1、BRITISH STANDARD BS 6215-2: 1981 ISO 6541:1981 Incorporating Amendment No. 1 Methods of Test for agricultural food products Part 2: Determination of crude fibre content (modified Scharrer method) UDC 664:633/635:543.868BS6215-2:1981 This British Standard, having been prepared under the directionof t
2、he Food and Agriculture Standards Committee,was published underthe authority of the BoardofBSI and comes into effect on 30 November 1981 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference FAC/- Draft for comment 79/54941 DC ISBN 0 580 12473 8 Cooperatin
3、g organizations The Food and Agriculture Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following: Agricultural Co-operation and Marketing Services Agricultural Research Council (Meat Research Institute) British Food Manufacturing
4、Industries Research Association British Industrial Biological Research Association Ltd. Campden Food Preservation Research Association Consumer Standards Advisory Committee of BSI Department of Agriculture and Fisheries for Scotland Department of Agriculture (Government of Northern Ireland) Departme
5、nt of Industry (Laboratory of the Government Chemist)* Flour Milling and Baking Research Association* Food Manufacturers Federation Incorporated* Institute of Brewing Local Authorities Co-ordinating Body of Trading Standards Ministry of Agriculture, Fisheries and Food National Farmers Union National
6、 Farmers Union of Scotland Tobacco Advisory Council The organizations marked with an asterisk in the above list, together with the following, were directly represented on the Technical Committee entrusted with the preparation of this British Standard: Agricultural Research Council (Rowatt Research I
7、nstitute) United Kingdom Tea Association Amendments issued since publication Amd. No. Date of issue Comments 5061 April 1986 Indicated by a sideline in the marginBS6215-2:1981 BSI 12-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii 1 Scope 1 2 Field of applicati
8、on 1 3 Reference 1 4 Definition 1 5 Principle 1 6 Reagents and materials 1 7 Apparatus 1 8 Sampling 1 9 Procedure 2 10 Expression of results 3 11 Notes on procedure 3 12 Test report 4 Publications referred to Inside back coverBS6215-2:1981 ii BSI 12-1999 National foreword This Part of this British S
9、tandard has been prepared under the direction of the Food and Agriculture Standards Committee. It is identical with ISO6541 “Agricultural food products Determination of crude fibre content Modified Scharrer method” published in1981by the International Organization for Standardization (ISO) and prepa
10、red by Technical Committee34, Agricultural food products. It is intended to publish further Parts of this British Standard as other methods are agreed internationally and given UK approval. Terminology and conventions. The text of the International Standard has been approved as suitable for publicat
11、ion as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is especially drawn to the following. Wherever the words “International Standard” appear, referring to this standard, they should be read as “Britis
12、h Standard”. The comma has been used throughout as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. The technical committee has reviewed the provisions of ISO3310-1:1975, referred to in6.4 and 7.2, and has decided that they are
13、acceptable for use in conjunction with this standard. BS410:1976 “Specification for test sieves” is related to ISO3310-1. Additional information Water. Water complying with the requirements of BS3978 “Water for laboratory use” is suitable for use. Sand. Commercially available acid washed sand ready
14、for use is suitable in place of sea sand (see6.4). Drying oven. A drying oven complying with the requirements of BS2648 “Performance requirements for electrically-heated laboratory drying ovens” will satisfy the requirements of7.8. Dietary fibre. The method described in this British Standard is not
15、suitable for the determination of dietary fibre. NOTECorrect sampling requires most careful attention. Emphasis cannot therefore be too strongly placed on the necessity of obtaining a truly representative sample. Careless or inaccurate practices could lead to misunderstanding and possible unwarrante
