1、BRITISH STANDARD BS 4317-2: 1987 ISO 711:1985 Methods of test for Cereals and pulses Part 2: Determination of moisture content of cereals and cereal products (reference method) ISO title: Cereals and cereal products Determination of moisture content (Basic reference method) UDC 633.1/.3:664.7:543.81
2、BS4317-2:1987 This British Standard, having been prepared under the directionof the Food and Agriculture Standards Committee,was published underthe authority of the BoardofBSI and comes into effect on 30January1987 BSI 02-2000 First published April1968 First revision May1980 Second revision January1
3、987 The following BSI reference relateto the work on this standard: Committee reference FAC/4 Draft (ref.86/51282) announced inBSI News June1986 ISBN 0 580 15669 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Food and Agriculture Stan
4、dards Committee (FAC/-) to Technical Committee FAC/4 upon which the following bodies were represented: Agricultural Engineers Association Association of Public Analysts British Edible Pulse Association British Maize Refiners Association Department of Trade and Industry (Laboratory of the Government
5、Chemist) Flour Milling and Baking Research Association Food and Drink Federation Grain and Feed Trade Association Home Grown Cereals Authority Incorporated National Association of British and Irish Millers Institute of Food Science and Technology Intervention Board for Agricultural Produce Ministry
6、of Agriculture, Fisheries and Food National Association of Commodity Cargo Superintendents and Surveyors National Farmers Union National Institute of Agricultural Engineering Overseas Development Administration (Tropical Development and ResearchInstitute) Society of Chemical Industry Ulster Farmers
7、Union UnitedKingdom Agricultural Supply Trade Association Ltd. Amendments issued since publication Amd. No. Date of issue CommentsBS4317-2:1987 BSI 02-2000 i Contents Page Committees responsible Inside front cover National foreword ii 0 Introduction 1 1 Scope and field of application 1 2 References
8、1 3 Definition 1 4 Principle 1 5 Apparatus 1 6 Sampling 1 7 Procedure 2 8 Expression of results 3 9 Notes on procedure 3 10 Test report 3 Figure 1 Diagram of suitable metal dish and lid 4 Figure 2 Diagram of suitable drying tube 5 Publications referred to Inside back coverBS4317-2:1987 ii BSI 02-200
9、0 National foreword This revision of this Part of BS4317 has been prepared under the direction of the Food and Agriculture Standards Committee. It is identical with ISO711:1985 “Cereals and cereal products Determination of moisture content (Basic reference method)”, published by the International Or
10、ganization for Standardization (ISO), and in the preparation of which the UnitedKingdom played a full part. It differs from BS4317-2:1980 principally in that rice is required to be pre-conditioned before grinding if the moisture content exceeds15%. BS 4317-2:1980 is withdrawn. Terminology and conven
11、tions. 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 following. In British Standards i
12、t is current practice to use a full point on the baseline as the decimal marker instead of a comma. Wherever the words “International Standard” appear, referring to this Standard, they should be read as “Part of BS4317”. A British Standard does not purport to include all the necessary provisions of
13、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. Cross-references International Standard Corresponding British Standard ISO 712:1985 BS 4317 Methods of test for cereals
14、and pulses Part 3:1986 Determination of moisture content of cereals and cereal products (routine method) (Identical) ISO 950:1979 BS 4510:1980 Methods for sampling cereals (as grain) (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to
15、6, 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.BS4317-2:1987 BSI 02-2000 1 0 Introduction The basic reference method specified in this Inte
16、rnational Standard ensures complete removal of moisture from the product, as has been demonstrated by tests of reversibility and addition of moisture, while avoiding any alteration in its chemical composition, particularly oxidation and loss of volatile organic substances. 1 Scope and field of appli
