1、BRITISH STANDARD BS 5752-2: 1984 ISO 1447:1978 Methods of test for Coffee and coffee products Part 2: Green coffee: determination of moisture content (routine method) UDC 633.73 + 663.93:620.113BS5752-2:1984 This British Standard, having been prepared under the directionof the Food and Agriculture S
2、tandards Committee,was published underthe authorityof the BoardofBSI andcomes into effect on 28September 1984 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference FAC/15 Draft for comment 84/50250 DC ISBN 0 580 14014 8 Committees responsible for this Brit
3、ish 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 Coffee Trade Fed
4、eration Ltd. Department of Trade and 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 Development and Research Institute)
5、Amendments issued since publication Amd. No. Date of issue CommentsBS5752-2:1984 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 Procedure 1 7 Ex
6、pression of results 2 8 Notes 2 9 Test report 2 Publications referred to Inside back coverBS5752-2:1984 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 and is identical with ISO1447-1978 “Green
7、coffee Determination of moisture content (Routine method)”, published by the International Organization for Standardization (ISO). This Part of this standard embodies an agreement, in which the UK has taken part, reached in subcommittee15, Coffee, of Technical Committee34, Agricultural food products
8、, of ISO. Terminology and conventions. The text of the International Standard 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 f
9、ollowing. The comma has been used as a decimal marker. In British 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”. Cross-references Ad
10、ditional information. This Part of BS5752 is identical with ISO1447:1978, which was confirmed by ISO in1984. In general in the UK, loss in mass at105 C (as described in BS5752-7) is determined on a routine basis, rather than moisture content. However, the method described in BS5752-7 gives results t
11、hat are up to1% lower than results found when using the basic reference method of BS5752-1. The method in this Part of BS 5752, which is not as convenient as that described in BS 5752-7, is less cumbersome than the basic reference method and in most cases gives comparable results. A British Standard
12、 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 from legal obligations. International Standards Corresponding British Standards ISO
13、 1446:1978 BS 5752 Methods of test for coffee and coffee products Part 1:1979 Green coffee Determination of moisture content (Basic reference method) (Identical) ISO 4072:1982 a BS 6379 Sampling of coffee and coffee products Part 1:1983 Method of sampling green coffee in bags (Identical) a Referred
14、to in clause 2 as at the stage of draft, but now published. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated
15、. This will be indicated in the amendment table on the inside front cover.BS5752-2:1984 BSI 10-1999 1 0 Introduction The routine method for the determination of the moisture content of green coffee is based on the principle of the compensation of errors leading to a low result (moisture not complete
16、ly removed, oxidation of products) and errors leading to a high result (removal of substances other than water). It is observed, indeed, that the loss in mass after the first period in the oven is less than the moisture content determined by the basic reference method (ISO1446) and that the total lo
17、ss in mass after the second period of drying is greater than this moisture content. The loss in mass after the first period in the oven may, therefore, be considered as an underestimate of the moisture content. The compensation between these two errors is made by means of an empirical correction det
18、ermined experimentally. 1 Scope and field of application This International Standard specifies a routine method for the determination of the moisture content of green coffee. 2 References ISO 1446, Green coffee Determination of moisture content (Basic reference method). ISO 4072, Green coffee in bag
19、s Sampling 1) . 3 Definition moisture of green coffee conventionally, the loss in mass determined under the operating conditions specified below the moisture content is expressed as a percentage by mass 4 Principle Drying of a test portion at a temperature of130 2 C, at atmospheric pressure, in two
20、stages with an intermediate rest period, in order to redistribute uniformly the moisture in the bean. The result thus obtained, after a correction has been applied, is regarded as agreeing with that provided by the basic reference method (ISO1446). 5 Apparatus 5.1 Electrically heated constant-temper