16、d financial adjustment. Samples should be obtained in accordance with the British Standard, if any, relevant to the product concerned. In the case of animal feeding stuffs, attention is drawn to The Feeding Stuffs (Sampling and Analysis) Regulations1982 which provide guidance and which are to be fol
17、lowed for legislative purposes. 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 from legal obligations. Cross-ref
18、erence International Standard Corresponding British Standard ISO 5498:1981 BS 6215 Methods of test for agricultural food products Part 1:1981 Determination of crude fibre content (general method) (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and i
19、i, pages1 to 4, 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.BS6215-2:1981 BSI 12-1999 1 1 Scope This International Standard specifies a con
20、ventional method for the determination of the crude fibre content of agricultural food products. 2 Field of application The method is applicable to cereals and cereal products, as well as to certain products containing less than1% of crude fibre, for example yeasts, which are excluded from the field
21、 of application of ISO5498. 3 Reference ISO 5498, Agricultural food products Determination of crude fibre content General method. 4 Definition 4.1 crude fibre content conventionally, the whole of the substances which are insoluble and combustible under the operating conditions described in this Inte
22、rnational Standard the crude fibre content is expressed as a percentage by mass, referred either to the product as received or to the dry matter content of the product NOTEIn French, the term “indice dinsoluble dit cellulosique” has been adopted for “crude fibre” rather than the alternative “cellulo
23、se brute”. 5 Principle After any necessary grinding and defatting, boiling with a mixture of acetic acid, nitric acid and trichloroacetic acid (Scharrer reagent). Separation and washing of the insoluble residue on a filter crucible. Drying and weighing of the insoluble residue, and determination of
24、the loss of mass on incineration. 6 Reagents and materials All reagents shall be of recognized analytical quality and the water used shall be distilled water or water of at least equivalent purity. 6.1 Scharrer reagent, consisting of a mixture having the following composition: 6.2 Aceton 6.3 Diethyl
25、 ether 6.4 Sea sand, prepared as follows. Sieve the sand successively through sieves of wire gauze of aperture sizes1604m and1254m, complying with the requirements of ISO3310-1. Boil the sand retained by the1254m aperture size sieve for30min in 4mol/l hydrochloric acid solution. Rinse the sand with
26、water until the rinsing water is free from chloride, as indicated by the absence of a reaction with silver nitrate solution, and incinerate in the muffle furnace (7.9) at550 25 C to constant mass (usually at least6h are required). 6.5 Boiling aid: crushed porcelain. 7 Apparatus Usual laboratory appa
27、ratus, and in particular 7.1 Grinding device, easy to clean, suited to the nature of the product and allowing grinding of the product without causing undue heating or significant change in the moisture content. 7.2 Sieve, of metal wire cloth, aperture size1mm, complying with the requirements of ISO3
28、310-1. 7.3 Wide-mouthed vessel, provided with a condenser, for example a conical flask of capacity200to300ml, fitted with a reflux condenser. 7.4 Suction flask 7.5 Water-jet pump 7.6 Filter crucible, of silica, having a fritted silica plate of porosity gradeP100 (pore diameter40to1004m), prepared as
29、 indicated in11.1. 7.7 Desiccator, containing an efficient desiccant. 7.8 Drying oven, capable of being controlled at130 2 C. 7.9 Muffle furnace, capable of being controlled at550 25 C. 7.10 Analytical balance 8 Sampling Refer to the International Standard appropriate to the product concerned. aceti
30、c acid solution, prepared by diluting 730 g of 96 % (m/m) glacial aceticacid with water to 1000g 900 ml nitric acid, concentrated, 20= 1,38 g/ml 60 ml trichloroacetic acid, crystalline 24 gBS6215-2:1981 2 BSI 12-1999 9 Procedure 9.1 Preparation of test sample 9.1.1 Preliminary drying In the case of
31、products having moisture contents too high for them to be mixed or ground as received, carry out a preliminary drying of the product at an appropriate temperature. In this case, weigh the product before the preliminary drying and again just before preparation of the test sample (9.1.2 or9.1.3). 9.1.
