BS EN ISO 3960-2017 Animal and vegetable fats and oils Determination of peroxide value Iodometric (visual) endpoint determination《动植物脂肪和油 过氧化值测定 碘量（可视的）终点测定》.pdf

1、BS EN ISO 3960:2017Animal and vegetable fatsand oils Determinationof peroxide value Iodometric (visual) endpointdetermination (ISO 3960:2017)BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN ISO 3960:2017 BRITISH STANDARDNational forewordThis British Standard is

2、the UK implementation of EN ISO 3960:2017. It supersedes BS EN ISO 3960:2010 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee AW/307, Oilseeds, animal and vegetable fats and oils and their by-products.A list of organizations represented on this committe

3、e can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017.Published by BSI Standards Limited 2017ISBN 978 0 580 94413 0 ICS 67.200.10

4、 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 February 2017.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dEUROPEAN STANDARD NOR

5、ME EUROPENNE EUROPISCHE NORM EN ISO 3960 February 2017 ICS 67.200.10 Supersedes EN ISO 3960:2010English Version Animal and vegetable fats and oils - Determination of peroxide value - Iodometric (visual) endpoint determination (ISO 3960:2017) Corps gras dorigines animale et vgtale - Dtermination de l

6、indice de peroxyde - Dtermination avec point darrt iodomtrique (ISO 3960:2017) Tierische und pflanzliche Fette und le - Bestimmung der Peroxidzahl - Iodometrische (visuelle) Endpunktbestimmung (ISO 3960:2017) This European Standard was approved by CEN on 8 February 2017. CEN members are bound to com

7、ply 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-CENELE

8、C 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 s

9、ame status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembour

10、g, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Br

11、ussels 2017 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 3960:2017 EBS EN ISO 3960:2017EN ISO 3960:2017 (E) 3 European foreword This document (EN ISO 3960:2017) has been prepared by Technical Committee ISO/TC 34 “Food produc

12、ts” 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 o

13、f an identical text or by endorsement, at the latest by August 2017, and conflicting national standards shall be withdrawn at the latest by August 2017. 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

14、be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 3960:2010. 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,

15、Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

16、Turkey and the United Kingdom. Endorsement notice The text of ISO 3960:2017 has been approved by CEN as EN ISO 3960:2017 without any modification. BS EN ISO 3960:2017ISO 3960:2017(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 25 Reagents 26 Appa

17、ratus . 37 Sampling 48 Preparation of test sample . 49 Procedure. 49.1 General . 49.2 Preparation and titre determination of the 0,01 N sodium thiosulfate standard solution . 49.2.1 Preparation of the 0,01 N sodium thiosulfate standard solution 49.2.2 Determination of the titre of the 0,01 N sodium

18、thiosulfate standard solution (factor determination) 59.3 Determination of peroxide value . 510 Calculation and expression of results . 611 Precision of the method 611.1 Interlaboratory test. 611.2 Repeatability . 611.3 Reproducibility . 712 Test report . 7Annex A (informative) Results of an interla

19、boratory test 8Bibliography .10 ISO 2017 All rights reserved iiiContents PageBS EN ISO 3960:2017ISO 3960:2017(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards i

20、s 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 par

21、t in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particul

22、ar the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www. iso. org/ directives).Attention is drawn to the possibility that some of the elements of th

23、is document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www

24、. iso. org/ patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to

25、the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www .iso. org/ iso/ foreword. html.This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal and vegetable fats and oils.This fifth edition cance

26、ls and replaces the fourth edition (ISO 3960:2007), of which it constitutes a minor revision to exclude fat coming from milk and milk products.iv ISO 2017 All rights reservedBS EN ISO 3960:2017ISO 3960:2017(E)IntroductionOver a period of many years, various methods have been developed for the determ

27、ination of peroxides in fats and oils. The general principle of most of the methods is the liberation of iodine from potassium iodide in an acid medium. The method according to Wheeler was standardized more than 50 years ago by different standardization bodies, and it is widely used to control commo

28、dities by producers, receivers and official laboratories. In national and international food legislation (including the Codex Alimentarius), acceptable limits for the peroxide values are often specified. Due to anomalies in the reproducibility of the results, it was noticed that there are slight dif

29、ferences 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) is a highly empirical procedure, ISO/TC 34/SC 11 has decided to fix the sample mass at 5 g for PV grea

30、ter 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 per kilogram. The user of this document should be aware that the results obtained can be slightly low

