《BS 1742-4-1991.pdf》由会员分享，可在线阅读，更多相关《BS 1742-4-1991.pdf（8页珍藏版）》请在三一文库上搜索。
1、BRITISH STANDARD BS 1742-4: 1991 Methods for Chemical analysis of condensed milks Part 4: Determination of ash from condensed milks Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1742-4:1991 This British Standard, having been prepared un
2、der the direction of the Agriculture and Food Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 28 June 1991 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference AFC/3 Draft for comment 89/51962
3、DC ISBN 0 580 19652 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Agriculture and Food Standards Policy Committee (AFC/-) to Technical Committee AFC/3, upon which the following bodies were represented: Association of British Preserve
4、d Milk Manufacturers Association of Public Analysts of Scotland Creamery Proprietors Association Department of Trade and Industry (Laboratory of the Government Chemist) Intervention Board for Agricultural Produce Joint Committee of the Milk Marketing Board and the Dairy Trade Federation Milk Marketi
5、ng Board Milk Marketing Board for Northern Ireland Ministry of Agriculture, Fisheries and Food Royal Association of British Dairy Farmers Royal Society of Chemistry Society of Chemical Industry Society of Dairy Technology Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffi
6、eldun sheffieldun, na, Fri Nov 24 08:01:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1742-4:1991 BSI 10-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Definition1 3Principle1 4Reagent1 5Apparatus1 6Sampling1 7Procedure1 8Expression of results1 9Precision2 10Test
7、 report2 Publication(s) referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1742-4:1991 ii BSI 10-1999 Foreword This Part of BS 1742 has been prepared under the direction of the Agriculture and Food Standards Poli
8、cy Committee. It is a revision of the method described in clause 6 of BS 1742:1951, which is deleted by amendment. NOTEThis Part should be read in conjunction with Part 1 “General introduction, including preparation of samples”, published separately. A British Standard does not purport to include al
9、l the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and
10、 ii, pages 1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:34 GMT+00:00
11、2006, Uncontrolled Copy, (c) BSI BS 1742-4:1991 BSI 10-19991 1 Scope This Part of BS 1742 describes a method for the determination of the ash from condensed milk. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definition For the purposes of thi
12、s Part of BS 1742, the following definition applies. ash from condensed milk the quantity of ash as determined under the conditions specified in this Part of BS 1742 and expressed as a percentage by mass of the sample 3 Principle The organic matter is destroyed by heating at 525 25 C to constant mas
13、s. 4 Reagent 4.1 Distilled water, complying with grade 3 of BS 3978. 5 Apparatus Ordinary laboratory apparatus together with the following. 5.1 Dish, of diameter 80 mm to 95 mm, and depth 25 mm to 35 mm, of silica or porcelain, or 125 mL beaker made from heat-resisting glass. 5.2 Muffle furnace, cap
14、able of being controlled at 525 25 C. 5.3 Desiccator, containing an efficient desiccant. 5.4 Boiling water bath or hot plate, capable of being controlled at about 100 C. 5.5 Infra-red lamp or hot plate, capable of operating at about 300 C. 5.6 Balance, capable of weighing to 0.0001 g. 6 Sampling Tak
15、e a representative sample of the condensed milk to be tested using, where appropriate, the procedure described in BS 1742-1. 7 Procedure 7.1 Number of determinations Carry out duplicate determinations using two test portions taken from the same test sample. 7.2 Preparation of the dish Heat the dish
16、or beaker (5.1) for 1 h in the muffle furnace (5.2) controlled at 525 25 C. Cool in the desiccator (5.3) for at least 1 h. After cooling, weigh to the nearest 0.0001 g. 7.3 Test portion Transfer about 5 g of the test sample (see clause 6) into the prepared dish and weigh to the nearest 0.0001 g. 7.4
17、 Determination Carefully evaporate the condensed milk to dryness using, for example, the boiling water bath or hot plate (5.4) or a low bunsen flame. Char the residue, avoiding incandescence, by using, for example, the infra-red lamp or hot plate (5.5), until smoke is no longer driven off. The test
18、sample may swell considerably during the charring process and it is necessary to keep it under observation, and to remove the dish or beaker from the heat source if the test sample shows evidence of impending swelling over the sides. Transfer the dish or beaker to the muffle furnace, controlled at 5
