1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ICS 67.200.10 ISBN 0-626-14599-6 SANS 3657:2003 Edition 1 ISO 3657:2002 Edition 3 SOUTH AFRICAN NATIONAL STANDARD Animal and vegetable fats and oils Dete
4、rmination of saponification value This national standard is the identical implementation of ISO 3657:2002 and is adopted with the permission of the International Organization for Standardization. Published by Standards South Africa 1 dr lategan road groenkloof private bag x191 pretoria 0001 tel: 012
5、 428 7911 fax: 012 344 1568 international code + 27 12 www.stansa.co.za Standards South Africa 2003 SANS 3657:2003 Edition 1 ISO 3657:2002 Edition 3 Table of changes Change No. Date Scope National foreword This South African standard was approved by National Committee STANSA SC 5140.23E, Edible oils
6、, in accordance with procedures of Standards South Africa, in compliance with annex 3 of the WTO/TBT agreement. INTERNATIONALSTANDARDISO3657Third edition2002-06-01Reference numberISO 3657:2002(E) ISO 2002Animal and vegetable fats and oils Determination of saponification valueCorps gras dorigines ani
7、male et vgtale Dtermination de lindice de saponificationISO 3657:2002(E)ii ISO 2002 All rights reservedPDF disclaimerThis PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not beedited unless the typefaces which are embe
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12、ights reserved iiiForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISOmember bodies). The work of preparing International Standards is normally carried out through ISO technicalcommittees. Each member body interested in a subjec
13、t for which a technical committee has been established hasthe right to be represented on that committee. International organizations, governmental and non-governmental, inliaison with ISO, also take part in the work. ISO collaborates closely with the International ElectrotechnicalCommission (IEC) on
14、 all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.Publication as an International S
15、tandard 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 International Standard may be the subject ofpatent rights. ISO shall not be held responsible for identifying any or all such patent rights.Internatio
16、nal Standard ISO 3657 was prepared by Technical Committee ISO/TC 34, Food products, SubcommitteeSC 11, Animal and vegetable fats and oils.This third edition cancels and replaces the second edition (ISO 3657:1988), which has been technically revised.Annex A of this International Standard is for infor
17、mation only.This page is intentionally left blankINTERNATIONAL STANDARD ISO 3657:2002(E) ISO 2002 All rights reserved 1Animal and vegetable fats and oils Determination of saponification value1 ScopeThis International Standard specifies a method for the determination of the saponification value of an
18、imal andvegetable fats and oils. The saponification value is a measure of the free and esterified acids present in fats and fattyacids.The method is applicable to refined and crude vegetable and animal fats.If mineral acids are present, the results given by this method are not interpretable unless t
19、he mineral acids aredetermined separately.2 Normative referenceThe following normative document contains provisions which, through reference in this text, constitute provisions ofthis International Standard. For dated references, subsequent amendments to, or revisions of, this publication do notappl
20、y. However, parties to agreements based on this International Standard are encouraged to investigate thepossibility of applying the most recent edition of the normative document indicated below. For undated references,the latest edition of the normative document referred to applies. Members of ISO a
21、nd IEC maintain registers ofcurrently valid International Standards.ISO 661, Animal and vegetable fats and oils Preparation of test sample3 Term and definitionFor the purposes of this International Standard, the following term and definition applies.3.1 saponification valueamount of potassium hydrox
22、ide in milligrams required to saponify of fat under the conditions specified in thisInternational Standard4 PrincipleThe test sample is saponified by boiling under reflux with an excess of ethanolic potassium hydroxide, followed bytitration of the excess potassium hydroxide with standard volumetric
23、hydrochloric acid solution.1gISO 3657:2002(E)2 ISO 2002 All rights reserved5ReagentsUse only reagents of recognized analytical grade, and distilled or demineralized water of equivalent purity.5.1 Potassium hydroxide, solution in ethanol (volume fraction).This solution shall be colourless or straw ye
24、llow. A stable colourless solution can be prepared by either of thefollowing procedures.a) Reflux 1 litre of ethanol with of potassium hydroxide and of aluminium pellets for , then distilimmediately. Dissolve the required amount of potassium hydroxide (approx. ) in the distillate. Allow to standfor
25、several days, then decant the clear supernatant liquid from the precipitated potassium carbonate into a brown-glass stock bottle.b) Add of aluminium tert-butylate to 1 litre of ethanol and allow the mixture to stand for several days. Decant thesupernatant liquid and dissolve in it the required amoun
26、t of potassium hydroxide. Allow to stand for several days,then decant the clear supernatant liquid from the precipitated potassium carbonate into a brown-glass stockbottle.5.2 Hydrochloric acid, standard volumetric solution, .5.3 Phenolphthalein solution, ( ) in ethanol (volume fraction).5.4 Alkali
27、blue 6B solution, ( ) in ethanol (volume fraction).5.5 Boiling aids.6 ApparatusUsual laboratory apparatus and, in particular, the following.6.1 Conical flask, of capacity, made of alkali-resistant glass and having a ground neck.6.2 Reflux condenser, with a ground glass joint which fits the conical f