31、er than with previous standards. ISO 2017 All rights reserved vBS EN ISO 3960:2017BS EN ISO 3960:2017Animal and vegetable fats and oils Determination of peroxide value Iodometric (visual) endpoint determination1 ScopeThis document specifies a method for the iodometric determination of the peroxide v

32、alue of animal and vegetable fats and oils with a visual endpoint detection. The peroxide value is a measure of the amount of oxygen chemically bound to an oil or fat as peroxides, particularly hydroperoxides.The method is applicable to all animal and vegetable fats and oils, fatty acids and their m

33、ixtures with peroxide values from 0 meq to 30 meq (milliequivalents) of active oxygen per kilogram. It is also applicable to margarines and fat spreads with varying water content. The method is not suitable for milk fats and is not applicable to lecithins.It is to be noted that the peroxide value is

34、 a dynamic parameter, whose value is dependent upon the history of the sample. Furthermore, the determination of the peroxide value is a highly empirical procedure and the value obtained depends on the sample mass. It is stressed that, due to the prescribed sample mass, the peroxide values obtained

35、can be slightly lower than those obtained with a lower sample mass.Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document.NOTE 1 A preferred method for the iodometric determination of the peroxide value for milk fats is specified in ISO 3976.N

36、OTE 2 A method for the potentiometric determination of the peroxide value is given in ISO 27107.2 Normative referencesThe 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

37、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 sample3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.ISO and IE

38、C maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p s :/ www .iso .org/ obp/ INTERNATIONAL STANDARD ISO 3960:2017(E) ISO 2017 All rights reserve

39、d 1BS EN ISO 3960:2017ISO 3960:2017(E)3.1peroxide valuePVquantity of those substances in the sample, expressed in terms of active oxygen, that oxidize potassium iodide under the conditions specified in this documentNote 1 to entry: The peroxide value is usually expressed in milliequivalents (meq) of

40、 active oxygen per kilogram of oil, but it may also be expressed (in SI units) as millimoles (mmol) of active oxygen per kilogram of oil. The value expressed in millimoles of active oxygen per kilogram is half of that expressed in milliequivalents of active oxygen per kilogram. Multiplication of the

41、 peroxide value (meq of active oxygen per kilogram) by the equivalent mass of oxygen (equalling 8) gives the milligrams of active oxygen per kilogram of oil.4 PrincipleThe test sample is dissolved in isooctane and glacial acetic acid, and potassium iodide is added. The iodine liberated by the peroxi

42、des is determined iodometrically (visually) with a starch indicator and a sodium thiosulfate standard solution. The endpoint of the titration is determined iodometrically (visually).5 ReagentsWARNING Attention is drawn to the national regulations that specify the handling of hazardous substances and

43、 users obligations thereunder. Technical, organizational and personal safety measures shall be followed.Use only reagents of recognized analytical grade, unless otherwise specified. All reagents shall be free of dissolved oxygen.5.1 Water, demineralized, boiled and cooled down to 20 C.5.2 Glacial ac

44、etic acid, mass fraction of 100 %; degassed in an ultrasonic bath under vacuum or by purging with a current of pure and dry inert gas (carbon dioxide or nitrogen).5.3 Isooctane, degassed in an ultrasonic bath under vacuum or by purging with a current of pure and dry inert gas (carbon dioxide or nitr

45、ogen).5.4 Glacial acetic acid/isooctane solution, prepared by mixing 60 ml of glacial acetic acid and 40 ml of isooctane (volume fraction of glacial acetic acid: = 60 ml/100 ml, and volume fraction of isooctane: = 40 ml/100 ml).The mixture is degassed in an ultrasonic bath under vacuum or by purging

46、 with a current of pure and dry inert gas (carbon dioxide or nitrogen).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 of potassium iodide in approximately 8 g of freshly boiled water at ro

47、om temperature. Make sure the solution remains saturated (undissolved crystals). 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 in 30 ml of the glacial acetic acid/isooctane solution (5.4). If a blue c

48、olour is formed and if more than one drop of sodium thiosulfate standard solution (5.7) is needed to remove it, discard the potassium iodide solution.2 ISO 2017 All rights reservedBS EN ISO 3960:2017ISO 3960:2017(E)5.7 0,1 N sodium thiosulfate standard solution, c(Na2S2O3) = 0,1 mol/l.Use only fresh

49、ly boiled water for the preparation of this solution, possibly purged with nitrogen. This solution can be used for one month and is stored in an amber-stained bottle.5.8 0,01 N sodium thiosulfate standard solution, c(Na2S2O3) = 0,01 mol/l (see 9.2).It is necessary to prepare this solution freshly from the 0,1 mol/l sodium thiosulfate standard solution before use or to 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 boile