1、October 2009DEUTSCHE NORM English price group 11No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 67.200.10!$Z4P“1551745
2、www.din.deDDIN EN ISO 660Animal and vegetable fats and oils Determination of acid value and acidity (ISO 660:2009)English version of DIN EN ISO 660:2009-10Tierische und pflanzliche Fette und le Bestimmung der Surezahl und der Aziditt (ISO 660:2009)Englische Fassung DIN EN ISO 660:2009-10SupersedesDI
3、N EN ISO 660:2005-11www.beuth.deDocument comprises 16 pagesDIN EN ISO 600:2009-10 2 National foreword This standard has been prepared by Technical Committee ISO/TC 34 “Food products” (Secretariat: AFNOR, France), Subcommittee SC 11 “Animal and vegetable fats and oils” (Secretariat: BSI, United Kingd
4、om) in collaboration with Technical Committee CEN/TC 307 “Oilseeds, vegetable and animal fats and oils and their by-products Methods of sampling and analysis” (Secretariat: AFNOR, France). The responsible German bodies involved in its preparation were the Normenausschuss Lebensmittel und landwirtsch
5、aftliche Produkte (Food and Agricultural Products Standards Committee) and the Deutsche Gesellschaft fr Fettwissenschaft e. V. (German Fat Research Society) in the Joint Committee Gemein-schaftsausschuss fr die Analytik von Fetten, len, Fettprodukten, verwandten Stoffen und Rohstoffen. The DIN Stand
6、ards corresponding to the International Standards referred to in this document are as follows: ISO 385 DIN EN ISO 385 ISO 661 DIN EN ISO 661 ISO 1042 DIN EN ISO 1042 ISO 3696 DIN ISO 3696 ISO 5555 DIN EN ISO 5555 ISO 5725 DIN ISO 5725 (all parts) Amendments This standard differs from DIN EN ISO 660:
7、2005-11 as follows: a) Clause 1 “Scope” has been modified. b) In the definition of 3.2 “acidity”, the note has been deleted. c) All clauses (from clause 4) have been renumbered. d) Clause 4 “Principle” has been added. e) Clause 5 “Reagents” has been extended. f) Clause 6 “Apparatus” has been extende
8、d. g) Clause 9 “Procedure” has been reformulated. h) Table 1 has been extended to include product group examples and the concentration of KOH. i) Clause 11 “Precision” has been updated. j) Annex A “Results of interlaboratory tests” has been updated. k) The Bibliography has been extended. l) The stan
9、dard has been brought in line with the current rules of presentation. Previous editions DIN EN ISO 660: 1999-08, 2005-11 DIN EN ISO 600:2009-10 3 National Annex NA (informative) Bibliography DIN EN ISO 385, Laboratory glassware Burettes DIN EN ISO 661, Animal and vegetable fats and oils Preparation
10、of test sample DIN EN ISO 1042, Laboratory glassware One-mark volumetric flasks DIN EN ISO 5555, Animal and vegetable fats and oils Sampling DIN ISO 3696, Water for analytical laboratory use Specification and test methods DIN ISO 5725 (all parts), Accuracy (trueness and precision) of measurement met
11、hods and results DIN EN ISO 600:2009-10 4 This page is intentionally blank EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 660June 2009ICS 67.200.10 Supersedes EN ISO 660:1999 English VersionAnimal and vegetable fats and oils - Determination of acid valueand acidity (ISO 660:2009)Corps gras do
12、rigines animale et vgtale - Dterminationde lindice dacide et de lacidit (ISO 660:2009)Tierische und pflanzliche Fette und le - Bestimmung derSurezahl und der Aziditt (ISO 660:2009)This European Standard was approved by CEN on 20 May 2009.CEN members are bound to comply with the CEN/CENELEC Internal
13、Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.Thi
14、s European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the
15、 national standards bodies of Austria, Belgium, Bulgaria, 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 a
16、nd United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 660:200
17、9: EContents Page Foreword3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Principle5 5 Reagents.5 6 Apparatus .6 7 Sampling.6 8 Preparation of test sample6 9 Procedure .6 10 Calculation8 11 Precision.9 12 Test report 9 Bibliography. 12 2 EN ISO 660:2009 (E) DIN EN ISO 600:2009-10 A
18、nnex A (informative) Results of interlaboratory tests 10 Foreword This document (EN ISO 660:2009) 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 sam