17、cation This International Standard specifies the basic reference method for the determination of the moisture content of cereals and cereal products. 1) The method is not applicable to maize, for which an identical method, called the absolute method, is specified in the annex to ISO6540, Maize Deter
18、mination of moisture content (on milled grains and on whole grains). This basic reference method, which necessitates the employment of special equipment and experienced analysts, is therefore only suitable for use in specialized laboratories, and is intended to serve as a standard for checking and p
19、erfecting routine methods for the determination of moisture content (see particularly ISO712). It is not intended to be used for settling commercial disputes. 2 References ISO 712, Cereals and cereal products Determination of moisture content (Routine reference method). ISO 950, Cereals Sampling (as
20、 grain). 3 Definition moisture content the loss in mass, expressed as a percentage, undergone by the product under the conditions specified in this International Standard 4 Principle If necessary, grinding of a sample, after conditioning, if required. Drying of a test portion under reduced pressure,
21、 at a temperature between45 and50 C and in the presence of a desiccant, until constant mass is reached. 5 Apparatus 5.1 Analytical balance 5.2 Apparatus for reducing pressure to1,3 to2,6kPa, 2)for example a water pump. 5.3 Grinding mill, having the following characteristics: a) made of material whic
22、h does not absorb moisture; b) easy to clean and having as little dead space as possible; c) enabling grinding to be carried out rapidly and uniformly, without appreciable development of heat and, as far as possible, without contact with the outside air; d) adjustable so as to obtain particles of th
23、e dimensions indicated in7.1.1. 5.4 Metal dish, 3)non-corrodible under the test conditions, with a sufficiently tight-fitting lid and having an effective surface area such as to allow the test portion to be distributed in a layer having a mass per unit area of not more than0,3g/cm 2 . 5.5 Cup, made
24、from glass or porcelain. 5.6 Drying tube, 4)of glass, in two parts, one of which, intended to receive the dish(5.4), is closed at one end, while the other, intended to receive the cup(5.5), carries a semi-capillary tube, with a stopcock, for evacuation purposes. The two parts are connected by a grou
25、nd glass joint. The test portion may be cooled in this apparatus after drying, a desiccator(5.9) being then unnecessary for this operation. 5.7 Constant-temperature oven, electrically heated, enabling the part of the drying tube(5.6) containing the dish(5.4) to be maintained at a temperature between
26、45 and50 C. 5.8 Air-drying train: gas-washing bottle containing pure analytical grade sulfuric acid ( 20 W 1,83 g/ml), connected to a tube containing pure analytical grade diphosphorus pentaoxide spread on glass wool. 5.9 Desiccator, containing an efficient desiccant. 6 Sampling See ISO 950. 1) This
27、 method has been applied successfully to the following products: wheat, rice (paddy, husked and milled rice), barley, millet, rye and oats, in the form of grains, milled grains, semolina or flour. 2) 1,3 to2,6 kPa=13 to26 mbar = 10 to20mmHg. 3) A suitable metal dish is shown, for information only, i
28、nFigure 1. 4) A suitable drying tube is shown, for information only, inFigure 2.BS4317-2:1987 2 BSI 02-2000 7 Procedure 7.1 Preparation of the test sample 7.1.1 Products not requiring to be ground Products having particles of sizes less than or equal to1,7mm, less than10%(m/m) being over1mm and more
29、 than50% (m/m) being less than0,5mm, do not need to be ground before the determination. Mix the laboratory sample thoroughly before taking the test portion (7.2.1). 7.1.2 Products requiring to be ground If the sample does not have the particle size characteristics mentioned in7.1.1, it shall be grou
30、nd either without pre-conditioning (7.1.2.1) or with pre-conditioning (7.1.2.2). 7.1.2.1 Grinding without pre-conditioning For products which are not likely to undergo variations in moisture content in the course of grinding in general, products with a moisture content between7 and17% (m/m) 5)(see9.