21、ature oven having effective ventilation and capable of being regulated in such a way that the temperature of the air and of the shelves carrying the test portions is130 2 C in the vicinity of the test portions. The oven shall have a heating capacity such that having been set at a temperature of130 C
22、, it is able to regain this temperature in less than45min (preferably in less than30min) after the insertion of the maximum number of test portions that can be dried simultaneously. 5.2 Dish with lid, of corrosion-resistant metal or of glass, with an effective surface area of at least18cm 2(for exam
23、ple50mm minimum diameter and25to30mm deep). 5.3 Desiccator containing reagent-grade phosphorus(V) oxide (P 2 O 5 ) or any other effective dehydrating agent. 5.4 Analytical balance 6 Procedure 6.1 Test portion Weigh the dried dish (5.2) with its lid, to the nearest0,002g. Introduce approximately5g of
24、 green coffee taken from the laboratory sample obtained as specified in ISO4072. Spread this test portion over the bottom of the dish in a single layer of beans. If the test portion contains a heavy impurity (nail, stone, piece of wood, etc.), discard the test portion and take a new portion from the
25、 laboratory sample. Cover the dish with its lid and weigh the dish plus lid plus test portion to the nearest0,002g. (See8.1.) 6.2 Determination 6.2.1 First period in the oven Place the lid of the dish in the oven (5.1), controlled at130 2 C, and place on the lid the dish containing the test portion
26、(6.1). Remove the dish after a period of6h 15min, cover it with the lid and place it in the desiccator (5.3). After cooling to ambient temperature (from30to40min after placing it in the desiccator), weigh it, still closed, to the nearest0,002g. After weighing, replace the dish in the desiccator for
27、at least15h. 6.2.2 Second period in the oven Under the same conditions as specified in 6.2.1, replace the dish in the oven at130 2 C and let it remain there for4h 15min. Remove it, allow it to cool to ambient temperature in the desiccator and weigh again. 6.3 Number of determinations Carry out at le
28、ast two determinations on the same sample. 1) At present at the stage of draft.BS5752-2:1984 2 BSI 10-1999 7 Expression of results 7.1 Method of calculation and formulae 7.1.1 First period in the oven The loss in mass, P 1 , during the first drying in the oven, expressed in grams per100g of initial
29、sample, is given by the following formula: where 7.1.2 Second period in the oven The loss in mass, P 2 , during the two periods(6+4=10h) in the oven, expressed in grams per100g of initial sample, is given by the following formula: where 7.1.3 Moisture content (see8.2) The moisture content of the sam
30、ple, P, expressed as a percentage by mass, is equal to the loss in mass observed after the first period in the oven, plus half the additional loss in mass observed after the second period in the oven: Take as the result the arithmetic mean of the two determinations, provided that the requirement con
31、cerning repeatability (see 7.2) is satisfied. 7.2 Repeatability The difference between the results of two determinations carried out simultaneously or in rapid succession by the same analyst should not be greater than0,3g of moisture per100g of sample. The individual results generally differ from th
32、e moisture content obtained by the basic reference method (ISO1446) by less than0,3g of moisture per100g of sample. 8 Notes 8.1 After the test portion has been weighed, the dish may be left standing, for example in the case of a series of weighings. 8.2 The difference between the losses in mass obse
33、rved after6h (see7.1.1) and6+4=10h (see7.1.2) in the oven at130 C, i.e.the difference between P 1and P 2 , should normally be less than1,0g per100g of sample. If this is not the case, the test should be repeated or the basic reference method (ISO1446) should be used. 9 Test report The test report sh
34、all show the method used and the result obtained. It shall also mention any operating conditions not specified in this International Standard, or regarded as optional, as well as any circumstances that may have influenced the result. The report shall include all details required for complete identif
35、ication of the sample. m 0 is the initial mass, in grams, of the test portion (6.1); m 1 is the mass, in grams, of the test portion after the first (6 h) period in the oven (6.2.1). m 0 is the initial mass, in grams, of the test portion (6.1); m 2 is the mass, in grams, of the test portion after the
36、 second (4 h) period in the oven (6.2.2). P 1 m 0 m 1 () 100 m 0 - = P 2 m 0 m 1 () 100 m 0 - = PP 1 P 2 P 1 2 - + =BS5752-2:1984 BSI 10-1999 Publications referred to See national foreword.BS 5752-2: 1984 ISO 1447:1978 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is th
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