28、lask (6.1).6.3 Heating device (e.g. a water bath, electric hot-plate or other suitable apparatus).A naked flame is not suitable.6.4 Burette, of capacity, graduated in divisions, or an automatic burette.6.5 Pipette, of capacity, or an automatic pipette.6.6 Analytical balance.7 SamplingIt is important
29、 that the laboratory receive a sample which is truly representative and has not been damaged orchanged during transportation or storage.Sampling is not part of this method specified in this International Standard. A recommended sampling method isgiven in ISO 5555.c(KOH)=0,5 mol/l 95 %8g 5g 1h35 g4gc
30、(HCl)=0,5 mol/l = 0,1 g/100 ml 95 % = 2,5 g/100 ml 95 %250 ml50 ml 0,1 ml25 mlISO 3657:2002(E) ISO 2002 All rights reserved 38 Preparation of test samplePrepare the test sample in accordance with ISO 661.The test samples shall be carefully mixed and filtered if visible impurities are present. If fil
31、tration is necessary, thisshall be mentioned in the test report.9 Procedure9.1 Test portionWeigh, to the nearest , about of the test sample (clause 8) into a conical flask (6.1).The test portion of has been determined on the basis of saponification values of 170 to 200. For othersaponification value
32、s, the mass should be altered accordingly so that about half the ethanolic potassium hydroxidesolution is neutralized. Recommendations for the mass of the test portion are given in Table 1.9.2 Determination9.2.1 Using a pipette (6.5), add to the test portion of the ethanolic potassium hydroxide solu
33、tion (5.1) andsome boiling aids (5.5). Connect the reflux condenser (6.2) to the flask, place the flask on the heating device (6.3)and boil gently, shaking from time to time, for or for in the case of oils and fats having a high melting pointand which are difficult to saponify.9.2.2 Add to the hot s
34、olution to of the phenolphthalein solution (5.3) and titrate with the hydrochloric acid(5.2) until the pink colour of the indicator just disappears. If the solution is strongly coloured, use to ofalkali blue 6B solution (5.3).9.3 Blank testCarry out a blank test following the procedure specified in
35、9.2, using again of the ethanolic potassiumhydroxide solution (5.1) but omitting the test portion.10 Expression of resultsThe saponification value is given by the formulawhereis the volume, in millilitres, of the hydrochloric acid (5.2) used for the blank test;is the volume, in millilitres, of the h
36、ydrochloric acid (5.2) used for the determination;Table 1 Mass of test portionExpected saponification value Mass of test portion150 to 200 to 200 to 250 to 250 to 300 to to 5mg 2g2g2,2 g 1,8 g1,7 g 1,4 g1,3 g 1,2 g 300 1,1 g 1,0 g25,0 ml60 min 2 h0,5 ml 1 ml0,5 ml 1 ml25,0 mlIsIs=(V0V1)c 56,1mV0V1IS
37、O 3657:2002(E)4 ISO 2002 All rights reservedis the exact concentration, in moles per litre, of the hydrochloric acid (5.2);is the mass, in grams, of the test portion (9.1).Take as the result the arithmetic mean of the two determinations, provided that the requirement for repeatability(11.2) is satis
38、fied.Express the result as a whole number.11 Precision11.1 Interlaboratory testAn interlaboratory test, carried out at the international level in 2000 by DIN, in which 22 laboratories participated,each of which carried out two determinations on each sample, gave the statistical results shown in anne
39、x A.11.2 RepeatabilityThe absolute difference between two independent single test results, obtained using the same method on identicaltest material in the same laboratory by the same operator using the same equipment within a short interval of time,will in not more than of cases be greater than the
40、repeatability limit, , given in annex A.11.3 ReproducibilityThe absolute difference between two single test results, obtained using the same method on identical test material indifferent laboratories with different operators using different equipment, will in not more than of cases be greaterthan th
41、e reproducibility limit, , given in annex A.12 Test reportThe test report shall specify: all information necessary for the complete identification of the sample; the sampling method used, if known; the test method used, with reference to this International Standard; which indicator has been used, (5
42、.3) or (5.4); all operating details not specified in this International Standard, or regarded as optional, together with details ofany incidents which may have influenced the result; the test result(s) obtained or, if the repeatability has been checked, the final result obtained.cm5% r5%RISO 3657:20
43、02(E) ISO 2002 All rights reserved 5Annex A(informative)Results of an interlaboratory testAn international collaborative test involving 22 laboratories in 8 countries was carried out on the following samples: coconut oil (A); palm oil (B); rapeseed oil (C); oil with medium-chain triglycerides (MCT);
44、 mixture of A and MCT.The test was organized by DIN in 2000 and the results obtained were subjected to statistical analysis in accordancewith ISO 5725-2 to give the precision data shown in Table A.1.Table A.1 Precision dataSampleRapeseed oil Palm oil Coconut oil A MCT oilD(C) (B) (A) (E) (D)Number o
45、f participating laboratories22 22 22 22 20Number of laboratories retained after eliminating outliers19 17 20 18 16Number of individual test results of all laboratories on each sample38 34 40 36 32Mean value 190,2 199,5 256,8 287,5 334,1Repeatability standard deviation ()0,7 0,6 0,7 0,7 1,4Repeatabil
46、ity coefficient of variation, 0,4 0,3 0,3 0,2 0,4Repeatability limit ( ) 2,1 1,6 2,0 2,0 3,9Reproducibility standard deviation ()1,8 2,0 4,2 2,4 2,9Reproducibility coefficient of variation, 0,9 1,0 1,6 0,8 0,9Reproducibility limit ( ) 5,0 5,7 11,7 6,6 8,060 % 40 %60 % +40 %sr%rsR%RISO 3657:2002(E)6
47、ISO 2002 All rights reservedBibliography1 ISO 5555, Animal and vegetable fats and oils Sampling2 ISO 5725-1:1994, Accuracy (trueness and precision) of measurement methods and results Part 1: Generalprinciples and definitions3 ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results Part 2: Basicmethod for the determination of repeatability and reproducibility of a standard measurement method