31、1), carryout grinding without pre-conditioning. Adjust the grinding mill (5.3) to obtain particles of the dimensions indicated in7.1.1, grind a small quantity of the laboratory sample and discard it. Then quickly grind about3,5g of the laboratory sample, and immediately proceed in accordance with7.2
32、2. 7.1.2.2 Grinding with pre-conditioning Products which are likely to undergo changes in moisture content in the course of grinding in general, products with a moisture content more than 17% (m/m) 5)or less than7% (m/m) 5)shall be pre-conditioned so as to bring their moisture content to between7 a
33、nd17% (m/m) 5)if possible between9 and15% (m/m) (see9.1), before grinding. If the moisture content is more than17% (m/m) 5)(the more frequent case), weigh, to the nearest0,2mg, about3,5g of the laboratory sample and pre-dry it in accordance with7.3, except that the drying time shall be1,5 to2h (see9
34、2) and it is unnecessary to renew the diphosphorus pentaoxide. If the moisture content is less than7% (m/m), place about3,5g of the laboratory sample, weighed to the nearest0,2mg, in a suitable atmosphere (usually that of the laboratory) and leave it to acquire a moisture content within the limits
35、specified above. After conditioning, weigh the sample to the nearest0,2mg, grind it immediately in the grinding mill (5.3), adjusted to obtain particles of the dimensions indicated in7.1.1, and immediately proceed in accordance with7.2.2. 7.2 Test portion 7.2.1 For products not requiring to be groun
36、d, rapidly weigh, to the nearest0,2mg, about3g of the test sample (7.1.1) into the dish (5.4), previously dried and weighed, together with its lid, to the nearest0,2mg. 7.2.2 In the case of products which have had to be ground, rapidly weigh all the grindings obtained(7.1.2.1 or7.1.2.2) into the dis
37、h (5.4), previously dried and weighed, together with its lid, to the nearest0,2mg. 7.3 Drying Place the open dish (leaving its lid in the desiccator) containing the test portion (7.2) at the closed end of the drying tube (5.6); introduce, near to it, the cup(5.5) containing a layer of diphosphorus p
38、entaoxide about1cm thick. Fit the two parts of the drying tube together and reduce the pressure in the assembled tube to a value of the order of1,3 to2,6kPa, using the vacuum apparatus (5.2); this should be done gradually in order to avoid material being thrown out of the dish. Close the connection
39、to the vacuum apparatus, and place the part of the tube containing the test portion in the oven (5.7), controlled at45 to50 C (see9.4). When the diphosphorus pentaoxide agglomerates at the surface, renew it after restoring atmospheric pressure inside the drying tube by causing air, which has passed
40、through the drying train (5.8), to enter slowly through the semi-capillary tube. Reduce the pressure in the drying tube again and continue the drying as before. After about100h, take the tube out of the oven, allow it to cool to laboratory temperature and restore atmospheric pressure inside it as de
41、scribed above. Disconnect the two parts of the tube, quickly remove the dish, cover and weigh it to the nearest0,2mg. Repeat the operations specified above until the mass is practically constant (i.e.until the difference between two successive weighings at an interval of48h is less than0,6mg) (see9.
42、3). 7.4 Number of determinations Carry out two determinations on test portions taken from different test samples but from the same laboratory sample. 5) 15% (m/m) in the case of oats and rice (paddy, husked and milled rice).BS4317-2:1987 BSI 02-2000 3 8 Expression of results 8.1 Method of calculatio
43、n and formulae The moisture content, expressed as a percentage by mass of the product as received, is given by the following formulae: a) without pre-conditioning: where m 0 is the mass, in grams, of the test portion(7.2.1 or 7.2.2); m 1 is the mass, in grams, of the test portion after drying (7.3).
44、 b) with pre-conditioning: where m 0 is the mass, in grams, of the test portion(7.2.2); m 1 is the mass, in grams, of the test portion after drying (7.3); m 2 is the mass, in grams, of sample taken before preconditioning (7.1.2.2); m 3 is the mass, in grams, of the pre-conditioned sample (7.1.2.2).
45、Take as the result the arithmetic mean of the two values obtained, if the requirement for repeatability (see8.2) is satisfied. If it is not, the determinations shall be repeated. Express the result to the second decimal place. 8.2 Repeatability The difference between the values obtained from two det
46、erminations (see7.4) carried out simultaneously or in rapid succession by the same analyst shall not exceed0,10g of moisture per100g of sample. NOTEWith a little practice, differences of less than0,05g of moisture per100g of sample can be obtained in the same laboratory. 9 Notes on procedure 9.1 The
47、 range of moisture contents given for conditioning products before grinding corresponds approximately to a laboratory atmosphere of temperature20 C and relative humidity40 to70%. It should be modified for other atmospheric conditions. 9.2 The duration of pre-drying is given only for guidance. Check
48、that it enables the desired conditioning to be obtained with the apparatus and the products used. 9.3 The drying period is of the order of 150 h at least. 9.4 A coloration at the surface of the diphosphorus pentaoxide indicates the loss of traces of volatile organic substances from the test portion.
49、 With certain deteriorated products, if the coloration becomes sufficiently pronounced, it is expedient to reduce the temperature of heating. 10 Test report The test report shall show the method used and the result obtained. It shall also mention all operating details not specified in this International Standard, or regarded as optional, as well as any incidents which may have influenced the result. The report shall include all details required for the complete identification of the sample, and in particular the date on which the analysis was carried
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