1、BS EN ISO27107:2010ICS 67.200.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDAnimal and vegetablefats and oils Determination ofperoxide value Potentiometric end-point determination(ISO 27107:2008,corrected version2009-05-15 )This British Standardwas published
2、 under theauthority of the StandardsPolicy and StrategyCommittee on 31 May2010. BSI 2010ISBN 978 0 580 69814 9Amendments/corrigenda issued since publicationDate CommentsBS EN ISO 27107:2010National forewordThis British Standard is the UK implementation of EN ISO 27107:2010.It is identical to ISO 271
3、07:2008. It supersedes BS EN ISO 27107:2008which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee AW/307, Oil seeds, animal and vegetable fats and oils andtheir by products.A list of organizations represented on this committee can be obtained onrequest to its
4、secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 27107 April 201
5、0 ICS 67.200.10 Supersedes EN ISO 27107:2008English Version Animal and vegetable fats and oils - Determination of peroxide value - Potentiometric end-point determination (ISO 27107:2008, corrected version 2009-05-15 ) Corps gras dorigines animale et vgtale - Dtermination de lindice de peroxyde - Dte
6、rmination avec point darrt potentiomtrique (ISO 27107:2008, version corrige 2009-05-15) Tierische und pflanzliche Fette und le - Bestimmung der Peroxidzahl - Potentiometrische Endpunktbestimmung (ISO 27107:2008, korrigierte Fassung 2009-05-15) This European Standard was approved by CEN on 13 March 2
7、010. 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
8、 on application to the CEN 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 Management
9、 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,
10、 Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2010 CEN All rights of exploitation in any
11、form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 27107:2010: EBS EN ISO 27107:2010EN ISO 27107:2010 (E) 3 Foreword The text of ISO 27107:2008, corrected version 2009-05-15 has been prepared by Technical Committee ISO/TC 34 “Food products” of the International Organi
12、zation for Standardization (ISO) and has been taken over as EN ISO 27107:2010 by 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
13、 status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2010, and conflicting national standards shall be withdrawn at the latest by October 2010. Attention is drawn to the possibility that some of the elements of this document may be th
14、e 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 27107:2008. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to impl
15、ement 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, Sw
16、itzerland and the United Kingdom. Endorsement notice The text of ISO 27107:2008, corrected version 2009-05-15 has been approved by CEN as a EN ISO 27107:2010 without any modification. ISO 27107:2008(E) ISO 2008 All rights reserved iiiForeword ISO (the International Organization for Standardization)
17、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 repres
18、ented 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
19、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
20、 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 27107 was prepa
21、red by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal and vegetable fats and oils. This corrected version of ISO 27107:2008 incorporates the following corrections: Introduction, lines 9 and 10, “greater than” and “less than or equal to” replace “” and “u”, respectively; Int
22、roduction, line 11, “0 mmol to 15 mmol” has become “0 meq to 30 meq”; 5.6, final sentence, has been reedited to correct details of blue colour formation; 6.5 now contains a readability figure of 0,000 1 g, not 0,001 g; 9.2.2, line 1, now refers to 0,001 g instead of 0,001 mg; 9.2.2, paragraph 4, now
23、 contains a reedited calculation of the factor, using symbol F rather than f; the heading “10.1 Calculation” has been deleted; Clause 10, paragraph 1, has been revised to incorporate factor, F, from the revised 9.2.2; In Figure A.1, “PV =” has become “PV:” (five times). BS EN ISO 27107:2010ISO 27107
24、:2008(E) iv ISO 2008 All rights reservedIntroduction Over many years, various methods have been developed for the determination of peroxides in fats and oils. Their general principle is the liberation of iodine from potassium iodide in an acid medium. The method according to Wheeler (Reference 6) wa
25、s first adopted in standards more than 50 years ago by different bodies, and is widely used to control commodities by producers, receivers, and official laboratories. In national and international food legislation (including Codex Alimentarius), acceptable limits for peroxide values are often specif
26、ied. Due to anomalies in the reproducibility of the results, it was noticed that there are slight differences between the standardized methods. A very important point is the dependence of the result on the amount of sample used for the determination. As the determination of the peroxide value (PV) i
27、s a highly empirical procedure, ISO/TC 34/SC 11 has decided to fix the sample mass at 5 g for PV greater than 1, and at 10 g for PV less than or equal to 1, and to limit the applicability of this method to animal and vegetable fats and oils with peroxide values from 0 meq to 30 meq of active oxygen
28、per kilogram. The users of this International Standard should be aware that the results obtained can be slightly lower than with previous standards. BS EN ISO 27107:2010INTERNATIONAL STANDARD ISO 27107:2008(E) ISO 2008 All rights reserved 1Animal and vegetable fats and oils Determination of peroxide
29、 value Potentiometric end-point determination 1 Scope This International Standard specifies a method for the potentiometric end-point determination of the peroxide value, in milliequivalents of active oxygen per kilogram, of animal and vegetable fats and oils. The method is applicable to all animal
30、and vegetable fats and oils, fatty acids and their mixtures with peroxide values from 0 meq to 30 meq of active oxygen per kilogram. It is also applicable to margarines and fat spreads with varying water content. The method is not applicable to milk fats or lecithins. NOTE A method for the iodometri