19、pling 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 December 2009, and conflicting national standards shall be withdrawn at the latest b
20、y December 2009. 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 660:1999. According to the CEN/CENELE
21、C Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembou
22、rg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 660:2009 has been approved by CEN as a EN ISO 660:2009 without any modification. 3 DIN EN ISO 600:2009-10 EN ISO 660:2009 (E) 1 Scope T
23、his International Standard specifies three methods (two titrimetric and one potentiometric) for the determination of the acidity in animal and vegetable fats and oils, hereinafter referred to as fats. The acidity is expressed preferably as acid value, or alternatively as acidity calculated conventio
24、nally. This International Standard is applicable to refined and crude vegetable or animal fats and oils, soap stock fatty acids or technical fatty acids. The methods are not applicable to waxes. Since the methods are completely non-specific, they cannot be used to differentiate between mineral acids
25、, free fatty acids, and other organic acids. The acid value, therefore, also includes any mineral acids that may be present. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For und
26、ated references, the latest edition of the referenced document applies. ISO 661, Animal and vegetable fats and oils Preparation of test sample ISO 3696, Water for analytical laboratory use Specification and test methods 3 Terms and definitions For the purposes of this document, the following terms a
27、nd definitions apply. 3.1 acid value number of milligrams of potassium hydroxide required to neutralize the free fatty acids present in 1 g of fat, when determined in accordance with the procedure specified in this International Standard NOTE The acid value is expressed in milligrams per gram. 3.2 a
28、cidity content of free fatty acids determined according to the procedure specified in this International Standard NOTE The acidity is expressed as a percentage by mass. If the result of the determination is reported as acidity without further explanation, this is, by convention, the acidity based on
29、 the oleic acid content. 4 EN ISO 660:2009 (E) DIN EN ISO 600:2009-10 4 Principle The sample is dissolved in a suitable solvent mixture, and the acids present are titrated with an ethanolic or methanolic solution of potassium or sodium hydroxide. The methods specified in 9.1 and 9.2 are reference me
30、thods. 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. Use only reagents of recognized analytical grade, unless otherwise specified. 5.1 Solvent A for solvent mixtur
31、e (5.3): ethanol, volume fraction, 96 %. As a replacement, propan-2-ol, volume fraction, 99 %, can be used. 5.2 Solvent B for solvent mixture (5.3): diethyl ether, peroxide-free. As a replacement, tert-butyl methyl ether, light petroleum (boiling range 40 C to 60 C) or toluene can be used. WARNING D
32、iethyl ether is very flammable and may form explosive peroxides. Use with great caution. 5.3 Solvent mixture, mix equal volumes of solvent A and B, (e.g. A= 50 ml/100 ml and B= 50 ml/100 ml). For hard or animal fats, a solvent mixture of one volume of solvent A (e.g. 25 ml) and three volumes of tert
33、-butyl methyl ether or toluene (e.g. 75 ml) is recommended. Neutralize, just before use, by adding potassium hydroxide solution in the presence of 0,3 ml of the phenolphthalein solution per 100 ml of solvent mixture. For the titration with aqueous KOH, the solvent propan-2-ol can be used. 5.4 Ethano
34、l or methanol, of minimum volume fraction, = 95 %. 5.5 Sodium hydroxide or potassium hydroxide, ethanolic or methanolic standard volumetric solutions, amount of substance concentration c(NaOH) or c(KOH) = 0,1 mol/l and 0,5 mol/l. The concentration shall be checked with a standard volumetric HCl solu
35、tion. NOTE The ethanolic/methanolic sodium/potassium hydroxide solution may be replaced by an aqueous sodium/potassium hydroxide solution, but only if the volume of water introduced does not lead to phase separation. 5.6 Phenolphthalein, solution in ethanol, mass concentration, = 1 g/100 ml. 5.7 Thy