19、25 25 C, until the ash is grey or white. Remove from the furnace and allow to cool. Moisten the ash with a few drops of water (4.1), evaporate to dryness as described above and then heat for 1 h in the muffle furnace controlled at 525 25 C. (If necessary, repeat the moistening, evaporation and heati
20、ng, until the ash is white and visibly free from carbon particles.) Allow the dish or beaker to cool in the desiccator and weigh. Heat the dish or beaker again in the furnace for 30 min, cool and weigh. Repeat these operations, if necessary, until the difference between two successive weighings does
21、 not exceed 0.001 g. 8 Expression of results Calculate the ash yielded by the test sample, expressed as a percentage by mass, using the following expression: where m0 is the mass of the dish or beaker (in g); m1 is the mass of the dish or beaker and the test portion (in g); m2 is the mass of the dis
22、h or beaker and the ash (in g). m2m0 m1m0 - -100 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1742-4:1991 2 BSI 10-1999 Take as the result the arithmetic mean of the results of two determinations, provided that the requirement for repe
23、atability (see 9.1) is satisfied. Express the result to two decimal places. 9 Precision NOTEThe precision data were obtained from a collaborative study undertaken in 1991 involving nine laboratories and two sweetened and two unsweetened condensed milks. 9.1 Repeatability The difference between the v
24、alues obtained from two determinations carried out simultaneously or in rapid succession by the same analyst using the same apparatus should not exceed 0.10 % (m/m). 9.2 Reproducibility The difference between the results obtained on samples of the same test material by two different analysts in diff
25、erent laboratories (where each result is the mean of two values that comply with the repeatability requirement) should not exceed 0.17 % (m/m). 10 Test report The test report shall be in accordance BS 1742-1. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:34 GMT+00:00 2006, Uncontrolle
26、d Copy, (c) BSI BS 1742-4:1991 BSI 10-1999 Publication(s) referred to BS 1742, Methods for chemical analysis of condensed milk. BS 1742-1, General introduction, including preparation of test samples. BS 3978, Specification for water for laboratory use. Licensed Copy: sheffieldun sheffieldun, na, Fri
27、 Nov 24 08:01:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1742-4: 1991 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the internati
28、onal level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We wo
29、uld be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: 020 8996 9000. Fax: 020 8996 7400. BSI offers members an individual upd
30、ating service called PLUS which ensures that subscribers automatically receive the latest editions of standards. Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services. Tel: 020 8996 9001. Fax: 020 8996 7001. In response to orde
31、rs for international standards, it is BSI policy to supply the BSI implementation of those that have been published as British Standards, unless otherwise requested. Information on standards BSI provides a wide range of information on national, European and international standards through its Librar
32、y and its Technical Help to Exporters Service. Various BSI electronic information services are also available which give details on all its products and services. Contact the Information Centre. Tel: 020 8996 7111. Fax: 020 8996 7048. Subscribing members of BSI are kept up to date with standards dev
33、elopments and receive substantial discounts on the purchase price of standards. For details of these and other benefits contact Membership Administration. Tel: 020 8996 7002. Fax: 020 8996 7001. Copyright Copyright subsists in all BSI publications. BSI also holds the copyright, in the UK, of the pub
34、lications of the international standardization bodies. Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, photocopying, recording or otherwise without prior written pe
35、rmission from BSI. This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations. If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained. If permission is granted, the terms may include royalty payments or a licensing agreement. Details and advice can be obtained from the Copyright Manager. Tel: 020 8996 7070. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI