1、BRITISH STANDARD CONFIRMED JUNE 1993 BS 4401-12: 1979 ISO 5554:1978 Incorporating Amendment No. 1 Methods of test for Meat and meat products Part 12: Determination of starch content of meat products (reference method) ISO title: Meat products Determination of starch content (Reference method) UDC 63
2、7.5:664.91/.94:543.854.746BS4401-12:1979 This British Standard, having been prepared under the directionof the Food and Agriculture Standards Committee,was published underthe authority of the Executive Board and came intoeffect on 28 February 1979 BSI 10-1999 The following BSI references relate to t
3、he work on this standard: Committee reference FAC/6 Draft for comment 76/53487 DC ISBN 0 580 10599 7 Cooperating organizations The Food and Agriculture Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following Government departments
4、 and scientific and industrial organizations: Agricultural Co-operation and Marketing Services Agricultural Research Council, Meat Research Institute British Food Manufacturing Industries Research Association* British Industrial Biological Research Association Ltd. Campden Food Preservation Research
5、 Association Consumer Standards Advisory Committee of BSI Department of Agriculture and Fisheries for Scotland Department of Agriculture Government of Northern Ireland Department of Industry Laboratory of the Government Chemist* Flour Milling and Baking Research Association Food and Drink Industries
6、 Council Food Manufacturers Federation Incorporated Institute of Brewing Local Authority Joint Advisory Committee on Food Standards Ministry of Agriculture, Fisheries and Food* National Farmers Union* National Farmers Union of Scotland Tobacco Advisory Committee The organizations marked with an aste
7、risk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: Agricultural Research Council British Poultry Federation Limited Chemical Society, Analytical Division Institute of Meat Licensed Animal Slaughtere
8、rs and Salvage Association Meat and Livestock Commission Meat Manufacturers Association National Federation of Meat Traders Associations (Inc) Public Health Laboratory Service Society of Chemical Industry Ulster Farmers Union Amendments issued since publication Amd. No. Date of issue Comments 3032 J
9、une 1979 Indicated by a sideline in the marginBS4401-12:1979 BSI 10-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii 1 Scope 1 2 Field of application 1 3 Reference 1 4 Definition 1 5 Principle 1 6 Reagents 1 7 Apparatus 2 8 Sample 2 9 Procedure 2 10 Expression o
10、f results 3 11 Test report 3 Figure Graph for conversion of millilitres of 0,1 N sodium thiosulphatesolution to milligrams of glucose 5 Table Conversion of millilitres of 0,1 N sodium thiosulphate solutiontomilligrams of glucose 4 Publications referred to Inside back coverBS4401-12:1979 ii BSI 10-19
11、99 National foreword This Part of this British Standard is identical with ISO 5554 “Meat products Determination of starch content (Reference method)” which was prepared by Subcommittee6, Meat and meat products of ISO/TC34, Agricultural food products. Further Parts will be published as they become av
12、ailable, subject to approval by the UnitedKingdom of the corresponding International Standards. Terminology and conventions. The text of the International Standard has been approved as suitable for publication, without deviation, as a British Standard. Some terminology and certain conventions are no
13、t identical with those used in British Standards; attention is especially drawn to the following. 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. Wherever the words “International Standard”
14、 appear, referring to this standard, they should be interpreted as “British Standard”. NOTEThe general reference to ISO3100 in clause3 and8.1 applies at present only to ISO 3100-I:1975 which is related to BS 5348-1:1976; subsequent Parts of ISO 3100 are expected to be published as dual-numbered Part
15、s of BS5348. Additional information. With reference to clause6, water complying with the requirements of BS 3978 is suitable. 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. Complianc
16、e with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard ISO 3100 (see note) BS 5348 Methods for sampling meat and meat products ISO/R385:1964 BS 846:1962 Burettes and bulb burettes (Related) Summary o
17、f pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 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 co
18、ver.BS4401-12:1979 BSI 10-1999 1 1 Scope This International Standard specifies a reference method for the determination of the starch content of meat products. 2 Field of application This International Standard applies only to products which do not contain added substances, other than starch, that y
19、ield reducing sugars on hydrolysis. 3 Reference ISO 3100, Meat and meat products Sampling. 4 Definition starch content of meat products the starch content determined according to the procedure described in this International Standard and expressed as a percentage by mass 5 Principle Heating of a tes
20、t portion with ethanolic potassium hydroxide solution until the meat components are totally dissolved. Decantation, washing of the remaining residue with hot ethanol, filtering, dissolution in hydrochloric acid, and hydrolysis. Titrimetric determination of the glucose formed. 6 Reagents All reagents
21、 shall be of recognized analytical quality. The water used shall be distilled water or water of at least equivalent purity. 6.1 Potassium hydroxide, ethanolic solution. Dissolve 50g of potassium hydroxide in800ml of95% (V/V) ethanol and dilute to 1000ml with the same ethanol. 6.2 Ethanol, 80% (V/V).
22、 6.3 Hydrochloric acid, 1,0M solution (chlorine-free). 6.4 Bromothymol blue, 10 g/l solution in 95% (V/V) ethanol. 6.5 Sodium hydroxide, 300 g/l solution. 6.6 Solutions for precipitation of proteins Solution I Dissolve 106 g of potassium hexacyanoferrate(II) trihydrate K 4 Fe(CN) 6 .3H 2 O in water
23、in a 1000ml one-mark volumetric flask and dilute to the mark. Solution II Dissolve 220 g of zinc acetate dihydrate Zn(CH 3 COO) 2 .2H 2 O in water in a1 000ml one-mark volumetric flask. Add30ml of glacial acetic acid, and dilute to the mark with water. 6.7 Copper reagent Prepare the following soluti
24、ons: a) 25g of copper(II) sulphate pentahydrate (CuSO 4 .5H 2 O) in100ml of water; b) 144 g of sodium carbonate (Na 2 CO 3 ) in 300 to400 ml of water at50 C; c) 50 g of citric acid monohydrate (C 6 H 8 O 7 .H 2 O) in50 ml of water. Add solution c) slowly and carefully, stirring continuously, to solu
25、tion b). Continue stirring until evolution of carbon dioxide ceases. Add solution a) to this mixture, stirring continuously. Allow to cool to room temperature, transfer quantitatively to a 1000ml one-mark volumetric flask, dilute to the mark and filter after24h. The pH of the solution, after 1 + 49
26、dilution with freshly boiled and cooled water, should be 10,0 0,1. 6.8 Starch indicator solution Add a mixture of 10g of soluble starch, 10mg of mercury(II) iodide (as a preservative) and30ml of water to1litre of boiling water. Continue boiling for3min and cool. 6.9 Sodium thiosulphate, approximatel
27、y 0,1N standard volumetric solution. 6.9.1 Preparation Dissolve, in 1000 ml of freshly boiled and cooled water,25g of sodium thiosulphate pentahydrate (Na 2 S 2 O 3 .5H 2 O) and add0,2g of sodium carbonate decahydrate (Na 2 CO 3 .10H 2 O). Allow the solution to stand for one day before standardizing
28、. 6.9.2 Standardization Weigh 150,0 mg of dried potassium iodate, dissolve it in25ml of water and add 2g of potassium iodide and10ml of the hydrochloric acid solution (6.3). Titrate with the solution thiosulphate solution while stirring continuously. Add1ml of the starch indicator solution (6.8) whe
29、n the solution has become pale yellow, and continue the titration until the blue colour disappears. The normality T of the sodium thiosulphate solution is then calculated from the formula: where m is the mass, in milligrams, of the potassium iodate; V is the volume, in millilitres, of the sodium thi
30、osulphate solution added to the potassium iodate solution; T 6 m 214,0 V - =BS4401-12:1979 2 BSI 10-1999 6.10 Potassium iodide, 100 g/l solution. Dissolve 10g of potassium iodide in water, and dilute to 100ml. Store the solution in a dark brown bottle. 6.11 Hydrochloric acid, 25% (m/m) solution (chl
31、orine-free). Dilute 100 ml of concentrated, chlorine-free hydrochloric acid ( 201,19 g/ml) with 60ml of water. 7 Apparatus Usual laboratory apparatus not otherwise specified, and in particular: 7.1 Mechanical meat mincer, laboratory size, fitted with a plate having holes not exceeding4mm in diameter
32、. 7.2 Boiling water bath 7.3 Fluted filter paper, diameter 15 cm, starch-free. 7.4 Asbestos plate with a circular hole, fitting the bottom of the conical flask (7.5). 7.5 Conical flask, capacity250 to300ml, with ground neck, and provided with a glass stopper. 7.6 Condenser, air-cooled, with conical
33、joint fitting the conical flask (7.5). 7.7 Boiling aids (for example pumice stone or glass beads). 7.8 Burette, capacity 50ml, complying with classA of ISO/R385. 7.9 pH meter 8 Sample 8.1 Proceed from a representative sample of at least200 g. See ISO3100. 8.2 Store the sample, if necessary, in such
34、a way that deterioration and change in composition are prevented. 9 Procedure 9.1 Preparation of the test sample Homogenize the sample by passing it at least twice through the meat mincer (7.1) and mixing. Keep it in a completely filled, air-tight, closed container and store it, if necessary, in suc
35、h a way that deterioration and change in composition are prevented. Analyse the sample as soon as possible after homogenization, but always within24h. 9.2 Test portion Weigh into a 500 or 600ml beaker, to the nearest0,1g, about25g of the test sample (9.1). If the mass of starch in this test portion
