Ta mednarodni standard opredeljuje metodo za določanje ultravijolične absorpcije pri ultravijoličnih valovnih dolžinah živalskih in rastlinskih maščob in olj.
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
01-maj-2011
1DGRPHãþD
SIST EN ISO 3656:2002
5DVWOLQVNHLQåLYDOVNHPDãþREHLQROMD'RORþDQMHXOWUDYLMROLþQHDEVRUSFLMH
L]UDåHQHNRWVSHFLILþQD89HNVWLQNFLMD ,62
Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed
as specific UV extinction (ISO 3656:2011)
Tierische und pflanzliche Fette und Öle - Bestimmung der Ultraviolett-Absorption,
ausgedrückt als spezifische UV-Extinktion (ISO 3656:2011)
Corps gras d'origines animale et végétale - Détermination de l'absorbance dans
l'ultraviolet, exprimée sous la forme d'extinction spécifique en lumière ultraviolette (ISO
3656:2011)
Ta slovenski standard je istoveten z: EN ISO 3656:2011
ICS:
67.200.10 5DVWOLQVNHLQåLYDOVNH Animal and vegetable fats
PDãþREHLQROMD and oils
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN ISO 3656
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2011
ICS 67.200.10 Supersedes EN ISO 3656:2002
English Version
Animal and vegetable fats and oils - Determination of ultraviolet
absorbance expressed as specific UV extinction (ISO
3656:2011)
Corps gras d'origines animale et végétale - Détermination Tierische und pflanzliche Fette und Öle - Bestimmung der
de l'absorbance dans l'ultraviolet, exprimée sous la forme Ultraviolett-Absorption, ausgedrückt als spezifische UV-
d'extinction spécifique en lumière ultraviolette (ISO Extinktion (ISO 3656:2011)
3656:2011)
This European Standard was approved by CEN on 22 January 2011.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 3656:2011: E
worldwide for CEN national Members.
Contents Page
Foreword .3
Foreword
This document (EN ISO 3656:2011) has been prepared by Technical Committee ISO/TC 34 "Food products"
in collaboration with Technical Committee CEN/TC 307 “Oilseeds, vegetable and animal fats and oils and their
by-products - Methods of sampling and analysis” the secretariat of which is held by AFNOR.
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 August 2011, and conflicting national standards shall be withdrawn at
the latest by August 2011.
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.
This document supersedes EN ISO 3656:2002.
According to the CEN/CENELEC Internal Regulations, the national standards organizations 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, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 3656:2011 has been approved by CEN as a EN ISO 3656:2011 without any modification.
INTERNATIONAL ISO
STANDARD 3656
Fourth edition
2011-02-01
Animal and vegetable fats and oils —
Determination of ultraviolet absorbance
expressed as specific UV extinction
Corps gras d'origines animale et végétale — Détermination de
l'absorbance dans l'ultraviolet, exprimée sous la forme d'extinction
spécifique en lumière ultraviolette
Reference number
ISO 3656:2011(E)
©
ISO 2011
ISO 3656:2011(E)
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ii © ISO 2011 – All rights reserved
ISO 3656:2011(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 3656 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal
and vegetable fats and oils.
This fourth edition cancels and replaces the third edition (ISO 3656:2002), which has been technically revised.
ISO 3656:2011(E)
Introduction
This International Standard describes a method for the determination of the absorbance of light in the
ultraviolet (UV) spectrum by fats and oils. Changes in absorption in the UV region are used as quality, purity,
and authenticity criteria for fats and oils. Refining causes the formation of conjugated dienes and trienes and
increased values of K and K , which then indicate the presence of refined oils. The oxidation of linoleic
232 268
and linolenic acids results in the formation of hydroperoxides in which the double bonds become conjugated.
Furthermore, the formation of either carbon-carbon bonds or carbon-oxygen bonds (α,β-unsaturated carbonyl
compounds) as secondary autoxidation products are observed. These compounds all lead to an increase of
the absorption in the region between 225 nm and 325 nm.
The third edition of this International Standard allowed the determination of the UV absorbance at 232 nm and
268 nm using three different solvents (isooctane, cyclohexane or n-hexane). However, it is known that the
solvents themselves have an effect on the UV absorbance between 260 nm and 276 nm in vegetable oils.
