1、BRITISH STANDARD BS 5752-6: 1983 ISO 3726: 1983 Methods of test for Coffee and coffee products Part 6: Instant coffee: determination of loss in mass at70 C under reduced pressure UDC 633.73 + 663.938.8:620.113BS5752-6:1983 This British Standard, having been prepared under the directionof the Food an
2、d Agriculture Standards Committee,was published underthe authorityof the BoardofBSI andcomes into effect on 31October 1983 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference FAC/15 Draft for comment 75/51000 DC ISBN 0 580 13473 3 Committees responsible
3、for this British Standard The preparation of this British Standard was entrusted by the Food and Agriculture Standards Committee (FAC/-) to Technical Committee FAC/15 upon which the following bodies were represented: Association of Public Analysts British Soluble Coffee Manufacturers Association Cof
4、fee Trade Federation Ltd. Department of Industry (Laboratory of the Government Chemist) Food Manufacturers Federation Incorporated Institute of Trading Standards Administration Ministry of Agriculture, Fisheries and Food Overseas Development Administration (Tropical Products Institute) Amendments is
5、sued since publication Amd. No. Date of issue CommentsBS5752-6:1983 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 0 Introduction 1 1 Scope and field of application 1 2 References 1 3 Definition 1 4 Principle 1 5 Apparatus 1 6 Sampling 1 7 Procedure 1 8 Ex
6、pression of results 2 9 Precision 2 10 Test report 2 Table 2 Publications referred to Inside back coverBS5752-6:1983 ii BSI 10-1999 National foreword This Part of this British Standard has been prepared under the direction of the Food and Agriculture Standards Committee. It is identical with ISO3726
7、:1983 “Instant coffee Determination of loss in mass at70 C under reduced pressure” published by the International Organization for Standardization (ISO). This Part embodies an agreement, in which the UK has taken part, reached in subcommittee15, Coffee, of Technical Committee34, Agricultural food pr
8、oducts, of ISO. BS 5752 will consist of Parts corresponding to International Standards as they are published. Subject to UK acceptance of the International Standards the Parts of BS5752 will be identical with the corresponding ISO texts. Terminology and conventions. The text of the International Sta
9、ndard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following: The comma has been used throughout as a decimal marker. In Bri
10、tish Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. NOTEUntil ISO 6670 is published, users of this standard should ensure that the s
11、ampling procedures employed result in a representative sample. 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 Standard does not of itself confer immunity fr
12、om legal obligations. Cross-references International Standards Corresponding British Standards ISO 3509:1976 BS 5456:1977 Glossary of terms relating to coffee and its products (Identical) ISO 5725:1981 BS 5497 Precision of test methods Part 1:1979 Guide to the determination of repeatability and repr
13、oducibility for a standard test method (Technically equivalent) ISO 6670 a BS 6379 Sampling of coffee and coffee products Part 2 aMethod for instant coffee in cases with liners (Identical) a In course of preparation. Summary of pages This document comprises a front cover, an inside front cover, page
14、s i and ii, pages1and 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.BS5752-6:1983 BSI 10-1999 1 0 Introduction In the method described in t
15、his International Standard, a temperature of70 C and an absolute pressure of5000Pa are used, since higher temperatures may cause decomposition of carbohydrates normally present in instant coffee, resulting in the formation of water as a reaction product. The drying period of16h has been chosen becau
16、se tests on instant coffees representative of those on the market demonstrated that no further loss in mass occurred when the drying period was extended. 1 Scope and field of application This International Standard specifies a method for the determination of the loss in mass at70 C, under reduced pr
17、essure, of instant coffee. It is applicable to all types of instant coffee, as defined in ISO3509. It does not apply to liquid coffee extracts. 2 References ISO 3509, Coffee and its products Vocabulary. ISO 6670, Instant coffee in cases with liners Sampling 1) . 3 Definition loss in mass at 70 C und
18、er reduced pressure principally water and small quantities of volatile matter vaporized under the conditions specified in this International Standard, and expressed as a percentage by mass 4 Principle Heating a test portion at 70 C for 16 h under reduced pressure (5000Pa). 5 Apparatus Usual laborato
