ISO-6540-1980.pdf

International Standard ( 6540. k!Ji#d INTERNATIONAL ORGANIZATION FOR STANDARDIZATIONME)KC1YHAPOflHAR OPI-AHM3AUMR fl0 CTAH,QAPTM3Al#lM.ORGANISATION INTERNATIONALE DE NORMALISATION Maize - Determination of moisture content (on milled grains and on whole grains) Mais - D b) easy to clean and having as little dead space as pos- sible; c) enabling grinding sf 30 g of maize grains to be carried out rapidly and uniformly, without appreciable development of heat and, as far as possible, without contact with the out- side air; d) adjustable so as to obtain particles of the dimensions indicated in 7.1.1. 5.3 Metal boat, without lid, with an effective surface area enabling 100 g of maize grains to be distributed in a Single layer. 5.4 Metal dish, of suitable dimensions, non-corrodible under the test conditions, or, failing this, a glass dish, with a sufficiently tight-fitting lid, and having an effective surface area such as to allow distribution of the test Portion with no more than 0,3 g per Square centimetre. 5.5 Constant-temperature oven, electrically heated, eapable of being maintained between 60 and 80 OC, and with adequate Ventilation. 2 5. Constant-temperature oven, eiectriclly heated, capable of being controlled in such a vvay that the temperature 0% the air and sf the shelves carrying the test portions is within the range of 130 to 133 OC in the neighhourhood of the test portions, in normal working. The oven shall have a heat capacity such that, when initially ad- justed to a temperature of 131 OC, it tan again resch this temperature in less than 45 min (preferably in less than 30 min) after insertion sf the maximum number o-f test portions that tan be dried simultaneously. The effectiveness of the Ventilation shall be determined using durum wheat semolina, with a maximum particle size of 1 mm, as the test material. The Ventilation shall be such that after in- serting all the test portions that the oven tan hold and drying at a temperature of 130 to 133 OC, the results after a heating period of 2 h and then a further 1 h will not differ by more than 0,15 g of moisture per 100 g of Sample. 5.7 Desiccator, containing an efficient desiccant. ampling See ISO 950. 7 Procedure (See figure I) 7.1 7A.l Preparation 0% the test sample Products not requiring to be ground Products which have particles of sizes less than or equal to 1,7 mm, less than 10 % (mlm) being over 1 mm and more than 50 % (mlm) being less than 0,5 mm, do not need to be ground before the determination. IVlix the laboratory Sample thoroughly before Portion (7.2). taking the test 7.1.2 Products requiring to be ground If the laboratory Sample does not have the particle size characteristics mentioned in 7.1 .l, it shall be ground either without pre-conditioning (7.1.2.1) or with pre-conditioning (7.1.2.2) as required. 7.1.2.1 Ginding without pre-conditioning For products which arc not likely to undergo variations in moisture content in the course of grinding in general, products with a moisture content between 9 and 15 % (mlm) (sec 9.1), carry out grinding without pre-conditioning. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 09:20:52 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 6540-1980 (El Adjust the grinding mill (5.2) to obtain particles of the dimen- sions indicated in 7.1.1, grind a small quantity of the laboratory Sample and discard it. Then quickly grind about 30 g of the laboratory samp lle, mix with a spatula and proceed immed iately as specified in 7.2. 7.1.2.2 Grinding with pre-conditioning Products which are likely to undergo changes in moisture con- tent in the course of grinding in general, products with a moisture content more than 15 % (mlm) or less than 9 % (mlm) shall be pre-conditioned to bring their moisture content to between 9 and 15 % (mlm) (sec 9.1) before grinding. If the moisture content is greater than 15 % (mlm) (the more frequent case), weigh, to the nearest 10 mg, about 100 g of the laboratory Sample in the metal boat (5.3), place this in the oven (5.5) controlled at between 60 and 80 OC, and leave it for the time necessary to bring the moisture content to between 9 and 15 % (mlm). Take the boat out of the oven and allow it to stand in the laboratory atmosphere for the time necessary (at least 2 h) for the pre-conditioned Sample to return to the laboratory temperature and for the moisture distribution to be relatively uniform. After conditioning, weigh the Sample to the nearest 10 mg, then, proceeding rapidly, grind about 30 g of this product. Mix using a spatula. NOTE - lf the moisture content is less than 9 % (m/m), place about 100 g of the laboratory Sample, weighed to the nearest 10 mg, in a suitable atmosphere (usually that of the laboratory) and leave it until a moisture content within the limits specified above is obtained. 