36、molphthalein, solution in ethanol, mass concentration, = 2 g/100 ml. 5.8 Alkali blue 6B, solution in ethanol, mass concentration, = 2 g/100 ml. For dark-coloured fats, alkali blue or thymolphthalein shall be used. 5.9 Water in accordance with ISO 3696, grade 3. 5 DIN EN ISO 600:2009-10 EN ISO 660:20
37、09 (E) 6 Apparatus Usual laboratory equipment and, in particular, the following. 6.1 Burette, capacity 10 ml, graduated in 0,02 ml, ISO 3851class A. 6.2 Burette, capacity 25 ml, graduated in 0,05 ml, ISO 3851class A. 6.3 Analytical balance, capable of being read to the nearest 0,001 g. 6.4 Automatic
38、 titration apparatus (based on potentiometric electrode) or potentiometer. 6.5 Combined pH electrode for non-aqueous acid/base titrations. 6.6 Graduated volumetric flasks, volume 1 000 ml, ISO 10422class A. 7 Sampling A representative sample should have been sent to the laboratory. It should not hav
39、e been damaged or changed during transport or storage. Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 5555 3. 8 Preparation of test sample Prepare the test sample in accordance with ISO 661, except that if the sample contain
40、s volatile fatty acids, the test sample shall not be heated and filtered. 9 Procedure 9.1 Cold solvent method using indicator (Reference method) 9.1.1 Depending on the expected magnitude of the acid value, select the test portion mass and alkali concentration from Table 1. 9.1.2 According to Table 1
41、 weigh the test portion into a 250 ml conical flask. 9.1.3 Add 50 ml to 100 ml of the neutralized solvent mixture (5.3) and dissolve the test portion if necessary with gentle warming. For high melting point samples, use an ethanol-toluene mixture. 9.1.4 After the addition of an indicator (5.6, 5.7 o
42、r 5.8), titrate with constant swirling using standard potassium hydroxide solution (5.5). The endpoint of the titration is reached when the addition of a single drop of alkali produces a slight but definite colour change persisting for at least 15 s. 6 EN ISO 660:2009 (E) DIN EN ISO 600:2009-10 Tabl
43、e 1 Test portion masses and alkali concentrations Product group (examples) Acid value approx. Mass of test portion Concentration of KOH Accuracy of weighing of the test portion g mol/l g Refined vegetable oils Animal fats 0 to 1 20 0,1 0,05 Crude vegetable oils Technical grade animal fats 1 to 4 4 t
44、o 15 10 2,5 0,1 0,1 0,02 0,01 Soap stock fatty acids 15 to 75 0,5 3,0 0,1 0,5 0,001 Technical fatty acids 75 0,2 1,0 0,1 0,5 0,001 9.2 Cold solvent method using potentiometric titration (Reference method) 9.2.1 According to Table 1, weigh the test portion into a 150 ml beaker. 9.2.2 Add 50 ml to 100
45、 ml of the neutralized solvent mixture (5.3) and dissolve the sample, if necessary with gentle warming. For high melting point samples, use an ethanol-toluene mixture. 9.2.3 Introduce the combined electrode in the solvent mixture and connect it with the automatic titration apparatus. 9.2.4 Start the
46、 stirrer for at least 30 s and then titrate with constant swirling using standard potassium hydroxide solution (5.5). 9.2.5 As soon as the equivalence point is reached, record the amount of standard solution used. 9.3 Hot ethanol method using indicator 9.3.1 Under the conditions specified in this me
47、thod, short-chain fatty acids, if present, are volatile. 9.3.2 Weigh into a flask a sufficient mass of the test sample as shown in Table 1, according to the colour and expected acid value. 9.3.3 Heat to boiling 50 ml of the ethanol containing 0,5 ml of the phenolphthalein indicator in a second flask
48、. While the temperature of the ethanol is still above 70 C, neutralize it carefully with a solution of 0,1 mol/l sodium or potassium hydroxide. The endpoint of the titration is reached when the addition of a single drop of alkali produces a slight but definite colour change persisting for at least 1
49、5 s. Larger volumes of ethanol and indicator may be necessary for dark-coloured fats. Moreover, for dark-coloured fats, alkali blue or thymolphthalein shall be used. 9.3.4 Add the neutralized ethanol to the test portion in the first flask and mix thoroughly. Bring the contents to the boil and titrate with the sodium or potassium hydroxide solution, agitating the flask contents vigorously during the titration. 7 DIN EN ISO 600:2009-10 EN ISO 660:2009 (E) 10 Calculation The acid value, wAV, or the fr
