1、BRITISH STANDARD BS ISO 1738:2004 Butter Determination of salt content ICS 67.100.20 BS ISO 1738:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 October 2004 BSI 28 October 2004 ISBN 0 580 44693 X National foreword This British Standa
2、rd reproduces verbatim ISO 1738:2004 and implements it as the UK national standard. It supersedes BS 5086-5:1998 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee AW/5, Milk and milk products, which has the responsibility to: A list of organizations rep
3、resented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by us
4、ing the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity
5、from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in t
6、he UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 5 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date
7、Comments Reference numbers ISO 1738:2004(E) IDF 12:2004(E) OSI DI dnaF 4002INTERNATIONAL STANDARD ISO 1738 IDF 12 Third edition 2004-10-15 Butter Determination of salt content Beurre Dtermination de la teneur en sel BSISO1738:2004IS:8371 O4002(E) ID:21 F4002(E) DPlcsid Fremia ihTs PDF file may ctnoi
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13、.is.o gro We bwww.fil-idf.o gr Plbuisdehi n Switlrez dnaii ISO dnaID 4002 FA ll rihgtsser edevrBSISO1738:2004IS:8371 O4002(E) ID:21 F4002(E) I SO dna ID 4002 F All irhgts seredevr iiiForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bod
14、ies (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 represented on that committee. International organization
15、s, 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 drafted in accordance with the rules given in the I
16、SO/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 Standard requires approval by at least 75 % of the
17、 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 1738 IDF 12 was prepared by Technical Committee ISO/TC 34, Food pr
18、oducts, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF), in collaboration with AOAC International. It is being published jointly by ISO and IDF and separately by AOAC International. This edition of ISO 1738 IDF 12 cancels and replaces ISO 1738:1997, of which i
19、t constitutes a minor revision. BSISO1738:2004IS:8371 O4002(E) ID:21 F4002(E) iv I SO dna ID 4002 F All irhgts seredevrForeword IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a National Committee in every member country. Every National Committee has the r
20、ight to be represented on the IDF Standing Committees carrying out the technical work. IDF collaborates with ISO and AOAC International in the development of standard methods of analysis and sampling for milk and milk products. Draft International Standards adopted by the Action Teams and Standing C
21、ommittees are circulated to the National Committees for voting. Publication as an International Standard requires approval by at least 50 % of the National Committees casting a vote. ISO 1738 IDF 12 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk produc
22、ts, and the International Dairy Federation (IDF), in collaboration with AOAC International. It is being published jointly by ISO and IDF and separately by AOAC International. All work was carried out by the Joint ISO/IDF/AOAC Group of Experts on Minerals and minor compounds (E602), under the aegis o
23、f its chairman, Mr G. Brthen (NO). This edition of ISO 1738 IDF 12 cancels and replaces IDF 12C:2000, of which it constitutes a minor revision. BSISO1738:2004NITERNATNOIAL STANDARD IS:8371 O4002(E) ID:21 F4002(E)I SO dna ID 4002 F All irhgts seredevr 1Butter Determination of salt content 1 Scope Thi
24、s International Standard specifies a method for the determination of the salt content of butter. The method is applicable to all types of butter containing more than 0,1 % (mass fraction) of salt. 2 Normative references The following referenced documents are indispensable for the application of this
25、 document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 385-1:1984, Laboratory glassware Burettes Part 1: General requirements ISO 648, Laboratory glassware One-mark pipettes ISO 47
26、88, Laboratory glassware Graduated measuring cylinders 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 salt content mass fraction of substances determined by the method specified in this International Standard NOTE It is expressed as the equi
27、valent content of sodium chloride as a mass fraction in percent. 4 Principle A test portion of butter is melted by adding boiling water. The dissolved chlorides in the mixture are titrated with a solution of silver nitrate, using potassium chromate as indicator (the Mohr procedure). 5 Reagents Use o
28、nly reagents of recognized analytical grade, unless otherwise specified, and distilled or demineralized water or water of equivalent purity, free from chlorides. 5.1 Silver nitrate standard volumetric solution (AgNO 3 ), of known concentration in the range 0,08 mol/l to 0,10 mol/l. Dissolve an amoun
29、t of between 13,6 g to 20,4 g of silver nitrate in water which is practically free from carbon dioxide in a 1 000 ml volumetric flask. Dilute to the mark with water. Calibrate the silver nitrate solution against 100 ml of a solution containing 0,400 g/l of sodium chloride (NaCl), which has previousl
30、y been dried at 300 C, BSISO1738:2004IS:8371 O4002(E) ID:21 F4002(E) 2 I SO dna ID 4002 F All irhgts seredevrfollowing the procedure specified in 9.3.2 and 9.4. Express the concentration of the silver nitrate solution in moles per litre to four decimals. Store the solution away from direct sunlight.