31、c (visual) determination of the peroxide value is given in ISO 3960. For milk fats, a method is specified in ISO 3976. 2 Normative references The following referenced documents are indispensable for the application of this document. For undated references, the latest edition of the referenced docume
32、nt (including any amendments) applies. ISO 661, Animal and vegetable fats and oils Preparation of test sample 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 peroxide value PV quantity of those substances in the sample, expressed in terms of
33、active oxygen, that oxidize potassium iodide under the conditions specified in this International Standard NOTE The peroxide value is usually expressed in milliequivalents of active oxygen per kilogram of oil, but it may also be expressed (in SI units) as millimoles of active oxygen per kilogram of
34、oil. The value expressed in millimoles of active oxygen per kilogram is half that expressed in milliequivalents of active oxygen per kilogram. Multiplication of the peroxide value (milliequivalents of active oxygen per kilogram) by the equivalent mass of oxygen (equalling 8) gives the active oxygen
35、mass fraction in milligrams per kilogram of oil. 4 Principle The sample is dissolved in isooctane and glacial acetic acid, and potassium iodide is added. The iodide liberated by the peroxides is determined volumetrically with a sodium thiosulfate standard solution. The end-point of the titration is
36、determined electrochemically. BS EN ISO 27107:2010ISO 27107:2008(E) 2 ISO 2008 All rights reserved5 Reagents WARNING Attention is drawn to national regulations that specify the handling of hazardous substances, and users obligations thereunder. Technical, organizational and personal safety measures
37、shall be followed. Unless otherwise specified, use only reagents of recognized analytical grade. All reagents shall be free of dissolved oxygen. 5.1 Water, distilled, boiled, and cooled to 20 C. 5.2 Glacial acetic acid, mass fraction 100 %, degassed in an ultrasonic bath under vacuum or by purging w
38、ith a stream of pure and dry inert gas (carbon dioxide or nitrogen). 5.3 Isooctane (2,2,4-trimethylpentane), degassed in an ultrasonic bath under vacuum or by purging with a stream of pure and dry inert gas (carbon dioxide or nitrogen). 5.4 Glacial acetic acid/isooctane solution, prepared by mixing
39、60 ml glacial acetic acid (5.2) and 40 ml isooctane (5.3). Volume fraction of glacial acetic acid: = 60 ml/100 ml; volume fraction of isooctane: = 40 ml/100 ml. The mixture is degassed in an ultrasonic bath under vacuum or by purging with a stream of pure and dry inert gas (carbon dioxide or nitroge
40、n). 5.5 Potassium iodide, free from iodine and iodates. 5.6 Saturated potassium iodide solution, mass concentration (KI) = 175 g/100 ml. Dissolve approximately 14 g potassium iodide in approximately 8 g freshly boiled water (5.1) at room temperature. Make sure the solution remains saturated (i.e. so
41、me undissolved crystals remain in the container). Store in the dark and prepare freshly every day. Test the solution as follows: add two drops of starch solution to 0,5 ml of the potassium iodide solution in 30 ml of the glacial acetic acid/isooctane solution (5.4). If a blue colour is formed and if
42、 more than one drop of sodium thiosulfate standard solution (5.7) is needed to remove it, discard the potassium iodide solution. 5.7 0,1 N sodium thiosulfate standard solution, amount of substance concentration c(Na2S2O3) = 0,1 mol/l. Use only freshly boiled water (5.1) for the preparation of this s
43、olution, possibly purged with nitrogen. This solution can be used for 1 month and shall be stored in an amber-stained bottle. 5.8 0,01 N sodium thiosulfate standard solution, amount of substance concentration c(Na2S2O3) = 0,01 mol/l. Pipette (6.3) 100 ml of the 0,1 N sodium thiosulfate standard solu
44、tion (5.7) into a volumetric flask of capacity 1 000 ml (6.9). Make up to the mark with water (5.1). After homogenization, transfer the obtained 0,01 N sodium thiosulfate standard solution to an amber-stained bottle. Prepare the 0,01 N sodium thiosulfate standard solution freshly from the 0,1 N sodi
45、um thiosulfate standard solution just before use or determine the titre daily. As experience shows, the stability is limited and depends upon the pH value and the content of free carbon dioxide. Use only freshly boiled water (5.1) for the dilution, possibly purged with nitrogen. 5.9 Potassium iodate
46、(V) volumetric standard, secondary reference material, traceable to the National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA. 5.10 Hydrochloric acid, amount of substance concentration c(HCl) = 4 mol/l. BS EN ISO 27107:2010ISO 27107:2008(E) ISO 2008 All rights reserved 36 Appa
47、ratus Usual laboratory apparatus and, in particular, the following. 6.1 Automatic titrator with processor, dosing device, stirrer and electrodes. If other apparatus is used, the procedure shall be optimized for the relevant apparatus. The apparatus shall be able to perform a dynamic titration (fast
48、at the beginning, slow near the end-point). This is necessary to minimize the titration time whilst achieving a slow titration near the end-point. 6.2 Combined platinum electrode. 6.3 Pipettes, of capacities 0,5 ml, 1 ml, 10 ml and 100 ml. Suitable automatic pipettes may also be used. 6.4 Measuring
49、cylinders, of capacities 50 ml and 100 ml. 6.5 Analytical balance, readable to 0,000 1 g. 6.6 Magnetic stirrer, with magnetic stirring rod of length 25 mm, and heating plate. 6.7 Erlenmeyer flask, of capacity 250 ml. 6.8 Beaker, of capacity 250 ml, and of tall form. 6.9 Volumetric flask, of capacity 1 000 ml. 6.10 Volumetric flask, of capacity 250 ml. 6.11 Volumetric flask, of capacity 500 ml. 6.12 Microwave oven. 6.13 Amber-stained bottles, of capacity 1 000 ml. 7 Sampling A representative sample should have been se
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