SVENSK STANDARD SS-EN ISO 3961:2018

SVENSK STANDARDSS-EN ISO 3961:2018Fastställd/Approved: 2018-08-27Utgåva/Edition: 4Språk/Language: engelska/EnglishICS: 67.200.10

Animaliska och vegetabiliska fetter och oljor – Bestämning av jodtal (ISO 3961:2018)

Animal and vegetable fats and oils – Determination of iodine value (ISO 3961:2018)

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Europastandarden EN ISO 3961:2018 gäller som svensk standard. Detta dokument innehåller den officiella engelska versionen av EN ISO 3961:2018.

Denna standard ersätter SS-EN ISO 3961:2013, utgåva 3

The European Standard EN ISO 3961:2018 has the status of a Swedish Standard. This document contains the official version of EN ISO 3961:2018.

This standard supersedes the SS-EN ISO 3961:2013, edition 3

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EUROPEAN STANDARD

NORME EUROPÉENNE

EUROPÄISCHE NORM

EN ISO 3961

August 2018

ICS 67.200.10 Supersedes EN ISO 3961:2013

EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2018 CEN Ref. No. EN ISO 3961:2018: EAll rights of exploitation in any form and by any means reserved worldwide for CEN national Members

Animal and vegetable fats and oils - Determination of iodine value (ISO 3961:2018)

Corps gras d'origines animale et végétale - Détermination de l'indice d'iode (ISO 3961:2018)

Tierische und pflanzliche Fette und Öle - Bestimmung der Iodzahl (ISO 3961:2018)

This European Standard was approved by CEN on 24 August 2018.

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, 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, Turkey and United Kingdom.

English Version


Contents Page

European foreword ...................................................................................................................................................vii1 Scope ................................................................................................................................................................... 12 Normative references ................................................................................................................................... 13 Termsanddefinitions ................................................................................................................................... 14 Principle ............................................................................................................................................................ 15 Reagents ............................................................................................................................................................ 16 Apparatus .......................................................................................................................................................... 27 Sampling ............................................................................................................................................................ 28 Preparation of the test sample and test portion .................................................................................. 29 Procedure.......................................................................................................................................................... 310 Calculation ........................................................................................................................................................ 411 Precision ............................................................................................................................................................ 4

11.1 Interlaboratory test .............................................................................................................................................411.2 Repeatability limit, r ............................................................................................................................................411.3 Reproducibility limit, R ......................................................................................................................................4

12 Test report ........................................................................................................................................................ 5Annex A (informative) Interlaboratory test ......................................................................................................... 6Annex B (informative)Calculatediodinevaluefornon-fishoils................................................................... 8Bibliography ................................................................................................................................................................11

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SS-EN ISO 3961:2018 (E)This preview is downloaded from www.sis.se. Buy the entire standard via https://www.sis.se/std-80006318

European foreword

This document (EN ISO 3961:2018) 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 February 2019, and conflicting national standards shall be withdrawn at the latest by February 2019.

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 ISO 3961:2013.

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, 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, Turkey and the United Kingdom.

Endorsement noticeThe text of ISO 3961:2018 has been approved by CEN as EN ISO 3961:2018 without any modification.

vii


Animal and vegetable fats and oils — Determination of iodine value

1 Scope

This document specifies a reference method for the determination of the iodine value (commonly known in the industry as IV) of animal and vegetable fats and oils, hereinafter referred to as fats.

Annex B describes a method for the calculation of the IV from fatty acid compositional data. This method is not applicable to fish oils. Furthermore, cold-pressed, crude and unrefined vegetable oils as well as (partially) hydrogenated oils can give different results by the two methods. The calculated IV is affected by impurities and thermal degradation products.

NOTE The method in Annex B is based upon the AOCS Official method Cd 1c-85[10].

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.

ISO 661, Animal and vegetable fats and oils — Preparation of test sample

3 Termsanddefinitions

For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp

— IEC Electropedia: available at http: //www .electropedia .org/

3.1iodine valueIVmass of halogen, expressed as iodine, absorbed by the test portion following the specified procedure, divided by the mass of the test portion

Note 1 to entry: The IV is expressed as a mass fraction in grams per 100 g of fat.

4 Principle

Dissolution of a test portion in solvent and addition of Wijs reagent. After a specified time, addition of potassium iodide and water, and titration of the liberated iodine with sodium thiosulfate solution.

NOTE Annex B describes a method for the calculation of the IV from fatty acid compositional data. However, this is not intended to be a rapid method. The method gives two results from one analytical procedure. The volumetric method is the reference method.

5 Reagents

Use only reagents of recognized analytical grade.

WARNING — Attention is drawn to the regulations which specify the handling of hazardous substances. Technical, organizational and personal safety measures shall be followed. Wijs

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https://www.iso.org/obp/ui

http://www.electropedia.org/

reagent causes severe burns; vapours can cause lung and eye damage. A fume hood shall be used for the work.