31、 NOTE If a solution containing 14,53 g/l (0,085 5 mol/l) of silver nitrate is used, 1 ml of this solution is equivalent to 5 mg of sodium chloride, thus making the calculation of the salt content of the butter easier. 5.2 Potassium chromate indicator solution Dissolve 50 g of potassium chromate (K 2
32、 CrO 4 ) in 1 000 ml of water. WARNING Hexavalent chromium is a carcinogenic agent. 6 Apparatus Usual laboratory apparatus and, in particular, the following. 6.1 Analytical balance, capable of being read to the nearest 0,001 g. 6.2 Titration vessel, made of glass, for example, a conical flask or bea
33、ker of capacity 250 ml. 6.3 Graduated measuring cylinder, of capacity 100 ml, complying with ISO 4788. 6.4 Pipette, capable of delivering 2,0 ml, complying with ISO 648. 6.5 Burette, of capacity 50 ml, complying with ISO 385:1984, Class B. 6.6 Greaseproof paper or plastic film, chloride free or of s
34、ufficiently low chloride content as to not affect the results. The use of filter paper is not recommended. 7 Sampling A representative sample should have been sent to the laboratory. It should not have been damaged or changed during transport or storage. Sampling is not part of the method specified
35、in this International Standard. A recommended sampling method is given in ISO 707. Store the sample in such a way that deterioration and change in composition are prevented. 8 Preparation of test sample Take a representative sample of butter to be tested. If the test sample is visibly not homogeneou
36、s, or if the history of the test sample (age, storage conditions) is such that inhomogeneity is to be expected, mix the test sample as follows. Warm the test sample in the original unopened container, which should be from one-half to two-thirds full, to a temperature that preferably should not excee
37、d 30 C. At this temperature the sample will be soft enough to facilitate thorough mixing to a homogeneous state (either by a mechanical shaker or by hand). Cool the sample to ambient temperature, continuing to mix until cooling is complete. Immediately after cooling, open the sample container and st
38、ir briefly with a suitable device, for example a spoon or spatula, for no longer than 10 s before weighing. BSISO1738:2004IS:8371 O4002(E) ID:21 F4002(E) I SO dna ID 4002 F All irhgts seredevr 39 Procedure 9.1 Number of determinations If it is required to check whether the repeatability limit (11.1)
39、 is met, carry out two single determinations in accordance with 9.2 and 9.3. 9.2 Test portion Weigh, to the nearest 0,05 g, a test portion of between 4,5 g to 5,5 g either directly into the titration vessel (6.2) or on a piece of greaseproof paper or plastic film (6.6) which is transferred with the
40、test sample to the titration vessel. Add 100 ml of boiling water or 100 ml of cold water and heat to boiling. Mix the contents of the vessel. 9.3 Determination 9.3.1 The titration may be carried out on the hot solution or after cooling. It is essential, however, that each laboratory standardize its
41、own procedure for the determination by always bringing the contents of the titration vessel to approximately the same temperature before titration. The titration should preferably be carried out a temperature of about 50 C. This temperature may (partially) prevent coagulation of the butterfat which
42、influences the orange tint. 9.3.2 Cool, while mixing, the contents of the titration vessel to the laboratory standardized temperature. Add 2,0 ml of the potassium chromate indicator (5.2). Titrate the solution with the silver nitrate solution (5.1), with stirring, until an orange tint is obtained wh
43、ich persists for 30 s. Record the volume, in millilitres, of silver nitrate used. 9.4 Blank test Carry out a blank test using all the reagents but omitting the test portion. 10 Calculation and expression of results 10.1 Calculation 10.1.1 Calculate the salt content of butter, w, expressed as a mass
44、fraction in percent, using the following equation: ( ) ss0 5,844 % cVV w m = where V s is the numerical value of the volume, in millilitres, of silver nitrate solution used in the titration of the test portion (9.3.2); V 0 is the numerical value of the volume, in millilitres, of silver nitrate solut
45、ion used in the titration of the blank test (9.4); c sis the numerical value of the concentration of the silver nitrate solution, in moles per litre; m is the numerical value of the mass, in grams, of the test portion; BSISO1738:2004IS:8371 O4002(E) ID:21 F4002(E) 4 I SO dna ID 4002 F All irhgts ser
46、edevr5,844 is the mass of NaCl equivalent of 1 ml of standard volumetric solution, c(AgNO 3 ) = 1 mol/l, divided by a factor 10 obtained by dividing 100 (%) by 1 000 (ml). 10.1.2 If a solution containing 14,53 g/l of silver nitrate is used and 5 g of the test portion is weighed to the nearest 0,01 g
47、, the calculation of w, the salt content of butter, may be simplified using the following equation: s0 % 10 VV w = where V sis the numerical value of the volume, in millilitres, of a silver nitrate solution containing 14,53 g/l of silver nitrate. 10.2 Expression of results Round the result to the ne
48、arest 0,01 % (mass fraction). 11 Precision Details of an interlaboratory test on the precision of the method are summarized in Reference 5. The study was carried out in accordance with ISO 5725:1986 (now withdrawn). The values derived from this interlaboratory test may not be applicable to concentra
49、tion ranges and matrices other than those given. 11.1 Repeatability The absolute difference between two independent single test results, obtained using the same method on identical test material in the same laboratory by the same operator using the same equipment within a short interval of time, will in not more than 5 % of cases be greater than 0,03 % (mass fraction). 11.2 Reproducibility The absolute difference between two single test r
