BS 1742-1-1990 Methods for chemical analysis of condensed milks - General introduction including preparation of test samples《炼乳的化学分析方法 第1部分 一般介绍(包括试样制备)》.pdf

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1、BRITISH STANDARD BS 1742-1: 1990 Methods for Chemical analysis of condensed milks Part 1: General introduction, including preparation of test samplesBS1742-1:1990 This British Standard, having been prepared under the directionof the Dairying Standards Policy Committee, waspublished under the authori

2、tyof the Board of BSI and comes into effect on 31August1990 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference DAC/3 Draft for comment 88/55637 DC ISBN 0 580 18259 2 Committees responsible for this British Standard The preparation of this British Standa

3、rd was entrusted by the Dairying Standards Policy Committee (DAC/-) to Technical Committee DAC/3, upon which the following bodies were represented: AFRC Institute of Food Research (Reading Laboratory) Association of British Preserved Milk Manufacturers Association of Public Analysts Association of P

4、ublic Analysts of Scotland Creamery Proprietors Association Department of Trade and Industry (Laboratory of the Government Chemist) Ice Cream Alliance Limited Intervention Board for Agricultural Produce Joint Committee of the Milk Marketing Board and the Dairy Trade Federation Milk Marketing Board M

5、ilk 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. Date of issue CommentsBS1742-1:1990 BSI 12-

6、1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Determinations supplementary to those given in BS1742 1 4 Sampling 1 5 Preparation of sample 1 6 Reagents 1 7 Rounding of numbers 1 8 Test reports 1 Publications referred to Inside back coverBS1742

7、-1:1990 ii BSI 12-1999 Foreword This Part of BS1742, which has been prepared under the direction of the Dairying Standards Policy Committee, is a Part of the revision of BS1742:1951. In this revision of the standard, the various methods of analysis are described in individual Parts, which will be pu

8、blished separately in looseleaf format. This Part of BS1742 supersedes clauses1 and2, and also clause3 insofar as it applies to unsweetened condensed milk, of BS1742:1951, which are deleted by amendment. The methods in this revision have been aligned as far as possible with the corresponding methods

9、 developed by joint working groups of the International Organization for Standardization (ISO), the International Dairy Federation (IDF) and the Association of Official Analytical Chemists (AOAC). The Parts of BS1742 are as follows: Part 1: General introduction including preparation of samples; Part

10、 2: Determination of total solids content and total milk solids content of sweetened condensed milk (will implement ISO6734, which is in preparation); Part 3: Determination of fat content; Part 4: Determination of ash 1) ; Part 5: Determination of nitrogen content; Section 5.1: Reference method 1) ;

11、 Section 5.2: Routine method 1) ; Part 6: Determination of sucrose content of sweetened condensed milk. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Stand

12、ard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated

13、. This will be indicated in the amendment table on the inside front cover. 1) In preparation.BS1742-1:1990 BSI 12-1999 1 1 Scope This Part of BS1742 gives a general introduction to the methods of chemical analysis of condensed milks and gives general instructions on sampling and preparation of sampl

14、es. This Part should be read in conjunction with each of the methods described in the other Parts of BS1742. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Standard, the following definitions apply.

15、2.1 condensed milk milk, partly skimmed milk or skimmed milk or any combination thereof, whether with or without the addition of cream, dried milk or sucrose, which has been concentrated by the partial removal of water, but which does not include dried milk 2.2 sweetened condensed milk a condensed m

16、ilk (see2.1) to which sucrose has been added 2.3 unsweetened condensed milk a condensed milk (see2.1) which contains no sucrose NOTEThe above definitions do not necessarily align with the definitions of condensed milk products and their reserved descriptions given in the Condensed Milk and Dried Mil

17、k Regulations (SI1977 No.928). 3 Determinations supplementary to those given in BS1742 Reference should be made to the following methods in respect of determinations supplementary to those given in BS1742: a) for determination of total solids content of unsweetened condensed milk see BS1741-2; b) fo

18、r determination of copper content see BS6394-1; c) for determination of iron content see BS6394-2; d) for determination of lead content see BS6394-3 2) . 4 Sampling Carry out sampling in accordance with the methods described in BS809 for unsweetened and sweetened condensed milk, as appropriate. 5 Pr

19、eparation of sample 5.1 Unsweetened condensed milk Shake and invert the sample, then pour into a second container and mix by repeated transfer between the two containers. Ensure any sample adhering to the original container is incorporated during mixing, then remove the test portion. During storage

20、a cream layer may separate. If it is suspected that separation may have occurred, place the unopened container in a water bath at a temperature of40 C to60 C. Shake the container vigorously every15min, then after2h cool to20 2 C in a water bath. Open the container, mix thoroughly by stirring and rem

21、ove the test portion. 5.2 Sweetened condensed milk Thoroughly mix the sample using a spoon or spatula in an up and down rotary movement so that the top layers and the contents of the lower corners are moved and mixed. Ensure any sample adhering to the inside of the container is incorporated during m

22、ixing, then remove the test portion. During storage a cream layer may separate and/or crystallization may occur. If it is suspected that separation or crystallization may have occurred, place the unopened container in a water bath at a temperature of30 C to40 C. Open the container and mix well by st

23、irring as above, then cool to20 2 C in a water bath and mix again before removing the test portion. 6 Reagents Unless otherwise stated, use reagents of recognized analytical grade and, wherever the use of water is required, use distilled or demineralized water complying with grade3 of BS3978. 7 Roun

24、ding of numbers In carrying out the methods described in the various Parts of BS1742 use the method of rounding numbers specified in BS1957. NOTEFor example, if95.14, 95.15 and95.16 are to be rounded to the nearest0.1, the rounded numbers are95.1, 95.2 and95.2 respectively, i.e.where5 occurs in the

25、second decimal place, the rounding is to the nearest even number in the first decimal place. 8 Test reports The test report shall include the following information: a) the result of each test carried out, expressed in accordance with the clause headed “Expression of results” in the appropriate Part

26、of BS1742; 2) In preparation.BS1742-1:1990 2 BSI 12-1999 b) a full reference to the method of test, e.g.“Part 5.1” (Reference method) of BS1742; c) a note of any special factor that may have affected the result; d) details of the sample identity.BS1742-1:1990 BSI 12-1999 Publications referred to BS

27、809, Methods for sampling of milk and milk products. BS 1741, Methods for chemical analysis of liquid milk and cream. BS 1741-2, Determination of total solids content of liquid milk, cream and unsweetened condensed milk. BS 1742, Methods for chemical analysis of condensed milks 3) . BS 1742-1, Gener

28、al introduction, including preparation of samples 4) . BS 1742-2, Determination of total solids content of sweetened condensed milk (implements ISO6734 4) . BS 1742-3, Determination of fat content 4) . BS 1742-4, Determination of ash 4) . BS 1742-5, Determination of nitrogen content 4) . BS 1742-5.1

29、, Reference method. BS 1742-5.2, Routine method. BS 1742-6, Determination of sucrose content of sweetened condensed milk 4) . BS 1957, Presentation of numerical values (fineness of expression; rounding of numbers). BS 3978, Specification for water for laboratory use. BS 6394, Trace elements in milk

30、and milk products. BS 6394-1, Method for the determination of copper content (reference method). BS 6394-2, Method for the determination of iron content (reference method). BS 6394-3, Method for the determination of lead content (reference method) 3) . SI 1977 No. 928, Condensed milk and dried milk

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