36、is expected to be more than1g, reduce the mass of the test portion accordingly. 9.3 Isolation of starch Add to the test portion, while stirring with a glass rod, 300ml of hot ethanolic potassium hydroxide solution (6.1) and cover the beaker with a watch glass. Heat on the boiling water bath (7.2) fo
37、r1h, stirring occasionally. Decant the solution through a filter paper (7.3) and then wash the starch quantitatively on the filter paper using hot ethanol(6.2) and with the aid of a rubber-tipped glass rod. Keep the filter moist. NOTEIn some cases, centrifuging may be more advantageous than filtrati
38、on, 9.4 Hydrolysis Immediately loosen the precipitate from the paper by means of a glass rod. Pierce a hole in the filter paper and wash the starch through it into a250ml beaker, using 100ml of hot hydrochloric acid solution (6.3). Cover the beaker with a watch glass and immerse it in the boiling wa
39、ter bath for 2,5h, stirring the solution occasionally with a glass rod. Cool the solution and neutralize by adding the sodium hydroxide solution (6.5) drop by drop, taking care that the pH does not exceed6,5; check this with the pH meter (7.9). Transfer the mixture quantitatively into a 200ml volume
40、tric flask, washing with water, add3ml of SolutionI (6.6) and, after mixing,3ml of SolutionII(6.6) and dilute to the mark. Mix and filter through a fluted filter paper (7.3). Immediately before pipetting an aliquot portion for the next stage, make the filtrate alkaline to bromothymol blue (6.4) by a
41、dding1 or2 drops of the sodium hydroxide solution (6.5). 9.5 Determination of glucose If the approximate starch content of the sample is unknown, carry out a preliminary trial analysis to estimate it. Dilute an aliquot portion (V 2 ) of the filtrate (9.4) with water to a known volume (V 3 ) so that2
42、5ml of the diluted solution contain preferably40 to50mg of glucose and in no circumstances more than60mg of glucose. Mix and pipette 25,0ml of the diluted solution into the conical flask (7.5). Pipette25,0 ml of the copper reagent (6.7) into the flask and add some boiling aids (7.7). NOTEIt is essen
43、tial that the total volume of liquid at this stage is always50,0ml. is the relative molecular mass of potassium iodate. 214,0 6 -BS4401-12:1979 BSI 10-1999 3 Fit the condenser(7.6) to the flask. Place the flask and condenser on a metal wire gauze surmounted by the asbestos plate(7.4). Bring the liqu
44、id to the boil over a gas flame in about2min and continue to boil gently for exactly10 min. Then cool quickly to room temperature. Remove the condenser and add30ml of the potassium iodide solution (6.10) and next, carefully but as quickly as possible, 25ml of the hydrochloric acid solution (6.11). S
45、topper the flask until titration. Titrate the liberated iodine with the standard volumetric sodium thiosulphate solution (6.9). When the solution has become pale yellow, add about1ml of the starch indicator solution (6.8) and continue the titration until the blue colour disappears. 9.6 Blank determi
46、nation Carry out a blank determination, following the same procedure as in9.5, taking25,0ml of water instead of 25,0ml of the diluted filtrate. 10 Expression of results 10.1 Calculation and formulae Calculate the difference between the volumes noted in the two titrations, expressed in millilitres of
47、 exactly0,1N sodium thiosulphate solution, from the formula 10 T (V 0 V 1 ) where Calculate the starch content, as a percentage by mass, from the formula where Report the result to the nearest0,1%. 10.2 Precision 10.2.1 Repeatability The difference between the results of two determinations carried o
48、ut simultaneously or in rapid succession by the same analyst shall not be greater than0,2g of starch per100g of sample. 10.2.2 Reproducibility The difference between the results of two determinations carried out in two laboratories on the same sample shall not exceed0,3g of starch per100g of sample.
49、 11 Test report The test report shall 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 identification of the sample. T is the normality of the standard volumetric sodium thiosulphate solution (see6.9.2); V 0is the volume, in millilitres, of the standard volumetric sodium thiosu
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