7.2 Test portion Rapidly weigh, to the nearest 1 mg, about 8 g of the test Sample (7.1 .l, 7.1.2.1 or 7.1.2.2, as appropriate) in the dish (5.4), which has been previously dried and weighed, together with its lid, to the nearest 1 mg. 7.3 Drying Place the open dish containing the test Portion, and the lid, in the oven (5.6) controlled at 130 to 133 OC and leave it for 4 h, taken from the moment when the oven temperature is again between 130 to 133 OC. Proceeding rapidly, take the dish out of the oven, cover it and place in the desiccator (5.7); when several tests are being carried out simultaneously, never place dishes on top of one another in the desiccator. When the dish has cooled to laboratory temperature (generally between 30 and 45 min after it has been placed in the desic- cator), weigh it to the nearest 1 mg. 7.4 Mumber of determinations Carry out two determinations on test portions taken from dif- ferent test samples, but from the same laboratory Sample (sec figure 1). Expression of results 8.1 Method of calculation and formulae The moisture content, expressed as a percentage by mass the product as received, is given by th e following formulae of a) without pre-conditioning : 100 (mg - m,)- mg where m. is the mass, in grams, of the test Portion (7.2); m1 is the mass, in grams, of the test Portion after drying (7.3). b) with pre-conditioning : 1 100 - m,) !rz + m2 - m3 - mg m2 = 100 6 -z) mg is the mass, in grams, sf the test Portion (7.2); m1 is the mass, in grams, of the test Portion after drying (7.3); m2 is the mass, in grams, of the Sample before con- ditioning (7.1.2.2); m3 is the mass, in grams, of the Sample after condition- ing (7.1.2.2). Take as the result the arithmetic mean of the two values ob- tained, provided that the requirement for repeatability (sec 8.2) is satisfied. If it is not, repeat the determinations. Express the result to the second decimal place. 8.2 Repeatability The differente between the values obtained from the two determinations, carried out simultaneously or in rapid succes- sion by the same analyst, shall not exceed 0,15 g of moisture per 100 g of Sample. 8;3 Remark The results compared with those obtained by the absolute method (see the annex) generally differ by less than 0,15 g of moisture per 100 g of Sample. 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 09:20:52 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 6540-1980 (El 9 Notes on procedure 9.1 The range of moisture contents given for conditioning products before grinding corresponds approximately to a laboratory atmosphere of temperature 20 OC and relative humidity 40 to 70 %. lt should be modified for different atmospheric conditions. 9.2 Never place moist products in an oven containing test portions at the end of dehydration, as this will result in partial rehydration of the latter. 9.3 The conditioning and grinding carried out on 100 g and 30 g respectively for a test portion sf 8 g are intended to Without conditioning Laboratorv Sample Grinding Grinding Test Sample Test sam ple i Test porti on mO =8g Drying Drying provide a more representative Sample. A s;ple of 8 g would correspond to an insufficient quantity of ground product to be representative and would lead to too great a dispersion of the results. IO Test report The test report shall show the method used and the result ob- tained. lt shall also mention all operating details not specified in this section, or regarded as optional, as weil as any incidents which may have influenced the result. The report shall include all details required for complete iden- tification of the Sample, and in particular the date on which the analysis was carried out. With conditioning Laboratory Sample Conditioning Conditioning Rest Grinding Grinding Test Sample Test Sample NOTE - The weighing operations are boxed. Drying Drying Figure 1 - Diagram of the two possible procedures for products requirinq to be ground . Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 09:20:52 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 65404980 (E) Section tvvo : Routine method on whole grains 11 Scope and field of application This section specifies a method for the evaluation of the moisture content of maize in whole grains. It is not suitable for use for experts reports, or for calibration or checking of humidity meters. 12 Reference ISO 950, Cereals - Sampling las grain). 13 Definition moisture content of maize : Conventionally, the loss in mass, expressed as a percentage, undergone by the product under the conditions specified in this section. 