32、2 Products not requiring grinding 9.1.2.1 Products of which95% pass through the sieve (7.2) do not need to be ground before the determination. Mix well before taking the test portion. 9.1.2.2 If the results are to be expressed relative to the dry matter content, determine beforehand the dry matter c
33、ontent of the test sample (9.1.2.1) by an appropriate method. 9.1.3 Products requiring grinding Products of which less than95% pass through the sieve (7.2) shall be ground. 9.1.3.1 If the results are to be expressed relative to the product as received, determine beforehand the dry matter content of
34、the sample by an appropriate method. 9.1.3.2 Grind the laboratory sample in the grinding device (7.1) so that at least95% of the product passes through the sieve (7.2). NOTESuch a degree of fineness of grinding is unnecessary for products containing parts which are rich in cellulosic substances, suc
35、h as grains in husk or husks of grain. 9.1.3.3 Determine the dry matter content of the test sample (9.1.3.2) by an appropriate method. 9.2 Test portion Weigh, to the nearest1mg, a mass of the prepared test sample (9.1) corresponding to0,05to0,15g of crude fibre i.e.1to3g for a crude fibre content of
36、5% (m/m). For products with low crude fibre contents, and in particular those having crude fibre contents less than1% (m/m), take a test portion of3g. 9.3 Determination NOTEProducts rich in fatty substances may require defatting beforehand (methods are described in Annex A of ISO5498). This operatio
37、n is not required for cereal and cereal products or for yeasts. 9.3.1 Digestion Transfer the test portion to the digestion vessel (7.3) and suspend it in about one-third of the total volume of the Scharrer reagent (6.1). Generally, the total volume, in millilitres, of the Scharrer reagent is numeric
38、ally twenty times the mass, in grams, of the test portion (in no case shall the volume used be less than40ml). Using a glass rod, which shall be left in the digestion vessel, break up any large lumps that may have been formed. Carefully rinse the interior walls of the digestion vessel with the remai
39、ning two-thirds of the Scharrer reagent in order to remove any particles of the product adhering to the walls. Fit the condenser. Bring the contents of the vessel to the boil in3 0,5min and maintain boiling for301min (see11.2). Do not stir or shake while boiling. 9.3.2 Separation and washing of the
40、residue After the specified boiling period, transfer the boiling solution to the filter crucible (7.6) prepared as described in11.1, and filter under reduced pressure using the suction flask (7.4) and the water-jet pump (7.5). Rinse the vessel and the glass rod with50to70ml portions of water (temper
41、ature between95and100 C) and quantitatively transfer the insoluble residue to the filter crucible using a glass rod fitted with a rubber cap. Repeat the washing until the filtrate is substantially neutral to litmus paper; this usually requires300to400ml water. After washing, disconnect the water-jet
42、 pump, immediately empty the suction flask and fill the filter crucible three times with the acetone (6.2), allowing the solvent to drain through under gravity. If this operation requires too much time, apply gentle suction to obtain a flow rate not exceeding one drop per second. Rinse twice with th
43、e diethyl ether (6.3) and remove the ether by filtration under reduced pressure using the suction flask and water-jet pump. 9.3.3 Drying Dry the filter crucible with its contents in the drying oven (7.8) maintained at130 2 C. Allow them to cool to room temperature in the desiccator (7.7) and weigh t
44、hem rapidly to the nearest0,5mg. Repeat these operations until the difference between two successive weighings, separated by a period in the oven followed by cooling in the desiccator, does not exceed1mg. NOTEDrying for1h is generally sufficient.BS6215-2:1981 BSI 12-1999 3 9.3.4 Incineration After d
45、rying, incinerate the dry residue in the muffle furnace (7.9) at550 25 C for30min. Place the crucible on a refractory plate and allow to cool to room temperature in the desiccator (7.7). Weigh rapidly to the nearest0,5mg. 9.3.5 Number of determinations Carry out at least two determinations on the sa
46、me test sample. 10 Expression of results 10.1 Method of calculation and formulae 10.1.1 Crude fibre content relative to the product as received The crude fibre content, expressed as a percentage by mass relative to the product as received, is given by the formula a) for products not requiring grindi
47、ng b) for products requiring grinding where m 0 is the mass, in grams, of the test portion(9.2); m 1 is the total mass, in grams, of the dry residue and its support after drying (9.3.3); m 2 is the total mass, in grams, of the dry residue and its support after incineration (9.3.4); M S is the dry ma
48、tter content of the product as received, determined as indicated in9.1.3.1; M S is the dry matter content of the test sample, determined as indicated in9.1.2.2 or9.1.3.3. 10.1.2 Crude fibre content relative to the dry matter content of the product The crude fibre content, expressed as a percentage b
49、y mass relative to the dry matter content of the product is given by the formula where m 0 , m 1 , m 2and M Shave the same meanings as in 10.1.1. 10.1.3 Case of preliminary drying If a preliminary drying was carried out (see9.1.1), the crude fibre content, expressed as a percentage by mass relative to the product as received, is obtained by multiplying the result calculated according to 10.1.1 by the ratio where m 4 is the mass, in grams, of the initial moist sample before preliminary drying; m 5 is the mass, in grams, of the same sample aft