19、ry apparatus, and in particular : 5.1 Isothermal vacuum oven, electrically heated and adjustable so that the temperature of the shelves can be controlled at70 1 C. 5.2 Oven, capable of being controlled at103 2 C. 5.3 Vacuum pump, capable of reducing the pressure in the oven (5.1) to5000 100Pa 2) . 5
20、.4 Dish, flat-bottomed, with a closely fitting lid, resistant to attack under the conditions of the test, made, for example, of stainless steel or glass, of diameter approximately50mm and of height30mm. 5.5 Air drying apparatus, consisting of two washing bottles made of glass, filled with glycerol,
21、to form a bubble train, and two drying towers made of glass containing a desiccant. The bubble train and the drying system are connected in series with the vacuum oven (5.1), the drying towers being between the oven and the bubble train. 5.6 Desiccator, containing an efficient desiccant, for example
22、 phosphorus(V) oxide or freshly dried silica gel. 5.7 Analytical balance 6 Sampling See ISO 6670. It is important to proceed as rapidly as possible when samples are exposed to the atmosphere, in order to prevent any pick up or loss of moisture according to the humidity of the air. 7 Procedure 7.1 Pr
23、eparation of the dish Dry the dish (5.4) and its lid for1h in the oven (5.2), controlled at103 2 C. Remove the dish and its lid from the oven and allow them to cool to room temperature in the desiccator(5.6) for about30min. Weigh the dish and lid to the nearest0,1mg. 7.2 Test portion Place a test po
24、rtion of approximately3g into the prepared dish (7.1) and spread it uniformly over the bottom of the dish. Cover the dish with its lid and weigh the whole to the nearest0,1mg. NOTEIf performing a series of tests, prepare dishes as described in7.1, and place the covered and weighed dishes in the desi
25、ccator in order to avoid any pick up or loss of moisture. 7.3 Determination Place the dish containing the test portion, with the lid removed but alongside the dish, in the oven (5.1). Set the oven at70 1 C and reduce the pressure slowly (during at least2min), using the vacuum pump (5.3), to5000 100P
26、a. 1) At present at the stage of draft. 2) 5 000 Pa=5000N/m 2 =50mbar=37,5mmHgBS5752-6:1983 2 BSI 10-1999 Allow dry air to enter the oven slowly through the drying system (5.5) at such a rate that one bubble per second passes through the bubble train. Dry for16 0,5h, maintaining the current of dry a
27、ir. At the end of the drying period, allow air to enter the oven slowly (for2 to3min) in order to avoid any air turbulence that may carry away part of the product from the dish. Fit the lid on the dish and place it in the desiccator(5.6). Allow to cool to room temperature for at least25min, and weig
28、h to the nearest0,1mg. 7.4 Number of determinations Carry out two determinations on the same test sample. 8 Expression of results The loss in mass at70 C under reduced pressure, expressed as a percentage by mass, is equal to where Take as the result the arithmetic mean of the two determinations (see
29、7.4). Express the result to the second decimal place. 9 Precision An inter-laboratory test, carried out at the international level, in which14laboratories, each performing two replicates, participated, gave the statistical information (evaluated in accordance with ISO5725 3) ) summarized in the foll
30、owing Table. Table 10 Test report The test report shall show the method used and the result obtained. It shall also mention any operating details not specified in this International Standard, or regarded as optional, as well as any circumstances that may have influenced the result. The test report s
31、hall include all details required for the complete identification of the sample. m 0 is the mass, in grams, of the dish and lid (see7.1); m 1 is the mass, in grams, of the dish, test portion and lid before drying (see7.2); m 2 is the mass, in grams, of the dish, test portion, and lid after drying (s
32、ee7.3). 3) ISO 5725, Precision of test methods Determination of repeatability and reproducibility by inter-laboratory tests. m 1 m 2 ()100 m 1 m 0 - Results expressed as percentages by mass Sample A B Number of laboratories retained after eliminating outliers 10 10 Mean 3,35 4,68 Standard deviation
33、of repeatability (s r ) 0,037 0,023 Coefficient of variation of repeatability 1,1 % 0,5 % Repeatability (2,83 s r ) 0,10 0,07 Standard deviation of reproducibility (s R ) 0,15 0,16 Coefficient of variation of reproducibility 4,4 % 3,4 % Reproducibility (2,83 s R ) 0,42 0,45BS5752-6:1983 BSI 10-1999
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