BS 6215-1-1981 Methods of test for agricultural food products - Determination of crude fibre content (general method)《农业食品试验方法 第1部分 粗纤维含量测定(通用方法)》.pdf

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1、BRITISH STANDARD BS 6215-1: 1981 ISO 5498:1981 Incorporating Amendment Nos. 1 and 2 Methods of Test for agricultural food products Part 1: Determination of crude fibre content (general method) UDC 664:633/635:543.868BS6215-1:1981 This British Standard, having been prepared under the directionof the

2、Food and Agriculture Standards Committee,was published underthe authority of the BoardofBSI and comes into effect on 30November1981 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference FAC/- Draft for comment 79/54942 DC ISBN 0 580 12472 X Cooperating org

3、anizations 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 Indus

4、tries 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) Department of

5、 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 Farm

6、ers 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 (Rowett Research Instit

7、ute) United Kingdom Tea Association Amendments issued since publication Amd. No. Date of issue Comments 5062 May 1986 7726 June 1993 Indicated by a sideline in the marginBS6215-1:1981 BSI 12-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii 0 Introduction 1 1 Sco

8、pe 1 2 Field of application 1 3 Reference 1 4 Definition 1 5 Principle 1 6 Reagents and materials 1 7 Apparatus 2 8 Sampling 2 9 Procedure 2 10 Expression of results 3 11 Notes on procedure 4 12 Test report 4 Annex A Methods of extraction of fatty substances 5 Annex B Various devices for the separat

9、ion of crude fibre and supplementary information on the procedures for their use 5 Publications referred to Inside back coverBS6215-1:1981 ii BSI 12-1999 National foreword This Part of this British Standard has been prepared under the direction of the Food and Agriculture Standards Committee. It is

10、identical with ISO5498 “Agricultural food products Determination of crude fibre content General method” published in1981 by the International Organization for Standardization (ISO), and prepared by Technical Committee34, Agricultural food products. It is intended to publish further Parts of this Bri

11、tish 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 publication as a British Standard without deviation. Some terminology and certain conventions are not identical with

12、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 “British Standard”. The comma has been used throughout as a decimal marker. In British Standards it is current pract

13、ice to use a full point on the baseline as the decimal marker. The technical committee has reviewed the provisions of ISO3310-1:1990, referred to in7.2, and has decided that they are acceptable for use in conjunction with this standard. BS410:1986 “Specification for test sieves” is related toISO3310

14、-1. Additional information Water. Water complying with the requirements of BS3978 “Water for laboratory use” is suitable for use. Dietary fibre. The method described in this British Standard is not suitable for the determination of dietary fibre. With regard toAnnex B, the use of asbestos is now dep

15、recated for health reasons. In the UK the procedure using asbestos as a filter aid described inB.2 andB.4 should be disregarded. NOTECorrect sampling requires most careful attention. Emphasis cannot therefore be too strongly placed on the necessity of obtaining a truly representative sample. Careles

16、s or inaccurate practices could lead to misunderstanding and possible unwarranted 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 (Sampl

17、ing and Analysis) Regulations1982 which provide guidance and which are to be followed 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 Briti

18、sh Standard does not of itself confer immunity from legal obligations. Cross-reference International Standard Corresponding British Standard ISO 6541:1981 BS 6215 Methods of test for agricultural food products Part 2:1981 Determination of crude fibre content (modified Scharrer method) (Identical) Su

19、mmary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 8, 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 f

20、ront cover.BS6215-1:1981 BSI 12-1999 1 0 Introduction There are numerous methods for the determination of the crude fibre content of agricultural food products and, for a given method, numerous variants are used according to the products analysed, or, for the same product, from laboratory to laborat

21、ory. This International Standard therefore fulfils a need for harmonization. It specifies a method of general application based on the Weende method, which is the most commonly used, and basically involves acid treatment followed by alkaline treatment. Studies carried out have demonstrated the need

22、to specify precisely the conditions for the acid and alkaline treatments and to describe the various procedures used for separating the insoluble matter. These procedures are described inAnnex B. 1 Scope This International Standard specifies a conventional method for the determination of the crude f

23、ibre content of agricultural food products. 2 Field of application The method is intended for general application; however, it may be necessary, in certain individual cases, to choose a more appropriate method, particularly in the case of yeasts and products containing less than1% of crude fibre for

24、 which the method described in ISO6541 shall be used. 3 Reference ISO 6541, Agricultural food products Determination of crude fibre content Modified Scharrer method. 4 Definition crude fibre content conventionally, the whole of the substances which are insoluble and combustible under the operating c

25、onditions described in this International 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” rath

26、er than the alternative “cellulose brute”. 5 Principle After any necessary grinding and defatting, boiling with sulphuric acid solution of standard concentration, and separation and washing of the insoluble residue. Boiling this residue with sodium hydroxide solution of standard concentration, then

27、separation, washing, drying and weighing of the insoluble residue, and determination of the loss in 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 Sulphuric

28、acid, standard volumetric solution, c(1/2 H 2 SO 4 ) = 0,255 0,005mol/l (corresponding to12,5g of sulphuric acid per litre of solution). 6.2 Sodium hydroxide, standard volumetric solution, c(NaOH)=0,313 0,005mol/l (corresponding to12,5g of sodium hydroxide per litre of solution). This solution shall

29、 be as free as possible from carbonates. 6.3 Acetone, or95% (V/V) ethanol, or methanol, or propan-2-ol. 6.4 Extraction solvent: Technical grade n-hexane, or light petroleum (having a boiling range between40and60 C), or diethyl ether, or another solvent or mixture of solvents more suitable for the ex