5.1 Water, in accordance with ISO 3696[4], grade 3.

5.2 Potassium iodide solution, mass concentration, ρ(KI) = 100 g/l, not containing iodate or free iodine.

5.3 Starch solution. Mix 5 g of soluble starch in 30 ml of water (5.1) and add to 1 000 ml of boiling water. Boil for 3 min and allow to cool. Prepare fresh starch solution every day.

5.4 Sodium thiosulfate, standard volumetric solution, amount of substance concentration c(Na2S2O3·5H2O) = 0,1 mol/l, standardized not more than 7 days before use.

5.5 Solvent, prepared by mixing one volume of cyclohexane (50 ml) and one volume of glacial acetic acid (50 ml), volume fractions φ = 50 ml/100 ml.

5.6 Wijs reagent, containing iodine monochloride in acetic acid. The I/Cl ratio of the Wijs reagent shall be within the limits 1,10 ± 0,1. Wijs reagent is sensitive to temperature, moisture, and light. Store in the dark at < 30 °C.

Use commercially available Wijs reagent. Observe any shelf-life limitation of the reagent.

6 Apparatus

Usual laboratory apparatus and, in particular, the following.

6.1 Glass weighing scoops, suitable for the test portion and for insertion into the flasks (6.2).

6.2 Conicalflasks, capacity 500 ml, fitted with ground glass stoppers and showing no evidence of the presence of moisture.

6.3 Analytical balance, readability 0,000 1 g and weighing accuracy 0,001 g.

6.4 Volumetricflask, capacity 1 000 ml, ISO 1042[3], class A.

6.5 Pipette, capacity 25 ml, automatic, ISO 8655-2[7], or ISO 648[2], class A, fitted with an aspiration bulb.

6.6 Burette, capacity 25 ml and 50 ml, graduated in 0,1 ml divisions, ISO 385[1], class A, autotitrator, ISO 8655-3[8], as an alternative.

7 Sampling

Sampling is not part of the method specified in this document. A recommended sampling method is given in ISO 5555[5].

It is important the laboratory receive a truly representative sample which has not been damaged or changed during transport or storage.

8 Preparation of the test sample and test portion

Prepare the sample in accordance with the method given in ISO 661.

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According to the IV expected for the sample, weigh (6.3), to the nearest 0,001 g or 0,000 5 g, in a glass weighing scoop (6.1), the mass of test portion indicated in Table 1.

If the expected IV is not known, pre-test different test portions. The mass of the sample shall be such that there is an excess of Wijs reagent of between 50 % and 60 % of the amount added, i.e. 100 % to 150 % of the amount absorbed.

Table 1 — Initial (theoretical) test portion mass for the expected iodine value

Expected iodine value

Initial mass for 150 % excess

Initial mass for 100 % excess

Initial mass accuracy Solvent mixture

g g g ml< 3 10 10 0,001 253 8,461 10,576 0,001 255 5,077 6,346 0,001 25

10 2,538 3,173 0,001 2020 0,846 1,586 0,001 2040 0,634 0,793 0,001 2060 0,432 0,529 0,001 2080 0,317 0,397 0,001 20

100 0,254 0,317 0,000 5 20120 0,212 0,264 0,000 5 20140 0,181 0,227 0,000 5 20160 0,159 0,198 0,000 5 20180 0,141 0,176 0,000 5 20200 0,127 0,159 0,000 5 20

9 Procedure

9.1 Place the glass scoop containing the test portion in a 500 ml conical flask (6.2) and add the volume of solvent (5.5) indicated in Table 1. Add 25,00 ml of the Wijs reagent (5.6) by pipette (6.5). Insert the stopper, swirl the contents and place the flask in the dark.

Melt and dissolve fats and oils with a IV of 20 or less (hard or hardened fats) in warm solvent (60 °C). It is also recommended that all flasks and reagents be warmed before use. Closed vessels shall be used to avoid evaporation and change in concentration when warming the reagents.

NOTE The scoop remains in the flask.

CAUTION — Do not use a mouth pipette for the Wijs reagent.

9.2 Prepare a blank with solvent and reagent as in 9.1 but omitting the test portion.

9.3 For samples having an IV below 150, leave the flasks in the dark for 1 h. For samples with IVs above 150, and for polymerized products and oils containing conjugated fatty acids (such as tung oil, dehydrated castor oil) and any oils containing keto fatty acids (such as some grades of hydrogenated castor oil) and products oxidized to a considerable extent, leave the flasks in the dark for 2 h.

9.4 At the end of the reaction time (9.3), add 20 ml of potassium iodide (5.2) and 150 ml of water (5.1). Titrate against standard sodium thiosulfate solution (5.4) until the yellow colour due to iodine has almost disappeared. Add a few drops of the starch solution (5.3) and continue the titration until the blue colour just disappears after vigorous shaking. Record the volume, V2, of sodium thiosulfate solution required to reach the end point. Note that potentiometric determination of the end point is permissible.

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SVENSK STANDARD SS-EN ISO 3961:2018

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