14 Principle Drying of whole grains for 38 h at a temperature between 130 and 133 OC. 15 Apparatus 15.1 Metal dish, non-corrodible under the test conditions, with a sufficiently tight-fitting lid, a diameter of 50 to 60 mm and a minimum height of 25 mm. 15.2 Constant-temperature oven, electrically heated, capable of being controlled in such a way that the temperature of the air and of the shelves carrying the test portions is within the range 130 to 133 OC, in the neighbourhood of the test portions, in normal working. 15.3 Desiccator, containing an efficient desiccant. 15.4 Balance. 16 Sampling See ISO 950. 17 Procedure 17.1 Test Portion Weigh, to the nearest 0,Ol g, the metal dish (15.1) and its lid, previously dried. 1) In practice, two nights and one day. Introduce rapidly, according to the diameter of the dish, from 25 to 40 g of whole grains. Immediately, close the dish and weigh to the nearest 0,Ol g. 17.2 Drying Place the open dish containing the test Portion, with the lid by its side, in the oven (15.2) controlled at 130 to 133 OC and leave it for 38 I!I 2 h.1) Following this period, proceeding rapidly, take the dish out of the oven, cover it and place it in the desiccator (15.3); when several tests are being carried out simultaneously, never place dishes on top of one another in the desiccator. When the dish has cooled to laboratory temperature (generally between 30 and 45 min after it has been placed in the desic- cator), weigh it to the nearest 0,Ol g. 17.3 Number of determinations Carry out at least two determinations on test portions taken from the same laboratory Sample. 18 Expression of results 18.1 Method of calculation and formulae The moisture content, expressed as a percentage by mass of the product as received, is given by the following formula : 100 (m, - m2) x m1 - mo where m. is the mass, in grams, of the empty dish and its lid; m1 is the mass, in grams, of the dish, its lid and the test Portion before drying; n2 is the mass, in grams, of the dish, its lid and the test Portion after drying. Take as the result the arithmetic mean of the values obtained, provided that the requirement for repeatability (see 18.2) is satisfied. If it is not, repeat the determinations. Express the result to one decimal place. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 09:20:52 MDTNo reproduction or networking permitted without license from IHS -,-,- BS0 6540-1980 (E) 18.2 Wegeatability at the end of dehydration, as this will res-ehydra- tion of the latter. The differente between the values obtained from the two determinations, carried out simultaneously or in rapid succes- sion by the same analyst, shall not exceed 0,2 g of moisture per 100 g of Sample. “88.3 Remark est report The results compared with those obtained by the absolute method (see the annex) generally differ by less than O,5 g of moisture per 100 g of Sample. The test report shall show the method used and the res b) easy to clean and having as little dead space as pos- sible; c) enabling grinding of 30 g of maize grains to be carried out rapidly and uniformly, without appreciable development of heat and, as far as possible, without contact with the out- side air; d) adjustable so as to obtain particles of the dimensions indicated in A.7.1.1. A.5.4 Metal boat, without lid, with an effective surface area enabling 100 g of maize grains to be distributed in a Single layer. A.5.5 Metal dish*), non-corrodible under the test con- ditions, with a sufficiently tight-fitting lid and having an effec- tive surface area such as to allow distribution of the test Portion with no more than 0,3 g per Square centimetre. A.5.6 Apparatus for drying at a reduced pressure, with a volume such that the metal boats (A.5.4) may be placed inside. A.5.7 Cup, made from glass or porcelain. A.5.8 Drying tubes), of glass, in two Parts, one of which, closed at one end, is intended to receive the dish (A.5.5) and the other, intended to contain the cup (A.5.7), carries a semi- capillary tube, with a stopcock, for connection to the vacuum Source (A.5.2). The two Parts are connected by a ground glass joint. The test Portion may be cooled in this apparatus after drying, the desiccator (A.5.11) being then unnecessary for this opera- tion. A.5.9 Constant-temperature oven, electrically heated, enabling the part of the drying tube (A.5.8) containing the dish (A.5.5) to be maintained at a temperature between 45 and 50 OC. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 09:20:52 MDTNo reproduction or networking permitted without license from IHS -,-,- 8 -,: P , , lfsss f/-j217! IO */* (917,fnf beir- owx 1 rm7 and mxe -tia-a 50 3/ui tm/m) beirigg less than O,5 mm, dv 3x31 33