Recent investigations have shown that the measurement of K and K for the same oil in isooctane or in
268 270
cyclohexane give significantly different results. In isooctane, the maxima appear at 267 nm to 268 nm
whereas in cyclohexane, the maxima appear at 268 nm to 269 nm. In the IOC standards for the determination
of the ultraviolet absorbance of (virgin) olive oils, the specified wavelengths are 232 nm and 270 nm.
Taking into account the above, the fourth edition of this International Standard specifies measurement at
268 nm when isooctane is used and measurement at 270 nm when cyclohexane is used. Moreover, the
variation of the specific extinction, ΔΚ, for olive oils has been introduced. Precision data from a new
collaborative trial have also been taken into consideration for this revision.
iv © ISO 2011 – All rights reserved
INTERNATIONAL STANDARD ISO 3656:2011(E)
Animal and vegetable fats and oils — Determination
of ultraviolet absorbance expressed as specific UV extinction
1 Scope
This International Standard specifies a method for the determination of the absorbance at ultraviolet
wavelengths of animal and vegetable fats and oils.
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 661, Animal and vegetable fats and oils — Preparation of test sample
3 Terms and definitions
[5]
NOTE The usual policy of ISO/TC 34/SC 11 of using symbols specified in International Standard 80000 is not
followed in this International Standard. The symbols are those used, for example, in Commission Regulation (EEC)
[6]
No 2568/91 .
For the purposes of this document, the following terms and definitions apply.
3.1
specific extinction (K – K – K )
232 268 270
absorbance of 1 g sample, dissolved in 100 ml isooctane or cyclohexane, measured in a 10 mm cell at the
specific wavelengths 232 nm, 268 nm, and 270 nm
4 Principle
A sample is dissolved in isooctane or cyclohexane and the absorbance is measured spectrophotometrically in
a specified ultraviolet wavelength range. The specific absorbance at 232 nm and 268 nm in isooctane or
232 nm and 270 nm in cyclohexane for a concentration of 1 g per 100 ml in a 10 mm cell is calculated.
5 Reagents
WARNING — Attention is drawn to the regulations which specify the handling of hazardous
substances. Technical, organizational and personal safety measures shall be followed.
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and distilled or
demineralized water or water of equivalent purity.
5.1 Solvent: isooctane (2,2,4-trimethylpentane) for the measurement at 232 nm and 268 nm or
cyclohexane for the measurement at 232 nm and 270 nm, having an absorbance less than 0,12 at 232 nm
and less than 0,05 at 250 nm against water, measured in a 10 mm cell.
ISO 3656:2011(E)
6 Apparatus
The glassware used for the determination shall be thoroughly cleaned and rinsed with the solvent (5.1) before
use so that it is free from impurities having an absorbance within the wavelength range of 220 nm to 360 nm.
Usual laboratory apparatus and, in particular, the following.
[1]
6.1 One-mark volumetric flasks, capacity 25 ml, ISO 1042 class A.
6.2 Analytical balance, capable of being read to the nearest 0,000 1 g.
6.3 Spectrometer, with quartz cells of pathlength 10 mm, suitable for measurements at ultraviolet
wavelengths (220 nm to 360 nm).
6.3.1 General. Before use it is recommended that the wavelength and absorbance scales of the
spectrometer be checked as specified in 6.3.2 and 6.3.3.
6.3.2 Wavelength scale. Check this using a reference material consisting of an optical glass filter
containing holmium oxide which has distinct absorption bands. The reference material is designed for the
verification and calibration of the wavelength scales of visible and ultraviolet spectrophotometers having
nominal spectral bandwidths of 5 nm or less. The holmium glass filter is measured in the absorbance mode
against an air blank, over the wavelength range 640 nm to 240 nm. For each spectral bandwidth (0,10, 0,25,
0,50, 1,00, 1,50, 2,00, and 3,00), a baseline correction is performed with an empty cell holder. The
1)
wavelengths of the spectral bandwidth are listed in the certificate of the reference material .
6.3.3 Absorbance scale. This may be checked using a reference material consisting of four solutions of
potassium dichromate in perchloric acid sealed in far UV quartz cells to measure the linearity and photometric
accuracy reference in the UV. The potassium dichromate fill
...
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