30、traction of fatty substances from certain products to be analysed. 6.5 Hydrochloric acid, 0,5mol/l solution (in the case of products rich in carbonates). (See11.1.) 6.6 Filter aid (in cases where the separation techniques described in clausesB.2 orB.3 ofAnnex B are used). 6.7 Anti-foam agent, if nec

31、essary, known to have no effect on the results. 6.8 Anti-bumping agent, if necessary, resistant to attack under the test conditions or known to have no effect on the results.BS6215-1:1981 2 BSI 12-1999 7 Apparatus Usual laboratory apparatus, and in particular 7.1 Grinding device, easy to clean, suit

32、ed 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 ISO3310-1. 7.3 Drying oven, capable of being controlled at130 2 C. 7.

33、4 Wide-mouthed vessel, provided with a condenser, for example a flask having a minimum capacity of600ml fitted with a reflux condenser, or a beaker without spout, of capacity600ml, covered by a round-bottom flask of500ml capacity containing450ml of cold water. 7.5 Heating device, for example an elec

34、trically heated hot-plate fitted with a magnetic stirrer, capable of maintaining200ml of reagents6.1 and6.2 at a gentle boil. 7.6 Incineration dish, of capacity25to50ml, resistant to attack under the test conditions, or a filter crucible, suitable for separation and incineration of the residue. 7.7

35、Muffle furnace, provided with air circulation and temperature control, suitable for carrying out incineration at550 25 C. 7.8 Desiccator, containing an efficient desiccant. 7.9 Separating device Various types of separating devices are described inAnnex B. 7.10 Analytical balance 8 Sampling Refer to

36、the International Standard appropriate to the product concerned. 9 Procedure 9.1 Preparation of test sample 9.1.1 Preliminary drying In the case of 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 t

37、emperature. 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). 9.1.2 Products not requiring grinding 9.1.2.1 Products that pass through the sieve(7.2) without leaving a residue do not need to be ground before the determi

38、nation. 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 content of the test sample(9.1.2.1) by an appropriate method. 9.1.3 Products requiring grinding Products that do not pass through the te

39、st sieve(7.2) without leaving a residue 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 the sample by an appropriate method. 9.1.3.2 Grind the laboratory sample in the grinding device(7.1) so that the pro

40、duct passes through the sieve(7.2) without leaving a residue. 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 NOTEIf it is necessary to remove fatty matter (see9.3.1) and the technique described inA.1.3 ofAnnex A is to be used, the extr

41、action shall be carried out before the test portion is taken. Weigh, to the nearest1mg, about3g of the test sample (except in special cases) which has been prepared as described in9.1, and which is presumed to contain more than1% of crude fibre. 9.3 Determination 9.3.1 Extraction of fatty substances

42、 (see Annex A) If the fatty matter content is less than1%, extraction of fatty matter is unnecessary. Extraction is not absolutely essential, but is, nevertheless, recommended if the fatty matter content is between1 and10%. If the fatty matter content is more than10%, prior extraction is essential.

43、For products containing fatty substances which cannot be removed directly, the extraction shall be carried out after the acid treatment (seeA.1.5 ofAnnex A).BS6215-1:1981 BSI 12-1999 3 9.3.2 Acid treatment 9.3.2.1 Transfer the test portion, which may have had the fat and oils (see9.3.1) and carbonat

44、es (see11.1) removed, into the vessel(7.4). Add, if appropriate, the prescribed quantity of filter aid(6.6) (in the case of the variants described inclausesB.2 andB.3 ofAnnex B) and, if necessary, the anti-foam agent(6.7) and the anti-bumping agent(6.8). Measure200ml of the sulphuric acid solution(6

45、.1) at room temperature, bring it to a temperature of95to100 C (see11.2) and add it to the contents of the vessel(7.4). Fit the condenser. Bring rapidly to the boil (in about2min) using the heating device(7.5) and continue boiling gently for30 1min. Swirl the vessel from time to time so that any par

46、ticles adhering to the interior wall are returned to the solution. 9.3.2.2 After the specified boiling period, add about50ml of cold water and separate rapidly the insoluble residue using the separating device(7.9) chosen. Wash the vessel(7.4) with50ml portions of hot water (temperature95to100 C) an

47、d pour the washings over the insoluble residue remaining in the separating device. Repeat the washing of the insoluble residue until the filtrate is substantially neutral to litmus paper. The separation and washing of the insoluble residue shall be completed in less than30min. 9.3.3 Alkaline treatme

48、nt 9.3.3.1 Return the washed insoluble residue to the vessel(7.4) and add, if necessary, the anti-foam agent(6.7) and the anti-bumping agent(6.8). Measure200ml of the sodium hydroxide solution(6.2) at room temperature, bring it to a temperature of95to100 C (see11.2), and add it to the contents of th

49、e vessel(7.4) in small portions. Fit the condenser. Bring rapidly to the boil (in about2min) using the heating device(7.5) and continue to boil gently for30 1min. 9.3.3.2 After the specified boiling period, add about50ml of cold water and rapidly separate the insoluble residue using the separating device(7.9) chosen. Wash the residue with25ml of the sulphuric acid solution(6.1) measured at room temperature and then raised to a temperature of95to100 C (see11.2). Wash with water as described in9.3.2.2. Dry the residue with one of the reagents(6.3); wash wi