BS ISO 27871-2011 Cheese and processed cheese Determination of the nitrogenous fractions《奶酪和加工乳酪 含氮量测定》.pdf
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1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 27871:2011Cheese and processed cheese Determination of thenitrogenous fractionsBS ISO 27871:2011 BRITISH STANDARDNational forewordThis British Standard is the UK implement
2、ation of ISO 27871:2011.The UK participation in its preparation was entrusted to TechnicalCommittee AW/5, Chemical analysis of milk and milk products.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the
3、necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 69768 5ICS 67.100.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy
4、Committee on 30 November 2011.Amendments issued since publicationDate Text affectedBS ISO 27871:2011Reference numbersISO 27871:2011(E)IDF 224:2011(E)ISO and IDF 2011INTERNATIONAL STANDARD ISO27871IDF224First edition2011-10-15Cheese and processed cheese Determination of the nitrogenous fractions From
5、ages et fromages fondus Dtermination des fractions azotes BS ISO 27871:2011ISO 27871:2011(E) IDF 224:2011(E) COPYRIGHT PROTECTED DOCUMENT ISO and IDF 2011 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electroni
6、c or mechanical, including photocopying and microfilm, without permission in writing from either ISO or IDF at the respective address below. ISO copyright office International Dairy Federation Case postale 56 CH-1211 Geneva 20 Silver Building Boulevard Auguste Reyers 70/B B-1030 Brussels Tel. + 41 2
7、2 749 01 11 Tel. + 32 2 733 98 88 Fax + 41 22 749 09 47 Fax + 32 2 733 04 13 E-mail copyrightiso.org E-mail infofil-idf.org Web www.iso.org Web www.fil-idf.org Published in Switzerland ii ISO and IDF 2011 All rights reservedBS ISO 27871:2011ISO 27871:2011(E) IDF 224:2011(E) ISO and IDF 2011 All righ
8、ts reserved iiiForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subjec
9、t 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 part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC)
10、 on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committee
11、s are circulated to the member bodies for voting. Publication as an International Standard 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 document may be the subject of patent rights. ISO shall not be he
12、ld responsible for identifying any or all such patent rights. ISO 27871IDF 224 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO and IDF. BS ISO 27871:2011ISO 278
13、71:2011(E) IDF 224:2011(E) iv ISO and IDF 2011 All rights reservedForeword IDF (the International Dairy Federation) is a non-profit organization representing the dairy sector worldwide. IDF membership comprises National Committees in every member country as well as regional dairy associations having
14、 signed a formal agreement on cooperation with IDF. All members of IDF have the right to be represented on the IDF Standing Committees carrying out the technical work. IDF collaborates with ISO in the development of standard methods of analysis and sampling for milk and milk products. The main task
15、of Standing Committees is to prepare International Standards. Draft International Standards adopted by the Standing Committees are circulated to the National Committees for endorsement prior to publication as an International Standard. Publication as an International Standard requires approval by at
16、 least 50 % of IDF National Committees casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. IDF shall not be held responsible for identifying any or all such patent rights. ISO 27871IDF 224 was prepared by the Internati
17、onal Dairy Federation (IDF) and Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It is being published jointly by IDF and ISO. All work was carried out by the ISO-IDF Project Group on Nitrogen fractions of the Standing Committee on Analytical Methods for Compo
18、sition under the aegis of its project leader, Mr. P. Trossat (FR). BS ISO 27871:2011INTERNATIONAL STANDARD ISO 27871:2011(E)IDF 224:2011(E) ISO and IDF 2011 All rights reserved 1Cheese and processed cheese Determination of the nitrogenous fractions 1 Scope This International Standard specifies a met
19、hod for determining the nitrogenous fractions in cheeses and processed cheese from cow milk. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edit
20、ion of the referenced document (including any amendments) applies. ISO 8968-1IDF 20-1, Milk Determination of nitrogen content Part 1: Kjeldahl method ISO 8968-2IDF 20-2, Milk Determination of nitrogen content Part 2: Block-digestion method (Macro method) 3 Abbreviated terms TN total nitrogen mass fr
21、action g(N)/100 g SN soluble nitrogen mass fraction g(N)/100 g TCA-SN soluble nitrogen content in trichloroacetic acid g(N)/100 g PTA-SN soluble nitrogen content in phosphotungstic acid g(N)/100 g 4 Principle The fractions are obtained after separation by precipitation of the insolubles in a medium
22、having a pH of 4,4 (SN) or in 12 % trichloroacetic acid (TCA-SN) or in 5 % phosphotungstic acid (PTA-SN). The nitrogen content in each fraction is determined in the filtrates thus obtained in accordance with the procedures specified in ISO 8968-1IDF 20-1 or ISO 8968-2IDF 20-2. BS ISO 27871:2011ISO 2
23、7871:2011(E) IDF 224:2011(E) 2 ISO and IDF 2011 All rights reserved5 Reagents Use only reagents of recognized analytical grade, unless otherwise specified. 5.1 Water, ISO 36964, grade 3 or equivalent purity. 5.2 Trisodium citrate dihydrate solution, c(C6H5Na3O72H2O) = 0,5 mol/l. Weigh 147,05 g of tr
24、isodium citrate dihydrate in a 1 000 ml one-mark volumetric flask (6.8). Shake to dissolve. Make up to the mark with water and mix again. 5.3 Hydrochloric acid solution, c(HCl) = 1 mol/l. 5.4 Trichloroacetic (C2HCl3O2) acid solution (TCA), with a mass-volume fraction of 24 % of TCA. 5.5 Phosphotungs
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